RTP Payload Format for the Secure Communication Interoperability Protocol (SCIP) Codec
draft-ietf-avtcore-rtp-scip-05

Payload Working Group                                          D. Hanson
Internet-Draft                                                 M. Faller
Intended status: Standards Track                                K. Maver
Expires: 30 September 2023        General Dynamics Mission Systems, Inc.
                                                           29 March 2023

    RTP Payload Format for the Secure Communication Interoperability
                         Protocol (SCIP) Codec
                     draft-ietf-avtcore-rtp-scip-05

Abstract

   This document describes the RTP payload format of the Secure
   Communication Interoperability Protocol (SCIP).  SCIP is an
   application layer protocol that defines the establishment of reliable
   SCIP endpoint to SCIP endpoint secure communications over the RTP
   channel provided by network equipment.  The scope of this document is
   limited to defining the scip codecs and Session Description Protocol
   (SDP) and RTP parameters to be supported by network devices with
   minimal description of the SCIP Application Layer Protocol.  Since
   the SCIP RTP payload is encrypted, it is considered "opaque" to
   network devices.

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
   and may be updated, replaced, or obsoleted by other documents at any
   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 30 September 2023.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Hanson, et al.          Expires 30 September 2023               [Page 1]
Internet-Draft           SCIP RTP Payload Format              March 2023

   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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Media Format Description  . . . . . . . . . . . . . . . . . .   5
     3.1.  Congestion Control Considerations . . . . . . . . . . . .   5
   4.  Payload Format  . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  RTP Header Fields . . . . . . . . . . . . . . . . . . . .   7
   5.  Payload Format Parameters . . . . . . . . . . . . . . . . . .   7
     5.1.  Media Subtype "audio/scip"  . . . . . . . . . . . . . . .   7
     5.2.  Media Subtype "video/scip"  . . . . . . . . . . . . . . .   9
     5.3.  Mapping to SDP  . . . . . . . . . . . . . . . . . . . . .  10
     5.4.  SDP Offer/Answer Considerations . . . . . . . . . . . . .  11
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  SCIP Contact Information  . . . . . . . . . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   This document details usage of the "audio/scip" and "video/scip"
   pseudo-codecs [AUDIOSCIP], [VIDEOSCIP] as a secure session
   establishment protocol and media transport protocol over RTP.  It
   discusses that encrypted audio and video codec payloads are
   transported over RTP.  This document provides a reference for network
   security policymakers, network equipment OEMs, procurement personnel,
   and government agency and commercial industry representatives.  Note
   that the IP network layer does not implement SCIP as a protocol since
   SCIP operates at the application layer in endpoints.  However, the IP
   network layer should enable SCIP traffic to transparently pass
   through the network.  Some network devices do not recognize SCIP, and
   thus remove the scip codecs from the SDP media payload declaration.
   When the scip media subtype is removed from the SDP media payload
   declaration, SCIP endpoint devices will not operate on the network.

Hanson, et al.          Expires 30 September 2023               [Page 2]
Internet-Draft           SCIP RTP Payload Format              March 2023

   The purpose of this document is to provide enough information to
   enable SCIP payloads to be transported through the network without
   modification or filtering.

   SCIP is presently implemented in United States and NATO secure voice,
   video, and data products operating on commercial, private, and
   tactical IP networks worldwide using the scip media subtype.  The
   SCIP data traversing the network is encrypted, and network equipment
   in-line with the session cannot interpret the traffic stream in any
   way.  SCIP-based RTP traffic is opaque and can vary significantly in
   structure and frequency making traffic profiling not possible.  Also,
   as the SCIP protocol continues to evolve independently of this
   document, any network device that attempts to filter traffic (e.g.,
   deep packet inspection) based on current SCIP traffic profiles may
   cause unintended consequences in the future when changes to the SCIP
   traffic may not be recognized by the network device.

   Network devices do not need to know the details of SCIP protocol as
   defined in SCIP-210 [SCIP210] to allow it to traverse the network,
   therefore SCIP-210 is considered an Informative Reference in this
   document.

1.1.  Conventions

   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.

   Best current practices for writing an RTP payload format
   specification were followed [RFC2736] [RFC8088].

   When referring to the Secure Communication Interoperability Protocol,
   the uppercase acronym "SCIP" is used.  When referring to the media
   subtype scip, lowercase "scip" is used.

1.2.  Abbreviations

   The following abbreviations are used in this document.

   AVP:      Audio/Video Profile
   DTX:      Discontinuous Transmission
   ICWG:     Interoperability Control Working Group
   IICWG:    International Interoperability Control Working Group
   NATO:     North Atlantic Treaty Organization
   SCIP:     Secure Communication Interoperability Protocol
   SDP:      Session Description Protocol

Hanson, et al.          Expires 30 September 2023               [Page 3]
Internet-Draft           SCIP RTP Payload Format              March 2023

2.  Background

   The Secure Communication Interoperability Protocol (SCIP) allows the
   negotiation of several voice, data, and video applications using
   various cryptographic suites.  SCIP also provides several important
   characteristics that have led to its broad acceptance in the United
   States and within NATO.  These capabilities include end-to-end
   security at the application layer, authentication of user identity,
   the ability to apply different security levels for each secure
   session, and secure communication over any end-to-end data
   connection.

   SCIP began in the United States as the Future Narrowband Digital
   Terminal (FNBDT) Protocol in the late 1990s.  A combined U.S.
   Department of Defense and vendor consortium formed a governing
   organization named the Interoperability Control Working Group (ICWG)
   to manage the protocol.  In time, the group expanded to include NATO,
   NATO partners and European vendors under the name International
   Interoperability Control Working Group (IICWG), which was later
   renamed the SCIP Working Group.

   First generation SCIP devices operated on circuit-switched networks.
   SCIP was then expanded to radio and IP networks.  The scip media
   subtype transports SCIP secure session establishment signaling and
   secure application traffic.  The built-in negotiation and flexibility
   provided by the SCIP protocols make it a natural choice for many
   scenarios that require various secure applications and associated
   encryption suites.  SCIP has been adopted by NATO in STANAG 5068.
   SCIP standards are currently available to participating government/
   military communities and select OEMs of equipment that support SCIP.

   However, SCIP must operate over global networks (including private
   and commercial networks).  Without access to necessary information to
   support SCIP, some networks may not support the SCIP media subtypes.
   Issues may occur simply because information is not as readily
   available to OEMs, network administrators, and network architects.

   This document provides essential information about audio/scip and
   video/scip media subtypes that enables network equipment
   manufacturers to include settings for "scip" as a known audio and
   video media subtype in their equipment.  This enables network
   administrators to define and implement a compatible security policy
   which includes audio and video media subtypes scip/8000 and
   scip/90000 as permitted codecs on the network.

Hanson, et al.          Expires 30 September 2023               [Page 4]
Internet-Draft           SCIP RTP Payload Format              March 2023

   All current IP-based SCIP endpoints implement "scip" as a media
   subtype.  Registration of scip as a media subtype provides a common
   reference for network equipment manufacturers to recognize SCIP in a
   payload declaration.

3.  Media Format Description

   The "scip" media subtype indicates support for and identifies SCIP
   traffic that is being transported over RTP.  Transcoding, lossy
   compression, or other data modifications MUST NOT be performed by the
   network on the SCIP RTP payload.  The audio/scip and video/scip media
   subtype data streams within the network, including the VoIP network,
   MUST be a transparent relay and be treated as "clear-channel data",
   similar to the Clearmode media subtype defined by [RFC4040].

   RFC 4040 is referenced because Clearmode does not define specific RTP
   payload content, packet size, or packet intervals, but rather enables
   Clearmode devices to signal that they support a compatible mode of
   operation and defines a transparent channel on which devices may
   communicate.  This document takes a similar approach.  Network
   devices that implement support for SCIP need to enable SCIP endpoints
   to signal that they support SCIP and provide a transparent channel on
   which SCIP endpoints may communicate.

3.1.  Congestion Control Considerations

   The bitrate of SCIP may be adjusted depending on the capability of
   the underlying codec (MELPe, G.729D, etc.).  The number of encoded
   audio frames per packet may also be adjusted to control congestion.
   Discontinuous transmission (DTX) may also be used if supported by the
   underlying codec.

   Since UDP does not provide congestion control, applications that use
   RTP over UDP SHOULD implement their own congestion control above the
   UDP layer [RFC8085] and MAY also implement a transport circuit
   breaker [RFC8083].  Work in the RMCAT working group [RMCAT] describes
   the interactions and conceptual interfaces necessary between the
   application components that relate to congestion control, including
   the RTP layer, the higher-level media codec control layer, and the
   lower-level transport interface, as well as components dedicated to
   congestion control functions.

Hanson, et al.          Expires 30 September 2023               [Page 5]
Internet-Draft           SCIP RTP Payload Format              March 2023

4.  Payload Format

   SCIP is an application-layer protocol that is defined in SCIP-210
   [SCIP210].  The SCIP traffic consists of both SCIP control messages
   (some of which may be encrypted) and encrypted codec data.  The
   payload size and interval will vary considerably depending on the
   state of the SCIP device.

   The SCIP codec produces an encrypted bitstream that is transported
   over RTP.  Unlike other codecs, SCIP does not have its own upper
   layer syntax (e.g., no Network Adaptation Layer (NAL) units), but
   rather encrypts the output of the audio/video codecs that it uses
   (e.g., G.729D [RFC3551], H.264 [RFC6184], etc.).  SCIP achieves this
   by encapsulating the encrypted codec output that has been previously
   formatted according to the relevant RTP payload specification for
   that codec.  SCIP endpoints MAY employ mechanisms, such as Inter-
   media RTP Synchronization as described in [RFC8088] Section 3.3.4, to
   synchronize audio/scip and video/scip streams.

   Figure 1 below illustrates notionally how codec packets and SCIP
   control messages are packetized for transmission over RTP.

   +-----------+              +-----------------------+
   |   Codec   |              | SCIP control messages |
   +-----------+              +-----------------------+
         |                                |
         |                                |
         V                                V
   +--------------------------------------------------+
   |             Packetizer* (< MTU size)             |
   +--------------------------------------------------+
             |                        |
             |                        |
             V                        |
     +--------------+                 |
     |  Encryption  |                 |
     +--------------+                 |
             |                        |
             |                        |
             V                        V
   +--------------------------------------------------+
   |                      RTP                         |
   +--------------------------------------------------+

                      Figure 1: SCIP RTP Architecture

Hanson, et al.          Expires 30 September 2023               [Page 6]
Internet-Draft           SCIP RTP Payload Format              March 2023

      |  * Packetizer: Media codecs payloads are split into multiple RTP
      |  packets, if they exceed the MTU size, as defined in that media
      |  codec's RFC.  SCIP control messages are split into multiple RTP
      |  packets if they exceed the MTU size - the SCIP messages contain
      |  an overall message length field allowing segments to be
      |  reassembled by the receiver.

   As described above, the SCIP RTP payload format is highly variable
   and cannot be described in specificity in this document.  Details can
   be found in SCIP-210 [SCIP210].  SCIP will continue to evolve and as
   such the SCIP RTP traffic MUST NOT be filtered by network devices
   based upon what currently is observed or documented.  The focus of
   this document is for network devices to consider the SCIP RTP payload
   as opaque and allow it to traverse the network.  Network devices MUST
   NOT modify SCIP RTP packets.

4.1.  RTP Header Fields

   The SCIP RTP header fields SHALL conform to RFC 3550.

   SCIP traffic may be continuous or discontinuous.  The Timestamp field
   MUST increment based on the sampling clock for discontinuous
   transmission as described in [RFC3550], Section 5.1.  The Timestamp
   field for continuous transmission applications is dependent on the
   sampling rate of the media as specified in the media subtype's
   specification (e.g., MELPe [RFC8130]).  Note that during a SCIP
   session, both discontinuous and continuous traffic are highly
   probable.

   The Marker bit SHALL be set to zero for discontinuous traffic.  The
   Marker bit for continuous traffic is based on the underlying media
   subtype specification.  The underlying media is opaque within SCIP
   RTP packets.

5.  Payload Format Parameters

   The SCIP RTP payload format is identified using the scip media
   subtype, which is registered in accordance with [RFC4855] and per the
   media type registration template form [RFC6838].  A clock rate of
   8000 Hz SHALL be used for "audio/scip".  A clock rate of 90000 Hz
   SHALL be used for "video/scip".

5.1.  Media Subtype "audio/scip"

   Media type name: audio

   Media subtype name: scip

Hanson, et al.          Expires 30 September 2023               [Page 7]
Internet-Draft           SCIP RTP Payload Format              March 2023

   Required parameters: N/A

   Optional parameters: N/A

   Encoding considerations: Binary.  This media subtype is only defined
   for transfer via RTP.  There SHALL be no encoding/decoding
   (transcoding) of the audio stream as it traverses the network.

   Security considerations: See Section 6.

   Interoperability considerations: N/A

   Published specifications: [SCIP210]

   Applications which use this media: N/A

   Fragment Identifier considerations: none

   Restrictions on usage: N/A

   Additional information:

      1.  Deprecated alias names for this type: N/A

      2.  Magic number(s): N/A

      3.  File extension(s): N/A

      4.  Macintosh file type code: N/A

      5.  Object Identifiers: N/A

   Person to contact for further information:

      1.  Name: Michael Faller and Daniel Hanson

      2.  Email: michael.faller@gd-ms.com and dan.hanson@gd-ms.com

   Intended usage: Common, Government and Military

   Authors:

      Michael Faller - michael.faller@gd-ms.com

      Daniel Hanson - dan.hanson@gd-ms.com

   Change controller:

Hanson, et al.          Expires 30 September 2023               [Page 8]
Internet-Draft           SCIP RTP Payload Format              March 2023

      SCIP Working Group - ncia.cis3@ncia.nato.int

5.2.  Media Subtype "video/scip"

   Media type name: video

   Media subtype name: scip

   Required parameters: N/A

   Optional parameters: N/A

   Encoding considerations: Binary.  This media subtype is only defined
   for transfer via RTP.  There SHALL be no encoding/decoding
   (transcoding) of the video stream as it traverses the network.

   Security considerations: See Section 6.

   Interoperability considerations: N/A

   Published specifications: [SCIP210]

   Applications which use this media: N/A

   Fragment Identifier considerations: none

   Restrictions on usage: N/A

   Additional information:

      1.  Deprecated alias names for this type: N/A

      2.  Magic number(s): N/A

      3.  File extension(s): N/A

      4.  Macintosh file type code: N/A

      5.  Object Identifiers: N/A

   Person to contact for further information:

      1.  Name: Michael Faller and Daniel Hanson

      2.  Email: michael.faller@gd-ms.com and dan.hanson@gd-ms.com

   Intended usage: Common, Government and Military

Hanson, et al.          Expires 30 September 2023               [Page 9]
Internet-Draft           SCIP RTP Payload Format              March 2023

   Authors:

      Michael Faller - michael.faller@gd-ms.com

      Daniel Hanson - dan.hanson@gd-ms.com

   Change controller:

      SCIP Working Group - ncia.cis3@ncia.nato.int

5.3.  Mapping to SDP

   The mapping of the above defined payload format media subtype and its
   parameters SHALL be implemented according to Section 3 of [RFC4855].

   Since SCIP includes its own facilities for capabilities exchange, it
   is only necessary to negotiate the use of SCIP within SDP Offer/
   Answer; the specific codecs to be encapsulated within SCIP are then
   negotiated via the exchange of SCIP control messages.

   The information carried in the media type specification has a
   specific mapping to fields in the Session Description Protocol (SDP)
   [RFC8866], which is commonly used to describe RTP sessions.  When SDP
   is used to specify sessions employing the SCIP codec, the mapping is
   as follows:

   *  The media type ("audio") goes in SDP "m=" as the media name for
      audio/scip, and the media type ("video") goes in SDP "m=" as the
      media name for video/scip.

   *  The media subtype ("scip") goes in SDP "a=rtpmap" as the encoding
      name.  The required parameter "rate" also goes in "a=rtpmap" as
      the clock rate.

   *  The optional parameters "ptime" and "maxptime" go in the SDP
      "a=ptime" and "a=maxptime" attributes, respectively.

   An example mapping for audio/scip is:

     m=audio 50000 RTP/AVP 96
     a=rtpmap:96 scip/8000

   An example mapping for video/scip is:

     m=video 50002 RTP/AVP 97
     a=rtpmap:97 scip/90000

   An example mapping for both audio/scip and video/scip is:

Hanson, et al.          Expires 30 September 2023              [Page 10]
Internet-Draft           SCIP RTP Payload Format              March 2023

     m=audio 50000 RTP/AVP 96
     a=rtpmap:96 scip/8000
     m=video 50002 RTP/AVP 97
     a=rtpmap:97 scip/90000

   The application negotiation between endpoints will determine whether
   the audio and video streams are transported as separate streams over
   the audio and video payload types or as a single media stream on the
   video payload type.

5.4.  SDP Offer/Answer Considerations

   In accordance with the SDP Offer/Answer model [RFC3264], the SCIP
   device SHALL list the SCIP payload type number in order of preference
   in the "m" media line.

6.  Security Considerations

   RTP packets using the payload format defined in this specification
   are subject to the security considerations discussed in the RTP
   specification [RFC3550], and in any applicable RTP profile such as
   RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/
   SAVPF [RFC5124].  However, as "Securing the RTP Protocol Framework:
   Why RTP Does Not Mandate a Single Media Security Solution" [RFC7202]
   discusses, it is not an RTP payload format's responsibility to
   discuss or mandate what solutions are used to meet the basic security
   goals like confidentiality, integrity, and source authenticity for
   RTP in general.  This responsibility lays on anyone using RTP in an
   application.  They can find guidance on available security mechanisms
   and important considerations in "Options for Securing RTP Sessions"
   [RFC7201].  Applications SHOULD use one or more appropriate strong
   security mechanisms.  The rest of this Security Considerations
   section discusses the security impacting properties of the payload
   format itself.

   This RTP payload format and its media decoder do not exhibit any
   significant non-uniformity in the receiver-side computational
   complexity for packet processing, and thus do not inherently pose a
   denial-of-service threat due to the receipt of pathological data.
   Nor does the RTP payload format contain any active content.

7.  IANA Considerations

   The audio/scip and video/scip media subtypes have previously been
   registered with IANA [AUDIOSCIP] [VIDEOSCIP].  IANA should update
   [AUDIOSCIP] and [VIDEOSCIP] to reference this document upon
   publication.

Hanson, et al.          Expires 30 September 2023              [Page 11]
Internet-Draft           SCIP RTP Payload Format              March 2023

8.  SCIP Contact Information

   The SCIP protocol is maintained by the SCIP Working Group.

   SCIP Working Group, CIS3 Partnership
   NATO Communications and Information Agency
   Oude Waalsdorperweg 61, 2597AK
   The Hague, The Netherlands
   Email: ncia.cis3@ncia.nato.int

9.  References

9.1.  Normative References

   [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>.

   [RFC2736]  Handley, M. and C. Perkins, "Guidelines for Writers of RTP
              Payload Format Specifications", BCP 36, RFC 2736,
              DOI 10.17487/RFC2736, December 1999,
              <https://www.rfc-editor.org/info/rfc2736>.

   [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>.

   [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>.

   [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>.

   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol (SRTP)",
              RFC 3711, DOI 10.17487/RFC3711, March 2004,
              <https://www.rfc-editor.org/info/rfc3711>.

Hanson, et al.          Expires 30 September 2023              [Page 12]
Internet-Draft           SCIP RTP Payload Format              March 2023

   [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>.

   [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for
              Real-time Transport Control Protocol (RTCP)-Based Feedback
              (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
              2008, <https://www.rfc-editor.org/info/rfc5124>.

   [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>.

   [RFC8866]  Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
              Session Description Protocol", RFC 8866,
              DOI 10.17487/RFC8866, January 2021,
              <https://www.rfc-editor.org/info/rfc8866>.

9.2.  Informative References

   [AUDIOSCIP]
              Faller, M. and D. Hanson, "audio/scip: Internet Assigned
              Numbers Authority (IANA)", 28 January 2021,
              <https://www.iana.org/assignments/media-types/audio/scip>.

   [RFC4040]  Kreuter, R., "RTP Payload Format for a 64 kbit/s
              Transparent Call", RFC 4040, DOI 10.17487/RFC4040, April
              2005, <https://www.rfc-editor.org/info/rfc4040>.

   [RFC4855]  Casner, S., "Media Type Registration of RTP Payload
              Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
              <https://www.rfc-editor.org/info/rfc4855>.

   [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>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC7201]  Westerlund, M. and C. Perkins, "Options for Securing RTP
              Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
              <https://www.rfc-editor.org/info/rfc7201>.

Hanson, et al.          Expires 30 September 2023              [Page 13]
Internet-Draft           SCIP RTP Payload Format              March 2023

   [RFC7202]  Perkins, C. and M. Westerlund, "Securing the RTP
              Framework: Why RTP Does Not Mandate a Single Media
              Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
              2014, <https://www.rfc-editor.org/info/rfc7202>.

   [RFC8083]  Perkins, C. and V. Singh, "Multimedia Congestion Control:
              Circuit Breakers for Unicast RTP Sessions", RFC 8083,
              DOI 10.17487/RFC8083, March 2017,
              <https://www.rfc-editor.org/info/rfc8083>.

   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <https://www.rfc-editor.org/info/rfc8085>.

   [RFC8088]  Westerlund, M., "How to Write an RTP Payload Format",
              RFC 8088, DOI 10.17487/RFC8088, May 2017,
              <https://www.rfc-editor.org/info/rfc8088>.

   [RFC8130]  Demjanenko, V. and D. Satterlee, "RTP Payload Format for
              the Mixed Excitation Linear Prediction Enhanced (MELPe)
              Codec", RFC 8130, DOI 10.17487/RFC8130, March 2017,
              <https://www.rfc-editor.org/info/rfc8130>.

   [RMCAT]    IETF, "RTP Media Congestion Avoidance Techniques (rmcat)
              Working Group",
              <https://datatracker.ietf.org/wg/rmcat/about/>.

   [SCIP210]  SCIP Working Group, "SCIP Signaling Plan", SCIP-210,
              r3.10, October 2017.

   [VIDEOSCIP]
              Faller, M. and D. Hanson, "video/scip: Internet Assigned
              Numbers Authority (IANA)", 28 January 2021,
              <https://www.iana.org/assignments/media-types/video/scip>.

Authors' Addresses

   Daniel Hanson
   General Dynamics Mission Systems, Inc.
   150 Rustcraft Road
   Dedham, MA 02026
   United States of America
   Email: dan.hanson@gd-ms.com

Hanson, et al.          Expires 30 September 2023              [Page 14]
Internet-Draft           SCIP RTP Payload Format              March 2023

   Michael Faller
   General Dynamics Mission Systems, Inc.
   150 Rustcraft Road
   Dedham, MA 02026
   United States of America
   Email: michael.faller@gd-ms.com

   Keith Maver
   General Dynamics Mission Systems, Inc.
   150 Rustcraft Road
   Dedham, MA 02026
   United States of America
   Email: keith.maver@gd-ms.com

Hanson, et al.          Expires 30 September 2023              [Page 15]