Annotated Example SDP for WebRTC
draft-ietf-rtcweb-sdp-14

Document Type Active Internet-Draft (rtcweb WG)
Authors Suhas Nandakumar  , Cullen Jennings 
Last updated 2021-02-26 (latest revision 2020-12-17)
Replaces draft-nandakumar-rtcweb-sdp
Stream Internet Engineering Task Force (IETF)
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Document shepherd Ted Hardie
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Send notices to Ted Hardie <ted.ietf@gmail.com>
IANA IANA review state Version Changed - Review Needed
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Network Working Group                                      S. Nandakumar
Internet-Draft                                               C. Jennings
Intended status: Informational                                     Cisco
Expires: 20 June 2021                                   17 December 2020

                    Annotated Example SDP for WebRTC
                        draft-ietf-rtcweb-sdp-14

Abstract

   The Web Real Time Communications (WebRTC) family of protocols defines
   mechanism for direct interactive rich communication using audio,
   video, and data between two peers' web browsers.  With in the WebRTC
   framework, the Session Description Protocol (SDP) is used for
   negotiating session capabilities between the peers.  Such a
   negotiation happens based on the SDP offer/answer exchange mechanism

   This document provides an informational reference in describing the
   role of SDP and the offer/answer exchange mechanism for the most
   common WebRTC use cases.

   This document makes no changes to the SDP offer/answer exchange
   mechanism.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 20 June 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SDP and WebRTC  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Offer/Answer and the WebRTC . . . . . . . . . . . . . . . . .   6
   5.  WebRTC Session Description Examples . . . . . . . . . . . . .   6
     5.1.  Some Conventions  . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Basic Examples  . . . . . . . . . . . . . . . . . . . . .   9
       5.2.1.  Audio Only Session  . . . . . . . . . . . . . . . . .   9
       5.2.2.  Audio/Video Session . . . . . . . . . . . . . . . . .  13
         5.2.2.1.  IPv4 Audio/Video Session  . . . . . . . . . . . .  14
         5.2.2.2.  Dual Stack Audio/Video Session  . . . . . . . . .  19
       5.2.3.  Data-only Session . . . . . . . . . . . . . . . . . .  24
       5.2.4.  Audio Call On Hold  . . . . . . . . . . . . . . . . .  26
       5.2.5.  Audio with DTMF Session . . . . . . . . . . . . . . .  30
       5.2.6.  One-way Audio/Video Session - Document Camera . . . .  34
       5.2.7.  Audio, Video Session with BUNDLE Support Unknown  . .  39
       5.2.8.  Audio, Video, and Data Session  . . . . . . . . . . .  45
       5.2.9.  Audioa andVideo Session with BUNDLE Unsupported . . .  50
       5.2.10. Audio, Video BUNDLED, but Data Not BUNDLED  . . . . .  56
       5.2.11. Audio Only, Add Video to BUNDLE . . . . . . . . . . .  62
     5.3.  MultiResolution, RTX, FEC Examples  . . . . . . . . . . .  70
       5.3.1.  Send-only Simulcast Session with 2 Cameras and 2
               Encodings per Camera  . . . . . . . . . . . . . . . .  70
       5.3.2.  Successful SVC Video Session  . . . . . . . . . . . .  78
       5.3.3.  Successful Simulcast Video Session with
               Retransmission  . . . . . . . . . . . . . . . . . . .  82
       5.3.4.  Successful One-way Simulcast Session with 2 resolutions
               and RTX - One resolution rejected . . . . . . . . . .  88
       5.3.5.  Simulcast Video Session with Forward Error
               Correction  . . . . . . . . . . . . . . . . . . . . .  93
     5.4.  Others  . . . . . . . . . . . . . . . . . . . . . . . . .  99
       5.4.1.  Audio Session - Voice Activity Detection  . . . . . .  99
       5.4.2.  Audio Conference - Voice Activity Detection . . . . . 103
       5.4.3.  Successful Legacy Interop Fallback with
               bundle-only . . . . . . . . . . . . . . . . . . . . . 107
       5.4.4.  Legacy Interop with RTP/AVP profile . . . . . . . . . 112
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . 116

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   7.  Security Considerations . . . . . . . . . . . . . . . . . . . 117
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 117
   9.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . . 117
   10. Informative References  . . . . . . . . . . . . . . . . . . . 121
   Appendix A.  Appendix . . . . . . . . . . . . . . . . . . . . . . 126
     A.1.  JSEP SDP Attributes Checklist . . . . . . . . . . . . . . 126
       A.1.1.  Common Checklist  . . . . . . . . . . . . . . . . . . 126
       A.1.2.  RTP Media Description Checklist . . . . . . . . . . . 127
       A.1.3.  Data Channel Media Description checklist  . . . . . . 129
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 129

1.  Introduction

   JavaScript Session Establishment Protocol (JSEP)
   [I-D.ietf-rtcweb-jsep] specifies a generic protocol needed to
   generate [RFC3264] SDP offers and answers negotiated between the
   [WebRTC] peers for setting up, updating, and tearing down a WebRTC
   session.  For this purpose, SDP is used for describing (media and
   non-media) streams as appropriate for the recipients of the session
   description to participate in the session.

   The remainder of this document is organized as follows: Sections 3
   and 4 provide an overview of SDP and the offer/answer exchange
   mechanism.  Section 5 provides sample SDP generated for the most
   common WebRTC use cases.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Readers should be familiar with the terminology defined in [RFC3264]
   and in [RFC7656].

3.  SDP and WebRTC

   The purpose of this section is to provide a general overview of SDP
   and its components.  For a more in-depth understanding, the readers
   are advised to refer to [RFC4566].

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   The Session Description Protocol (SDP) [RFC4566] describes a
   multimedia session, which can contain audio, video, whiteboard, fax,
   modem, and other streams.  SDP provides a general purpose, standard
   representation to describe various aspects of multimedia sessions
   such as media capabilities, transport addresses, and related metadata
   in a transport agnostic manner, for the purposes of session
   announcement, session invitation, and parameter negotiation.

   SDP is widely used in the context of Session Initiation Protocol
   [RFC3261], Real-time Transport Protocol [RFC3550], and Real-time
   Streaming Protocol [RFC7826] applications.

   Figure 1 introduces a high-level breakup of SDP into components that
   semantically describe a multimedia session, in our case, a WebRTC
   session [WebRTC].  It by no means captures everything about SDP and
   hence, should be used for informational purposes only.

                                                 +---------------------+
                                                 |        v=           |
                                                 +---------------------+
                 +---------------------+         +---------------------+
         ====    |   Session Metadata  |  =====  |        o=           |
         |       +---------------------+         +----------------------
         |                                       +---------------------+
         |                                       |        t=           |
         |                                       +---------------------+
         |
         |
         |                                       +---------------------+
         |                                       |        c=           |
         |                                       +---------------------+
         |       +---------------------+
         ====    | Network Description |   =====
         |       +---------------------+
         |                                       +---------------------+
         |                                       |    a=candidate      |
         |                                       +---------------------+
         |
         |
         |                                       +---------------------+
         |                                       |        m=           |
         |                                       +---------------------+
         |        +---------------------+        +---------------------+
         ====     | Stream Description  |  ===== |      a=rtpmap       |
         |        +---------------------+        +----------------------
         |                                       +---------------------+
         |                                       |      a=fmtp         |
         |                                       +---------------------+

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         |                                       +---------------------+
         |                                       |      a=sendrecv..   |
         |                                       +---------------------+
 +---------------+
 |    SEMANTIC   |
 | COMPONENTS OF |
 |     SDP       |
 +---------------+
         |                                       +---------------------+
         |                                       |      a=crypto       |
         |                                       +---------------------+
         |         +---------------------+       +---------------------+
         ====      |Security Descriptions|  =====|      a=ice-frag     |
         |         +---------------------+       +----------------------
         |                                       +---------------------+
         |                                       |      a=ice-pwd      |
         |                                       +---------------------+
         |                                       +---------------------+
         |                                       |     a=fingerprint   |
         |                                       +---------------------+
         |
         |
         |
         |                                       +---------------------+
         |                                       |      a=rtcp-fb      |
         |                                       +---------------------+
         |         +---------------------+       +---------------------+
         ====      |   Qos,Grouping      |       |                     |
                   |   Descriptions      |  =====|       a=group       |
                   +---------------------+       +----------------------
                                                 +---------------------+
                                                 |       a=rtcpmux     |
                                                 +---------------------+

                  Figure 1: Semantic Components of SDP

   [WebRTC] is architected in such a way that the design of the control
   plane is specified and implemented by the JavaScript application, as
   described in the JSEP specification [I-D.ietf-rtcweb-jsep].  JSEP
   provides mechanisms to create session characterization and media
   definition information to conduct the session based on SDP exchanges.

   In this context, SDP serves two purposes:

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   1.  Provide grammatical structure syntactically.

   2.  Semantically convey a participant's intention and capabilities
       required to successfully negotiate a session.

4.  Offer/Answer and the WebRTC

   This section introduces the SDP offer/answer Exchange mechanism
   mandated by WebRTC for negotiating session capabilities while setting
   up, updating, and tearing down a WebRTC session.  This section is
   intentionally brief in nature, and interested readers are recommended
   to refer to [RFC3264] for specific details on the protocol
   operations.

   The offer/answer [RFC3264] model specifies rules for the bilateral
   exchange of Session Description Protocol (SDP) messages for creation
   of multimedia streams.  It defines a protocol with the involved
   participants exchanging desired session characteristics with each
   other constructed as SDP messages to negotiate the session between
   them.

   In the most basic form, the protocol operation begins by one of the
   participants sending an initial SDP offer describing its intent to
   start a multimedia communication session.  The participant receiving
   the offer may generate an SDP answer accepting the offer or it may
   reject the offer.  If the session is accepted the offer/answer model
   provides a common view of the multimedia session between the
   participants.

   Within the context of WebRTC, the offer/answer model defines the
   state-machinery for WebRTC peers to negotiate session descriptions
   between themselves during the initial setup stages as well as for
   eventual session updates.  The JSEP specification
   [I-D.ietf-rtcweb-jsep] for WebRTC provides the mechanism for
   generating [RFC3264] SDP offers and answers in order for both sides
   of the session to agree upon the details such as the list of media
   formats to be sent/received, bandwidth information, crypto
   parameters, and transport parameters, for example.

5.  WebRTC Session Description Examples

   A typical web-based real-time multimedia communication session can be
   characterized as follows:

   *  It has zero or more audio-only, video-only or audio/video RTP
      sessions,

   *  may contain zero or more non-media data sessions,

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   *  All the sessions are secured with DTLS-SRTP,

   *  Supports NAT traversal using the ICE mechanism,

   *  Provides RTCP-based feedback mechanisms,

   *  Sessions can be over IPv4-only or IPv6-only or dual-stack based
      clients,

   *  Supports BUNDLE-based grouping of media streams over a single
      5-tuple transport.

5.1.  Some Conventions

   The examples given in this document follow the conventions listed
   below:

   *  In all the examples, Alice and Bob are assumed to be the WebRTC
      peers.

   *  It is assumed that for most of the examples, the support for
      [I-D.ietf-mmusic-sdp-bundle-negotiation] is established a priori
      either out-of-band or as a consequence of a successful offer/
      answer negotiation between Alice and Bob, unless explicitly stated
      otherwise.

   *  Call-flow diagrams that accompany the use cases capture only the
      prominent aspects of the system behavior and intentionally are not
      detailed, to improve readability.

   *  Even though the call-flow diagrams show SDP being exchanged
      between the parties, it doesn't represent the only way an WebRTC
      setup is expected to work.  Other approaches may involve WebRTC
      applications to exchange the media setup information via non-SDP
      mechanisms as long as they conform to the [I-D.ietf-rtcweb-jsep]
      API specification.

   *  The SDP examples deviate from actual on-the-wire SDP notation in
      several ways.  This is done to facilitate readability and to
      conform to the restrictions imposed by the RFC formatting rules.

      -  Visual markers/Empty lines in any SDP example are inserted to
         make functional divisions in the SDP clearer, and are not
         actually part of the SDP syntax.

      -  Excepting the above two conventions, line endings are to be
         interpreted as <CR><LF> pairs (that is, a US-ASCII 13 followed
         by a US-ASCII 10).

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   *  Against each SDP line, pointers to the appropriate RFCs are
      provided for further informational reference.  Also an attempt has
      been made to provide explanatory notes to enable better
      understanding of the SDP usage, wherever appropriate.

   *  The following SDP details are common across all the use cases
      defined in this document unless mentioned otherwise.

      -  DTLS fingerprint for SRTP (a=fingerprint)

      -  RTP/RTCP Multiplexing (a=rtcp-mux)

      -  RTCP Feedback support (a=rtcp-fb)

      -  Host and server-reflexive candidate lines (a=candidate)

      -  DTLS-SRTP Setup framework parameters (a=setup)

      -  RTCP attribute (a=rtcp)

      -  RTP header extension indicating audio-levels from client to the
         mixer

      For specific details, readers must refer to the
      [I-D.ietf-rtcweb-jsep] specification.

   *  The term "session" is used rather loosely in this document to
      refer to either a "communication session" or an "RTP session" or a
      "RTP stream" depending on the context.

   *  Payload type 109 is usually used for OPUS, 0 for PCMU, 8 for PCMA,
      99 for H.264, and 120 for VP8 in most of the examples to maintain
      uniformity.

   *  The IP Address:Port combinations '192.0.2.4:61665' (host) and
      '203.0.113.141:54609' (Server Reflexive) are typically used for
      Alice.

   *  The IP Address:Port combinations '198.51.100.7:51556' (host) and
      '203.0.113.77:49203' (Server Reflexive) are typically used for
      Bob.

   *  The IPv6 addresses 2001:db8:8101:3a55:4858:a2a9:22ff:99b9 and
      2001:db8:30c:1266:5916:3779:22f6:77f7 are used to represent Alice
      and Bob's host addresses respectively.

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   *  In actual use the values that represent SSRCs, ICE candidate
      foundations, WebRTC MediaStream, and MediaStreamTrack IDs values
      shall be much larger than and/or random in comparison to the ones
      shown in the examples.

   *  tls-id attribute values 89J2LRATQ3ULA24G9AHWVR31VJWSLB68 and
      UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ are used for Alice.  The values
      CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31 and
      9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G are used for Bob.

   *  identity attribute values are split across multiple lines to
      enhance readability, thus any line breaks and indentations in the
      value must be ignored.

   *  SDP attributes in the examples closely follow the checklist
      defined in Appendix A.1.

5.2.  Basic Examples

5.2.1.  Audio Only Session

   This common scenario shows the SDP for a secure two-way audio session
   with Alice offering Opus, PCMU, PCMA and Bob accepting all the
   offered audio codecs.

   This example also shows the endpoints being [RFC8445] compliant by
   including "ice2" ice-options attribute.

           Two-way Audio Only Session

   Alice                                Bob
   |                                     |
   |                                     |
   |    offer(Audio:Opus,PCMU,PCMA)      |
   |------------------------------------>|
   |                                     |
   |                                     |
   |   answer(Audio:Opus,PCMU,PCMA)      |
   |<------------------------------------|
   |                                     |
   |                                     |
   |Two-way Opus Audio (preferred-codec) |
   |.....................................|
   |                                     |
   |                                     |

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   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=identity:eyJpZHAiOnsiZG9tYWluIjoibmlpZi5odSIsInByb3RvY29sIjoiaWRwLmh0bWwifSwiYXNzZXJ0a       |Section 7.4 of                          |
   |W9uIjoiZXlKaGJHY2lPaUpTVXpJMU5pSXNJblI1Y0NJNklrcFhVeUo5LmV5SmpiMjUwWlc1MGN5STZleUptYVc1b       |[I-D.ietf-rtcweb-security-arch]         |
   |lpYSndjbWx1ZENJNlczc2lZV3huYjNKcGRHaHRJam9pYzJoaExUSTFOaUlzSW1ScFoyVnpkQ0k2SWprek9rTXdPa       |                                        |
   |kl6T2pKR09rRXlPakF3T2pBd09qQkVPalV4T2tGRE9rUXlPalUwT2pZMU9rWTBPak5DT2pkRU9qa3lPa1JET2pnN       |                                        |
   |E9qTXpPalV4T2pJek9qUXdPamN5T2preE9qZ3pPalZDT2pBeE9qSkdPalV3T2pjNE9qTkdJbjFkZlN3aWFXUmxib       |                                        |
   |lJwZEhraU9pSnRhWE5wUUc1cGFXWXVhSFVpZlEuSTVQdGhKNFFDT05TOFVXd25OOUh3MEdaTDl3d0RBVGRrTWtFW       |                                        |
   |llmdlNVTTJ6Umd5R09WSGgzRmpnc2FPZklkRnFsNUx6azBFbndVOTNQOUlCQ0xZOWtia3V1c0V1S25YRGVNLTNIN       |                                        |
   |WFmdTJvZl9CTlZjUnB3MmdBdlNBbVR6SlltcEpqMFEtdmV0TmtVT1huZE9HLUIzT3ZGb3QwZVNENlZSNUdhb2wyc       |                                        |
   |GduS3FSTktOd3dacEZ1eUZZbFRodHJIdGNiT19WV3o4QnZpTThKS25OdExWd1JxNUhMX2ZLTlRCNzFDYkoyWmh5W       |                                        |
   |XU1UEdwWDhXcXJMWC1ybm5YSFY3RnhoTTh5OHdrLWd5cnRZazVnbFlZeUFrcTVqZklSXzRzWER5d19Qc1BWTW1aZ       |                                        |
   |XltenVGV3BQTzVFWlJYR0ZpRjFET0o4Q0Q3Z3Zta2dUdlBXSWpkemtBIn0=                                    |                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Opus Codec 48 kHz, 2        |
   |                                                                                               |channels                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Alice can perform RTP/RTCP  |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:60065 IN IP4 203.0.113.141                                                              |[RFC3605]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Alice intends to use reduced|
   |                                                                                               |size RTCP for this session              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464] Alice supports RTP header     |
   |                                                                                               |extension to indicate audio levels      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTP Host|
   |                                                                                               |Candidate                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp] - RTP     |
   |                                                                                               |Server Reflexive ICE Candidate          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 2 UDP 2122194687 192.0.2.4 61667 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |
   |                                                                                               |Host Candidate                          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.141 60065 typ srflx raddr 192.0.2.4 rport 61667       |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |
   |                                                                                               |Server Reflexive ICE Candidate          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                          Table 1: 5.2.1 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=identity:ew0KICAiaWRwIjp7DQogICAgImRvbWFpbiI6ICJjaXNjb3NwYXJrLmNvbSIsDQogICAg                |Section 7.4 of                          |
   |InByb3RvY29sIjogImRlZmF1bHQiDQogIH0sDQogICJhc3NlcnRpb24iOiAibEp3WkVocmFVOXBTblJo               |[I-D.ietf-rtcweb-security-arch]         |
   |V0U1d1VVYzFjR0ZYV1hWaFNGVnBabEV1U1RWUWRHaEtORkZEVDA1VE9GVlhkMjVPT1VoM01FZGFURGwz               |                                        |
   |ZDBSQlZHUnJUV3RGVw0KICAgICAgICAgICAgICBsbG1kbE5WVFRKNlVtZDVSMDlXU0dnelJtcG5jMkZQ               |                                        |
   |Wmtsa1JuRnNOVXg2YXpCRmJuZFZPVE5RT1VsQ1EweFpPV3RpYTNWMWMwVjFTMjVZUkdWTkxUTklODQog               |                                        |
   |ICAgICAgICAgICAgIFdGbWRUSnZabDlDVGxaalVuQjNNbWRCZGxOQmJWUjZTbGx0Y0VwcU1GRXRkbVYw               |                                        |
   |VG10VlQxaHVaRTlITFVJelQzWkdiM1F3WlZORU5sWlNOVWRoYjJ3eWMNCiAgICAgICAgICAgICAgR2R1               |                                        |
   |UzNGU1RrdE9kM2RhY0VaMWVVWlpiRlJvZEhKSWRHTmlUMTlXVjNvNFFuWnBUVGhLUzI1T2RFeFdkMUp4               |                                        |
   |TlVoTVgyWkxUbFJDTnpGRFlrb3lXbWg1VyINCn0=                                                       |                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |[I-D.ietf-mmusic-msid] Identifies       |
   |                                                                                               |MediaStream ID (ma) and MediaStreamTrack|
   |                                                                                               |ID (ta)                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv audio |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] Opus Codec                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:05067423                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:1747d1ee3474a28a397a4c3f3af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password parameter                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing on port 49203                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Bob intends to use reduced  |
   |                                                                                               |size RTCP for this session              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464] Bob supports audio level RTP  |
   |                                                                                               |header extension as well                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Host ICE Candidate                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Server Reflexive ICE Candidate          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 2: 5.2.1 SDP Answer

5.2.2.  Audio/Video Session

   Alice and Bob establish a two-way audio and video session with Opus
   as the audio codec and H.264 as the video codec.

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            Two-way Audio/Video Session

   Alice                                       Bob
   |                                            |
   |                                            |
   |offer(Audio:Opus,PCMU,PCMA Video:H.264,VP8) |
   |------------------------------------------->|
   |                                            |
   |                                            |
   |      answer(Audio:Opus,Video:H.264)        |
   |<-------------------------------------------|
   |                                            |
   |                                            |
   |     Two-way Opus Audio, H.264 Video        |
   |............................................|
   |                                            |

5.2.2.1.  IPv4 Audio/Video Session

   This section shows the IPv4-only offer/answer exchange.

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888] - Alice wants to lip sync her |
   |                                                                                               |audio and video streams                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |[I-D.ietf-mmusic-msid] Identifies       |
   |                                                                                               |MediaStream ID (ma) and MediaStreamTrack|
   |                                                                                               |ID (ta)                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Opus Codec 48 kHz, 2        |
   |                                                                                               |channels                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password parameter                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Alice can perform RTP/RTCP  |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Alice intends to use reduced|
   |                                                                                               |size RTCP for this session              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Host Candidate                          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|

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   |                                                                                               |Server Reflexive ICE Candidate          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 99 120                                                             |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |video                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:99 H264/90000                                                                         |[RFC6184] - H.264 Video Codec           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:99 profile-level-id=4d0028;packetization-mode=1                                         |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741] - VP8 video codec             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack                                                                              |[RFC4585] - Indicates NACK RTCP feedback|
   |                                                                                               |support                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack pli                                                                          |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 ccm fir                                                                           |[RFC5104] - Full Intra Frame Request-   |
   |                                                                                               |Codec Control Message support           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585] - Indicates NACK RTCP feedback|
   |                                                                                               |support                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104] - Full Intra Request-Codec    |
   |                                                                                               |Control Message support                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 3: 5.2.2.1 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888] - Bob agrees to do the same   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv audio |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Bob accepts only Opus Codec |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |username frag                           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Bob intends to use reduced  |
   |                                                                                               |size RTCP for this session              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 3618095783 198.51.100.7 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Host ICE Candidate                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 565689203 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556      |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Server Reflexive ICE Candidate          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 99                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv video |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:99 H264/90000                                                                         |[RFC6184] - Bob accepts H.264 Video     |
   |                                                                                               |Codec.                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:99 profile-level-id=4d0028;packetization-mode=1                                         |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack                                                                              |[RFC4585] - Indicates support for NACK- |
   |                                                                                               |based RTCP feedback                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack pli                                                                          |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 ccm fir                                                                           |[RFC5104] - Full Intra Request-Codec    |

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   |                                                                                               |Control Message support                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                        Table 4: 5.2.2.1 SDP Answer

5.2.2.2.  Dual Stack Audio/Video Session

   This section captures offer/answer exchange when Alice and Bob
   support both IPv4 and IPv6 host addresses.

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888] - Alice wants to lip sync her |
   |                                                                                               |audio and video streams                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Opus Codec 48 kHz, 2        |

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   |                                                                                               |channels                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password parameter                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Alice can perform RTP/RTCP  |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Alice intends to use reduced|
   |                                                                                               |size RTCP for this session              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Host Candidate                          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 2001:db8:8101:3a55:4858:a2a9:22ff:99b9 61665 typ host           |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |IPv6 Host Candidate                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 99 120                                                             |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |video                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:99 H264/90000                                                                         |[RFC6184] - H.264 Video Codec           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:99 profile-level-id=4d0028;packetization-mode=1                                         |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741] - VP8 video codec             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack                                                                              |[RFC4585] - Indicates NACK RTCP feedback|
   |                                                                                               |support                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack pli                                                                          |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 ccm fir                                                                           |[RFC5104] - Full Intra Request-Codec    |
   |                                                                                               |Control Message support                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585] - Indicates NACK RTCP feedback|
   |                                                                                               |support                                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104] - Full Intra Request-Codec    |
   |                                                                                               |Control Message support                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 5: 5.2.2.2 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888] - Bob agrees to do the same   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv audio |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Bob accepts only Opus Codec |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |username frag                           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Bob intends to use reduced  |
   |                                                                                               |size RTCP for this session              |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 3618095783 198.51.100.7 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |Host ICE Candidate                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 3618095783 2001:db8:30c:1266:5916:3779:22f6:77f7 49203 typ host            |[I-D.ietf-mmusic-ice-sip-sdp] - RTP/RTCP|
   |                                                                                               |IPv6 Host ICE Candidate                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 99                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv video |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:99 H264/90000                                                                         |[RFC6184] - Bob accepts H.264 Video     |
   |                                                                                               |Codec.                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:99 profile-level-id=4d0028;packetization-mode=1                                         |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack                                                                              |[RFC4585] - Indicates support for NACK- |
   |                                                                                               |based RTCP feedback                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 nack pli                                                                          |[RFC4585] - Indicates support for       |
   |                                                                                               |Picture loss Indication and NACK        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:99 ccm fir                                                                           |[RFC5104] - Full Intra Request- Codec   |
   |                                                                                               |Control Message support                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                        Table 6: 5.2.2.2 SDP Answer

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5.2.3.  Data-only Session

   This scenario illustrates the SDP negotiated to set up a data-only
   session based on the SCTP Data Channel, thus enabling use cases such
   as file transfer or real-time game control, for example.

         Two-way Data channel Session

   Alice                            Bob
   |                                 |
   |                                 |
   |                                 |
   |      offer(Data Channel)        |
   |-------------------------------->|
   |                                 |
   |                                 |
   |      answer(Data Channel)       |
   |<--------------------------------|
   |                                 |
   |                                 |
   | Two-way SCTP-based data channel |
   |.................................|
   |                                 |
   |                                 |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE data                                                                            |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=application 54609 UDP/DTLS/SCTP webrtc-datachannel                                           |[I-D.ietf-rtcweb-data-channel]          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv non-|
   |                                                                                               |media data                              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - Session |
   |                                                                                               |Level ICE parameter                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - Session |
   |                                                                                               |Level ICE parameter                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - Session DTLS Fingerprint for|
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|SRTP                                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                          Table 7: 5.2.3 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE data                                                                            |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |m=application 49203 UDP/DTLS/SCTP webrtc-datachannel                                           |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv non-  |
   |                                                                                               |media data                              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - Session |
   |                                                                                               |Level ICE username frag                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp] - Session |
   |                                                                                               |Level ICE password                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - Session DTLS Fingerprint for|
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|SRTP                                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 8: 5.2.3 SDP Answer

5.2.4.  Audio Call On Hold

   Alice calls Bob, but when Bob answers he places Alice on hold by
   setting the SDP direction attribute to a=inactive in the answer.

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              Audio On Hold

   Alice                            Bob
   |                                 |
   |                                 |
   |      offer(Audio:Opus)          |
   |-------------------------------->|
   |                                 |
   |                                 |
   |  answer(Audio:Opus,a=inactive)  |
   |<--------------------------------|
   |                                 |
   |                                 |
   |      One-way Opus Audio         |
   |.................................|
   |                                 |
   |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Opus Codec 48 kHz, 2        |
   |                                                                                               |channels                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Alice can perform RTP/RTCP  |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                          Table 9: 5.2.4 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=inactive                                                                                     |[RFC3264] - Bob puts call On Hold       |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Bob accepts Opus Codec      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |username frag                           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp] - Host    |

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   |                                                                                               |candidate                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 49203 typ srflx raddr 198.51.100.7 rport 51556    |[I-D.ietf-mmusic-ice-sip-sdp] - Server  |
   |                                                                                               |Reflexive candidate                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 10: 5.2.4 SDP Answer

5.2.5.  Audio with DTMF Session

   In this example, Alice wishes to establish two separate audio
   streams, one for normal audio and the other for telephone-events.
   Alice offers the first audio stream with three codecs and the other
   with [RFC4733] tones (for DTMF).  Bob accepts both the audio streams
   by choosing Opus as the audio codec and telephone-event for the other
   stream.

               Audio Session with DTMF

   Alice                                              Bob
   |                                                   |
   |                                                   |
   |                                                   |
   |  offer(Audio:Opus,PCMU,PCMA Audio:telephone-event)|
   |-------------------------------------------------->|
   |                                                   |
   |                                                   |
   |    answer(Audio:Opus, Audio:telephone-event)      |
   |<--------------------------------------------------|
   |                                                   |
   |                                                   |
   |   Opus audio stream and telephone-event stream    |
   |...................................................|
   |                                                   |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio dtmf                                                                      |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Opus Codec 48 kHz, 2        |
   |                                                                                               |channels                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE user|
   |                                                                                               |fragment                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password parameter                      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - DTLS Fingerprint for SRTP   |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Alice can perform RTP/RTCP  |
   |                                                                                               |Muxing                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** DTMF m=line *********                                                                   |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 0 UDP/TLS/RTP/SAVPF 126                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:dtmf                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Alice can send DTMF Events  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:126 telephone-event/8000                                                              |[RFC4733]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 11: 5.2.5 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio dtmf                                                                      |[I-D.ietf-mmusic-sdp-bundle-negotiation]|

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and receive    |
   |                                                                                               |Opus audio                              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Bob accepts Opus Codec      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |username frag                           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp] - ICE     |
   |                                                                                               |password                                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122] - Fingerprint for SRTP        |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing on port 49203                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506] - Alice intends to use        |
   |                                                                                               |reduced-size RTCP for this session      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** DTMF m=line *********                                                                   |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 0 UDP/TLS/RTP/SAVPF 126                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:dtmf                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264] - Alice can receive DTMF      |
   |                                                                                               |events                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:126 telephone-event/8000                                                              |[RFC4733]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 12: 5.2.5 SDP Answer

5.2.6.  One-way Audio/Video Session - Document Camera

   In this scenario Alice and Bob engage in a One-way audio and video
   session with Bob receiving Alice's audio and her presentation slides
   as video stream.

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      One-way Audio & Video Session - Document Camera

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |                                                      |
   |   Alice offers send-only audio and video streams.    |
   |  The video stream corresponds to her presentation    |
   |                                                      |
   |           offer(Audio:Opus, Video: VP8)              |
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |
   |            (Audio:Opus, Video: VP8)                  |
   |<-----------------------------------------------------|
   |                                                      |
   |                                                      |
   |          One-way Opus Audio, VP8 Video               |
   |......................................................|
   |   Bob can hear Alice and see her presentation slides.|
   |                                                      |
   |                                                      |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Send-only audio stream      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 203.0.113.141 54609 typ host                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Send-only video stream      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=content:slides                                                                               |[RFC4796] - Alice's presentation video  |
   |                                                                                               |stream                                  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 13: 5.2.6 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264] - Receive-only audio stream   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 203.0.113.77 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=content:slides                                                                               |[RFC4796] - presentation stream         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 14: 5.2.6 SDP Answer

5.2.7.  Audio, Video Session with BUNDLE Support Unknown

   In this example, since Alice is unsure of the Bob's support of the
   BUNDLE framework, the following steps are performed in order to
   negotiate and set up a BUNDLE Address for the session.

   *  An SDP offer, in which Alice assigns unique addresses to each "m="
      line in the BUNDLE group, and requests the answerer to select the
      offerer's BUNDLE address.

   *  An SDP answer, in which Bob indicates support for BUNDLE, selects
      the offerer's BUNDLE address, selects its own BUNDLE address and
      associates it with each BUNDLED m=line within the BUNDLE group.

   Once the offer/answer exchange completes, both Alice and Bob each end
   up using a single RTP session for both of the media streams.

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    Two-way Secure Audio and Video with BUNDLE support unknown

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |   Alice offers BUNDLE support with unique addresses  |
   |        for the audio and video m-line                |
   |                                                      |
   |                                                      |
   |          offer(Audio:Opus Video:VP8)                 |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |supports
   |                                                      |BUNDLE,
   |                                                      |Uses
   |                                                      |identical
   |                                                      |address
   |          answer(Audio:Opus Video:VP8)                |
   |<-----------------------------------------------------|
   |                                                      |
   |    Two-way Call with Audio and Video Multiplexed     |
   |......................................................|
   |                                                      |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:54610 IN IP4 203.0.113.141                                                              |[RFC3605] - RTCP port different from RTP|
   |                                                                                               |Port                                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTP host|
   |                                                                                               |candidate                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp] - RTP     |
   |                                                                                               |Server Reflexive candidate              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 2 UDP 2122194687 192.0.2.4 61666 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |
   |                                                                                               |host candidate                          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.141 54610 typ srflx raddr 192.0.2.4 rport 61666       |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |

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   |                                                                                               |Server Reflexive candidate              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 62537 UDP/TLS/RTP/SAVPF 120                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888] Video m=line part of the      |
   |                                                                                               |Bundle group with a unique port number  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:6550074c                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:74af08a068a28a397a4c3f31747d1ee34                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:62538 IN IP4 203.0.113.141                                                              |[RFC3605]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61886 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTP Host|
   |                                                                                               |candidate                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 62537 typ srflx raddr 192.0.2.4 rport 61886       |[I-D.ietf-mmusic-ice-sip-sdp] - RTP     |

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   |                                                                                               |Server Reflexive candidate              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 2 UDP 2122194687 192.0.2.4 61888 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |
   |                                                                                               |host candidate                          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.141 62538 typ srflx raddr 192.0.2.4 rport 61888       |[I-D.ietf-mmusic-ice-sip-sdp] - RTCP    |
   |                                                                                               |Server Reflexive candidate              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                     Table 15: 5.2.7 SDP Offer w/BUNDLE

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Bob supports BUNDLE semantics.          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888] Audio m=line part of the      |
   |                                                                                               |BUNDLE group                            |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS client      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 51556 typ srflx raddr 198.51.100.7 rport 49203     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888] Video m=line part of the      |
   |                                                                                               |BUNDLE group with the port from audio   |
   |                                                                                               |line repeated                           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                    Table 16: 5.2.7 SDP Answer w/BUNDLE

5.2.8.  Audio, Video, and Data Session

   This example shows SDP for negotiating a session with Audio, Video
   and data streams between Alice and Bob with BUNDLE support known.

       Audio,Video, and Data with BUNDLE support known

   Alice                                       Bob
   |                                            |
   |                                            |
   |   Alice indicates BUNDLE support with  an  |
   |  identical address across all the m=lines  |
   |                                            |
   |                                            |
   |     offer(Audio:Opus Video:VP8 Data)       |
   |------------------------------------------->|
   |                                            |Bob does
   |                                            |the same
   |    answer(Audio:Opus,Video:VP8 Data)       |
   |<-------------------------------------------|
   |                                            |
   |                                            |
   |                                            |
   |    Two-way Audio,Video, Data multiplexed   |
   |............................................|
   |                                            |
   |                                            |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video data                                                                |[I-D.ietf-mmusic-sdp-bundle-negotiation]|

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp]           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=application 0 UDP/DTLS/SCTP webrtc-datachannel                                               |[I-D.ietf-rtcweb-data-channel]          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 17: 5.2.8 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video data                                                                |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=application 0 UDP/DTLS/SCTP webrtc-datachannel                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 18: 5.2.8 SDP Answer

5.2.9.  Audioa andVideo Session with BUNDLE Unsupported

   This use case illustrates SDP offer/answer exchange where the far-end
   (Bob) either doesn't support media bundling or doesn't want to group
   m=lines over a single 5-tuple.

   This is indicated by dropping the "a=group:BUNDLE" line and BUNDLE
   RTP header extension in the answer SDP.

   On successful offer/answer exchange, Alice and Bob each end up using
   unique 5-tuple for audio and video media streams respectively.

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      Two-way Secure Audio and Video with BUNDLE Unsupported

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |     Alice offers BUNDLE support with unique address  |
   |           for the audio and video m-line             |
   |                                                      |
   |                                                      |
   |           offer(Audio:Opus Video:VP8)                |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |doesn't
   |                                                      |support
   |                                                      |BUNDLE
   |           answer(Audio:Opus Video:VP8)               |
   |<-----------------------------------------------------|
   |                                                      |Bob uses
   |                                                      |unique
   |                                                      |addresses
   |                                                      |across the
   |                                                      |m=lines
   |                                                      |
   |    Two-way Call with Audio and Video on              |
   |    different 5-tuples                                |
   |......................................................|
   |                                                      |
   |                                                      |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:55232 IN IP4 203.0.113.141                                                              |[RFC3605] - RTCP port different from RTP|
   |                                                                                               |port                                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 2 UDP 2122194687 192.0.2.4 61666 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.141 55232 typ srflx raddr 192.0.2.4 rport 61666       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 54332 UDP/TLS/RTP/SAVPF 120                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888] Video m=line part of the      |
   |                                                                                               |BUNDLE group with a unique port number  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:7872093                                                                            |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:ee3474af08a068a28a397a4c3f31747d1                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763] - Alice can act as DTLS client|
   |                                                                                               |or server                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:60052 IN IP4 203.0.113.141                                                              |[RFC3605]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2122194687 192.0.2.4 71775 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.141 54332 typ srflx raddr 192.0.2.4 rport 71775       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 2 UDP 2122194687 192.0.2.4 71776 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.141 60052 typ srflx raddr 192.0.2.4 rport 71776       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                     Table 19: 5.2.9 SDP Offer w/BUNDLE

   +===============================================================================================+=============================+
   |Answer SDP Contents                                                                            |RFC#/Notes                   |
   +===============================================================================================+=============================+
   |v=0                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |s=-                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |t=0 0                                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Audio m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=audio 53214 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID    |
   |                                                                                               |(ma) and MediaStreamTrack ID |
   |                                                                                               |(ta)                         |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

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   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS  |
   |                                                                                               |client                       |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]   |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 53214 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 2 UDP 2122194687 198.51.100.7 51558 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 2 UDP 1685987071 203.0.113.77 60065 typ srflx raddr 198.51.100.7 rport 51558     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Video m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=video 58679 UDP/TLS/RTP/SAVPF 120                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=mid:video                                                                                    |[RFC5888]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID    |
   |                                                                                               |(ma) and MediaStreamTrack ID |
   |                                                                                               |(tb)                         |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-ufrag:85bC300                                                                            |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:325921d5d47efbabd9a2de4e99bd291c                                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35                          |[RFC8122]                    |
   |:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08                                               |                             |

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   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=setup:active                                                                                 |[RFC5763] - Bob is the DTLS  |
   |                                                                                               |client                       |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=tls-id:9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G                                                      |[I-D.ietf-mmusic-dtls-sdp]   |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2122194687 198.51.100.7 61556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 1685987071 203.0.113.77 58679 typ srflx raddr 198.51.100.7 rport 61556     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+

                 Table 20: 5.2.9 SDP Answer without BUNDLE

5.2.10.  Audio, Video BUNDLED, but Data Not BUNDLED

   This example showcases SDP for negotiating a session with audio,
   video, and the data streams between Alice and Bob with data stream
   not being part of the BUNDLE group.  This is shown by assigning a
   unique port for the data media section and not adding the "mid"
   identification tag to the BUNDLE group.

Nandakumar & Jennings     Expires 20 June 2021                 [Page 56]
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          Audio, Video, with Data (Not in BUNDLE)

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |Alice wants to multiplex audio, video but not data    |
   |                                                      |
   |                                                      |
   |  offer(Audio:Opus Video:VP8, Data(not in BUNDLE))    |
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |
   |       answer(Audio:Opus Video:VP8, Data)             |
   |<-----------------------------------------------------|
   |                                                      |
   |                                                      |
   |Two-way Call with Audio, Video Multiplexed except data|
   |......................................................|
   |                                                      |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice wants to BUNDLE only audio and    |
   |                                                                                               |video media.                            |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 54609 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=application 10000 UDP/DTLS/SCTP webrtc-datachannel                                           |[I-D.ietf-rtcweb-data-channel]          |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:UKA29UQLTF69OJW4WNPNUO2Y0GF1FJOZ                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:89819013                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:1747d1ee3474af08a068a28a397a4c3f3                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |29:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 10000 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 21: 5.2.10 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |

Nandakumar & Jennings     Expires 20 June 2021                 [Page 60]
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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Application m=line *********                                                            |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=application 20000 UDP/DTLS/SCTP webrtc-datachannel                                           |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:data                                                                                     |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sctp-port:5000                                                                               |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

Nandakumar & Jennings     Expires 20 June 2021                 [Page 61]
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   |a=max-message-size:100000                                                                      |[I-D.ietf-mmusic-sctp-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:9AIFS8AQ009IXF5D6QQUJ7P8BXPEZJ8G                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:991Ca2a5e                                                                          |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:921d5d47efbabd9a2de4e99bd291c325                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |7B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 20000 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                        Table 22: 5.2.10 SDP Answer

5.2.11.  Audio Only, Add Video to BUNDLE

   This example involves 2 offer/answer exchanges.  The first one is
   used to negotiate and set up BUNDLE support for audio-only session
   followed by an updated offer/answer exchange to add video stream to
   the ongoing session.  Also the newly added video stream is BUNDLED
   with the audio stream.

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            Audio, Add Video and BUNDLE

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |        Alice indicates support for BUNDLE            |
   |                                                      |
   |                offer(Audio:Opus)                     |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |supports
   |                                                      |BUNDLE
   |                answer(Audio:Opus)                    |
   |<-----------------------------------------------------|
   |                                                      |Alice adds
   |                                                      |video stream
   |        Updated offer(Audio:Opus, Video:VP8)          |to BUNDLE
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |Bob accepts
   |        Updated answer(Audio:Opus, Video:VP8)         |
   |<-----------------------------------------------------|
   |                                                      |
   |   Two-way Call with Audio and Video Multiplexed      |
   |......................................................|
   |                                                      |
   |                                                      |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice adds audio m=line to the BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 23: 5.2.11 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                        Table 24: 5.2.10 SDP Answer

   +===============================================================================================+========================================+
   |Updated Offer SDP Contents                                                                     |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 1 IN IP4 0.0.0.0                                                                     |Version number incremented [RFC4566]    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]Alice wants to|
   |                                                                                               |use the same DTLS association           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                     Table 25: 5.2.11 SDP Updated Offer

   +===============================================================================================+========================================+
   |Updated Answer SDP Contents                                                                    |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566] Version number incremented    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 1 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio video                                                                     |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS audio video                                                                         |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp] - Bob agrees |
   |                                                                                               |to use the same DTLS association        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux-only                                                                                |[I-D.ietf-mmusic-mux-exclusive]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 120                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:video                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack                                                                             |[RFC4585]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                    Table 26: 5.2.11 SDP Updated Answer

5.3.  MultiResolution, RTX, FEC Examples

   This section provides examples related to multi-source, multi-stream
   negotiation such as layered coding and simulcast.  Further included
   are a few examples that cover techniques to deal with providing
   robustness against transmission errors such as FEC and RTX.  Also,
   mechanisms such as FEC and RTX could be envisioned in the above basic
   scenarios as well.

5.3.1.  Send-only Simulcast Session with 2 Cameras and 2 Encodings per
        Camera

   The SDP example below shows an offer/answer exchange with one audio
   and two video sources (say 2 video cameras).  Each of the video
   sources can be sent at two different resolutions.

   One video source corresponds to VP8 encoding, while the other
   corresponds to H.264 encoding.

   The [I-D.ietf-mmusic-rid] framework is used to further constrain the
   media format encodings and map the payload types (PT) to the 'rid'
   identifiers.

   The [I-D.ietf-mmusic-sdp-simulcast] framework identifies the
   simulcast streams via their 'rid' identifiers.

   The bundle-only attribute is used for the video sources in the offer
   to ensure enabling video sources solely in the context of BUNDLE
   alone.

   The BUNDLE grouping framework enables multiplexing of all 5 Source
   RTP Streams (1 audio stream + 4 video streams) over a single RTP
   session.

   Also, the audio and one video source RTP stream form a lip sync group
   while the other video source RTP stream represents non-interactive
   media data.

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          One-way Successful Simulcast w/BUNDLE

   Alice                                            Bob
   |                                                 |
   |                                                 |
   |     Alice offers 2 send-only video sources      |
   |     with 2 simulcast encodings per source       |
   |           and bundle-only for video             |
   |                                                 |
   |                                                 |
   |   offer(Audio:Opus,Video1:VP8,Video2:H.264)     |
   |------------------------------------------------>|
   |                                                 |
   |                                                 |
   |    answer(Audio:Opus Video1:VP8,Video2:H.264)   |
   |<------------------------------------------------|
   |                                                 |
   |One-way 1 Opus, 2 H.264, and 2 VP8 video streams,|
   | all multiplexed                                 |
   |.................................................|
   |                                                 |
   |                                                 |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1 m2                                                                        |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-1 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 100                                                             |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |

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   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Send-only video stream      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 max-fr=15                                                                           |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 send pt=98;max-width=1280;max-height=720                                               |[I-D.ietf-mmusic-rid] 1:1 rid mapping to|
   |                                                                                               |payload type and specify resolution     |
   |                                                                                               |constraints                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 send pt=100;max-width=640;max-height=480                                               |[I-D.ietf-mmusic-rid] 1:1 rid mapping to|
   |                                                                                               |payload type and specify resolution     |
   |                                                                                               |constraints                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:send 1;~2                                                                          |[I-D.ietf-mmusic-sdp-simulcast] Alice   |
   |                                                                                               |can send 2 resolutions identified by the|
   |                                                                                               |'rid' identifiers Also, the second      |
   |                                                                                               |stream is initially paused.             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-2 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 101 102                                                            |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m2                                                                                       |[RFC5888] Video m=line part of BUNDLE   |

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   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tc                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tc)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Send only video stream      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 H264/90000                                                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:102 H264/90000                                                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 profile-level-id=42401f;packetization-mode=0                                        |[RFC6184]Camera-2,Encoding-1            |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:102 profile-level-id=42401f;packetization-mode=1                                        |[RFC6184]Camera-2,Encoding-2            |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:3 send pt=101;max-width=1280;max-height=720;max-fr=30                                    |[I-D.ietf-mmusic-rid] 1:1 rid mapping to|
   |                                                                                               |payload type and specify resolution     |
   |                                                                                               |constraints                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:4 send pt=102;max-width=640;max-height=360;max-fr=15                                     |[I-D.ietf-mmusic-rid] 1:1 rid mapping to|
   |                                                                                               |payload type and specify resolution     |
   |                                                                                               |constraints                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:send 3;4                                                                           |[I-D.ietf-mmusic-sdp-simulcast] Alice   |
   |                                                                                               |can send 2 resolutions identified by the|
   |                                                                                               |'rid' identifiers                       |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 27: 5.3.1 SDP Offer

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1 m2                                                                        |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 61665 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 61665      |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-1 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 100                                                             |BUNDLE accepted                         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264] - receive only video stream   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 max-fr=15                                                                           |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 recv pt=98;max-width=1280;max-height=720                                               |[I-D.ietf-mmusic-rid] Bob accepts the   |
   |                                                                                               |offered payload format constraints      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 recv pt=100;max-width=640;max-height=480                                               |[I-D.ietf-mmusic-rid] Bob accepts the   |
   |                                                                                               |offered payload format constraints      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=simulcast:recv 1;2                                                                           |[I-D.ietf-mmusic-sdp-simulcast] Bob     |
   |                                                                                               |accepts the offered simulcast streams   |
   |                                                                                               |and removes the paused state of stream  |
   |                                                                                               |with 'rid' value 2.                     |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-2 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 101 102                                                            |BUNDLE accepted                         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m2                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tc                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tc)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 H264/90000                                                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:102 H264/90000                                                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 profile-level-id=42401f;packetization-mode=1                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:102 profile-level-id=42401f;packetization-mode=1                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:3 recv pt=101;max-width=1280;max-height=720;max-fr=30                                    |[I-D.ietf-mmusic-rid] Bob accepts the   |
   |                                                                                               |offered payload format constraints      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:4 recv pt=102;max-width=640;max-height=360;max-fr=15                                     |[I-D.ietf-mmusic-rid] Bob accepts the   |
   |                                                                                               |offered payload format constraints      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:recv 3;4                                                                           |[I-D.ietf-mmusic-sdp-simulcast] Bob     |
   |                                                                                               |accepts the offered simulcast streams.  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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                         Table 28: 5.3.1 SDP Answer

5.3.2.  Successful SVC Video Session

   This section shows an SDP offer/answer for a session with an audio
   and a single video source.  The video source is being encoded both as
   non-scalable and scalable H.264-SVC RTP streams (in the SST mode).

   The answerer picks the payload type corresponding to scalable
   encoding.

        SVC Session - 3 Layers w/BUNDLE

Alice                                            Bob
|                                                 |
|                                                 |
|      Alice offers a send-only video stream      |
|      with non-scalable and scalable encodings.  |
|                                                 |
|                                                 |
|  offer(Audio:Opus, Video:H.264/H.264-SVC)       |
|------------------------------------------------>|
|                                                 |
|                                                 |Bob accepts Alice's
|                                                 |offered codec
|                                                 |operation points
|                                                 |for scalable encoding
|                                                 |
|  answer(Audio:Opus, Video:H.264-SVC)            |
|<------------------------------------------------|
|                                                 |
| One-way Opus, H.264-SVC video streams           |
|.................................................|
|                                                 |
|                                                 |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 96 100                                                             |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264] - Send only video stream      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:96 H264/90000                                                                         |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:96 profile-level-id=4d0028; packetization-mode=1;max-fs=8040                            |[RFC6184]H.264 Non Scalable             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 H264-SVC/90000                                                                    |[RFC6190]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 profile-level-id=53001f;packetization-mode=0                                        |[RFC6190] H.264 Scalable Encoding       |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                     Table 29: 5.3.2 SDP Offer with SVC

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 100                                                                |BUNDLE accepted.                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264] - Receive only video stream   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 H264-SVC/90000                                                                    |[RFC6190]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 profile-level-id=53001f;packetization-mode=0                                        |[RFC6190]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                    Table 30: 5.3.2 SDP Answer with SVC

5.3.3.  Successful Simulcast Video Session with Retransmission

   This section shows an SDP offer/answer exchange for a simulcast
   scenario with 3 resolutions and has [RFC4588]-style retransmission
   flows.

   The [I-D.ietf-mmusic-rid] framework is used to specify all the (3)
   resolution constraints mapped to a single Payload Type (98).

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   The [I-D.ietf-mmusic-sdp-simulcast] framework identifies the
   simulcast streams via their 'rid' identifiers.

           Simulcast Streams with Retransmission

   Alice                                                    Bob
   |                                                         |
   |                                                         |
   |Alice offers single audio and simulcasted video streams  |
   |                                                         |
   |                                                         |
   |    offer(Audio:Opus Video:VP8 with 3 resolutions)       |
   |    and RTX stream                                       |
   |-------------------------------------------------------->|
   |                                                         |
   |                                                         |
   |          answer (Bob accepts Alice's offer)             |
   |<--------------------------------------------------------|
   |                                                         |
   |                                                         |
   |One-way 1 Opus, 3 VP8 and RTX video streams, all muxed   |
   |.........................................................|
   |                                                         |
   |                                                         |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 103                                                             |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:103 rtx/90000                                                                         |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:103 apt=98;rtx-time=200                                                                 |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 send pt=98;max-fs=921600;max-fr=30                                                     |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 send pt=98;max-fs=614400;max-fr=15                                                     |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:3 send pt=98;max-fs=230400;max-fr=30                                                     |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:send 1;2;3                                                                         |[I-D.ietf-mmusic-sdp-simulcast] Alice   |
   |                                                                                               |can send all the simulcast streams      |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                 Table 31: 5.3.3 SDP Offer w/Simulcast, RTX

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Bob supports grouping of m=lines under  |
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 103                                                             |BUNDLE accepted                         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:103 rtx/90000                                                                         |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:103 apt=98;rtx-time=200                                                                 |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 recv pt=98;max-fs=921600;max-fr=30                                                     |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 recv pt=98;max-fs=614400;max-fr=15                                                     |[I-D.ietf-mmusic-rid]                   |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:3 recv pt=98;max-fs=230400;max-fr=30                                                     |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:recv 1;2;3                                                                         |[I-D.ietf-mmusic-sdp-simulcast] Bob     |
   |                                                                                               |accepts the offered simulcast streams   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                Table 32: 5.3.3 SDP Answer w/Simulcast, RTX

5.3.4.  Successful One-way Simulcast Session with 2 resolutions and RTX
        - One resolution rejected

   This section shows an SDP offer/answer exchange for a simulcast
   scenario with two resolutions.

   It also showcases where Bob rejects one of the Simulcast Video
   streams, which results in the rejection of the associated repair
   stream implicitly.

     Simulcast Streams with Retransmission Rejected

Alice                                                    Bob
|                                                         |
|                                                         |
|Alice offers single audio and simulcasted video streams  |
| with bundle-only for video                              |
|                                                         |
|                                                         |
|offer(Audio:Opus Video:VP8 with 2 resolutions,RTX Stream)|
|-------------------------------------------------------->|
|                                                         |
|                                                         |Bob accepts 1
|                                                         |simulcast,rtx
|                                                         |rejects the
|                                                         |other
|   answer(Audio:Opus Video:VP8 with 1 res & RTX Stream)  |
|<--------------------------------------------------------|
|                                                         |
|                                                         |
|    One-way audio and video session and its associated   |
|    RTX stream, all multiplexed                          |
|.........................................................|
|                                                         |
|                                                         |

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   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 100 101 103                                                     |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb                 |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 rtx/90000                                                                         |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:103 rtx/90000                                                                         |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30;max-fs=8040                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 max-fr=15;max-fs=1200                                                               |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 apt=98;rtx-time=200                                                                 |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:103 apt=100;rtx-time=200                                                                |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 send pt=98                                                                             |[I-D.ietf-mmusic-rid] 1:1 mapping       |
   |                                                                                               |between the PT and the 'rid' identifier |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 send pt=100                                                                            |[I-D.ietf-mmusic-rid] 1:1 mapping       |
   |                                                                                               |between the PT and the 'rid' identifier |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:send 1;2                                                                           |[I-D.ietf-mmusic-sdp-simulcast]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                 Table 33: 5.3.4 SDP Offer w/Simulcast, RTX

   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Bob supports grouping of m=lines under  |
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 101                                                             |BUNDLE accepted                         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 rtx/90000                                                                         |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 apt=98;rtx-time=200                                                                 |[RFC4588]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 recv pt=98                                                                             |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:recv 1                                                                             |[I-D.ietf-mmusic-sdp-simulcast] Bob     |
   |                                                                                               |rejects the second simulcast stream and |
   |                                                                                               |the associated rtx stream.              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

            Table 34: 5.3.4 SDP Answer (one Simulcast Rejected)

5.3.5.  Simulcast Video Session with Forward Error Correction

   This section shows an SDP offer/answer exchange for a simulcast video
   stream at two resolutions with [RFC8627] based forward error
   correction mechanisms.

   On completion of the offer/answer exchange mechanism, we end up with
   one audio stream, 2 simulcast video streams, and associated FEC
   stream(s), all of which are sent over a single 5-tuple.

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      Simulcast Streams with Forward Error Correction

Alice                                                            Bob
|                                                               |
|                                                               |
|                                                               |
|Alice offers single audio and simulcasted video streams        |
|with bundle-only                                               |
|                                                               |
|                                                               |
|offer(Audio:Opus Video:VP8 with 2 resolutions with FEC Streams)|
|-------------------------------------------------------------->|
|                                                               |
|                                                               |Bob
|                                                               |accepts
|                                                               |Alice's
|                                                               |offer
|answer(Audio:Opus Video:VP8 with 2 resolutions w/FEC Streams)  |
|<--------------------------------------------------------------|
|                                                               |
|One-way Audio,Video session with 2 video streams and           |
| associated FEC stream(s)                                      |
|...............................................................|
|                                                               |
|                                                               |
|                                                               |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 100 101                                                         |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 flexfec/90000                                                                     |[RFC8627]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30;max-fs=8040                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 max-fr=15;max-fs=1200                                                               |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 repair-window=200000                                                                |[RFC8627]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 send pt=98                                                                             |[I-D.ietf-mmusic-rid] 1:1 mapping       |
   |                                                                                               |between the PT and the 'rid' identifier |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 send pt=100                                                                            |[I-D.ietf-mmusic-rid] 1:1 mapping       |
   |                                                                                               |between the PT and the 'rid' identifier |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:send 1;2                                                                           |[I-D.ietf-mmusic-sdp-simulcast]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 35: 5.3.5 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667326 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302206 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98 100 101                                                         |BUNDLE accepted.                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=recvonly                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:100 VP8/90000                                                                         |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 flexfec/90000                                                                     |[RFC8627]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30;max-fs=8040                                                                |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:100 max-fr=15;max-fs=1200                                                               |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 repair-window=200000                                                                |[RFC8627]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id                                       |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id                              |[I-D.ietf-avtext-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:1 recv pt=98                                                                             |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rid:2 recv pt=100                                                                            |[I-D.ietf-mmusic-rid]                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=simulcast:recv 1;2                                                                           |[I-D.ietf-mmusic-sdp-simulcast]         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 36: 5.3.5 SDP Answer

5.4.  Others

   The examples in this section provide SDP offer/answer exchanges for a
   variety of scenarios related to RTP Header extensions for conference
   usages, Legacy Interop scenarios, and more.

5.4.1.  Audio Session - Voice Activity Detection

   This example shows Alice indicating the support of the RTP header
   extension to include the audio level of the audio sample carried in
   the RTP packet.

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              Two-way Audio with VAD

    Alice                                    Bob
    |                                         |
    |                                         |
    |Alice indicates support for including    |
    |audio level in RTP header                |
    |                                         |
    |     offer(Audio:Opus,PCMU,PCMA)         |
    |---------------------------------------->|
    |                                         |
    |                                         |
    |     answer(Audio:Opus,PCMU,PCMA)        |
    |<----------------------------------------|
    |                                         |
    |                                         |Bob accepts and
    |                                         |indicates his
    |                                         |support as well
    |                                         |
    |     Two-way Opus Audio                  |
    |.........................................|
    |                                         |
    |Per packet audio-level is included in the|
    |RTP header                               |
    |                                         |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 37: 5.4.1 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Bob can send and recv audio |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587] - Bob accepts only Opus Codec |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761] - Bob can perform RTP/RTCP    |
   |                                                                                               |Muxing on port 49203                    |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 38: 5.4.1 SDP Answer

5.4.2.  Audio Conference - Voice Activity Detection

   This example of SDP highlights the RTP header RTP header extension
   that allows RTP-level mixers in audio conferences to deliver
   information about the audio level of individual participants.

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        Audio Conference with VAD Support

   Alice                                    Mixer
   |                                         |
   |Alice indicates her interest in audio    |
   |levels for the contributing sources      |
   |                                         |
   |offer(Audio:Opus,PCMU,PCMA)              |
   |---------------------------------------->|
   |                                         |
   |                                         |
   |answer(Audio:Opus,PCMU,PCMA)             |
   |<----------------------------------------|
   |                                         |
   |                                         |Mixer indicates
   |                                         |it can provide
   |                                         |audio-levels
   |Two-way Opus Audio                       |
   |.........................................|
   |                                         |
   |audio-levels per CSRCS are included in   |
   |the RTP header                           |
   |                                         |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264] - Alice can send and recv     |
   |                                                                                               |audio                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1/recvonly urn:ietf:params:rtp-hdrext:csrc-audio-level                                |[RFC6465]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:3 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 39: 5.4.2 SDP Offer

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   +===============================================================================================+========================================+
   |Answer SDP Contents                                                                            |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566] - Session Origin Information  |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE audio                                                                           |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8                                                        |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:audio                                                                                    |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:0 PCMU/8000                                                                           |[RFC3551] PCMU Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:8 PCMA/8000                                                                           |[RFC3551] PCMA Audio Codec              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:active                                                                                 |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:CJ6FF9ZZMJW7MDRJIR7XVIQM48GE1G31                                                      |[I-D.ietf-mmusic-dtls-sdp]              |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1/sendonly urn:ietf:params:rtp-hdrext:csrc-audio-level                                |[RFC6465]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556     |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=end-of-candidates                                                                            |[I-D.ietf-mmusic-trickle-ice]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                         Table 40: 5.4.2 SDP Answer

5.4.3.  Successful Legacy Interop Fallback with bundle-only

   In the scenario described below, Alice is a multi-stream capable
   WebRTC endpoint, while Bob is a legacy VOIP endpoint.  The SDP offer/
   answer exchange demonstrates successful session setup with fallback
   to an audio-only stream negotiated via the bundle-only framework
   between the endpoints.  Specifically:

   *  The offer from Alice describes 2 cameras via 2 video m=lines with
      both marked as bundle-only.

   *  Bob doesn't recognize the BUNDLE mechanism and since Alice has
      marked both the video m=lines with port 0, Bob accepts just the
      audio stream from Alice.

   NOTE: Alice is unaware of whether Bob supports the BUNDLE framework.
   Alice includes separate RTP/RTCP ports and candidate information.

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         Successful Two-way WebRTC <-> VOIP Interop

Alice                                                       Bob
|                                                           |
|                                                           |
|       Alice is a multistream capable WebRTC endpoint      |
|          & Bob is behind a legacy VOIP system             |
|                                                           |
|offer(Audio:Opus Video:1 VP8,1 H.264 Stream) with          |
|          bundle-only                                      |
|---------------------------------------------------------->|
|     Alice marks both the video streams as bundle-only     |
|                                                           |
|                                                           |
|                  answer(Audio:Opus)                       |
|<----------------------------------------------------------|
|                                                           |Bob
|                                                           |accepts the
|                                                           |audio
|                                                           |stream,
|                                                           |since he
|                                                           |doesn't
|                                                           |recognize
|                                                           |bundle-only
|                                                           |
|                   Two-way Opus Audio                      |
|...........................................................|
|                                                           |
|                                                           |

   +===============================================================================================+========================================+
   |Offer SDP Contents                                                                             |RFC#/Notes                              |
   +===============================================================================================+========================================+
   |v=0                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |s=-                                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |t=0 0                                                                                          |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:BUNDLE m0 m1 m2                                                                        |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   |                                                                                               |Alice supports grouping of m=lines under|
   |                                                                                               |BUNDLE semantics                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=group:LS m0 m1                                                                               |[RFC5888]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:trickle                                                                          |[I-D.ietf-mmusic-trickle-ice]           |

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   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-options:ice2                                                                             |[RFC8445]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Audio m=line *********                                                                  |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=audio 54609 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m0                                                                                       |[RFC5888] Audio m=line part of BUNDLE   |
   |                                                                                               |group with a unique port number         |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma ta                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (ta)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                               |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                                        |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=setup:actpass                                                                                |[RFC5763]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=tls-id:89J2LRATQ3ULA24G9AHWVR31VJWSLB68                                                      |[I-D.ietf-mmusic-dtls-sdp]              |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp:64678 IN IP4 203.0.113.141                                                              |[RFC3605]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 61665 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54609 typ srflx raddr 192.0.2.4 rport 61665        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=candidate:0 1 UDP 2113667326 192.0.2.4 61667 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=candidate:1 1 UDP 1694302206 203.0.113.141 64678 typ srflx raddr 192.0.2.4 rport 61667       |[I-D.ietf-mmusic-ice-sip-sdp]           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-1 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98                                                                 |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m1                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tb                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tb)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:98 VP8/90000                                                                          |[RFC7741]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=imageattr:98 [x=1280,y=720]                                                                  |[RFC6236]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:98 max-fr=30                                                                            |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |****** Video-2 m=line *********                                                                |*****************************           |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 101                                                                |bundle-only video line with port number |
   |                                                                                               |set to zero                             |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=bundle-only                                                                                  |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=mid:m2                                                                                       |[RFC5888] Video m=line part of BUNDLE   |
   |                                                                                               |group                                   |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=msid:ma tc                                                                                   |Identifies MediaStream ID (ma) and      |
   |                                                                                               |MediaStreamTrack ID (tc)                |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

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   |a=sendrecv                                                                                     |[RFC3264]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtpmap:101 H264/90000                                                                        |[RFC6184]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=fmtp:101 profile-level-id=4d0028;packetization-mode=1                                        |[RFC6184]Camera-2,Encoding-1 Resolution |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack                                                                               |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* nack pli                                                                           |[RFC4585]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=rtcp-fb:* ccm fir                                                                            |[RFC5104]                               |
   +-----------------------------------------------------------------------------------------------+----------------------------------------+
   |a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid                                                 |[I-D.ietf-mmusic-sdp-bundle-negotiation]|
   +-----------------------------------------------------------------------------------------------+----------------------------------------+

                 Table 41: 5.4.3 SDP Simulcast bundle-only

   +===============================================================================================+=============================+
   |Answer SDP Contents                                                                            |RFC#/Notes                   |
   +===============================================================================================+=============================+
   |v=0                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |o=- 20519 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |s=-                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |t=0 0                                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Audio m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=audio 49203 UDP/TLS/RTP/SAVPF 109                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp:60065 IN IP4 203.0.113.141                                                              |[RFC3605]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:109 opus/48000/2                                                                      |[RFC7587]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=maxptime:120                                                                                 |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |

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   |6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35:DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08|                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=setup:active                                                                                 |[RFC5763]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level                                         |[RFC6464]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 51556 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 51556      |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 2 UDP 2113667326 198.51.100.7 51558 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 2 UDP 1694302206 203.0.113.77 60065 typ srflx raddr 198.51.100.7 rport 51558     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Video m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 98                                                                 |Bob doesn't recognize bundle-|
   |                                                                                               |only and hence the m=line is |
   |                                                                                               |rejected implicitly due to   |
   |                                                                                               |port 0                       |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Video m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=video 0 UDP/TLS/RTP/SAVPF 101                                                                |Bob doesn't recognize bundle-|
   |                                                                                               |only and hence the m=line is |
   |                                                                                               |rejected implicitly due to   |
   |                                                                                               |port 0                       |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

                         Table 42: 5.4.3 SDP Answer

5.4.4.  Legacy Interop with RTP/AVP profile

   In the scenario described below, Alice is a legacy endpoint that
   sends an [RFC3264] offer with RTP/AVP-based audio and video
   descriptions along with a DTLS fingerprint and RTCP feedback
   information.

   On the other hand, Bob, being a WebRTC endpoint, follows the
   procedures in section 5.1.2 of [I-D.ietf-rtcweb-jsep] and accepts the
   Alice's offer for a DTLS-SRTP-based session with RTCP feedback.

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           Successful Two-way WebRTC <-> VOIP Interop

Alice                                                       Bob
|                                                            |
|                                                            |
|Alice is a legacy VOIP endpoint & Bob is a WebRTC endpoint  |
|                                                            |
|                                                            |
|                                                            |
|              offer(Audio:Opus Video:H.264)                 |
|----------------------------------------------------------->|
|                                                            |
|                                                            |
|Alice includes :                                            |
|Legacy-compliant media description (RTP/AVP) with DTLS      |
|fingerprint and RTCP feedback support                       |
|                                                            |
|             answer(Audio:Opus, Video:H.264)                |
|<-----------------------------------------------------------|
|                                                            |Bob
|                                                            |accepts
|                                                            |"legacy
|                                                            |-compliant"
|                                                            |m=line
|                                                            |
|                                                            |
|             Two-way Opus Audio, H.264 Video                |
|............................................................|
|       Session also supports RTP/RTCP Mux, RTCP Feedback    |
|                                                            |

   +===============================================================================================+=============================+
   |Offer SDP Contents                                                                             |RFC#/Notes                   |
   +===============================================================================================+=============================+
   |v=0                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |o=- 20518 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |s=-                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |t=0 0                                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-ufrag:074c6550                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068                                                    |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-rsize                                                                                   |[RFC5506]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

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   |****** Audio m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=audio 54732 RTP/AVP 109                                                                      |[RFC4566]Alice includes RTP/ |
   |                                                                                               |AVP audio stream description |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |
   |19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04:BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2|                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:109 opus/48000                                                                        |                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ptime:20                                                                                     |                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]Alice still includes|
   |                                                                                               |RTP/RTCP Mux support         |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp:64678 IN IP4 203.0.113.141                                                              |[RFC3605]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2113667327 192.0.2.4 54732 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 694302207 203.0.113.141 54732 typ srflx raddr 192.0.2.4 rport 54732        |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 2 UDP 2113667326 192.0.2.4 64678 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 2 UDP 1694302206 203.0.113.141 64678 typ srflx raddr 192.0.2.4 rport 64678       |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Video m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=video 62445 RTP/AVP 120                                                                      |[RFC4566]Alice includes RTP/ |
   |                                                                                               |AVP video stream description |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.141                                                                         |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |
   |DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08:6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35|                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]Alice intends to    |
   |                                                                                               |perform RTP/RTCP Mux         |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp:54721 IN IP4 203.0.113.141                                                              |[RFC3605]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

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   |a=candidate:0 1 UDP 2113667327 192.0.2.4 62445 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.141 62537 typ srflx raddr 192.0.2.4 rport 62445       |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 2 UDP 2113667326 192.0.2.4 54721 typ host                                        |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 2 UDP 1694302206 203.0.113.141 54721 typ srflx raddr 192.0.2.4 rport 54721       |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585] Alice indicates    |
   |                                                                                               |support for Picture Loss     |
   |                                                                                               |Indication and NACK RTCP     |
   |                                                                                               |feedback                     |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

                         Table 43: 5.4.5 SDP Offer

   +===============================================================================================+=============================+
   |Answer SDP Contents                                                                            |RFC#/Notes                   |
   +===============================================================================================+=============================+
   |v=0                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |o=- 16833 0 IN IP4 0.0.0.0                                                                     |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |s=-                                                                                            |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |t=0 0                                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Audio m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=audio 49203 RTP/AVP 109                                                                      |[RFC4566] Bob accepts RTP/   |
   |                                                                                               |AVP-based audio stream       |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:109 opus/48000                                                                        |                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ptime:20                                                                                     |                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-ufrag:c300d85b                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:de4e99bd291c325921d5d47efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |

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   |BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2:19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04|                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 49203 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 49203 typ srflx raddr 198.51.100.7 rport 49203     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |****** Video m=line *********                                                                  |*****************************|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |m=video 63130 RTP/AVP 120                                                                      |[RFC4566] Bob accepts RTP/   |
   |                                                                                               |AVP-based video stram        |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |c=IN IP4 203.0.113.77                                                                          |[RFC4566]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtpmap:120 VP8/90000                                                                         |[RFC7741]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=sendrecv                                                                                     |[RFC3264]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-ufrag:e39091na                                                                           |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=ice-pwd:dbc325921d5dd29e4e99147efbabd9a2                                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=fingerprint:sha-256                                                                          |[RFC8122]                    |
   |BB:0A:0E:05:E9:26:33:E8:70:88:A2:2F:70:9F:04:19:E2:1C:3B:4B:9F:81:56:2F:70:9F:04:F4:A5:A8:D8   |                             |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-mux                                                                                     |[RFC5761]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:0 1 UDP 2113667327 198.51.100.7 63130 typ host                                     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=candidate:1 1 UDP 1694302207 203.0.113.77 63130 typ srflx raddr 198.51.100.7 rport 63130     |[I-D.ietf-mmusic-ice-sip-sdp]|
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 nack pli                                                                         |[RFC4585]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+
   |a=rtcp-fb:120 ccm fir                                                                          |[RFC5104]                    |
   +-----------------------------------------------------------------------------------------------+-----------------------------+

                         Table 44: 5.4.5 SDP Answer

6.  IANA Considerations

   This document requires no actions from IANA.

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7.  Security Considerations

   The IETF has published separate documents
   [I-D.ietf-rtcweb-security-arch] [I-D.ietf-rtcweb-security] describing
   the security architecture for WebRTC as a whole.

   In addition, since the SDP offer and answer messages can contain
   private information about addresses and sessions to be established
   between parties, if this information needs to be kept private, some
   security mechanism (using the TLS transport, for example) in the
   protocol used to carry the offers and answers must be used.

8.  Acknowledgments

   We would like to thank Justin Uberti, Chris Flo, Paul Kyzivat, Nils
   Ohlmeier, Flemming Andreason, Magnus Westerlund for their detailed
   review and inputs.  Thanks to Adam Roach for providing a syntax
   validation script to help highlight syntax and formatting errors.

   Thanks to experts at IESG for careful review and feedback.

   Thanks to Peter Yee for a detailed Genart review and suggestions.

9.  Change Log

   [RFC EDITOR NOTE: Please remove this section when publishing]

   Changes from draft-ietf-rtcweb-sdp-11

   *  Address Magnus Westerlund Review comments.

   *  Remove reference to RFC5245 and use ice-sip-sdp instead.

   *  Add an ice2 example for RFC8445.

   Changes from draft-ietf-rtcweb-sdp-09

   *  Review feedback incorporated from Flemming Andreason in
      Section 5.4

   Changes from draft-ietf-rtcweb-sdp-08

   *  Fixed formatting and syntax issues pointed out by Adam Roach's
      validator script.  List of issues are here:
      https://github.com/fluffy/ietf/issues?q=is%3Aissue+is%3Aclosed

   *  Align examples to match latest bundle specification as pointed by
      Christer Holmberg

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   Changes from draft-ietf-rtcweb-sdp-07

   *  Incorporate review from Nils.

   Changes from draft-ietf-rtcweb-sdp-06

   *  Keep Alive Version.

   Changes from draft-ietf-rtcweb-sdp-05

   *  Title change.

   Changes from draft-ietf-rtcweb-sdp-04

   *  Add IPv6 Example.

   *  Add a=rtcp-mux-only and fix a=rtcp in examples.

   *  Fix Idnits.

   *  Add Security Considerations section.

   Changes from draft-ietf-rtcweb-sdp-02 to draft-ietf-rtcweb-sdp-04

   *  Alignment with JSEP-19.

   *  Added a=identity example.

   *  Added a=dtls-id, a=group:LS in the examples.

   *  Added Appendix section to capture list of checklists for the
      attributes.

   *  Removed SSRC lines to match JSEP-19.

   *  Closed open issues on a=fingerprint, a=rtcp and a=rtcp-mux-only
      from ietf96 to reflect JSEP-19.

   *  Simplied Inter-op example

   Changes from draft-ietf-rtcweb-sdp-02

   *  Version increment to avoid expiry

   Changes from draft-ietf-rtcweb-sdp-01

   *  Complete face-lift

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   *  Added visual markers around m=lines to indicate their type, added
      spacing between tables for aiding readers

   *  Updated table names to indicate offer vs answer

   *  Attempted to align to latest versions of SCTP, BUNDLE, MSID drafts

   *  Added mid header extensions to all the lines

   *  Harmonized BUNDLE semantics and conventions updated.

   Changes from draft-ietf-rtcweb-sdp-00

   *  Updated Simulcast/FEC/RTX examples to use RID framework

   *  Fixed BUNDLE references for a=bundle-only

   Changes from draft-nandakumar-rtcweb-sdp-08

   *  Fixed typos

   *  Moved to a WG version

   Changes from draft-nandakumar-rtcweb-sdp-06 and draft-nandakumar-
   rtcweb-sdp-07

   *  Added clarification on Call-Flow diagram usage

   *  More cleanups

   Changes from draft-nandakumar-rtcweb-sdp-05

   *  Added Ascii chart for all the SDP Eaxamples

   *  Improved text and updated SDP Examples for Simulcast and FEC

   *  Fixed MediaStream ID Semantics SDP Errors

   Changes from draft-nandakumar-rtcweb-sdp-04

   *  Interim version of the draft to avert expiry

   *  Corrected placement of c= line as per RFC4566

   *  Updated simulcast SDP to reflect draft-westerlund-avtcore-rtp-
      simulcast-04

   Changes from draft-nandakumar-rtcweb-sdp-03

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   *  Aligned more closely with JSEP version -05

   *  Added Conventions to help readability

   *  Add more examples to clarify BUNDLE use cases

   Changes from draft-nandakumar-rtcweb-sdp-02

   *  Major refactoring was done to group the examples in to categories

   *  SDP was updated through out to reflect JSEP-04 style of defining
      attributes per m=line than at the session level.

   *  Added 8 new examples.

   *  Updated references for Trickle, Unified Plan

   *  Add section to explain the syntax conventions followed in the
      examples.

   Changes from draft-nandakumar-rtcweb-sdp-01

   *  Updated references to OPUS RTP Payload Specification.

   *  Updated BUNDLE examples based on the latest draft-ietf-mmusic-sdp-
      bundle-negotiation.

   *  Added examples for multiple audio and video flows based on Unified
      Plan.

   *  Added new examples for RTX and FEC streams

   *  Updated Simulcast and SVC examples

   Changes from draft-nandakumar-rtcweb-sdp-00

   *  Fixed editorial comments on the mailing list.

   *  Updated Data-channel SDP information based on draft-ietf-mmusic-
      sctp-sdp.

   *  Updated BUNDLE examples based on draft-ietf-mmusic-sdp-bundle-
      negotiation.

   *  Added examples for few more BUNDLE variants

   *  Added new examples for Simulcast and SVC

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10.  Informative References

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              DOI 10.17487/RFC3264, June 2002,
              <https://www.rfc-editor.org/info/rfc3264>.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
              July 2006, <https://www.rfc-editor.org/info/rfc4566>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5506]  Johansson, I. and M. Westerlund, "Support for Reduced-Size
              Real-Time Transport Control Protocol (RTCP): Opportunities
              and Consequences", RFC 5506, DOI 10.17487/RFC5506, April
              2009, <https://www.rfc-editor.org/info/rfc5506>.

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", STD 65, RFC 3551,
              DOI 10.17487/RFC3551, July 2003,
              <https://www.rfc-editor.org/info/rfc3551>.

   [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
              Protocol (SDP) Content Attribute", RFC 4796,
              DOI 10.17487/RFC4796, February 2007,
              <https://www.rfc-editor.org/info/rfc4796>.

   [RFC5761]  Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
              Control Packets on a Single Port", RFC 5761,
              DOI 10.17487/RFC5761, April 2010,
              <https://www.rfc-editor.org/info/rfc5761>.

   [RFC5763]  Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
              for Establishing a Secure Real-time Transport Protocol
              (SRTP) Security Context Using Datagram Transport Layer
              Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May
              2010, <https://www.rfc-editor.org/info/rfc5763>.

   [RFC5104]  Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
              "Codec Control Messages in the RTP Audio-Visual Profile
              with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
              February 2008, <https://www.rfc-editor.org/info/rfc5104>.

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   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
              "Extended RTP Profile for Real-time Transport Control
              Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
              DOI 10.17487/RFC4585, July 2006,
              <https://www.rfc-editor.org/info/rfc4585>.

   [RFC4588]  Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
              Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
              DOI 10.17487/RFC4588, July 2006,
              <https://www.rfc-editor.org/info/rfc4588>.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
              Protocol (SDP) Grouping Framework", RFC 5888,
              DOI 10.17487/RFC5888, June 2010,
              <https://www.rfc-editor.org/info/rfc5888>.

   [RFC6236]  Johansson, I. and K. Jung, "Negotiation of Generic Image
              Attributes in the Session Description Protocol (SDP)",
              RFC 6236, DOI 10.17487/RFC6236, May 2011,
              <https://www.rfc-editor.org/info/rfc6236>.

   [RFC6184]  Wang, Y.-K., Even, R., Kristensen, T., and R. Jesup, "RTP
              Payload Format for H.264 Video", RFC 6184,
              DOI 10.17487/RFC6184, May 2011,
              <https://www.rfc-editor.org/info/rfc6184>.

   [RFC6190]  Wenger, S., Wang, Y.-K., Schierl, T., and A.
              Eleftheriadis, "RTP Payload Format for Scalable Video
              Coding", RFC 6190, DOI 10.17487/RFC6190, May 2011,
              <https://www.rfc-editor.org/info/rfc6190>.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
              July 2003, <https://www.rfc-editor.org/info/rfc3550>.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <https://www.rfc-editor.org/info/rfc3261>.

   [RFC3605]  Huitema, C., "Real Time Control Protocol (RTCP) attribute
              in Session Description Protocol (SDP)", RFC 3605,
              DOI 10.17487/RFC3605, October 2003,
              <https://www.rfc-editor.org/info/rfc3605>.

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   [RFC4733]  Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
              Digits, Telephony Tones, and Telephony Signals", RFC 4733,
              DOI 10.17487/RFC4733, December 2006,
              <https://www.rfc-editor.org/info/rfc4733>.

   [RFC6464]  Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time
              Transport Protocol (RTP) Header Extension for Client-to-
              Mixer Audio Level Indication", RFC 6464,
              DOI 10.17487/RFC6464, December 2011,
              <https://www.rfc-editor.org/info/rfc6464>.

   [RFC6465]  Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real-
              time Transport Protocol (RTP) Header Extension for Mixer-
              to-Client Audio Level Indication", RFC 6465,
              DOI 10.17487/RFC6465, December 2011,
              <https://www.rfc-editor.org/info/rfc6465>.

   [RFC7587]  Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format
              for the Opus Speech and Audio Codec", RFC 7587,
              DOI 10.17487/RFC7587, June 2015,
              <https://www.rfc-editor.org/info/rfc7587>.

   [RFC7656]  Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
              B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
              for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
              DOI 10.17487/RFC7656, November 2015,
              <https://www.rfc-editor.org/info/rfc7656>.

   [RFC7741]  Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
              Galligan, "RTP Payload Format for VP8 Video", RFC 7741,
              DOI 10.17487/RFC7741, March 2016,
              <https://www.rfc-editor.org/info/rfc7741>.

   [RFC7826]  Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
              and M. Stiemerling, Ed., "Real-Time Streaming Protocol
              Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
              2016, <https://www.rfc-editor.org/info/rfc7826>.

   [RFC8122]  Lennox, J. and C. Holmberg, "Connection-Oriented Media
              Transport over the Transport Layer Security (TLS) Protocol
              in the Session Description Protocol (SDP)", RFC 8122,
              DOI 10.17487/RFC8122, March 2017,
              <https://www.rfc-editor.org/info/rfc8122>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

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   [RFC8445]  Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive
              Connectivity Establishment (ICE): A Protocol for Network
              Address Translator (NAT) Traversal", RFC 8445,
              DOI 10.17487/RFC8445, July 2018,
              <https://www.rfc-editor.org/info/rfc8445>.

   [RFC8627]  Zanaty, M., Singh, V., Begen, A., and G. Mandyam, "RTP
              Payload Format for Flexible Forward Error Correction
              (FEC)", RFC 8627, DOI 10.17487/RFC8627, July 2019,
              <https://www.rfc-editor.org/info/rfc8627>.

   [I-D.ietf-mmusic-sdp-bundle-negotiation]
              Holmberg, C., Alvestrand, H., and C. Jennings,
              "Negotiating Media Multiplexing Using the Session
              Description Protocol (SDP)", Work in Progress, Internet-
              Draft, draft-ietf-mmusic-sdp-bundle-negotiation-54, 14
              December 2018, <http://www.ietf.org/internet-drafts/draft-
              ietf-mmusic-sdp-bundle-negotiation-54.txt>.

   [I-D.ietf-mmusic-sdp-simulcast]
              Burman, B., Westerlund, M., Nandakumar, S., and M. Zanaty,
              "Using Simulcast in SDP and RTP Sessions", Work in
              Progress, Internet-Draft, draft-ietf-mmusic-sdp-simulcast-
              14, 5 March 2019, <http://www.ietf.org/internet-drafts/
              draft-ietf-mmusic-sdp-simulcast-14.txt>.

   [I-D.ietf-mmusic-rid]
              Roach, A., "RTP Payload Format Restrictions", Work in
              Progress, Internet-Draft, draft-ietf-mmusic-rid-15, 15 May
              2018, <http://www.ietf.org/internet-drafts/draft-ietf-
              mmusic-rid-15.txt>.

   [I-D.ietf-mmusic-ice-sip-sdp]
              Petit-Huguenin, M., Nandakumar, S., Holmberg, C., Keranen,
              A., and R. Shpount, "Session Description Protocol (SDP)
              Offer/Answer procedures for Interactive Connectivity
              Establishment (ICE)", Work in Progress, Internet-Draft,
              draft-ietf-mmusic-ice-sip-sdp-39, 13 August 2019,
              <http://www.ietf.org/internet-drafts/draft-ietf-mmusic-
              ice-sip-sdp-39.txt>.

   [I-D.ietf-rtcweb-jsep]
              Uberti, J., Jennings, C., and E. Rescorla, "JavaScript
              Session Establishment Protocol", Work in Progress,
              Internet-Draft, draft-ietf-rtcweb-jsep-26, 27 February
              2019, <http://www.ietf.org/internet-drafts/draft-ietf-
              rtcweb-jsep-26.txt>.

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   [I-D.ietf-mmusic-trickle-ice]
              Ivov, E., Rescorla, E., and J. Uberti, "Trickle ICE:
              Incremental Provisioning of Candidates for the Interactive
              Connectivity Establishment (ICE) Protocol", Work in
              Progress, Internet-Draft, draft-ietf-mmusic-trickle-ice-
              02, 15 January 2015, <http://www.ietf.org/internet-drafts/
              draft-ietf-mmusic-trickle-ice-02.txt>.

   [I-D.ietf-mmusic-msid]
              Alvestrand, H., "WebRTC MediaStream Identification in the
              Session Description Protocol", Work in Progress, Internet-
              Draft, draft-ietf-mmusic-msid-17, 13 December 2018,
              <http://www.ietf.org/internet-drafts/draft-ietf-mmusic-
              msid-17.txt>.

   [I-D.ietf-mmusic-sctp-sdp]
              Holmberg, C., Shpount, R., Loreto, S., and G. Camarillo,
              "Session Description Protocol (SDP) Offer/Answer
              Procedures For Stream Control Transmission Protocol (SCTP)
              over Datagram Transport Layer Security (DTLS) Transport.",
              Work in Progress, Internet-Draft, draft-ietf-mmusic-sctp-
              sdp-26, 20 April 2017, <http://www.ietf.org/internet-
              drafts/draft-ietf-mmusic-sctp-sdp-26.txt>.

   [I-D.ietf-rtcweb-data-channel]
              Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
              Channels", Work in Progress, Internet-Draft, draft-ietf-
              rtcweb-data-channel-13, 4 January 2015,
              <http://www.ietf.org/internet-drafts/draft-ietf-rtcweb-
              data-channel-13.txt>.

   [I-D.ietf-mmusic-mux-exclusive]
              Holmberg, C., "Indicating Exclusive Support of RTP/RTCP
              Multiplexing using SDP", Work in Progress, Internet-Draft,
              draft-ietf-mmusic-mux-exclusive-12, 5 May 2017,
              <http://www.ietf.org/internet-drafts/draft-ietf-mmusic-
              mux-exclusive-12.txt>.

   [I-D.ietf-mmusic-dtls-sdp]
              Holmberg, C. and R. Shpount, "Session Description Protocol
              (SDP) Offer/Answer Considerations for Datagram Transport
              Layer Security (DTLS) and Transport Layer Security (TLS)",
              Work in Progress, Internet-Draft, draft-ietf-mmusic-dtls-
              sdp-32, 29 October 2017, <http://www.ietf.org/internet-
              drafts/draft-ietf-mmusic-dtls-sdp-32.txt>.

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   [I-D.ietf-rtcweb-security-arch]
              Rescorla, E., "WebRTC Security Architecture", Work in
              Progress, Internet-Draft, draft-ietf-rtcweb-security-arch-
              20, 22 July 2019, <http://www.ietf.org/internet-drafts/
              draft-ietf-rtcweb-security-arch-20.txt>.

   [I-D.ietf-rtcweb-security]
              Rescorla, E., "Security Considerations for WebRTC", Work
              in Progress, Internet-Draft, draft-ietf-rtcweb-security-
              12, 5 July 2019, <http://www.ietf.org/internet-drafts/
              draft-ietf-rtcweb-security-12.txt>.

   [I-D.ietf-avtext-rid]
              Roach, A., Nandakumar, S., and P. Thatcher, "RTP Stream
              Identifier Source Description (SDES)", Work in Progress,
              Internet-Draft, draft-ietf-avtext-rid-09, 6 October 2016,
              <http://www.ietf.org/internet-drafts/draft-ietf-avtext-
              rid-09.txt>.

   [WebRTC]   W3C, "WebRTC 1.0: Real-time Communication Between
              Browsers",
              <http://dev.w3.org/2011/webrtc/editor/webrtc.html> .

Appendix A.  Appendix

A.1.  JSEP SDP Attributes Checklist

   This section compiles a high-level checklist of the required SDP
   attributes to be verified against the examples defined in this
   specification.  The goal here is to ensure that the examples are
   compliant with the rules defined in section 5 of the
   [I-D.ietf-rtcweb-jsep] specification.

A.1.1.  Common Checklist

   This subsection lists SDP attributes that mostly apply at the session
   level.

   *  v=0 MUST be the first SDP line.

   *  o= line MUST follow with values '-' for username, a 64-bit value
      for session id and dummy values for 'nettype', 'addrtype', and
      'unicast-address' (for example: IN IP4 0.0.0.0).

   *  o= line MUST have the session version incremented in the case of
      subsequent offers.

   *  s= MUST be the third line and have the value of '-'.

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   *  t= line MUST follow with the values for 'start-time' and 'stop-
      time' set to zeroes.

   *  a=identity line MUST be included at the session level if WebRTC
      Identity mechanism is being used.

   *  a=ice-options:trickle MUST be present at the session level in all
      offers and answers when supported.

   *  a=ice-options:ice3 MUST be present at the session level in all
      offers and answers when supported.

A.1.2.  RTP Media Description Checklist

   The following set of checklist items apply to RTP audio and video
   media descriptions.

   *  The media description's port value MUST either be set to the dummy
      value of '9' or MUST use the port from the default candidate, if
      available.

   *  The media description's proto value MUST be 'UDP/TLS/RTP/SAVPF'
      for JSEP offers.

   *  The JSEP answerer MUST support any combination of "RTP/[S]AVP[F]"
      for interoperability scenarios as defined in section 5 of
      [I-D.ietf-rtcweb-jsep]

   *  c= line MUST be the first line in a media description.  A dummy
      value of 'IN IP 0.0.0.0' is set if there are no candidates
      gathered or its value MUST match the default candidate.

   *  a=mid attribute MUST be included.

   *  One of a=sendrecv/a=sendonly/a=recvonly/a=inactive SDP direction
      attributes MUST be present.

   *  a=rtpmap and a=fmtp attributes per primary, retransmission, and
      forward error correction media format MUST be included.

   *  a=rtcp-fb lines for each supported feedback mechanism MUST be
      included when using RTP with feedback.

   *  a=imageattr can be optionally present for video media
      descriptions.

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   *  a=msid line MUST be included for all the media senders identifying
      the MediaStreamTrack (i.e., when a=sendonly/a=sendrecv attribute
      is present).

   *  a=extmap line identifying the RTP MID header extension" MUST be
      present.

   *  a=extmap line for other supported RTP header extensions MUST be
      included.

   *  a=rid line 'per encoding' with the direction of 'send' MUST be
      included when further constraining the media format or multiple
      encodings per media format is needed.

   *  a=simulcast line MUST be present if there exists more than one
      'a=rid' lines for the media senders.

   *  a=bundle-only attribute MUST be present for media descriptions
      that are impacted by various bundle policies (such as max-bundle/
      balanced)

   *  For media descriptions that aren't "a=bundle-only" and that have
      unique address, the following attributes MUST be present:

      -  a=ice-ufrag and a=ice-pwd

      -  a=fingerprint

      -  a=setup with value 'actpass' in the offers and a value of
         'active'/'passive' in the answerer.

      -  a=tls-id

      -  a=rtcp

      -  a=rtcp-mux

      -  For offerers requiring RTCP to be multiplexed, 'a=rtcp-mux-
         only' line

      -  a=rtcp-rsize

   *  a=group:BUNDLE line with all the 'mid' identifiers part of the
      BUNDLE group is included at the session-level.

   *  a=group:LS session level attribute MUST be included wth the 'mid'
      identifiers that are part of the same lip sync group.

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A.1.3.  Data Channel Media Description checklist

   If a data channel is required, an 'application' type media
   description MUST be included with the following properties:

   *  Media description's proto value MUST be 'UDP/DTLS/SCTP' in the
      JSEP offers.

   *  A JSEP answerer MUST support reception of
      'UDP/DTLS/SCTP'/'TCP/DTLS/SCTP'/'DTLS/SCTP' for backward
      compatibility reasons.

   *  A value of 'webrtc-datachannel' MUST be used for the media
      description 'fmt' value.

   *  a=mid line MUST be present.

   *  a=sctp-port with an SCTP port number MUST be included.

   *  a=max-message-size MAY be included, if appropriate.

Authors' Addresses

   Suhas Nandakumar
   Cisco
   170 West Tasman Drive
   San Jose, CA 95134
   United States of America

   Email: snandaku@cisco.com

   Cullen Jennings
   Cisco
   170 West Tasman Drive
   San Jose, CA 95134
   United States of America

   Phone: +1 408 421-9990
   Email: fluffy@cisco.com

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