Network Working Group S. Nandakumar Internet-Draft Cisco Intended status: Standards Track September 22, 2016 Expires: March 26, 2017 A Framework for SDP Attributes when Multiplexing draft-ietf-mmusic-sdp-mux-attributes-14 Abstract The purpose of this specification is to provide a framework for analyzing the multiplexing characteristics of Session Description Protocol (SDP) attributes when SDP is used to negotiate the usage of single 5-tuple for sending and receiving media associated with multiple media descriptions. This specification also categorizes the existing SDP attributes based on the framework described herein. 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 http://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 March 26, 2017. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://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 Nandakumar Expires March 26, 2017 [Page 1]
Internet-Draft SDP Attribute Multiplexing September 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 6 4.1. Category: NORMAL . . . . . . . . . . . . . . . . . . . . 7 4.2. Category: CAUTION . . . . . . . . . . . . . . . . . . . . 7 4.3. Category: IDENTICAL . . . . . . . . . . . . . . . . . . . 8 4.4. Category: SUM . . . . . . . . . . . . . . . . . . . . . . 8 4.5. Category: TRANSPORT . . . . . . . . . . . . . . . . . . . 9 4.6. Category: INHERIT . . . . . . . . . . . . . . . . . . . . 10 4.7. Category: IDENTICAL-PER-PT . . . . . . . . . . . . . . . 10 4.8. Category: SPECIAL . . . . . . . . . . . . . . . . . . . . 11 4.9. Category: TBD . . . . . . . . . . . . . . . . . . . . . . 11 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 12 5.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 12 5.2. RFC4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . . 14 5.3. RFC5761: Multiplexing RTP and RTCP . . . . . . . . . . . 14 5.4. RFC3312: Integration of Resource Management and SIP . . . 14 5.5. RFC4574: SDP Label Attribute . . . . . . . . . . . . . . 15 5.6. RFC5432: QOS Mechanism Selection in SDP . . . . . . . . . 15 5.7. RFC4568: SDP Security Descriptions . . . . . . . . . . . 16 5.8. RFC5762: RTP over DCCP . . . . . . . . . . . . . . . . . 16 5.9. RFC6773: DCCP-UDP Encapsulation . . . . . . . . . . . . . 17 5.10. RFC5506: Reduced-Size RTCP in RTP Profile . . . . . . . . 18 5.11. RFC6787: Media Resource Control Protocol Version 2 . . . 18 5.12. RFC5245: ICE . . . . . . . . . . . . . . . . . . . . . . 19 5.13. RFC5285: RTP Header Extensions . . . . . . . . . . . . . 20 5.14. RFC3605: RTCP attribute in SDP . . . . . . . . . . . . . 21 5.15. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 21 5.16. RFC7273: RTP Clock Source Signalling . . . . . . . . . . 22 5.17. RFC6236: Image Attributes in SDP . . . . . . . . . . . . 23 5.18. RFC7197: Duplication Delay Attribute in SDP . . . . . . . 24 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting . . . . 24 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions . . 24 5.21. RFC6230: Media Control Channel Framework . . . . . . . . 25 5.22. RFC6364: SDP Elements for FEC Framework . . . . . . . . . 25 5.23. RFC4796: Content Attribute . . . . . . . . . . . . . . . 26 5.24. RFC3407: SDP Simple Capability Declaration . . . . . . . 26 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP Sessions . . . . . . . . . . . . . . . . . . . . . . . . 27 5.26. RFC6714: MSRP-CEMA . . . . . . . . . . . . . . . . . . . 28 5.27. RFC4583: SDP Format for BFCP Streams . . . . . . . . . . 28 Nandakumar Expires March 26, 2017 [Page 2]
Internet-Draft SDP Attribute Multiplexing September 2016 5.28. RFC5547: SDP Offer/Answer for File Transfer . . . . . . . 29 5.29. RFC6849: SDP and RTP Media Loopback Extension . . . . . . 30 5.30. RFC5760: RTCP with Unicast Feedback . . . . . . . . . . . 30 5.31. RFC3611: RTCP XR . . . . . . . . . . . . . . . . . . . . 31 5.32. RFC5939: SDP Capability Negotiation . . . . . . . . . . . 31 5.33. RFC6871: SDP Media Capabilities Negotiation . . . . . . . 32 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP . . . 33 5.35. RFC4567: Key Management Extensions for SDP and RTSP . . . 34 5.36. RFC4572: Comedia over TLS in SDP . . . . . . . . . . . . 35 5.37. RFC4570: SDP Source Filters . . . . . . . . . . . . . . . 35 5.38. RFC6128: RTCP Port for Multicast Sessions . . . . . . . . 36 5.39. RFC6189: ZRTP . . . . . . . . . . . . . . . . . . . . . . 36 5.40. RFC4145: Connection-Oriented Media . . . . . . . . . . . 37 5.41. RFC6947: The SDP altc Attribute . . . . . . . . . . . . . 37 5.42. RFC7195: SDP Extension for Circuit Switched Bearers in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 38 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) . . . 38 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP Attributes . . . . . . . . . . . . . . . . . . . . . . . 39 5.45. RFC6193: Media Description for IKE in SDP . . . . . . . . 39 5.46. RFC2326: Real Time Streaming Protocol . . . . . . . . . . 40 5.47. RFC6064: SDP and RTSP Extensions for 3GPP . . . . . . . . 41 5.48. RFC3108: ATM SDP . . . . . . . . . . . . . . . . . . . . 43 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 45 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 46 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 46 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 47 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 47 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 48 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 50 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 50 5.57. RFC4975: The Message Session Relay Protocol . . . . . . . 51 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 52 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 52 6.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 53 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth . . . 53 6.3. RFC3890: Bandwidth Modifier for SDP . . . . . . . . . . . 54 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 54 7.1. RFC4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . . 54 7.2. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 55 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP Sessions (RAMS) . . . . . . . . . . . . . . . . . . . . . 56 7.4. RFC6679: ECN for RTP over UDP/IP . . . . . . . . . . . . 56 7.5. RFC6642: Third-Party Loss Report . . . . . . . . . . . . 57 7.6. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 58 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 58 8.1. RFC5888: SDP Grouping Framework . . . . . . . . . . . . . 58 8.2. RFC3524: Mapping Media Streams to Resource Nandakumar Expires March 26, 2017 [Page 3]
Internet-Draft SDP Attribute Multiplexing September 2016 Reservation Flows . . . . . . . . . . . . . . . . . . . . 59 8.3. RFC4091: ANAT Semantics . . . . . . . . . . . . . . . . . 59 8.4. RFC5956: FEC Grouping Semantics in SDP . . . . . . . . . 59 8.5. RFC5583: Signaling Media Decoding Dependency in SDP . . . 60 8.6. RFC7104: Duplication Grouping Semantics in the SDP . . . 60 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 61 9.1. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 61 9.2. RFC7104: Duplication Grouping Semantics in the SDP . . . 61 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 62 10.1. RFC5432: QoS Mechanism Selection in SDP . . . . . . . . 62 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 62 11.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 63 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 63 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 63 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 64 13.1. RFC5109: RTP Payload Format for Generic FEC . . . . . . 64 14. Multiplexing Considerations for Encapsulating Attributes . . 64 14.1. RFC3407: cpar Attribute Analysis . . . . . . . . . . . . 65 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 65 14.2.1. Recommendation: Procedures for Potential Configuration Pairing . . . . . . . . . . . . . . . 66 14.2.1.1. Example: Transport Capability Multiplexing . . . 67 14.2.1.2. Example: Attribute Capability Multiplexing . . . 68 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 69 14.3.1. Recommendation: Dealing with Payload Type Numbers . 69 14.3.1.1. Example: Attribute Capability Under Shared Payload Type . . . . . . . . . . . . . . . . . . 69 14.3.2. Recommendation: Dealing with Latent Configurations . 70 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 71 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 71 15.2. 'Mux Category' column for subregistries . . . . . . . . 72 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 72 15.2.2. Table: att-field (session level) . . . . . . . . . . 73 15.2.3. Table: att-field (both session and media level) . . 73 15.2.4. Table: att-field (media level only) . . . . . . . . 75 15.2.5. Table: att-field (source level) . . . . . . . . . . 78 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 79 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 79 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 80 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 80 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 80 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 81 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 81 15.2.13. Table: SDP/RTSP key management protocol identifiers 81 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 82 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 82 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 82 15.2.17. Table: Timestamp Reference Clock Source Parameters . 83 Nandakumar Expires March 26, 2017 [Page 4]
Internet-Draft SDP Attribute Multiplexing September 2016 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 83 16. Security Considerations . . . . . . . . . . . . . . . . . . . 84 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 84 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 84 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 87 19.1. Normative References . . . . . . . . . . . . . . . . . . 87 19.2. Informative References . . . . . . . . . . . . . . . . . 88 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 96 1. Introduction SDP defines several attributes for capturing characteristics that apply to the individual media descriptions (described by "m=" lines") and the overall multimedia session. Typically different media types (audio, video, etc.) described using different media descriptions represent separate RTP sessions that are carried over individual transport layer flows. However [I-D.ietf-mmusic-sdp-bundle-negotiation] defines a way to use a single address:port combination (BUNDLE address) for receiving media associated with multiple SDP media descriptions. This would, for example allow the usage of a single set of Interactive Connectivity Establishment (ICE) [RFC5245] candidates for multiple media descriptions. This in turn has made it necessary to understand the interpretation and usage of the SDP attributes defined for the multiplexed media descriptions. Given the number of SDP attributes registered with the [IANA] and possibility of new attributes being defined in the future, there is need for a framework to analyze these attributes for their applicability in the transport multiplexing use-cases. The document starts with providing the motivation for requiring such a framework. This is followed by introduction to the SDP attribute analysis framework/procedures, following which several sections apply the framework to the SDP attributes registered with the [IANA]. 2. Terminology 5-tuple: A collection of the following values: source address, source port, destination address, destination port, and transport-layer protocol. 3GPP: Third Generation Partnership Project; see http://www.3gpp.org for more information about this organization. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Nandakumar Expires March 26, 2017 [Page 5]
Internet-Draft SDP Attribute Multiplexing September 2016 3. Motivation The time and complications of setting up ICE [RFC5245] and Datagram Transport Layer Security (DTLS) based Secure Real-time Transport Protocol (SRTP) [RFC5763] transports for use by RTP, reasons to conserve ports bindings on the Network Address Translators (NAT), forms a requirement to try and reduce the number of transport level flows needed. This has resulted in the definition of ways, such as [I-D.ietf-mmusic-sdp-bundle-negotiation] to multiplex RTP over a single transport flow in order to preserve network resources such as port numbers. This imposes further restrictions on applicability of the SDP attributes as they are defined today. The specific problem is that there are attribute combinations which make sense when specified on independent "m=" lines -- as with classical SDP -- that do not make sense when those "m=" lines are then multiplexed over the same transport. To give an obvious example, ICE permits each "m=" line to have an independently specified ice-ufrag attribute. However, if the media from multiple "m=" lines is multiplexed over the same ICE component, then the meaning of media-level ice-ufrag attributes becomes muddled. At the time of writing this document there are close to 250 SDP attributes registered with the [IANA] and more will be added in the future. There is no clearly defined procedure to establish the validity/applicability of these attributes when used with transport multiplexing. 4. SDP Attribute Analysis Framework Attributes in an SDP session description can be defined at the session-level or media-level or source-level. Informally, there are various semantic groupings for these attributes. One such grouping could be notes as below: o Attributes related to media content such as media type, encoding schemes and payload types. o Attributes specifying media transport characteristics like RTP/RTP Control Protocol (RTCP) port numbers, network addresses and QOS. o Metadata description attributes capturing session timing and origin information. o Attributes establishing relationships between media descriptions such as grouping framework [RFC5888] Nandakumar Expires March 26, 2017 [Page 6]
Internet-Draft SDP Attribute Multiplexing September 2016 The proposed framework analyzes the SDP attributes usage under multiplexing and assigns each SDP attribute to an appropriate multiplexing category. Since the multiplexing categories defined in this specification are independent of any informal semantic groupings of the SDP attributes, the categorizations assigned are normative. 4.1. Category: NORMAL The attributes in the NORMAL category can be independently specified when multiplexed and they retain their original semantics. In the example given below, the direction and label attributes are independently specified for audio and video "m=" lines. These attributes are not impacted by multiplexing these media streams over a single transport layer flow. v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 m=audio 49172 RTP/AVP 99 a=sendonly a=label:1 a=rtpmap:99 iLBC/8000 m=video 49172 RTP/AVP 31 a=recvonly a=label:2 a=rtpmap:31 H261/90000 4.2. Category: CAUTION The attributes in the CAUTION category are advised against multiplexing since their usage under multiplexing might lead to incorrect behavior. Example: Multiplexing media descriptions over a single Datagram Congestion Control Protocol (DCCP) transport [RFC5762] is not recommended since DCCP being a connection oriented protocol doesn't allow multiple connections on the same 5-tuple. Nandakumar Expires March 26, 2017 [Page 7]
Internet-Draft SDP Attribute Multiplexing September 2016 v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s= c=IN IP4 client.biloxi.example.com t=0 0 m=video 5004 DCCP/RTP/AVP 99 a=rtpmap:99 h261/9000 a=dccp-service-code:SC=x52545056 a=setup:passive a=connection:new m=video 5004 DCCP/RTP/AVP 100 a=rtpmap:100 h261/9000 a=dccp-service-code:SC=x5254504f a=setup:passive a=connection:new 4.3. Category: IDENTICAL The attributes and their associated values (if any) in the IDENTICAL category MUST be repeated across all the media descriptions under multiplexing. Attributes such as rtcp-mux fall into this category. Since RTCP reporting is done per RTP session, RTCP Multiplexing MUST be enabled for both the audio and video "m=" lines if they are transported over a single 5-tuple. v=0 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com s= c=IN IP4 client.biloxi.example.com t=0 0 m=audio 34567 RTP/AVP 97 a=rtcp-mux m=video 34567 RTP/AVP 31 a=rtpmap:31 H261/90000 a=rtcp-mux 4.4. Category: SUM The attributes in the SUM category can be set as they are normally used but software using them in the multiplexing scenario MUST apply the sum of all the attributes being multiplexed instead of trying to use them independently. This is typically used for bandwidth or other rate limiting attributes to the underlying transport. The software parsing the SDP sample below, should use the aggregate Application Specific (AS) bandwidth value from the individual media Nandakumar Expires March 26, 2017 [Page 8]
Internet-Draft SDP Attribute Multiplexing September 2016 descriptions to determine the AS value for the multiplexed session. Thus the calculated AS value would be 256+64 kilobits per second for the given example. v=0 o=test 2890844526 2890842807 IN IP4 client.biloxi.example.com c=IN IP4 client.biloxi.example.com t=0 0 m=audio 49170 RTP/AVP 0 b=AS:64 m=video 51372 RTP/AVP 31 b=AS:256 4.5. Category: TRANSPORT The attributes in the TRANSPORT category can be set normally for multiple items in a multiplexed group but the software MUST pick the one that's associated with the "m=" line whose information is used for setting up the underlying transport. In the example below, "a=crypto" attribute is defined for both the audio and the video "m=" lines. The video media line's a=crypto attribute is chosen since its mid value (bar) appears first in the a=group:BUNDLE line. This is due to BUNDLE grouping semantic [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values from "m=" line corresponding to the mid appearing first on the a=group:BUNDLE line to be considered for setting up the RTP Transport. v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 a=group:BUNDLE bar foo m=audio 49172 RTP/AVP 99 a=mid:foo a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 a=rtpmap:99 iLBC/8000 m=video 51374 RTP/AVP 31 a=mid:bar a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 a=rtpmap:96 H261/90000 Nandakumar Expires March 26, 2017 [Page 9]
Internet-Draft SDP Attribute Multiplexing September 2016 4.6. Category: INHERIT The attributes in the INHERIT category encapsulate other SDP attributes or parameters. These attributes inherit their multiplexing characteristics from the attributes or parameters they encapsulate. Such attributes are defined in [RFC3407], [RFC5939] and [RFC6871] as part of a generic framework for indicating and negotiating transport, media, and media format related capabilities in the SDP. The inheritance manifests itself when the encapsulated attribute or parameter is being leveraged. In the case of SDP Capability Negotiation [RFC5939] for example, this occurs when a capability (encapsulating attribute) is used as part of a configuration; the configuration inherits the multiplexing category of each of its constituent (encapsulated) attributes and parameters. The inherited attributes MUST be coherent in order to form a valid configuration from a multiplexing point of view (see Section 14 for further details). v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 m=video 3456 RTP/AVP 100 a=rtpmap:100 VP8/90000 a=fmtp:100 max-fr=30;max-fs=8040 a=sqn: 0 a=cdsc: 1 video RTP/AVP 100 a=cpar: a=rtcp-mux m=video 3456 RTP/AVP 101 a=rtpmap:101 VP8/90000 a=fmtp:100 max-fr=15;max-fs=1200 a=cdsc: 2 video RTP/AVP 101 a=cpar: a=rtcp-mux In the above example, the category IDENTICAL is inherited by the cpar encapsulated rtcp-mux attribute. 4.7. Category: IDENTICAL-PER-PT The attributes in the IDENTICAL-PER-PT category define the RTP payload configuration on per Payload Type basis and MUST have identical values across all the media descriptions for a given RTP Payload Type when repeated. These Payload Types identify the same codec configuration as defined in the Section 10.1.2 of [I-D.ietf-mmusic-sdp-bundle-negotiation] under this context. Nandakumar Expires March 26, 2017 [Page 10]
Internet-Draft SDP Attribute Multiplexing September 2016 In the SDP example below, Payload Types 96 and 97 are repeated across all the video "m=" lines and all the payload specific parameters (ex: rtpmap, fmtp) are identical (Note: some line breaks included are due to formatting only). v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 a=group:BUNDLE cam1 cam2 m=video 96 97 a=mid:cam1 a=rtpmap:96 H264/90000 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; max-mbps=108000; max-br=1000 a=rtpmap:97 H264/90000 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; max-mbps=7200; max-br=200 m=video 96 97 a=mid:cam2 a=rtpmap:96 H264/90000 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; max-mbps=108000; max-br=1000 a=rtpmap:97 H264/90000 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; max-mbps=7200; max-br=200 4.8. Category: SPECIAL For the attributes in the SPECIAL category, the text in the specification defining the attribute MUST be consulted for further handling when multiplexed. As an exampe, for the attribute extmap [RFC5285], the specification defining the extension needs to be referred to understand the multiplexing implications. 4.9. Category: TBD The attributes in the TBD category have not been analyzed under the proposed multiplexing framework and SHOULD NOT be multiplexed. Nandakumar Expires March 26, 2017 [Page 11]
Internet-Draft SDP Attribute Multiplexing September 2016 5. Analysis of Existing Attributes This section analyzes attributes listed in [IANA], grouped under the IETF document that defines them. The "Level" column indicates whether the attribute is currently specified as: o S -- Session level o M -- Media level o B -- Both o SR -- Source-level (for a single SSRC) [RFC5576] The "Mux Category" column identifies multiplexing category assigned per attribute and the "Notes" column captures additional informative details regarding the assigned category, wherever necessary. 5.1. RFC4566: SDP [RFC4566] defines SDP that is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. +-----------------+---------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +-----------------+---------------------+-------+-------------------+ | sendrecv | Not impacted | B | NORMAL | | | | | | | sendonly | Not impacted | B | NORMAL | | | | | | | recvonly | Not impacted | B | NORMAL | | | | | | | inactive | Not impacted | B | NORMAL | | | | | | | cat | Not impacted | S | NORMAL | | | | | | | ptime | The attribute value | M | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | | | | | | | maxptime | The attribute value | M | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | Nandakumar Expires March 26, 2017 [Page 12]
Internet-Draft SDP Attribute Multiplexing September 2016 | | | | | | orient | Not Impacted | M | NORMAL | | | | | | | framerate | The attribute value | M | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | | | | | | | quality | Not Impacted | M | NORMAL | | | | | | | rtpmap | The attribute value | M | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | | | | | | | fmtp | The attribute value | M | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | | | | | | | keywds | Not impacted | S | NORMAL | | | | | | | type | Not Impacted | S | NORMAL | | | | | | | type:broadcast | Not Impacted | S | NORMAL | | | | | | | type:H332 | Not Impacted | S | NORMAL | | | | | | | type:meeting | Not Impacted | S | NORMAL | | | | | | | type:moderated | Not Impacted | S | NORMAL | | | | | | | type:test | Not Impacted | S | NORMAL | | | | | | | tool | Not Impacted | S | NORMAL | | | | | | | charset | Not Impacted | S | NORMAL | | | | | | | sdplang | Not Impacted | B | NORMAL | | | | | | | lang | Not Impacted | B | NORMAL | | | | | | +-----------------+---------------------+-------+-------------------+ 5.1 RFC4566 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 13]
Internet-Draft SDP Attribute Multiplexing September 2016 5.2. RFC4585: RTP/AVPF [RFC4585] defines an extension to the Audio-visual Profile (AVP) that enables receivers to provide, statistically, more immediate feedback to the senders and thus allows for short-term adaptation and efficient feedback-based repair mechanisms to be implemented. +----------+----------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +----------+----------------------------+-------+-------------------+ | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT | | | attributes are Payload | | | | | Type (PT) scoped, their | | | | | values MUST be identical | | | | | for a given PT across the | | | | | multiplexed "m=" lines. | | | | | | | | +----------+----------------------------+-------+-------------------+ 5.2 RFC4585 Attribute Analysis 5.3. RFC5761: Multiplexing RTP and RTCP [RFC5761] discusses issues that arise when multiplexing RTP data packets and RTP Control Protocol (RTCP) packets on a single UDP port. It describes when such multiplexing is and is not appropriate, and it explains how the SDP can be used to signal multiplexed sessions. +-----------+----------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-----------+----------------------------------+-------+------------+ | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL | | | affects the entire RTP session | | | | | | | | +-----------+----------------------------------+-------+------------+ 5.3 RFC5761 Attribute Analysis 5.4. RFC3312: Integration of Resource Management and SIP [RFC3312] defines a generic framework for preconditions, which are extensible through IANA registration. This document also discusses how network quality of service can be made a precondition for establishment of sessions initiated by the Session Initiation Protocol (SIP). These preconditions require that the participant reserve network resources before continuing with the session. Nandakumar Expires March 26, 2017 [Page 14]
Internet-Draft SDP Attribute Multiplexing September 2016 +-------+-----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-------+-----------------------+-------+--------------+ | des | Refer to notes below | M | CAUTION | | | | | | | conf | Refer to notes below | M | CAUTION | | | | | | | curr | Refer to notes below | M | CAUTION | | | | | | +-------+-----------------------+-------+--------------+ 5.4 RFC3312 Attribute Analysis NOTE: A mismatched set of preconditions across media descriptions results in Session establishment failures due to inability to meet right resource reservations requested. 5.5. RFC4574: SDP Label Attribute [RFC4574] defines a new SDP media-level attribute: "label". The "label" attribute carries a pointer to a media stream in the context of an arbitrary network application that uses SDP. The sender of the SDP document can attach the "label" attribute to a particular media stream or streams. The application can then use the provided pointer to refer to each particular media stream in its context. +--------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +--------+---------------+-------+--------------+ | label | Not Impacted | M | NORMAL | | | | | | +--------+---------------+-------+--------------+ 5.5 RFC4574 Attribute Analysis 5.6. RFC5432: QOS Mechanism Selection in SDP [RFC5432] defines procedures to negotiate QOS mechanisms using the SDP offer/answer model. Nandakumar Expires March 26, 2017 [Page 15]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------------+-----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +----------------+-----------------------+-------+--------------+ | qos-mech-send | Refer to Section 10 | B | TRANSPORT | | | | | | | qos-mech-recv | Refer to Section 10 | B | TRANSPORT | | | | | | +----------------+-----------------------+-------+--------------+ 5.6 RFC5432 Attribute Analysis 5.7. RFC4568: SDP Security Descriptions [RFC4568] defines a SDP cryptographic attribute for unicast media streams. The attribute describes a cryptographic key and other parameters that serve to configure security for a unicast media stream in either a single message or a roundtrip exchange. +---------+------------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +---------+------------------------------------+-------+------------+ | crypto | crypto attribute MUST be the one | M | TRANSPORT | | | that corresponds to the "m=" line | | | | | chosen for setting up the | | | | | underlying transport flow | | | | | | | | +---------+------------------------------------+-------+------------+ 5.7 RFC4568 Attribute Analysis 5.8. RFC5762: RTP over DCCP RTP is a widely used transport for real-time multimedia on IP networks. DCCP is a transport protocol that provides desirable services for real-time applications. [RFC5762] specifies a mapping of RTP onto DCCP, along with associated signaling, such that real- time applications can make use of the services provided by DCCP. Nandakumar Expires March 26, 2017 [Page 16]
Internet-Draft SDP Attribute Multiplexing September 2016 +--------------------+-------------------------+---------+----------+ | Name | Notes | Current | Mux | | | | | Category | +--------------------+-------------------------+---------+----------+ | dccp-service-code | If RFC6773 is not being | M | CAUTION | | | used in addition to | | | | | RFC5762, the port in | | | | | the "m=" line is a DCCP | | | | | port. DCCP being a | | | | | connection oriented | | | | | protocol does not allow | | | | | multiple connections on | | | | | the same 5-tuple | | | | | | | | +--------------------+-------------------------+---------+----------+ 5.8 RFC5762 Attribute Analysis NOTE: If RFC6773 is being used in addition to RFC5762 and provided that DCCP-in-UDP layer has additional demultiplexing, then it can be possible to use different DCCP service codes for each DCCP flow, given each uses a different DCCP port. Although doing so might conflict with the media type of the "m=" line. None of this is standardized yet and it wouldn't work as explained. Hence performing multiplexing is not recommended even in this alternate scenario. 5.9. RFC6773: DCCP-UDP Encapsulation [RFC6773] specifies an alternative encapsulation of DCCP, referred to as DCCP-UDP. This encapsulation allows DCCP to be carried through the current generation of Network Address Translation (NAT) middle boxes without modification of those middle boxes. +------------+-----------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------------+-----------------------------------+-------+----------+ | dccp-port | Multiplexing is not recommended | M | CAUTION | | | due to potential conflict between | | | | | the port used for DCCP | | | | | en/decapsulation and the RTP | | | | | | | | +------------+-----------------------------------+-------+----------+ 5.9 RFC6773 Attribute Analysis NOTE: RFC6773 is about tunneling DCCP in UDP, with the UDP port being the port of the DCCP en-/de-capsulation service. This encapsulation Nandakumar Expires March 26, 2017 [Page 17]
Internet-Draft SDP Attribute Multiplexing September 2016 allows arbitrary DCCP packets to be encapsulated and the DCCP port chosen can conflict with the port chosen for the RTP traffic. For multiplexing several DCCP-in-UDP encapsulations on the same UDP port with no RTP traffic on the same port implies collapsing several DCCP port spaces together. This can or cannot work depending on the nature of DCCP encapsulation and ports choices thus rendering it to be very application dependent. 5.10. RFC5506: Reduced-Size RTCP in RTP Profile [RFC5506] discusses benefits and issues that arise when allowing RTCP packets to be transmitted with reduced size. +-------------+--------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------------+--------------------------------+-------+------------+ | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL | | | entire RTP session | | | | | | | | +-------------+--------------------------------+-------+------------+ 5.10 RFC5506 Attribute Analysis 5.11. RFC6787: Media Resource Control Protocol Version 2 The Media Resource Control Protocol Version 2 (MRCPv2) allows client hosts to control media service resources such as speech synthesizers, recognizers, verifiers, and identifiers residing in servers on the network. MRCPv2 is not a "stand-alone" protocol -- it relies on other protocols, such as the SIP, to coordinate MRCPv2 clients and servers, and manage session between them, and SDP to describe, discover, and exchange capabilities. It also depends on SIP and SDP to establish the media sessions and associated parameters between the media source or sink and the media server. Once this is done, the MRCPv2 exchange operates over the control session established above, allowing the client to control the media processing resources on the speech resource server. [RFC6787] defines attributes for this purpose. Nandakumar Expires March 26, 2017 [Page 18]
Internet-Draft SDP Attribute Multiplexing September 2016 +-----------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-----------+---------------+-------+--------------+ | resource | Not Impacted | M | NORMAL | | | | | | | channel | Not Impacted | M | NORMAL | | | | | | | cmid | Not Impacted | M | NORMAL | | | | | | +-----------+---------------+-------+--------------+ 5.11 RFC6787 Attribute Analysis 5.12. RFC5245: ICE [RFC5245] describes a protocol for NAT traversal for UDP-based multimedia sessions established with the offer/answer model. ICE makes use of the Session Traversal Utilities for NAT (STUN) protocol and its extension, Traversal Using Relay NAT (TURN). ICE can be used by any protocol utilizing the offer/answer model, such as the SIP. Nandakumar Expires March 26, 2017 [Page 19]
Internet-Draft SDP Attribute Multiplexing September 2016 +--------------------+-------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +--------------------+-------------------------+-------+------------+ | ice-lite | Not Impacted | S | NORMAL | | | | | | | ice-options | Not Impacted | S | NORMAL | | | | | | | ice-mismatch | Not Impacted | S | NORMAL | | | | | | | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT | | | that corresponds to the | | | | | "m=" line chosen for | | | | | setting up the | | | | | underlying transport | | | | | flow | | | | | | | | | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | | | one that corresponds to | | | | | the "m=" line chosen | | | | | for setting up the | | | | | underlying transport | | | | | flow | | | | | | | | | candidate | ice candidate MUST be | M | TRANSPORT | | | the one that | | | | | corresponds to the "m=" | | | | | line chosen for setting | | | | | up the underlying | | | | | transport flow | | | | | | | | | remote-candidates | ice remote candidate | M | TRANSPORT | | | MUST be the one that | | | | | corresponds to the "m=" | | | | | line chosen for setting | | | | | up the underlying | | | | | transport flow | | | | | | | | +--------------------+-------------------------+-------+------------+ 5.12 RFC5245 Attribute Analysis 5.13. RFC5285: RTP Header Extensions [RFC5285] provides a general mechanism to use the header extension feature of RTP. It provides the option to use a small number of small extensions in each RTP packet, where the universe of possible extensions is large and registration is de-centralized. The actual Nandakumar Expires March 26, 2017 [Page 20]
Internet-Draft SDP Attribute Multiplexing September 2016 extensions in use in a session are signaled in the setup information for that session. +---------+--------------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +---------+--------------------------------------+-------+----------+ | extmap | Refer to the document defining the | B | SPECIAL | | | specific RTP Extension | | | | | | | | +---------+--------------------------------------+-------+----------+ 5.13 RFC5285 Attribute Analysis 5.14. RFC3605: RTCP attribute in SDP Originally, SDP assumed that RTP and RTCP were carried on consecutive ports. However, this is not always true when NATs are involved. [RFC3605] specifies an early mechanism to indicate the RTCP port. +-------+--------------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------+--------------------------------------+-------+------------+ | rtcp | RTCP Port MUST be the one that | M | TRANSPORT | | | corresponds to the "m=" line chosen | | | | | for setting up the underlying | | | | | transport flow. | | | | | | | | +-------+--------------------------------------+-------+------------+ 5.14 RFC3605 Attribute Analysis 5.15. RFC5576: Source-Specific SDP Attributes [RFC5576] defines a mechanism to describe RTP media sources, which are identified by their synchronization source (SSRC) identifiers, in SDP, to associate attributes with these sources, and to express relationships among sources. It also defines several source-level attributes that can be used to describe properties of media sources. Nandakumar Expires March 26, 2017 [Page 21]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------------+----------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +----------------+----------------------+-------+-------------------+ | ssrc | Refer to Notes below | M | NORMAL | | | | | | | ssrc-group | Refer to Section 9 | M | NORMAL | | | for specific | | | | | analysis of the | | | | | grouping semantics | | | | | | | | | cname | Not Impacted | SR | NORMAL | | | | | | | previous-ssrc | Refer to notes below | SR | NORMAL | | | | | | | fmtp | The attribute value | SR | IDENTICAL-PER-PT | | | MUST be same for a | | | | | given codec | | | | | configuration | | | | | | | | +----------------+----------------------+-------+-------------------+ 5.15 RFC5576 Attribute Analysis NOTE: If SSRCs are repeated across "m=" lines being multiplexed, they MUST all represent the same underlying RTP Source. 5.16. RFC7273: RTP Clock Source Signalling [RFC7273] specifies SDP signalling that identifies timestamp reference clock sources and SDP signalling that identifies the media clock sources in a multimedia session. Nandakumar Expires March 26, 2017 [Page 22]
Internet-Draft SDP Attribute Multiplexing September 2016 +--------------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +--------------------+---------------+-------+--------------+ | ts-refclk | Not Impacted | B | NORMAL | | | | | | | mediaclk | Not Impacted | B | NORMAL | | | | | | | ts-refclk:ntp | Not Impacted | B | NORMAL | | | | | | | ts-refclk:ptp | Not Impacted | B | NORMAL | | | | | | | ts-refclk:gps | Not Impacted | B | NORMAL | | | | | | | ts-refclk:gal | Not Impacted | B | NORMAL | | | | | | | ts-refclk:glonass | Not Impacted | B | NORMAL | | | | | | | ts-refclk:local | Not Impacted | B | NORMAL | | | | | | | ts-refclk:private | Not Impacted | B | NORMAL | | | | | | | mediaclk:sender | Not Impacted | B | NORMAL | | | | | | | mediaclk:direct | Not Impacted | B | NORMAL | | | | | | | mediaclk:IEEE1722 | Not Impacted | B | NORMAL | | | | | | +--------------------+---------------+-------+--------------+ 5.16 RFC7273 Attribute Analysis 5.17. RFC6236: Image Attributes in SDP [RFC6236] proposes a new generic session setup attribute to make it possible to negotiate different image attributes such as image size. A possible use case is to make it possible for a low-end hand-held terminal to display video without the need to rescale the image, something that may consume large amounts of memory and processing power. The document also helps to maintain an optimal bitrate for video as only the image size that is desired by the receiver is transmitted. Nandakumar Expires March 26, 2017 [Page 23]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+--------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +------------+--------------------------+-------+-------------------+ | imageattr | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given | | | | | codec configuration | | | | | | | | +------------+--------------------------+-------+-------------------+ 5.17 RFC6236 Attribute Analysis 5.18. RFC7197: Duplication Delay Attribute in SDP [RFC7197] defines an attribute to indicate the presence of temporally redundant media streams and the duplication delay in SDP. +--------------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +--------------------+---------------+-------+--------------+ | duplication-delay | Not Impacted | B | NORMAL | | | | | | +--------------------+---------------+-------+--------------+ 5.18 RFC7197 Attribute Analysis 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting [RFC7266] defines an RTCP Extended Report (XR) Block including two new segment types and associated SDP parameters that allow the reporting of mean opinion score (MOS) Metrics for use in a range of RTP applications. +-------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-------------+---------------+-------+--------------+ | calgextmap | Not Impacted | B | NORMAL | | | | | | +-------------+---------------+-------+--------------+ 5.19 RFC7266 Attribute Analysis 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions [RFC6285] describes a method using the existing RTP and RTCP machinery that reduces the acquisition delay. In this method, an auxiliary unicast RTP session carrying the Reference Information to the receiver precedes or accompanies the multicast stream. This unicast RTP flow can be transmitted at a faster than natural bitrate Nandakumar Expires March 26, 2017 [Page 24]
Internet-Draft SDP Attribute Multiplexing September 2016 to further accelerate the acquisition. The motivating use case for this capability is multicast applications that carry real-time compressed audio and video. +---------------+-------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------------+-------------------+-------+--------------+ | rams-updates | Not recommended | M | CAUTION | | | | | | +---------------+-------------------+-------+--------------+ 5.20 RFC6285 Attribute Analysis 5.21. RFC6230: Media Control Channel Framework [RFC6230] describes a framework and protocol for application deployment where the application programming logic and media processing are distributed. This implies that application programming logic can seamlessly gain access to appropriate resources that are not co-located on the same physical network entity. The framework uses SIP to establish an application-level control mechanism between application servers and associated external servers such as media servers. +---------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------+---------------+-------+--------------+ | cfw-id | Not Impacted | M | NORMAL | | | | | | +---------+---------------+-------+--------------+ 5.21 RFC6230 Attribute Analysis 5.22. RFC6364: SDP Elements for FEC Framework [RFC6364] specifies the use of SDP to describe the parameters required to signal the Forward Error Correction (FEC) Framework Configuration Information between the sender(s) and receiver(s). This document also provides examples that show the semantics for grouping multiple source and repair flows together for the applications that simultaneously use multiple instances of the FEC Framework. Nandakumar Expires March 26, 2017 [Page 25]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------------+-----------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------------------+-----------------------------+-------+----------+ | fec-source-flow | Refer to the document | M | SPECIAL | | | defining specific FEC | | | | | Scheme | | | | | | | | | fec-repair-flow | Refer to the document | M | SPECIAL | | | defining specific FEC | | | | | Scheme | | | | | | | | | repair-window | Refer to the document | M | SPECIAL | | | defining specific FEC | | | | | Scheme | | | | | | | | +------------------+-----------------------------+-------+----------+ 5.22 RFC6364 Attribute Analysis 5.23. RFC4796: Content Attribute [RFC4796] defines a new SDP media-level attribute, 'content'. The 'content' attribute defines the content of the media stream to a more detailed level than the media description line. The sender of an SDP session description can attach the 'content' attribute to one or more media streams. The receiving application can then treat each media stream differently (e.g., show it on a big or small screen) based on its content. +----------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +----------+---------------+-------+--------------+ | content | Not Impacted | M | NORMAL | | | | | | +----------+---------------+-------+--------------+ 5.23 RFC4796 Attribute Analysis 5.24. RFC3407: SDP Simple Capability Declaration [RFC3407] defines a set of SDP attributes that enables SDP to provide a minimal and backwards compatible capability declaration mechanism. Nandakumar Expires March 26, 2017 [Page 26]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------+------------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +----------+------------------------+-------+--------------+ | sqn | Not Impacted | B | NORMAL | | | | | | | cdsc | Not Impacted. | B | NORMAL | | | | | | | cpar | Refer to Section 14 | B | INHERIT | | | | | | | cparmin | Refer to notes below | B | SPECIAL | | | | | | | cparmax | Refer to notes below | B | SPECIAL | | | | | | +----------+------------------------+-------+--------------+ 5.24 RFC3407 Attribute Analysis NOTE: The attributes (a=cparmin and a=cparmax) define minimum and maximum numerical values associated with the attributes described in a=cpar. Since the cpar attribute can either define a 'b=' attribute or any 'a=' attribute, the multiplexing category depends on actual attribute being encapsulated and the implications of the numerical values assigned. Hence it is recommended to consult the specification defining attributes (cparmin/cparmax) to further analyze their behavior under multiplexing. 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP Sessions [RFC6284] presents a port mapping solution that allows RTP receivers to choose their own ports for an auxiliary unicast session in RTP applications using both unicast and multicast services. The solution provides protection against denial-of-service or packet amplification attacks that could be used to cause one or more RTP packets to be sent to a victim client. +------------------+-----------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------------------+-----------------------------+-------+----------+ | portmapping-req | Not recommended, if port | M | CAUTION | | | mapping is required by the | | | | | application | | | | | | | | +------------------+-----------------------------+-------+----------+ 5.25 RFC6284 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 27]
Internet-Draft SDP Attribute Multiplexing September 2016 5.26. RFC6714: MSRP-CEMA [RFC6714] defines a Message Session Relay Protocol (MSRP) extension, Connection Establishment for Media Anchoring (CEMA). Support of this extension is optional. The extension allows middle boxes to anchor the MSRP connection, without the need for middle boxes to modify the MSRP messages; thus, it also enables secure end-to-end MSRP communication in networks where such middle boxes are deployed. This document also defines a SDP attribute, 'msrp-cema', that MSRP endpoints use to indicate support of the CEMA extension. +------------+-----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+-----------------------+-------+--------------+ | msrp-cema | Refer to notes below | M | TBD | | | | | | +------------+-----------------------+-------+--------------+ 5.26 RFC6714 Attribute Analysis NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], there exists no publicly available specification that defines procedures for multiplexing/demultiplexing MRSP flows over a single 5-tuple. Once such a specification is available, the multiplexing categories assignments for the attributes in this section could be revisited. 5.27. RFC4583: SDP Format for BFCP Streams [RFC4583] document specifies how to describe Binary Floor Control Protocol (BFCP) streams in SDP descriptions. User agents using the offer/answer model to establish BFCP streams use this format in their offers and answers. Nandakumar Expires March 26, 2017 [Page 28]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+---------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +------------+---------------------------------+-------+------------+ | floorctrl | The attribute MUST be repeated | M | IDENTICAL | | | across all the multiplexed "m=" | | | | | lines | | | | | | | | | confid | Not Impacted | M | NORMAL | | | | | | | userid | Not Impacted | M | NORMAL | | | | | | | floorid | Not Impacted | M | NORMAL | | | | | | +------------+---------------------------------+-------+------------+ 5.27 RFC4583 Attribute Analysis 5.28. RFC5547: SDP Offer/Answer for File Transfer [RFC5547] provides a mechanism to negotiate the transfer of one or more files between two endpoints by using the SDP offer/answer model specified in [RFC3264]. +-------------------+-----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-------------------+-----------------------+-------+--------------+ | file-selector | Refer to notes below | M | TBD | | | | | | | file-transfer-id | Refer to notes below | M | TBD | | | | | | | file-disposition | Refer to notes below | M | TBD | | | | | | | file-date | Refer to notes below | M | TBD | | | | | | | file-icon | Refer to notes below | M | TBD | | | | | | | file-range | Refer to notes below | M | TBD | | | | | | +-------------------+-----------------------+-------+--------------+ 5.28 RFC5547 Attribute Analysis NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], there exists no publicly available specification that defines procedures for multiplexing/demultiplexing MRSP flows over a single 5-tuple. Once such a specification is available, the multiplexing Nandakumar Expires March 26, 2017 [Page 29]
Internet-Draft SDP Attribute Multiplexing September 2016 categories assignments for attributes in this section could be revisited. 5.29. RFC6849: SDP and RTP Media Loopback Extension [RFC6849] adds new SDP media types and attributes, which enable establishment of media sessions where the media is looped back to the transmitter. Such media sessions will serve as monitoring and troubleshooting tools by providing the means for measurement of more advanced Voice over IP (VoIP), Real-time Text, and Video over IP performance metrics. +---------------------+-----------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +---------------------+-----------------+-------+-------------------+ | loopback rtp-pkt- | The attribute | M | IDENTICAL-PER-PT | | loopback | value MUST be | | | | | same for a | | | | | given codec | | | | | configuration | | | | | | | | | loopback rtp-media- | The attribute | M | IDENTICAL-PER-PT | | loopback | value MUST be | | | | | same for a | | | | | given codec | | | | | configuration | | | | | | | | | loopback-source | Not Impacted | M | NORMAL | | | | | | | loopback-mirror | Not Impacted | M | NORMAL | | | | | | +---------------------+-----------------+-------+-------------------+ 5.29 RFC6849 Analysis 5.30. RFC5760: RTCP with Unicast Feedback [RFC5760] specifies an extension to RTCP to use unicast feedback to a multicast sender. The proposed extension is useful for single-source multicast sessions such as Source-Specific Multicast (SSM) communication where the traditional model of many-to-many group communication is either not available or not desired. Nandakumar Expires March 26, 2017 [Page 30]
Internet-Draft SDP Attribute Multiplexing September 2016 +---------------+------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +---------------+------------------------------+-------+------------+ | rtcp-unicast | The attribute MUST be | M | IDENTICAL | | | reported across all "m=" | | | | | lines multiplexed | | | | | | | | +---------------+------------------------------+-------+------------+ 5.30 RFC5760 Attribute Analysis 5.31. RFC3611: RTCP XR [RFC3611] defines the Extended Report (XR) packet type for RTCP, and defines how the use of XR packets can be signaled by an application if it employs the Session Description Protocol (SDP). +----------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +----------+---------------+-------+--------------+ | rtcp-xr | Not Impacted | B | NORMAL | | | | | | +----------+---------------+-------+--------------+ 5.31 RFC3611 Attribute Analysis 5.32. RFC5939: SDP Capability Negotiation [RFC5939] defines a general SDP Capability Negotiation framework. It also specifies how to provide attributes and transport protocols as capabilities and negotiate them using the framework. Extensions for other types of capabilities (e.g., media types and media formats) may be provided in other documents. Nandakumar Expires March 26, 2017 [Page 31]
Internet-Draft SDP Attribute Multiplexing September 2016 +---------+-----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------+-----------------------+-------+--------------+ | pcfg | Refer to Section 14 | M | SPECIAL | | | | | | | acfg | Refer to Section 14 | M | SPECIAL | | | | | | | csup | Not Impacted | B | NORMAL | | | | | | | creq | Not Impacted | B | NORMAL | | | | | | | acap | Refer to Section 14 | B | INHERIT | | | | | | | tcap | Refer to Section 14 | B | INHERIT | | | | | | | cap-v0 | Not Impacted | B | NORMAL | | | | | | +---------+-----------------------+-------+--------------+ 5.32 RFC5939 Attribute Analysis 5.33. RFC6871: SDP Media Capabilities Negotiation SDP capability negotiation provides a general framework for indicating and negotiating capabilities in SDP. The base framework defines only capabilities for negotiating transport protocols and attributes. [RFC6871] extends the framework by defining media capabilities that can be used to negotiate media types and their associated parameters. Nandakumar Expires March 26, 2017 [Page 32]
Internet-Draft SDP Attribute Multiplexing September 2016 +---------+-----------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +---------+-----------------------+-------+-------------------+ | rmcap | Refer to Section 14 | B | IDENTICAL-PER-PT | | | | | | | omcap | Not Impacted | B | NORMAL | | | | | | | mfcap | Refer to Section 14 | B | IDENTICAL-PER-PT | | | | | | | mscap | Refer to Section 14 | B | INHERIT | | | | | | | lcfg | Refer to Section 14 | B | SPECIAL | | | | | | | sescap | Refer to notes below | S | CAUTION | | | | | | | med-v0 | Not Impacted | S | NORMAL | | | | | | +---------+-----------------------+-------+-------------------+ 5.33 RFC6871 - Attribute Analysis NOTE: The "sescap" attribute is not recommended for use with multiplexing. The reason is that it requires the use of unique configuration numbers across the entire SDP (per [RFC6871]) as opposed to within a media description only (per [RFC5939]). As described in Section 14, the use of identical configuration numbers between multiplexed (bundled) media descriptions is the default way of indicating compatible configurations in a bundle. 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP [RFC7006] extends the SDP capability negotiation framework to allow endpoints to negotiate three additional SDP capabilities. In particular, this memo provides a mechanism to negotiate bandwidth ("b=" line), connection data ("c=" line), and session or media titles ("i=" line for each session or media). Nandakumar Expires March 26, 2017 [Page 33]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------+-----------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +----------+-----------------------------------+-------+------------+ | bcap | Inherit the category SUM as | B | INHERIT | | | applicable to b= attribute | | | | | | | | | bcap-v0 | Not Impacted | B | NORMAL | | | | | | | ccap | The connection address type MUST | B | IDENTICAL | | | be identical across all the | | | | | multiplexed "m=" lines | | | | | | | | | ccap-v0 | Not Impacted | B | NORMAL | | | | | | | icap | Not Impacted | B | NORMAL | | | | | | | icap-v0 | Not Impacted | B | NORMAL | | | | | | +----------+-----------------------------------+-------+------------+ 5.34 RFC7006 - Attribute Analysis 5.35. RFC4567: Key Management Extensions for SDP and RTSP [RFC4567] defines general extensions for SDP and Real Time Streaming Protocol (RTSP) to carry messages, as specified by a key management protocol, in order to secure the media. These extensions are presented as a framework, to be used by one or more key management protocols. As such, their use is meaningful only when complemented by an appropriate key management protocol. +-----------+----------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-----------+----------------------------------+-------+------------+ | key-mgmt | Key management protocol MUST be | B | IDENTICAL | | | identical across all the "m=" | | | | | lines | | | | | | | | | mikey | Key management protocol MUST be | B | IDENTICAL | | | identical across all the "m=" | | | | | lines | | | | | | | | +-----------+----------------------------------+-------+------------+ 5.35 RFC4567 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 34]
Internet-Draft SDP Attribute Multiplexing September 2016 5.36. RFC4572: Comedia over TLS in SDP [RFC4572] specifies how to establish secure connection-oriented media transport sessions over the Transport Layer Security (TLS) protocol using SDP. It defines a new SDP protocol identifier, 'TCP/TLS'. It also defines the syntax and semantics for an SDP 'fingerprint' attribute that identifies the certificate that will be presented for the TLS session. This mechanism allows media transport over TLS connections to be established securely, so long as the integrity of session descriptions is assured. +--------------+-------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +--------------+-------------------------------+-------+------------+ | fingerprint | fingerprint value from the | B | TRANSPORT | | | "m=" line defining the | | | | | underlying transport is | | | | | chosen | | | | | | | | +--------------+-------------------------------+-------+------------+ 5.36 RFC4572 Attribute Analysis 5.37. RFC4570: SDP Source Filters [RFC4570] describes how to adapt SDP to express one or more source addresses as a source filter for one or more destination "connection" addresses. It defines the syntax and semantics for an SDP "source- filter" attribute that may reference either IPv4 or IPv6 address(es) as either an inclusive or exclusive source list for either multicast or unicast destinations. In particular, an inclusive source-filter can be used to specify a Source-Specific Multicast (SSM) session. +----------------+-----------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +----------------+-----------------------------+-------+------------+ | source-filter | The attribute MUST be | B | IDENTICAL | | | repeated across all "m=" | | | | | lines multiplexed | | | | | | | | +----------------+-----------------------------+-------+------------+ 5.37 RFC4570 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 35]
Internet-Draft SDP Attribute Multiplexing September 2016 5.38. RFC6128: RTCP Port for Multicast Sessions SDP has an attribute that allows RTP applications to specify an address and a port associated with the RTCP traffic. In RTP-based source-specific multicast (SSM) sessions, the same attribute is used to designate the address and the RTCP port of the Feedback Target in the SDP description. However, the RTCP port associated with the SSM session itself cannot be specified by the same attribute to avoid ambiguity, and thus, is required to be derived from the "m=" line of the media description. Deriving the RTCP port from the "m=" line imposes an unnecessary restriction. [RFC6128] removes this restriction by introducing a new SDP attribute. +-----------------+----------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-----------------+----------------------------+-------+------------+ | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | | | be identical across all | | | | | the "m=" lines | | | | | | | | +-----------------+----------------------------+-------+------------+ 5.38 RFC6128 Attribute Analysis 5.39. RFC6189: ZRTP [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman exchange to agree on a session key and parameters for establishing unicast SRTP sessions for (VoIP applications. +------------+---------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +------------+---------------------------------+-------+------------+ | zrtp-hash | zrtp-hash attribute MUST be the | M | TRANSPORT | | | one that corresponds to the | | | | | "m=" line chosen for setting up | | | | | the underlying transport flow | | | | | | | | +------------+---------------------------------+-------+------------+ 5.39 RFC6189 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 36]
Internet-Draft SDP Attribute Multiplexing September 2016 5.40. RFC4145: Connection-Oriented Media [RFC4145] describes how to express media transport over TCP using SDP. It defines the SDP 'TCP' protocol identifier, the SDP 'setup' attribute, which describes the connection setup procedure, and the SDP 'connection' attribute, which handles connection reestablishment. +-------------+--------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------------+--------------------------------+-------+------------+ | setup | The setup attribute MUST be | B | TRANSPORT | | | the one that corresponds to | | | | | the "m=" line chosen for | | | | | setting up the underlying | | | | | transport flow. | | | | | | | | | connection | The connection attribute MUST | B | TRANSPORT | | | be the one that corresponds to | | | | | the "m=" line chosen for | | | | | setting up the underlying | | | | | transport flow. | | | | | | | | +-------------+--------------------------------+-------+------------+ 5.40 RFC4145 Attribute Analysis 5.41. RFC6947: The SDP altc Attribute [RFC6947] proposes a mechanism that allows the same SDP offer to carry multiple IP addresses of different address families (e.g., IPv4 and IPv6). The proposed attribute, the "altc" attribute, solves the backward-compatibility problem that plagued Alternative Network Address Types (ANAT) due to their syntax. +-------+--------------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------+--------------------------------------+-------+------------+ | altc | The IP Address and port MUST be the | M | TRANSPORT | | | one that corresponds to the "m=" | | | | | line chosen for setting up the | | | | | underlying transport flow | | | | | | | | +-------+--------------------------------------+-------+------------+ 5.41 RFC6947 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 37]
Internet-Draft SDP Attribute Multiplexing September 2016 5.42. RFC7195: SDP Extension for Circuit Switched Bearers in PSTN [RFC7195] describes use cases, requirements, and protocol extensions for using SDP offer/answer model for establishing audio and video media streams over circuit-switched bearers in the Public Switched Telephone Network (PSTN). +--------------------------+-------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +--------------------------+-------------------+-------+------------+ | cs-correlation:callerid | Refer to notes | M | TBD | | | below | | | | | | | | | cs-correlation:uuie | Refer to notes | M | TBD | | | below | | | | | | | | | cs-correlation:dtmf | Refer to notes | M | TBD | | | below | | | | | | | | | cs-correlation:external | Refer to notes | M | TBD | | | below | | | | | | | | +--------------------------+-------------------+-------+------------+ 5.42 RFC7195 Attribute Analysis NOTE: [RFC7195] defines SDP attributes for establishing audio and video media streams over circuit-switched bearers by defining a new nettype value "PSTN". However, section 7.2 of [I-D.ietf-mmusic-sdp-bundle-negotiation] requires the "c=" line nettype value of "IN". If in future there exists a specification that defines procedures to multiplex media streams over nettype "PSTN", the multiplexing categories for attributes in this section could be revisited. 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) [RFC7272] defines a new RTCP Packet Type and an RTCP Extended Report (XR) Block Type to be used for achieving Inter-Destination Media Synchronization (IDMS). Nandakumar Expires March 26, 2017 [Page 38]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ | rtcp-idms | Not Impacted | M | NORMAL | | | | | | +------------+---------------+-------+--------------+ 5.43 RFC7272 Attribute Analysis 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP Attributes [RFC5159] provides descriptions of SDP attributes used by the Open Mobile Alliance's Broadcast Service and Content Protection specification. +---------------------+-----------------------+-------+-------------+ | Name | Notes | Level | Mux | | | | | Category | +---------------------+-----------------------+-------+-------------+ | bcastversion | Not Impacted | S | NORMAL | | | | | | | stkmstream | Not Impacted | B | NORMAL | | | | | | | SRTPAuthentication | Needs further | M | TBD | | | analysis | | | | | | | | | SRTPROCTxRate | Needs further | M | TBD | | | analysis | | | | | | | | +---------------------+-----------------------+-------+-------------+ 5.44 RFC5159 Attribute Analysis 5.45. RFC6193: Media Description for IKE in SDP [RFC6193] specifies how to establish a media session that represents a virtual private network using the Session Initiation Protocol for the purpose of on-demand media/application sharing between peers. It extends the protocol identifier of SDP so that it can negotiate use of the Internet Key Exchange Protocol (IKE) for media sessions in the SDP offer/answer model. Nandakumar Expires March 26, 2017 [Page 39]
Internet-Draft SDP Attribute Multiplexing September 2016 +-------------------+----------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +-------------------+----------------------------+-------+----------+ | ike-setup | Unlikely to use IKE in the | B | CAUTION | | | context of multiplexing | | | | | | | | | psk-fingerprint | Unlikely to use IKE in the | B | CAUTION | | | context of multiplexing | | | | | | | | | ike-esp | Unlikely to use IKE in the | B | CAUTION | | | context of multiplexing | | | | | | | | | ike-esp-udpencap | Unlikely to use IKE in the | B | CAUTION | | | context of multiplexing | | | | | | | | +-------------------+----------------------------+-------+----------+ 5.45 RFC6193 Attribute Analysis 5.46. RFC2326: Real Time Streaming Protocol The Real Time Streaming Protocol, or RTSP, is an application-level protocol for control over the delivery of data with real-time properties. RTSP provides an extensible framework to enable controlled, on-demand delivery of real-time data, such as audio and video. +----------+------------------------------------+-------+-----------+ | Name | Notes | Level | Mux | | | | | Category | +----------+------------------------------------+-------+-----------+ | etag | RTSP is not supported for RTP | B | CAUTION | | | Stream multiplexing | | | | | | | | | range | RTSP is not supported for RTP | B | CAUTION | | | Stream multiplexing | | | | | | | | | control | RTSP is not supported for RTP | B | CAUTION | | | Stream multiplexing | | | | | | | | | mtag | RTSP is not supported for RTP | B | CAUTION | | | Stream multiplexing | | | | | | | | +----------+------------------------------------+-------+-----------+ 5.46 RFC2326 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 40]
Internet-Draft SDP Attribute Multiplexing September 2016 NOTE: [RFC2326] defines SDP attributes that are applicable in the declarative usage of SDP alone. For purposes of this document, only the Offer/Answer usage of SDP is considered as mandated by [I-D.ietf-mmusic-sdp-bundle-negotiation]. 5.47. RFC6064: SDP and RTSP Extensions for 3GPP The Packet-switched Streaming Service (PSS) and the Multimedia Broadcast/Multicast Service (MBMS) defined by 3GPP use SDP and RTSP with some extensions. [RFC6064] provides information about these extensions and registers the RTSP and SDP extensions with IANA. +--------------------------------+---------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +--------------------------------+---------------+-------+----------+ | X-predecbufsize | Refer to | M | CAUTION | | | notes below | | | | | | | | | X-initpredecbufperiod | Refer to | M | CAUTION | | | notes below | | | | | | | | | X-initpostdecbufperiod | Refer to | M | CAUTION | | | notes below | | | | | | | | | X-decbyterate | Refer to | M | CAUTION | | | notes below | | | | | | | | | 3gpp-videopostdecbufsize | Refer to | M | CAUTION | | | notes below | | | | | | | | | framesize | Refer to | M | CAUTION | | | notes below | | | | | | | | | 3GPP-Integrity-Key | Refer to | S | CAUTION | | | notes below | | | | | | | | | 3GPP-SDP-Auth | Refer to | S | CAUTION | | | notes below | | | | | | | | | 3GPP-SRTP-Config | Refer to | M | CAUTION | | | notes below | | | | | | | | | alt | Refer to | M | CAUTION | | | notes below | | | | | | | | | alt-default-id | Refer to | M | CAUTION | | | notes below | | | Nandakumar Expires March 26, 2017 [Page 41]
Internet-Draft SDP Attribute Multiplexing September 2016 | | | | | | alt-group | Refer to | S | CAUTION | | | notes below | | | | | | | | | 3GPP-Adaptation-Support | Refer to | M | CAUTION | | | notes below | | | | | | | | | 3GPP-Asset-Information | Refer to | B | CAUTION | | | notes below | | | | | | | | | mbms-mode | Refer to | B | CAUTION | | | notes below | | | | | | | | | mbms-flowid | Refer to | M | CAUTION | | | notes below | | | | | | | | | mbms-repair | Refer to | B | CAUTION | | | notes below | | | | | | | | | 3GPP-QoE-Metrics | Refer to | M | CAUTION | | | notes below | | | | | | | | | 3GPP-QoE-Metrics:Corruption | Refer to | M | CAUTION | | duration | notes below | | | | | | | | | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | CAUTION | | duration | notes below | | | | | | | | | 3GPP-QoE-Metrics:Initial | Refer to | M | CAUTION | | buffering duration | notes below | | | | | | | | | 3GPP-QoE-Metrics:Successive | Refer to | M | CAUTION | | loss of RTP packets | notes below | | | | | | | | | 3GPP-QoE-Metrics:Frame rate | Refer to | M | CAUTION | | deviation | notes below | | | | | | | | | 3GPP-QoE-Metrics:Jitter | Refer to | M | CAUTION | | duration | notes below | | | | | | | | | 3GPP-QoE-Metrics:Content | Refer to | B | CAUTION | | Switch Time | notes below | | | | | | | | | 3GPP-QoE-Metrics:Average Codec | Refer to | M | CAUTION | | Bitrate | notes below | | | | | | | | | 3GPP-QoE-Metrics:Codec | Refer to | M | CAUTION | | Information | notes below | | | Nandakumar Expires March 26, 2017 [Page 42]
Internet-Draft SDP Attribute Multiplexing September 2016 | | | | | | 3GPP-QoE-Metrics:Buffer Status | Refer to | M | CAUTION | | | notes below | | | | | | | | +--------------------------------+---------------+-------+----------+ 5.47 RFC6064 Attribute Analysis NOTE: [RFC6064] defines SDP attributes that are applicable in the declarative usage of SDP alone. For purposes of this document, only the Offer/Answer usage of SDP is considered as mandated by [I-D.ietf-mmusic-sdp-bundle-negotiation]. 5.48. RFC3108: ATM SDP [RFC3108] describes conventions for using SDP described for controlling ATM Bearer Connections, and any associated ATM Adaptation Layer (AAL). +------------------------+--------------------+-------+-------------+ | Name | Notes | Level | Mux | | | | | Category | +------------------------+--------------------+-------+-------------+ | aalType | Refer to notes | B | CAUTION | | | below | | | | eecid | Refer to notes | B | CAUTION | | | below | | | | capability | Refer to notes | B | CAUTION | | | below | | | | qosClass | Refer to notes | B | CAUTION | | | below | | | | bcob | Refer to notes | B | CAUTION | | | below | | | | stc | Refer to notes | B | CAUTION | | | below | | | | upcc | Refer to notes | B | CAUTION | | | below | | | | atmQOSparms | Refer to notes | B | CAUTION | | | below | | | | atmTrfcDesc | Refer to notes | B | CAUTION | | | below | | | | abrParms | Refer to notes | B | CAUTION | | | below | | | | abrSetup | Refer to notes | B | CAUTION | | | below | | | | bearerType | Refer to notes | B | CAUTION | | | below | | | | lij | Refer to notes | B | CAUTION | Nandakumar Expires March 26, 2017 [Page 43]
Internet-Draft SDP Attribute Multiplexing September 2016 | | below | | | | anycast | Refer to notes | B | CAUTION | | | below | | | | cache | Refer to notes | B | CAUTION | | | below | | | | bearerSigIE | Refer to notes | B | CAUTION | | | below | | | | aalApp | Refer to notes | B | CAUTION | | | below | | | | cbrRate | Refer to notes | B | CAUTION | | | below | | | | sbc | Refer to notes | B | CAUTION | | | below | | | | clkrec | Refer to notes | B | CAUTION | | | below | | | | fec | Refer to notes | B | CAUTION | | | below | | | | prtfl | Refer to notes | B | CAUTION | | | below | | | | structure | Refer to notes | B | CAUTION | | | below | | | | cpsSDUsize | Refer to notes | B | CAUTION | | | below | | | | aal2CPS | Refer to notes | B | CAUTION | | | below | | | | aal2CPSSDUrate | Refer to notes | B | CAUTION | | | below | | | | aal2sscs3661unassured | Refer to notes | B | CAUTION | | | below | | | | aal2sscs3661assured | Refer to notes | B | CAUTION | | | below | | | | aal2sscs3662 | Refer to notes | B | CAUTION | | | below | | | | aal5sscop | Refer to notes | B | CAUTION | | | below | | | | atmmap | Refer to notes | B | CAUTION | | | below | | | | silenceSupp | Refer to notes | B | CAUTION | | | below | | | | ecan | Refer to notes | B | CAUTION | | | below | | | | gc | Refer to notes | B | CAUTION | | | below | | | | profileDesc | Refer to notes | B | CAUTION | | | below | | | | vsel | Refer to notes | B | CAUTION | | | below | | | | dsel | Refer to notes | B | CAUTION | Nandakumar Expires March 26, 2017 [Page 44]
Internet-Draft SDP Attribute Multiplexing September 2016 | | below | | | | fsel | Refer to notes | B | CAUTION | | | below | | | | onewaySel | Refer to notes | B | CAUTION | | | below | | | | codecconfig | Refer to notes | B | CAUTION | | | below | | | | isup_usi | Refer to notes | B | CAUTION | | | below | | | | uiLayer1_Prot | Refer to notes | B | CAUTION | | | below | | | | chain | Refer to notes | B | CAUTION | | | below | | | | | | | | +------------------------+--------------------+-------+-------------+ 5.48 RFC3108 Attribute Analysis NOTE: RFC3108 describes conventions for using SDP for characterizing ATM bearer connections using an AAL1, AAL2 or AAL5 adaptation layers. For AAL1, AAL2 and AAL5, bearer connections can be used to transport single media streams. In addition, for AAL1 and AAL2, multiple media streams can be multiplexed into a bearer connection. For all adaptation types (AAL1, AAL2 and AAL5), bearer connections can be bundled into a single media group. In all cases addressed by RFC3108, a real-time media stream (voice, video, voiceband data, pseudo-wire, and others) or a multiplex of media streams is mapped directly into an ATM connection. RFC3108 does not address cases where ATM serves as a low-level transport pipe for IP packets which in turn can carry one or more real-time (e.g. VoIP) media sessions with a life-cycle different from that of the underlying ATM transport. 5.49. 3GPP TS 26.114 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and interaction Nandakumar Expires March 26, 2017 [Page 45]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------------------+-------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +----------------------+-------------------------+-------+----------+ | 3gpp_sync_info | Usage defined for the | M | NORMAL | | | IP Multimedia Subsystem | | | | | | | | | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL | | | IP Multimedia Subsystem | | | | | | | | +----------------------+-------------------------+-------+----------+ 5.49 3GPP TS 26.114 Attribute Analysis 5.50. 3GPP TS 183.063 [R3GPPTS183.063] Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); +---------------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------------------+---------------+-------+--------------+ | PSCid | Not Impacted | S | NORMAL | | | | | | | bc_service | Not Impacted | S | NORMAL | | | | | | | bc_program | Not Impacted | S | NORMAL | | | | | | | bc_service_package | Not Impacted | S | NORMAL | | | | | | +---------------------+---------------+-------+--------------+ 5.50 3GPP TS 183.063 Attribute Analysis 5.51. 3GPP TS 24.182 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting tones Nandakumar Expires March 26, 2017 [Page 46]
Internet-Draft SDP Attribute Multiplexing September 2016 +-------------+---------------------------------+-------+-----------+ | Name | Notes | Level | Mux | | | | | Category | +-------------+---------------------------------+-------+-----------+ | g.3gpp.cat | Usage defined for the IP | M | NORMAL | | | Multimedia Subsystem | | | | | | | | +-------------+---------------------------------+-------+-----------+ 5.51 3GPP TS 24.182 Attribute Analysis 5.52. 3GPP TS 24.183 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing Signal +-------------+---------------------------------+-------+-----------+ | Name | Notes | Level | Mux | | | | | Category | +-------------+---------------------------------+-------+-----------+ | g.3gpp.crs | Usage defined for the IP | M | NORMAL | | | Multimedia Subsystem | | | | | | | | +-------------+---------------------------------+-------+-----------+ 5.52 3GPP TS 24.183 Attribute Analysis 5.53. 3GPP TS 24.229 [R3GPPTS24.229] specifies IP multimedia call control protocol based on Session Initial protocol and Session Description Protocol. Nandakumar Expires March 26, 2017 [Page 47]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------------+---------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +------------------+---------------------------+-------+------------+ | secondary-realm | secondary-realm MUST be | M | TRANSPORT | | | the one that corresponds | | | | | to the "m=" line chosen | | | | | for setting up the | | | | | underlying transport flow | | | | | | | | | visited-realm | visited-realm MUST be the | M | TRANSPORT | | | one that corresponds to | | | | | the "m=" line chosen for | | | | | setting up the underlying | | | | | transport flow | | | | | | | | | omr-m-cksum | Not Impacted | M | NORMAL | | | | | | | omr-s-cksum | Not Impacted | M | NORMAL | | | | | | | omr-m-att | Not Impacted | M | NORMAL | | | | | | | omr-s-att | Not Impacted | M | NORMAL | | | | | | | omr-m-bw | Not Impacted | M | NORMAL | | | | | | | omr-s-bw | Not Impacted | M | NORMAL | | | | | | | omr-codecs | Not Impacted | M | NORMAL | | | | | | +------------------+---------------------------+-------+------------+ 5.53 3GPP TS 24.229 Attribute Analysis 5.54. ITU T.38 [T.38] defines procedures for real-time Group 3 facsimile communications over IP networks. +------------------------+--------------------+-------+-------------+ | Name | Notes | Level | Mux | | | | | Category | +------------------------+--------------------+-------+-------------+ | T38FaxVersion | Refer to notes | M | TBD | | | below | | | | | | | | | T38MaxBitRate | Refer to notes | M | TBD | | | below | | | Nandakumar Expires March 26, 2017 [Page 48]
Internet-Draft SDP Attribute Multiplexing September 2016 | | | | | | T38FaxFillBitRemoval | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxTranscodingMMR | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxTranscodingJBIG | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxRateManagement | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxMaxBuffer | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxMaxDatagram | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxUdpEC | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxMaxIFP | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxUdpECDepth | Refer to notes | M | TBD | | | below | | | | | | | | | T38FaxUdpFECMaxSpan | Refer to notes | M | TBD | | | below | | | | | | | | | T38ModemType | Refer to notes | M | TBD | | | below | | | | | | | | | T38VendorInfo | Refer to notes | M | TBD | | | below | | | | | | | | +------------------------+--------------------+-------+-------------+ 5.54 ITU T.38 Attribute Analysis NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], there exists no publicly available specification that defines procedures for multiplexing/demultiplexing fax protocols flows over a single 5-tuple. Once such a specification is available, the multiplexing category assignments for the attributes in this section could be revisited. Nandakumar Expires March 26, 2017 [Page 49]
Internet-Draft SDP Attribute Multiplexing September 2016 5.55. ITU-T Q.1970 [Q.1970] defines Bearer Independent Call Control (BICC) IP bearer control protocol. +--------+---------------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +--------+---------------------------------------+-------+----------+ | ipbcp | ipbcp version identifies type of IP | S | SPECIAL | | | bearer control protocol (IPBCP) | | | | | message used in BICC (ITU-T Q.1901) | | | | | environment which are limited to | | | | | single media payload. Refer to the | | | | | pertinent ITU-T specifications while | | | | | multiplexing | | | | | | | | +--------+---------------------------------------+-------+----------+ 5.55 ITU-T Q.1970 Attribute Analysis 5.56. ITU-T H.248.15 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 package attribute Nandakumar Expires March 26, 2017 [Page 50]
Internet-Draft SDP Attribute Multiplexing September 2016 +-----------+------------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +-----------+------------------------------------+-------+----------+ | h248item | It is only applicable for | B | SPECIAL | | | signaling the inclusion of H.248 | | | | | extension packages to a gateway | | | | | via the local and remote | | | | | descriptors. The attribute itself | | | | | is unaffected by multiplexing, but | | | | | the packaged referenced in a | | | | | specific use of the attribute can | | | | | be impacted. Further analysis of | | | | | each package is needed to | | | | | determine if there is an issue. | | | | | This is only a concern in | | | | | environments using a decomposed | | | | | server/gateway with H.248 signaled | | | | | between them. The ITU-T will need | | | | | to do further analysis of various | | | | | packages when they specify how to | | | | | signal the use of multiplexing to | | | | | a gateway | | | | | | | | +-----------+------------------------------------+-------+----------+ 5.56 ITU-T H.248.15 Attribute Analysis 5.57. RFC4975: The Message Session Relay Protocol [RFC4975] the Message Session Relay Protocol, a protocol for transmitting a series of related instant messages in the context of a session. Message sessions are treated like any other media stream when set up via a rendezvous or session creation protocol such as the Session Initiation Protocol. Nandakumar Expires March 26, 2017 [Page 51]
Internet-Draft SDP Attribute Multiplexing September 2016 +-----------------------+---------------------+-------+-------------+ | Name | Notes | Level | Mux | | | | | Category | +-----------------------+---------------------+-------+-------------+ | accept-types | Refer to notes | M | TBD | | | below | | | | | | | | | accept-wrapped-types | Refer to notes | M | TBD | | | below | | | | | | | | | max-size | Refer to notes | M | TBD | | | below | | | | | | | | | path | Refer to notes | M | TBD | | | below | | | | | | | | +-----------------------+---------------------+-------+-------------+ 5.57 RFC4975 Attribute Analysis NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], there exists no publicly available specification that defines procedures for multiplexing/demultiplexing MRSP flows over a single 5-tuple. Once such a specification is available, the multiplexing categories assignments for the attributes in this section could be revisited. 5.58. Historical Attributes This section specifies analysis for the attributes that are included for historic usage alone by the [IANA]. +----------+----------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +----------+----------------------+-------+--------------+ | rtpred1 | Historic attributes | M | CAUTION | | | | | | | rtpred2 | Historic attributes | M | CAUTION | | | | | | +----------+----------------------+-------+--------------+ 5.58 Historical Attribute Analysis 6. bwtype Attribute Analysis This section specifies handling of specific bandwidth attributes when used in multiplexing scenarios. Nandakumar Expires March 26, 2017 [Page 52]
Internet-Draft SDP Attribute Multiplexing September 2016 6.1. RFC4566: SDP [RFC4566] defines SDP that is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. +------------+-----------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------------+-----------------------------------+-------+----------+ | bwtype:CT | Not Impacted | S | NORMAL | | | | | | | bwtype:AS | For the media level usage, the | B | SUM | | | aggregate of individual bandwidth | | | | | values is considered | | | | | | | | +------------+-----------------------------------+-------+----------+ 6.1 RFC4566 bwtype Analysis 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth [RFC3556] defines an extension to SDP to specify two additional modifiers for the bandwidth attribute. These modifiers may be used to specify the bandwidth allowed for RTCP packets in a RTP session. +------------+-----------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------------+-----------------------------------+-------+----------+ | bwtype:RS | Session level usage represents | B | SUM | | | session aggregate and media level | | | | | usage indicates SUM of the | | | | | individual values while | | | | | multiplexing | | | | | | | | | bwtype:RR | Session level usage represents | B | SUM | | | session aggregate and media level | | | | | usage indicates SUM of the | | | | | individual values while | | | | | multiplexing | | | | | | | | +------------+-----------------------------------+-------+----------+ 6.2 RFC3556 bwtype Analysis Nandakumar Expires March 26, 2017 [Page 53]
Internet-Draft SDP Attribute Multiplexing September 2016 6.3. RFC3890: Bandwidth Modifier for SDP [RFC3890] defines SDP Transport Independent Application Specific Maximum (TIAS) bandwidth modifier that does not include transport overhead; instead an additional packet rate attribute is defined. The transport independent bit-rate value together with the maximum packet rate can then be used to calculate the real bit-rate over the transport actually used. +--------------+---------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +--------------+---------------------------------+-------+----------+ | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL | | | defined under Offer/Answer | | | | | usage. | | | | | | | | | maxprate | The usage of TIAS and maxprate | B | SPECIAL | | | is not well defined under | | | | | multiplexing | | | | | | | | +--------------+---------------------------------+-------+----------+ 6.3 RFC3890 bwtype Analysis NOTE: The intention of TIAS is that the media level bit-rate is multiplied with the known per-packet overhead for the selected transport and the maxprate value to determine the worst case bit-rate from the transport to more accurately capture the required usage. Summing TIAS values independently across "m=" lines and multiplying the computed sum with maxprate and the per-packet overhead would inflate the value significantly. Instead performing multiplication and adding the individual values is a more appropriate usage. 7. rtcp-fb Attribute Analysis This section analyzes rtcp-fb SDP attributes. 7.1. RFC4585: RTP/AVPF [RFC4585] defines an extension to the Audio-visual Profile (AVP) that enables receivers to provide, statistically, more immediate feedback to the senders and thus allows for short-term adaptation and efficient feedback-based repair mechanisms to be implemented. Nandakumar Expires March 26, 2017 [Page 54]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------+----------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +----------+----------------------------+-------+-------------------+ | ack rpsi | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given codec | | | | | configuration | | | | | | | | | ack app | Feedback parameters MUST | M | SPECIAL | | | be handled in the app | | | | | specific way when | | | | | multiplexed | | | | | | | | | nack | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given codec | | | | | configuration | | | | | | | | | nack pli | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given codec | | | | | configuration | | | | | | | | | nack sli | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given codec | | | | | configuration | | | | | | | | | nack | The attribute value MUST | M | IDENTICAL-PER-PT | | rpsi | be same for a given codec | | | | | configuration | | | | | | | | | nack app | Feedback parameters MUST | M | SPECIAL | | | be handled in the app | | | | | specific way when | | | | | multiplexed | | | | | | | | | trr-int | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given codec | | | | | configuration | | | | | | | | +----------+----------------------------+-------+-------------------+ 7.1 RFC4585 Attribute Analysis 7.2. RFC5104: Codec Control Messages in AVPF [RFC5104] specifies a few extensions to the messages defined in the Audio-Visual Profile with Feedback (AVPF). They are helpful primarily in conversational multimedia scenarios where centralized multipoint functionalities are in use. However, some are also usable in smaller multicast environments and point-to-point calls. Nandakumar Expires March 26, 2017 [Page 55]
Internet-Draft SDP Attribute Multiplexing September 2016 +------+--------------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +------+--------------------------------+-------+-------------------+ | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | | | same for a given codec | | | | | configuration | | | | | | | | +------+--------------------------------+-------+-------------------+ 7.2 RFC5104 Attribute Analysis 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP Sessions (RAMS) [RFC6285] describes a method using the existing RTP and RTCP machinery that reduces the acquisition delay. In this method, an auxiliary unicast RTP session carrying the Reference Information to the receiver precedes or accompanies the multicast stream. This unicast RTP flow can be transmitted at a faster than natural bitrate to further accelerate the acquisition. The motivating use case for this capability is multicast applications that carry real-time compressed audio and video. +-------+-------------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +-------+-------------------------------+-------+-------------------+ | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | | rai | same for a given codec | | | | | configuration | | | | | | | | +-------+-------------------------------+-------+-------------------+ 7.3 RFC6285 Attribute Analysis 7.4. RFC6679: ECN for RTP over UDP/IP [RFC6679] specifies how Explicit Congestion Notification (ECN) can be used with the RTP running over UDP, using the RTCP as a feedback mechanism. It defines a new RTCP Extended Report (XR) block for periodic ECN feedback, a new RTCP transport feedback message for timely reporting of congestion events, and a STUN extension used in the optional initialization method using ICE. Nandakumar Expires March 26, 2017 [Page 56]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------------+---------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +------------------+---------------------------+-------+------------+ | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | | | the RTP session level | | | | | | | | | nack ecn | This attribute enables | M | IDENTICAL | | | ECN at the RTP session | | | | | level | | | | | | | | +------------------+---------------------------+-------+------------+ 7.4 RFC6679 Attribute Analysis 7.5. RFC6642: Third-Party Loss Report In a large RTP session using the RTCP feedback mechanism defined in [RFC4585], a feedback target may experience transient overload if some event causes a large number of receivers to send feedback at once. This overload is usually avoided by ensuring that feedback reports are forwarded to all receivers, allowing them to avoid sending duplicate feedback reports. However, there are cases where it is not recommended to forward feedback reports, and this may allow feedback implosion. [RFC6642] memo discusses these cases and defines a new RTCP Third-Party Loss Report that can be used to inform receivers that the feedback target is aware of some loss event, allowing them to suppress feedback. Associated SDP signaling is also defined. +--------+------------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +--------+------------------------------+-------+-------------------+ | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | | tllei | same for a given codec | | | | | configuration | | | | | | | | | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | | pslei | same for a given codec | | | | | configuration | | | | | | | | +--------+------------------------------+-------+-------------------+ 7.5 RFC6642 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 57]
Internet-Draft SDP Attribute Multiplexing September 2016 7.6. RFC5104: Codec Control Messages in AVPF [RFC5104] specifies a few extensions to the messages defined in the Audio-Visual Profile with Feedback (AVPF). They are helpful primarily in conversational multimedia scenarios where centralized multipoint functionalities are in use. However, some are also usable in smaller multicast environments and point-to-point calls. +--------+------------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +--------+------------------------------+-------+-------------------+ | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | | fir | same for a given codec | | | | | configuration | | | | | | | | | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | | tmmbr | same for a given codec | | | | | configuration | | | | | | | | | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | | tstr | same for a given codec | | | | | configuration | | | | | | | | | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | | vbcm | same for a given codec | | | | | configuration | | | | | | | | +--------+------------------------------+-------+-------------------+ 7.6 RFC5104 Attribute Analysis 8. group Attribute Analysis This section analyzes SDP "group" attribute semantics [RFC5888]. 8.1. RFC5888: SDP Grouping Framework [RFC5888] defines a framework to group "m" lines in SDP for different purposes. Nandakumar Expires March 26, 2017 [Page 58]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ | group:LS | Not Impacted | S | NORMAL | | | | | | | group:FID | Not Impacted | S | NORMAL | | | | | | +------------+---------------+-------+--------------+ 8.1 RFC5888 Attribute Analysis 8.2. RFC3524: Mapping Media Streams to Resource Reservation Flows [RFC3524] defines an extension to the SDP grouping framework. It allows requesting a group of media streams to be mapped into a single resource reservation flow. The SDP syntax needed is defined, as well as a new "semantics" attribute called Single Reservation Flow (SRF). +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ | group:SRF | Not Impacted | S | NORMAL | | | | | | +------------+---------------+-------+--------------+ 8.2 RFC3524 Attribute Analysis 8.3. RFC4091: ANAT Semantics [RFC4091] defines ANAT semantics for the SDP grouping framework. The ANAT semantics allow alternative types of network addresses to establish a particular media stream. +-------------+------------------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-------------+------------------------------+-------+--------------+ | group:ANAT | ANAT semantics is obsoleted | S | CAUTION | | | | | | +-------------+------------------------------+-------+--------------+ 8.3 RFC4091 Attribute Analysis 8.4. RFC5956: FEC Grouping Semantics in SDP [RFC5956] defines the semantics for grouping the associated source and FEC-based (Forward Error Correction) repair flows in SDP. The semantics defined in the document are to be used with the SDP Grouping Framework [RFC5888]. These semantics allow the description Nandakumar Expires March 26, 2017 [Page 59]
Internet-Draft SDP Attribute Multiplexing September 2016 of grouping relationships between the source and repair flows when one or more source and/or repair flows are associated in the same group, and they provide support for additive repair flows. SSRC- level (Synchronization Source) grouping semantics are also defined in this document for RTP streams using SSRC multiplexing. +---------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------------+---------------+-------+--------------+ | group:FEC-FR | Not Impacted | S | NORMAL | | | | | | +---------------+---------------+-------+--------------+ 8.4 RFC5956 Attribute Analysis 8.5. RFC5583: Signaling Media Decoding Dependency in SDP [RFC5583] defines semantics that allow for signaling the decoding dependency of different media descriptions with the same media type in SDP. This is required, for example, if media data is separated and transported in different network streams as a result of the use of a layered or multiple descriptive media coding process. +------------+--------------------------+-------+-------------------+ | Name | Notes | Level | Mux Category | +------------+--------------------------+-------+-------------------+ | group:DDP | Not Impacted | S | NORMAL | | | | | | | depend lay | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given | | | | | codec configuration | | | | | | | | | depend mdc | The attribute value MUST | M | IDENTICAL-PER-PT | | | be same for a given | | | | | codec configuration | | | | | | | | +------------+--------------------------+-------+-------------------+ 8.5 RFC5583 Attribute Analysis 8.6. RFC7104: Duplication Grouping Semantics in the SDP [RFC7104] defines the semantics for grouping redundant streams in SDP, The semantics defined in this document are to be used with the SDP Grouping Framework. Grouping semantics at the SSRC)level are also defined in this document for RTP streams using SSRC multiplexing. Nandakumar Expires March 26, 2017 [Page 60]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ | group:DUP | Not Impacted | S | NORMAL | | | | | | +------------+---------------+-------+--------------+ 8.6 RFC7104 Attribute Analysis 9. ssrc-group Attribute Analysis This section analyzes "ssrc-group" semantics. 9.1. RFC5576: Source-Specific SDP Attributes [RFC5576] defines a mechanism to describe RTP media sources, which are identified by their synchronization source (SSRC) identifiers, in SDP, to associate attributes with these sources, and to express relationships among sources. It also defines several source-level attributes that can be used to describe properties of media sources. +--------------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +--------------------+---------------+-------+--------------+ | ssrc-group:FID | Not Impacted | SR | NORMAL | | | | | | | ssrc-group:FEC | Not Impacted | SR | NORMAL | | | | | | | ssrc-group:FEC-FR | Not Impacted | SR | NORMAL | | | | | | +--------------------+---------------+-------+--------------+ 9.1 RFC5576 Attribute Analysis 9.2. RFC7104: Duplication Grouping Semantics in the SDP [RFC7104] defines the semantics for grouping redundant streams in SDP. The semantics defined in this document are to be used with the SDP Grouping Framework. Grouping semantics at the Synchronization Source (SSRC) level are also defined in this document for RTP streams using SSRC multiplexing. Nandakumar Expires March 26, 2017 [Page 61]
Internet-Draft SDP Attribute Multiplexing September 2016 +-----------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-----------------+---------------+-------+--------------+ | ssrc-group:DUP | Not Impacted | SR | NORMAL | | | | | | +-----------------+---------------+-------+--------------+ 9.2 RFC7104 Attribute Analysis 10. QoS Mechanism Token Analysis This section analyzes QoS tokes specified with SDP. 10.1. RFC5432: QoS Mechanism Selection in SDP [RFC5432] defines procedures to negotiate QOS mechanisms using the SDP offer/answer model. +-------+--------------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------+--------------------------------------+-------+------------+ | rsvp | rsvp attribute MUST be the one that | B | TRANSPORT | | | corresponds to the "m=" line chosen | | | | | for setting up the underlying | | | | | transport flow | | | | | | | | | nsis | rsvp attribute MUST be the one that | B | TRANSPORT | | | corresponds to the "m=" line chosen | | | | | for setting up the underlying | | | | | transport | | | | | | | | +-------+--------------------------------------+-------+------------+ 10.1 RFC5432 Attribute Analysis NOTE: A single Differentiated Services Code Point (DSCP) code point per flow being multiplexed doesn't impact multiplexing since QOS mechanisms are signaled/scoped per flow. For scenarios that involve having different DSCP code points for packets being transmitted over the same 5-tuple, issues as discussed in [RFC7657] need to be taken into consideration. 11. k= Attribute Analysis Nandakumar Expires March 26, 2017 [Page 62]
Internet-Draft SDP Attribute Multiplexing September 2016 11.1. RFC4566: SDP [RFC4566] defines SDP that is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. +------+-----------------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +------+-----------------------------------------+-------+----------+ | k= | It is not recommended to use this | S | CAUTION | | | attribute under multiplexing | | | | | | | | +------+-----------------------------------------+-------+----------+ 11.1 RFC4566 Attribute Analysis 12. content Attribute Analysis 12.1. RFC4796 [RFC4796] defines a new SDP media-level attribute, 'content'. The 'content' attribute defines the content of the media stream to a more detailed level than the media description line. The sender of an SDP session description can attach the 'content' attribute to one or more media streams. The receiving application can then treat each media stream differently (e.g., show it on a big or small screen) based on its content. +------------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------------+---------------+-------+--------------+ | content:slides | Not Impacted | M | NORMAL | | | | | | | content:speaker | Not Impacted | M | NORMAL | | | | | | | content:main | Not Impacted | M | NORMAL | | | | | | | content:sl | Not Impacted | M | NORMAL | | | | | | | content:alt | Not Impacted | M | NORMAL | | | | | | +------------------+---------------+-------+--------------+ 12.1 RFC4796 Attribute Analysis Nandakumar Expires March 26, 2017 [Page 63]
Internet-Draft SDP Attribute Multiplexing September 2016 13. Payload Formats 13.1. RFC5109: RTP Payload Format for Generic FEC [RFC5109] describes a payload format for generic Forward Error Correction (FEC) for media data encapsulated in RTP. It is based on the exclusive-or (parity) operation. The payload format allows end systems to apply protection using various protection lengths and levels, in addition to using various protection group sizes to adapt to different media and channel characteristics. It enables complete recovery of the protected packets or partial recovery of the critical parts of the payload depending on the packet loss situation. +---------------------+--------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +---------------------+--------------------------+-------+----------+ | audio/ulpfec | Not recommended for | M | CAUTION | | | multiplexing due to | | | | | reuse of SSRCs | | | | | | | | | video/ulpfec | Not recommended for | M | CAUTION | | | multiplexing due to | | | | | reuse of SSRCs | | | | | | | | | text/ulpfec | Not recommended for | M | CAUTION | | | multiplexing due to | | | | | reuse of SSRCs | | | | | | | | | application/ulpfec | Not recommended for | M | CAUTION | | | multiplexing due to | | | | | reuse of SSRCs | | | | | | | | +---------------------+--------------------------+-------+----------+ 13.1 RFC5109 Payload Format Analysis 14. Multiplexing Considerations for Encapsulating Attributes This sections deals with recommendations for defining the multiplexing characteristics of the SDP attributes that encapsulate other SDP attributes/parameters. Such attributes as of today, for example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of a generic framework for indicating and negotiating transport, media, and media format related capabilities in the SDP. The behavior of such attributes under multiplexing is in turn defined by the multiplexing behavior of the attributes they encapsulate which Nandakumar Expires March 26, 2017 [Page 64]
Internet-Draft SDP Attribute Multiplexing September 2016 are made known once the Offer/Answer negotiation process is completed. 14.1. RFC3407: cpar Attribute Analysis [RFC3407] capability parameter attribute (a=cpar) encapsulates b= (bandwidth) or an a= attribute. For bandwidth attribute encapsulation, the category SUM is inherited. For the case of a= attribute, the category corresponding to the SDP attribute being encapsulated is inherited. v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 m=video 3456 RTP/AVP 100 a=rtpmap:100 VP8/90000 a=sqn: 0 a=cdsc: 1 video RTP/AVP 100 a=cpar: a=rtcp-mux m=video 3456 RTP/AVP 101 a=rtpmap:101 VP8/90000 a=fmtp:100 max-fr=15;max-fs=1200 a=cdsc: 2 video RTP/AVP 101 a=cpar: a=rtcp-mux In the above example,the category IDENTICAL is inherited for the cpar encapsulated rtcp-mux attribute. 14.2. RFC5939 Analysis [RFC5939] defines a general SDP capability negotiation framework. It also specifies how to provide transport protocols and SDP attributes as capabilities and negotiate them using the framework. For this purpose, [RFC5939] defines the following o A set of capabilities for the session and its associated media stream components, supported by each side. The attribute ("a=acap") defines how to list an attribute name and its associated value (if any) as a capability. The attribute ("a=tcap") defines how to list transport protocols (e.g., "RTP/ AVP") as capabilities. o A set of potential configurations ("a=pcfg") provided by the offerer to indicate which combinations of those capabilities can be used for the session and its associated media stream Nandakumar Expires March 26, 2017 [Page 65]
Internet-Draft SDP Attribute Multiplexing September 2016 components. Potential configurations are not ready for use until fully negotiated. They provide an alternative that MAY be used, subject to SDP capability negotiation procedures. In particular the answerer MAY choose one of the potential configurations for use as part of the current Offer/Answer exchange. o An actual configuration ("a=acfg") for the session and its associated media stream components. The actual configuration identifies the potential configuration that was negotiated for use. Use of an actual configuration does not require any further negotiation. o A negotiation process that takes the current actual and the set of potential configurations (combinations of capabilities) as input and provides the negotiated actual configurations as output. In [RFC5939] the negotiation process is done independently for each media description. 14.2.1. Recommendation: Procedures for Potential Configuration Pairing This section provides recommendations for entities generating and processing SDP under the generic capability negotiation framework as defined in [RFC5939] under the context of media stream multiplexing. These recommendations are provided for the purposes of enabling the Offerer to make sure that the generated potential configurations between the multiplexed streams can (easily) be negotiated to be consistent between those streams. In particular, the procedures aim to simplify Answerer's procedure to choose potential configurations that are consistent across all the multiplexed media descriptions. A potential configuration selects a set of attributes and parameters that become part of the media description when negotiated. When multiplexing media descriptions with potential configurations specified, there MAY be a need for coordinating this selection between multiplexed media descriptions to ensure the right multiplexing behavior. Although it is possible to analyze the various potential configurations in multiplexed media descriptions to find combinations that satisfy such constraints, it can quickly become complicated to do so. The procedures defined in [RFC5939] state that each potential configuration in the SDP has a unique configuration number, however the scope of uniqueness is limited to each media description. To make it simple for the answerer to chose valid combinations of potential configurations across media descriptions in a given bundle Nandakumar Expires March 26, 2017 [Page 66]
Internet-Draft SDP Attribute Multiplexing September 2016 group, we provide a simple rule for constructing potential configurations o Let m-bundle be the set of media descriptions that form a given bundle . o Let m-bundle-pcfg be the set of media descriptions in m-bundle that include one or more potential configurations. o Each media description in m-bundle-pcfg MUST have at least one potential configuration with the same configuration number (e.g. "1"). o For each potential configuration with configuration number x in m- bundle-pcfg, the offerer MUST ensure that if the answerer chooses configuration number x in each of the media descriptions in m- bundle-pcfg, then the resulting SDP will have all multiplexing constraints satisfied for those media descriptions. o Since it is nearly impossible to define a generic mechanism for various capability extensions, this document does't provide procedures for dealing with the capability extension attributes. However, Section 14.3 provide analysis of media capability extension attributes as defined in [RFC6871]. The above allows the answerer to easily find multiplexing compatible combinations of potential configurations: The answerer simply choses a potential configuration (number) that is present in all of the media descriptions with potential configurations in the bundle. Note that it is still possible for the offerer to provide additional potential configurations with independent configuration numbers. The answerer will have to perform more complicated analysis to determine valid multiplexed combinations of those. 14.2.1.1. Example: Transport Capability Multiplexing Nandakumar Expires March 26, 2017 [Page 67]
Internet-Draft SDP Attribute Multiplexing September 2016 v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 a=tcap:1 RTP/SAVPF a=tcap:2 RTP/SAVP a=group:BUNDLE audio video m=audio a=mid:audio a=pcfg:1 t=1 a=pcfg:2 m=video a=mid:video a=pcfg:1 t=1 a=pcfg:2 t=2 In the example above, the potential configurations that offer transport protocol capability of RTP/SAVPF has the same configuration number "1" in both the audio and video media descriptions. 14.2.1.2. Example: Attribute Capability Multiplexing v=0 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com s= c=IN IP4 host.atlanta.example.com t=0 0 a=acap:1 a=rtcp-mux a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 a=group:BUNDLE audio video m=audio 49172 RTP/AVP 99 a=mid:audio a=pcfg:1 a=1 a=pcfg:2 m=video 560024 RTP/AVP 100 a=mid:video a=pcfg:1 a=1 a=pcfg:2 a=2 In the example above, the potential configuration number "1" is repeated while referring to attribute capability a=rtcp-mux, since the behavior is IDENTICAL for the attribute a=rtcp-mux under multiplexing. Nandakumar Expires March 26, 2017 [Page 68]
Internet-Draft SDP Attribute Multiplexing September 2016 14.3. RFC6871 Analysis [RFC6871] extends the capability negotiation framework described in [RFC5939] by defining media capabilities that can be used to indicate and negotiate media types and their associated format parameters. It also allows indication of latent configurations and session capabilities. 14.3.1. Recommendation: Dealing with Payload Type Numbers [RFC6871] defines a new payload type ("pt") parameter to be used with the potential, actual, and latent configuration parameters. The parameter associates RTP payload type numbers with the referenced RTP-based media format capabilities ("a=rmcap") defined in [RFC6871] and is appropriate only when the transport protocol uses RTP. This means that the same payload type number can be assigned as part of potential or actual configurations in different media descriptions in a bundle. There are rules for the usage of identical Payload Type values across multiplexed "m=" lines as described in [I-D.ietf-mmusic-sdp-bundle-negotiation], which must be followed here as well. As described in Section 14.2.1, the use of identical configuration numbers for compatible configurations in different media descriptions that are part of the bundle provides a way to ensure that the answerer can easily pick compatible configurations here as well. 14.3.1.1. Example: Attribute Capability Under Shared Payload Type The attributes (a=rmcap, a=mfcap) follow the above recommendations under multiplexing. Nandakumar Expires March 26, 2017 [Page 69]
Internet-Draft SDP Attribute Multiplexing September 2016 v=0 o=- 25678 753849 IN IP4 192.0.2.1 s= c=IN IP4 192.0.2.1 t=0 0 a=creq:med-v0 m=audio 54322 RTP/AVP 96 a=rtpmap:96 AMR-WB/16000/1 a=fmtp:96 mode-change-capability=1; max-red=220; mode-set=0,2,4,7 a=rmcap:1,3 audio AMR-WB/16000/1 a=rmcap:2 audio AMR/8000/1 a=mfcap:1,2 mode-change-capability=1 a=mfcap:3 mode-change-capability=2 a=pcfg:1 m=1 pt=1:96 a=pcfg:2 m=2 pt=2:97 a=pcfg:3 m=3 pt=3:98 m=audio 54322 RTP/AVP 96 a=rtpmap:96 AMR-WB/16000/1 a=fmtp:96 mode-change-capability=1; max-red=220; mode-set=0,2,4,7 a=rmcap:4 audio AMR/8000/1 a=rmcap:5 audio OPUS/48000/2 a=mfcap:5 minptime=40 a=mfcap:4 mode-change-capability=1 a=pcfg:1 m=4 pt=4:97 a=pcfg:4 m=5 pt=5:101 In the example above, the potential configuration number "1" is repeated when referring to media and media format capability used for the Payload Type 96. This implies that both the media capability 2 and 4 along with their media format capabilities MUST refer to the same codec configuration, as per the definition of IDENTICAL-PER-PT. 14.3.2. Recommendation: Dealing with Latent Configurations [RFC6871] adds the notion of a latent configurations, which provides configuration information that may be used to guide a subsequent offer/exchange, e.g. by adding another media stream or use alternative codec combinations not currently offered. Latent configurations have configuration numbers which cannot overlap with the potential configuration numbers [RFC6871]. Supported combinations of potential and latent configurations are indicated by use of the "a=sescap" attribute, however use of this attribute is not recommended with multiplexed media, since it requires the use of unique configuration numbers across the SDP. Taken together, this means there is no well-defined way to indicate supported combinations Nandakumar Expires March 26, 2017 [Page 70]
Internet-Draft SDP Attribute Multiplexing September 2016 of latent configurations, or combinations of latent and potential configurations with multiplexed media. It is still allowed to use the latent configuration attribute, however the limitations above will apply. To determine valid combinations, actual negotiation will have to be attempted subsequently instead. 15. IANA Considerations [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this document.] Section 15.1 defines a new subregistry to be added by the IANA for identifying the initial registrations for various multiplexing categories applicable, as proposed in this document. IANA is also requested to add a new column named "Mux Category" to several of the subregistries in the "Session Description Protocol (SDP) Parameters" registry. The tables in Section 15.2 identify name of an entry in the existing subregistry and specify the value to be put in the new "Mux Category" column of the associated IANA registry. 15.1. New 'Multiplexing Categories' subregistry A new sub-registry needs to be defined called the "Multiplexing Categories", with the following registrations created initially: "NORMAL", "CAUTION", "IDENTICAL", "TRANSPORT", "SUM", "INHERIT", "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this document. Initial value registration for "Multiplexing Categories". +-------------------------+-----------+ | Multiplexing Categories | Reference | +-------------------------+-----------+ | NORMAL | RFCXXXX | | CAUTION | RFCXXXX | | IDENTICAL | RFCXXXX | | TRANSPORT | RFCXXXX | | SUM | RFCXXXX | | INHERIT | RFCXXXX | | IDENTICAL-PER-PT | RFCXXXX | | SPECIAL | RFCXXXX | | TBD | RFCXXXX | +-------------------------+-----------+ Further entries can be registered using Standard Actions policies outlined in [RFC5226], which requires IESG review and approval and standards-track IETF RFC publication. Nandakumar Expires March 26, 2017 [Page 71]
Internet-Draft SDP Attribute Multiplexing September 2016 Each registration needs to indicate the multiplexing category value to be added to the "Multiplexing Categories" subregistry as defined in this section. Such a registration MUST also indicate the applicability of the newly defined multiplexing category value to various subregistries defined at the "Session Description Protocol (SDP) Parameters" registry. 15.2. 'Mux Category' column for subregistries Each sub-section identifies a subregistry in the "Session Description Protocol (SDP) Parameters" registry. The tables list the column that identifies the SDP attribute name/Token/Value from the corresponding subregistries and the values to be used for the new "Mux Category" column to be added. For the entries in the existing subregistries, under the "Session Description Protocol (SDP) Parameters" registry, that lack a value for the "Mux Category" in this specification will get a value of "TBD". Any future updates to the "Mux Category" column values needs to follow the existing registration policy of the affected table (Section 8.2.4.2 of [I-D.ietf-mmusic-rfc4566bis]). Also, the procedures from Section 8.2.4.1 of [I-D.ietf-mmusic-rfc4566bis] needs to be followed when assigning "Mux Category" value for the newly defined SDP attributes. 15.2.1. Table: SDP bwtype The following values are to be added to the 'SDP bwtype' subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +----------+--------------+ | SDP Name | Mux Category | +----------+--------------+ | CT | NORMAL | | AS | SUM | | RS | SUM | | RR | SUM | | TIAS | SPECIAL | +----------+--------------+ Nandakumar Expires March 26, 2017 [Page 72]
Internet-Draft SDP Attribute Multiplexing September 2016 15.2.2. Table: att-field (session level) The following values are to be added to the "att-field (session level)" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +---------------------+--------------+ | SDP Name | Mux Category | +---------------------+--------------+ | cat | NORMAL | | keywds | NORMAL | | type | NORMAL | | type:broadcast | NORMAL | | type:H332 | NORMAL | | type:meeting | NORMAL | | type:moderated | NORMAL | | type:test | NORMAL | | charset | NORMAL | | charset:iso8895-1 | NORMAL | | tool | NORMAL | | ipbcp | SPECIAL | | group | NORMAL | | ice-lite | NORMAL | | ice-options | NORMAL | | bcastversion | NORMAL | | 3GPP-Integrity-Key | CAUTION | | 3GPP-SDP-Auth | CAUTION | | alt-group | CAUTION | | PSCid | NORMAL | | bc_service | NORMAL | | bc_program | NORMAL | | bc_service_package | NORMAL | | sescap | CAUTION | | rtsp-ice-d-m | TBD | +---------------------+--------------+ 15.2.3. Table: att-field (both session and media level) The following values are to be added to the "att-field (both session and media level)" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. NOTE: The attributes from draft-ietf-rmt-flute-sdp ('flute-tsi', 'flute-ch', 'FEC-declaration', 'FEC-OTI-extension', 'content-desc') were not analyzed for their multiplexing behavior due to the expired Nandakumar Expires March 26, 2017 [Page 73]
Internet-Draft SDP Attribute Multiplexing September 2016 status of the draft. For purposes of this specification, the multiplexing category of 'TBD' is assigned. +-------------------------+-------------------+ | SDP Name | Mux Category | +-------------------------+-------------------+ | recvonly | NORMAL | | sendrecv | NORMAL | | sendonly | NORMAL | | sdplang | NORMAL | | lang | NORMAL | | h248item | SPECIAL | | sqn | NORMAL | | cdsc | NORMAL | | cpar | INHERIT | | cparmin | SPECIAL | | cparmax | SPECIAL | | rtcp-xr | NORMAL | | maxprate | SPECIAL | | setup | TRANSPORT | | connection | TRANSPORT | | key-mgmt | IDENTICAL | | source-filter | IDENTICAL | | inactive | NORMAL | | fingerprint | TRANSPORT | | flute-tsi | TBD | | flute-ch | TBD | | FEC-declaration | TBD | | FEC-OTI-extension | TBD | | content-desc | TBD | | ice-pwd | TRANSPORT | | ice-ufrag | TRANSPORT | | stkmstream | NORMAL | | extmap | SPECIAL | | qos-mech-send | TRANSPORT | | qos-mech-recv | TRANSPORT | | csup | NORMAL | | creq | NORMAL | | acap | INHERIT | | tcap | INHERIT | | 3GPP-QoE-Metrics | CAUTION | | 3GPP-Asset-Information | CAUTION | | mbms-mode | CAUTION | | mbms-repair | CAUTION | | ike-setup | IDENTICAL | | psk-fingerprint | IDENTICAL | | multicast-rtcp | IDENTICAL | | rmcap | IDENTICAL-PER-PT | Nandakumar Expires March 26, 2017 [Page 74]
Internet-Draft SDP Attribute Multiplexing September 2016 | omcap | NORMAL | | mfcap | IDENTICAL-PER-PT | | mscap | INHERIT | | 3gpp.iut.replication | TBD | | bcap | INHERIT | | ccap | IDENTICAL | | icap | NORMAL | | 3gpp_sync_info | NORMAL | | 3gpp_MaxRecvSDUSize | NORMAL | | etag | CAUTION | | duplication-delay | NORMAL | | range | CAUTION | | control | CAUTION | | mtag | CAUTION | | ts-refclk | NORMAL | | mediaclk | NORMAL | | calgextmap | NORMAL | +-------------------------+-------------------+ 15.2.4. Table: att-field (media level only) The following values are to be added to the "att-field (media level only)" registry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +---------------------------+-------------------+ | SDP Name | Mux Category | +---------------------------+-------------------+ | ptime | IDENTICAL-PER-PT | | orient | NORMAL | | orient:portrait | NORMAL | | orient:landscape | NORMAL | | orient:seascape | NORMAL | | framerate | IDENTICAL-PER-PT | | quality | NORMAL | | rtpmap | IDENTICAL-PER-PT | | fmtp | IDENTICAL-PER-PT | | rtpred1 | CAUTION | | rtpred2 | CAUTION | | T38FaxVersion | TBD | | T38MaxBitRate | TBD | | T38FaxFillBitRemoval | TBD | | T38FaxTranscodingMMR | TBD | | T38FaxTranscodingJBIG | TBD | | T38FaxRateManagement | TBD | | T38FaxMaxBuffer | TBD | | T38FaxMaxDatagram | TBD | Nandakumar Expires March 26, 2017 [Page 75]
Internet-Draft SDP Attribute Multiplexing September 2016 | T38FaxUdpEC | TBD | | maxptime | IDENTICAL-PER-PT | | des | CAUTION | | curr | CAUTION | | conf | CAUTION | | mid | NORMAL | | rtcp | TRANSPORT | | rtcp-fb | IDENTICAL-PER-PT | | label | NORMAL | | T38VendorInfo | TBD | | crypto | TRANSPORT | | eecid | CAUTION | | aalType | CAUTION | | capability | CAUTION | | qosClass | CAUTION | | bcob | CAUTION | | stc | CAUTION | | upcc | CAUTION | | atmQOSparms | CAUTION | | atmTrfcDesc | CAUTION | | abrParms | CAUTION | | abrSetup | CAUTION | | bearerType | CAUTION | | lij | CAUTION | | anycast | CAUTION | | cache | CAUTION | | bearerSigIE | CAUTION | | aalApp | CAUTION | | cbrRate | CAUTION | | sbc | CAUTION | | clkrec | CAUTION | | fec | CAUTION | | prtfl | CAUTION | | structure | CAUTION | | cpsSDUsize | CAUTION | | all2CPS | CAUTION | | all2CPSSDUrate | CAUTION | | aal2sscs3661unassured | CAUTION | | aal2sscs3661assured | CAUTION | | aal2sscs3662 | CAUTION | | aal5sscop | CAUTION | | atmmap | CAUTION | | silenceSupp | CAUTION | | ecan | CAUTION | | gc | CAUTION | | profileDesc | CAUTION | | vsel | CAUTION | | dsel | CAUTION | Nandakumar Expires March 26, 2017 [Page 76]
Internet-Draft SDP Attribute Multiplexing September 2016 | fsel | CAUTION | | onewaySel | CAUTION | | codecconfig | CAUTION | | isup_usi | CAUTION | | uiLayer1_Prot | CAUTION | | chain | CAUTION | | floorctrl | IDENTICAL | | confid | NORMAL | | userid | NORMAL | | floorid | NORMAL | | FEC | NORMAL | | accept-types | TBD | | accept-wrapped-types | TBD | | max-size | TBD | | path | TBD | | dccp-service-code | CAUTION | | rtcp-mux | IDENTICAL | | candidate | TRANSPORT | | ice-mismatch | NORMAL | | remote-candidates | TRANSPORT | | SRTPAuthentication | TBD | | SRTPROCTxRate | TBD | | rtcp-rsize | IDENTICAL | | file-selector | TBD | | file-transfer-id | TBD | | file-disposition | TBD | | file-date | TBD | | file-icon | TBD | | file-range | TBD | | depend | IDENTICAL-PER-PT | | ssrc | NORMAL | | ssrc-group | NORMAL | | rtcp-unicast | IDENTICAL | | pcfg | SPECIAL | | acfg | SPECIAL | | zrtp-hash | TRANSPORT | | X-predecbufsize | CAUTION | | X-initpredecbufperiod | CAUTION | | X-initpostdecbufperiod | CAUTION | | X-decbyterate | CAUTION | | 3gpp-videopostdecbufsize | CAUTION | | framesize | CAUTION | | 3GPP-SRTP-Config | CAUTION | | alt | CAUTION | | alt-default-id | CAUTION | | 3GPP-Adaption-Support | CAUTION | | mbms-flowid | CAUTION | | fec-source-flow | SPECIAL | Nandakumar Expires March 26, 2017 [Page 77]
Internet-Draft SDP Attribute Multiplexing September 2016 | fec-repair-flow | SPECIAL | | repair-window | SPECIAL | | rams-updates | CAUTION | | imageattr | IDENTICAL-PER-PT | | cfw-id | NORMAL | | portmapping-req | CAUTION | | g.3gpp.cat | NORMAL | | g.3gpp.crs | NORMAL | | ecn-capable-rtp | IDENTICAL | | visited-realm | TRANSPORT | | secondary-realm | TRANSPORT | | omr-s-cksum | NORMAL | | omr-m-cksum | NORMAL | | omr-codecs | NORMAL | | omr-m-att | NORMAL | | omr-s-att | NORMAL | | omr-m-bw | NORMAL | | omr-s-bw | NORMAL | | msrp-cema | TBD | | dccp-port | CAUTION | | resource | NORMAL | | channel | NORMAL | | cmid | NORMAL | | content | NORMAL | | lcfg | SPECIAL | | loopback | NORMAL | | loopback-source | NORMAL | | loopback-mirror | NORMAL | | chatroom | TBD | | altc | TRANSPORT | | T38FaxMaxIFP | TBD | | T38FaxUdpECDepth | TBD | | T38FaxUdpFECMaxSpan | TBD | | T38ModemType | TBD | | cs-correlation | TBD | | rtcp-idms | NORMAL | +---------------------------+-------------------+ 15.2.5. Table: att-field (source level) The following values are to be added to the "att-field (source level)" registry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. Nandakumar Expires March 26, 2017 [Page 78]
Internet-Draft SDP Attribute Multiplexing September 2016 +----------------+-------------------+ | SDP Name | Mux Category | +----------------+-------------------+ | cname | NORMAL | | previous-ssrc | NORMAL | | fmtp | IDENTICAL-PER-PT | | ts-refclk | NORMAL | | mediaclk | NORMAL | +----------------+-------------------+ 15.2.6. Table: content SDP Parameters The following values are to be added to the "content SDP Parameters" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +----------+--------------+ | SDP Name | Mux Category | +----------+--------------+ | slides | NORMAL | | speaker | NORMAL | | sl | NORMAL | | main | NORMAL | | alt | NORMAL | +----------+--------------+ 15.2.7. Table: Semantics for the 'group' SDP Attribute The following values are to be added to the "Semantics for the "group" SDP Attribute" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +---------+--------------+ | Token | Mux Category | +---------+--------------+ | LS | NORMAL | | FID | NORMAL | | SRF | NORMAL | | ANAT | CAUTION | | FEC | NORMAL | | FEC-FR | NORMAL | | CS | NORMAL | | DDP | NORMAL | | DUP | NORMAL | +---------+--------------+ Nandakumar Expires March 26, 2017 [Page 79]
Internet-Draft SDP Attribute Multiplexing September 2016 15.2.8. Table: 'rtcp-fb' Attribute Values The following values are to be added to the " 'rtcp-fb' Attribute Values" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +------------+-------------------+ | Value Name | Mux Category | +------------+-------------------+ | ack | IDENTICAL-PER-PT | | app | SPECIAL | | ccm | IDENTICAL-PER-PT | | nack | IDENTICAL-PER-PT | | trr-int | IDENTICAL-PER-PT | +------------+-------------------+ 15.2.9. Table: 'ack' and 'nack' Attribute Values The following values are to be added to the " 'ack' and 'nack' Attribute Values" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +------------+-------------------+ | Value Name | Mux Category | +------------+-------------------+ | sli | IDENTICAL-PER-PT | | pli | IDENTICAL-PER-PT | | rpsi | IDENTICAL-PER-PT | | app | SPECIAL | | rai | IDENTICAL-PER-PT | | tllei | IDENTICAL-PER-PT | | pslei | IDENTICAL-PER-PT | | ecn | IDENTICAL | +------------+-------------------+ 15.2.10. Table: 'depend' SDP Attribute Values The following values are to be added to the " 'depend' SDP Attribute Values" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. Nandakumar Expires March 26, 2017 [Page 80]
Internet-Draft SDP Attribute Multiplexing September 2016 +-------+-------------------+ | Token | Mux Category | +-------+-------------------+ | lay | IDENTICAL-PER-PT | | mdc | IDENTICAL-PER-PT | +-------+-------------------+ 15.2.11. Table: 'cs-correlation' Attribute Values The following values are to be added to the " "cs-correlation" Attribute Values" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +-----------+--------------+ | Value | Mux Category | +-----------+--------------+ | callerid | TBD | | uuie | TBD | | dtmf | TBD | | external | TBD | +-----------+--------------+ 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute The following values are to be added to the Semantics for the "Semantics for the "ssrc-group" SDP Attribute" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +---------+--------------+ | Token | Mux Category | +---------+--------------+ | FID | NORMAL | | FEC | NORMAL | | FEC-FR | NORMAL | | DUP | NORMAL | +---------+--------------+ 15.2.13. Table: SDP/RTSP key management protocol identifiers The following values are to be added to the "SDP/RTSP key management protocol identifiers" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. Nandakumar Expires March 26, 2017 [Page 81]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+--------------+ | Value Name | Mux Category | +------------+--------------+ | mikey | IDENTICAL | +------------+--------------+ 15.2.14. Table: Codec Control Messages The following values are to be added to the "Codec Control Messages" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +------------+-------------------+ | Value Name | Mux Category | +------------+-------------------+ | fir | IDENTICAL-PER-PT | | tmmbr | IDENTICAL-PER-PT | | tstr | IDENTICAL-PER-PT | | vbcm | IDENTICAL-PER-PT | +------------+-------------------+ 15.2.15. Table: QoS Mechanism Tokens The following values are to be added to the "QoS Mechanism Tokens" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +---------------+--------------+ | QoS Mechanism | Mux Category | +---------------+--------------+ | rsvp | TRANSPORT | | nsis | TRANSPORT | +---------------+--------------+ 15.2.16. Table: SDP Capability Negotiation Option Tags The following values are to be added to the "SDP Capability Negotiation Option Tags" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. Nandakumar Expires March 26, 2017 [Page 82]
Internet-Draft SDP Attribute Multiplexing September 2016 +------------+--------------+ | Option Tag | Mux Category | +------------+--------------+ | cap-v0 | NORMAL | | med-v0 | NORMAL | | bcap-v0 | NORMAL | | ccap-v0 | NORMAL | | icap-v0 | NORMAL | +------------+--------------+ 15.2.17. Table: Timestamp Reference Clock Source Parameters The following values are to be added to the "Timestamp Reference Clock Source Parameters" subregistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +----------+--------------+ | Name | Mux Category | +----------+--------------+ | ntp | NORMAL | | ptp | NORMAL | | gps | NORMAL | | gal | NORMAL | | glonass | NORMAL | | local | NORMAL | | private | NORMAL | +----------+--------------+ 15.2.18. Table: Media Clock Source Parameters The following values are to be added to the "Media Clock Source Parameters" subegistry in the "Session Description Protocol (SDP) Parameters" registry. The references should be updated to point at this RFC as well as the previous references. +-----------+--------------+ | Name | Mux Category | +-----------+--------------+ | sender | NORMAL | | direct | NORMAL | | IEEE1722 | NORMAL | +-----------+--------------+ Nandakumar Expires March 26, 2017 [Page 83]
Internet-Draft SDP Attribute Multiplexing September 2016 16. Security Considerations This document does not add any new security considerations beyond the existing considerations in the RTP RFCs ([RFC3550] and [RFC3711]) that are referenced by this specification. The primary security for RTP including the way it is used here is described in [RFC3550] and [RFC3711]. When multiplexing SDP attributes with the category "CAUTION", the implementations should be aware of possible issues as described in this specification. 17. Acknowledgments I would like to thank Cullen Jennings, Flemming Andreasen for suggesting the categories, contributing text and reviewing the draft. I would also link to thank Magnus Westerlund, Christer Holmberg, Jonathan Lennox, Bo Burman, Ari Keranen, and Dan Wing on suggesting structural changes helping improve the document readability. I would like also to thank following experts on their inputs and reviews as listed - Flemming Andreasen(5.24,5.32,5.33,14), Rohan Mahy(5.57), Eric Burger(5.26),Christian Huitema(5.14), Christer Holmberg(5.21,5.26,5.51,5.52), Richard Ejzak (5.44,5.53,5.54), Colin Perkins(5.7,5.8,5.9,5.58), Magnus Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Roni Evens(5.12,5.27,8.4), Subha Dhesikan(5.6,10), Dan Wing(5.7,5.12,5.35,5.39,5.45), Cullen Jennings (5.40), Ali C Begen(5.1,5.20,5.22,5.25,5.38,7.3,8.2,8.4,8.6,9.2,13.1), Bo Burman (7.2,7.6), Charles Eckel(5.15,5.27,5.28,9.1,8.5), Paul Kyzivat(5.24), Ian Johansson(5.15), Saravanan Shanmugham(5.11), Paul E Jones(5.30), Rajesh Kumar(5.48), Jonathan Lennox(5.36,5,15,9.1,11.1), Mo Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Christian Huitema (5.14), Qin Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves (5.48,5.55), Thomas Stach. I would like to thank Chris Lonvick for the SECDIR review, Dan Romascanu for th Gen-ART review and Sabrina Tanamal for the IANA review. Thanks to Ben Campbell for AD review suggestions. 18. Change Log [RFC EDITOR NOTE: Please remove this section when publishing] Nandakumar Expires March 26, 2017 [Page 84]
Internet-Draft SDP Attribute Multiplexing September 2016 Changes from draft-ietf-mmusic-sdp-mux-attributes-10 - draft-ietf- mmusic-sdp-mux-attributes-13 o Incorporated Comments from WGLC review and AD Evaluation Changes from draft-ietf-mmusic-sdp-mux-attributes-10 o Incorporated Comments from Bo Burman for publication request Changes from draft-ietf-mmusic-sdp-mux-attributes-08 to draft-ietf- mmusic-sdp-mux-attributes-10 o Minor nits and version update to advert expiration Changes from draft-ietf-mmusic-sdp-mux-attributes-06 to draft-ietf- mmusic-sdp-mux-attributes-08 o Assigned TBD category to all the attributes for whom there exists no specification on multiplexing behavior over the underlying transport protocol today. o Incorporated comments from Flemming and Ari (post last call) Changes from draft-ietf-mmusic-sdp-mux-attributes-06 o Incorporated last call review comments from Thomas Stach and Ari Keranen. o Fixed more nits to prep for the LastCall. Changes from draft-ietf-mmusic-sdp-mux-attributes-05 o Incorporated review comments from Christian Grooves and Ari Keranen. o Fixed more nits to prep for the LastCall. Changes from draft-ietf-mmusic-sdp-mux-attributes-04 o Fixed minor nits overall. o Updated Acknowledgement Sections o Last Call Version. Changes from draft-ietf-mmusic-sdp-mux-attributes-03 o More re-work on the IANA section. Nandakumar Expires March 26, 2017 [Page 85]
Internet-Draft SDP Attribute Multiplexing September 2016 o Clean ups preparing for the last call. Changes from draft-ietf-mmusic-sdp-mux-attributes-02 o Incorporated suggestions from Flemming on Capability Negotiation. o Closed open issues from IETF90 o Added IANA section to list the categories for all the SDP attributes anlayzed o Lots of cleanup o Reformatted Refernces section to use short-form notation Changes from draft-ietf-mmusic-sdp-mux-attributes-01 o Updated section 15 to provide detailed recommendation on dealing with encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 to refer to Section 15. o Added new categories IDENTICAL-PER-PT and INHERIT o Updated Sections 16 to add the new categories. o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the category IDENTICAL-PER-PT. o Reformatted section 4 to add individual categories to their own sections. Changes from draft-ietf-mmusic-sdp-mux-attributes-00 o Added Section 15 to provide recommendations on multiplexing SDP encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 to refer to Section 15. o Updated Section 5.38 to incorporate PM-dir review inputs from Qin Wu o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more clarity. o Fixed few nits regarding sentence clarity and fill-in the NOTES section where information was lacking. Changes from draft-nandakumar-mmusic-mux-attributes-05 Nandakumar Expires March 26, 2017 [Page 86]
Internet-Draft SDP Attribute Multiplexing September 2016 o Renamed the document to be a WG document. o Added Section 14. o Updated Open Issues based on IETF88 discussions. Changes from draft-nandakumar-mmusic-mux-attributes-04 o Added few OPEN ISSUES that needs to be discussed. o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 o Updated Table Column name Current to Level and improved TRANSPORT category explanation on suggestions form Dan Wing. o Grouped all the rtcp-fb attribute analysis under a single section as suggested by Magnus/ Changes from draft-nandakumar-mmusic-mux-attributes-03 o Maintenance change to clean up grammatical nits and wordings. Changes from draft-nandakumar-mmusic-mux-attributes-02 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 5.37,5.40,5.41,5.42,5.43,5.44,5.45,6.1,6.2,6.3,8,3,12.1 based on the inputs from the respective RFC Authors. Changes from draft-nandakumar-mmusic-mux-attributes-01 o Replaced Category BAD with NOT-RECOMMENDED. o Added Category TBD. o Updated IANA Consideration Section. Changes from draft-nandakumar-mmusic-mux-attributes-00 o Added new section for dealing with FEC payload types. 19. References 19.1. Normative References Nandakumar Expires March 26, 2017 [Page 87]
Internet-Draft SDP Attribute Multiplexing September 2016 [I-D.ietf-mmusic-rfc4566bis] Handley, M., Jacobson, V., Perkins, C., and A. Begen, "SDP: Session Description Protocol", draft-ietf-mmusic- rfc4566bis-17 (work in progress), June 2016. [I-D.ietf-mmusic-sdp-bundle-negotiation] Holmberg, C., Alvestrand, H., and C. Jennings, "Negotiating Media Multiplexing Using the Session Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- negotiation-24 (work in progress), January 2016. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, DOI 10.17487/RFC4566, July 2006, <http://www.rfc-editor.org/info/rfc4566>. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <http://www.rfc-editor.org/info/rfc5226>. 19.2. Informative References [H.248.15] "Gateway control protocol: SDP H.248 package attribute", <http://www.itu.int/rec/T-REC-H.248.15>. [IANA] "Session Description Protocol (SDP) Parameters", <http://www.iana.org/assignments/sdp-parameters/ sdp-parameters.xml>. [Q.1970] "Q.1970 : BICC IP bearer control protocol", <https://www.itu.int/rec/T-REC-Q.1970-200609-I/en>. [R3GPPTS183.063] "TISPAN - IMS based ITPV Stage 3 specification.", <http://www.etsi.org/deliver/ etsi_ts/183000_183099/183063/02.01.00_60/ ts_183063v020100p.pdf>. [R3GPPTS24.182] "IP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT); Protocol specification", <http://www.3gpp.org/ftp/Specs/html-info/24182.htm>. Nandakumar Expires March 26, 2017 [Page 88]
Internet-Draft SDP Attribute Multiplexing September 2016 [R3GPPTS24.183] "IP Multimedia Subsystem (IMS) Customized Ringing Signal (CRS); Protocol specification", <http://www.3gpp.org/ftp/Specs/html-info/24183.htm>. [R3GPPTS24.229] "IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP);", <http://www.3gpp.org/ftp/Specs/html-info/24229.htm>. [R3GPPTS26.114] "IP multimedia Subsystem : Media Handling and interaction", <http://www.3gpp.org/DynaReport/26114.htm>. [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming Protocol (RTSP)", RFC 2326, DOI 10.17487/ RFC2326, April 1998, <http://www.rfc-editor.org/info/rfc2326>. [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the Session Description Protocol (SDP) for ATM Bearer Connections", RFC 3108, DOI 10.17487/RFC3108, May 2001, <http://www.rfc-editor.org/info/rfc3108>. [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, DOI 10.17487/RFC3264, June 2002, <http://www.rfc-editor.org/info/rfc3264>. [RFC3312] Camarillo, G., Ed., Marshall, W., Ed., and J. Rosenberg, "Integration of Resource Management and Session Initiation Protocol (SIP)", RFC 3312, DOI 10.17487/RFC3312, October 2002, <http://www.rfc-editor.org/info/rfc3312>. [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple Capability Declaration", RFC 3407, DOI 10.17487/RFC3407, October 2002, <http://www.rfc-editor.org/info/rfc3407>. [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to Resource Reservation Flows", RFC 3524, DOI 10.17487/ RFC3524, April 2003, <http://www.rfc-editor.org/info/rfc3524>. [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, <http://www.rfc-editor.org/info/rfc3550>. Nandakumar Expires March 26, 2017 [Page 89]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3556, DOI 10.17487/RFC3556, July 2003, <http://www.rfc-editor.org/info/rfc3556>. [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute in Session Description Protocol (SDP)", RFC 3605, DOI 10.17487/RFC3605, October 2003, <http://www.rfc-editor.org/info/rfc3605>. [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, DOI 10.17487/RFC3611, November 2003, <http://www.rfc-editor.org/info/rfc3611>. [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, <http://www.rfc-editor.org/info/rfc3711>. [RFC3890] Westerlund, M., "A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)", RFC 3890, DOI 10.17487/RFC3890, September 2004, <http://www.rfc-editor.org/info/rfc3890>. [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network Address Types (ANAT) Semantics for the Session Description Protocol (SDP) Grouping Framework", RFC 4091, DOI 10.17487/RFC4091, June 2005, <http://www.rfc-editor.org/info/rfc4091>. [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in the Session Description Protocol (SDP)", RFC 4145, DOI 10.17487/RFC4145, September 2005, <http://www.rfc-editor.org/info/rfc4145>. [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. Carrara, "Key Management Extensions for Session Description Protocol (SDP) and Real Time Streaming Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July 2006, <http://www.rfc-editor.org/info/rfc4567>. [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session Description Protocol (SDP) Security Descriptions for Media Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006, <http://www.rfc-editor.org/info/rfc4568>. Nandakumar Expires March 26, 2017 [Page 90]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol (SDP) Source Filters", RFC 4570, DOI 10.17487/RFC4570, July 2006, <http://www.rfc-editor.org/info/rfc4570>. [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the Transport Layer Security (TLS) Protocol in the Session Description Protocol (SDP)", RFC 4572, DOI 10.17487/ RFC4572, July 2006, <http://www.rfc-editor.org/info/rfc4572>. [RFC4574] Levin, O. and G. Camarillo, "The Session Description Protocol (SDP) Label Attribute", RFC 4574, DOI 10.17487/ RFC4574, August 2006, <http://www.rfc-editor.org/info/rfc4574>. [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams", RFC 4583, DOI 10.17487/RFC4583, November 2006, <http://www.rfc-editor.org/info/rfc4583>. [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, <http://www.rfc-editor.org/info/rfc4585>. [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description Protocol (SDP) Content Attribute", RFC 4796, DOI 10.17487/ RFC4796, February 2007, <http://www.rfc-editor.org/info/rfc4796>. [RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed., "The Message Session Relay Protocol (MSRP)", RFC 4975, DOI 10.17487/RFC4975, September 2007, <http://www.rfc-editor.org/info/rfc4975>. [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, <http://www.rfc-editor.org/info/rfc5104>. [RFC5109] Li, A., Ed., "RTP Payload Format for Generic Forward Error Correction", RFC 5109, DOI 10.17487/RFC5109, December 2007, <http://www.rfc-editor.org/info/rfc5109>. Nandakumar Expires March 26, 2017 [Page 91]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC5159] Dondeti, L., Ed. and A. Jerichow, "Session Description Protocol (SDP) Attributes for Open Mobile Alliance (OMA) Broadcast (BCAST) Service and Content Protection", RFC 5159, DOI 10.17487/RFC5159, March 2008, <http://www.rfc-editor.org/info/rfc5159>. [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols", RFC 5245, DOI 10.17487/RFC5245, April 2010, <http://www.rfc-editor.org/info/rfc5245>. [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July 2008, <http://www.rfc-editor.org/info/rfc5285>. [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of Service (QoS) Mechanism Selection in the Session Description Protocol (SDP)", RFC 5432, DOI 10.17487/ RFC5432, March 2009, <http://www.rfc-editor.org/info/rfc5432>. [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, <http://www.rfc-editor.org/info/rfc5506>. [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., and P. Kyzivat, "A Session Description Protocol (SDP) Offer/Answer Mechanism to Enable File Transfer", RFC 5547, DOI 10.17487/RFC5547, May 2009, <http://www.rfc-editor.org/info/rfc5547>. [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific Media Attributes in the Session Description Protocol (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009, <http://www.rfc-editor.org/info/rfc5576>. [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding Dependency in the Session Description Protocol (SDP)", RFC 5583, DOI 10.17487/RFC5583, July 2009, <http://www.rfc-editor.org/info/rfc5583>. [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control Protocol (RTCP) Extensions for Single-Source Multicast Sessions with Unicast Feedback", RFC 5760, DOI 10.17487/ RFC5760, February 2010, <http://www.rfc-editor.org/info/rfc5760>. Nandakumar Expires March 26, 2017 [Page 92]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and Control Packets on a Single Port", RFC 5761, DOI 10.17487/ RFC5761, April 2010, <http://www.rfc-editor.org/info/rfc5761>. [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control Protocol (DCCP)", RFC 5762, DOI 10.17487/RFC5762, April 2010, <http://www.rfc-editor.org/info/rfc5762>. [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, <http://www.rfc-editor.org/info/rfc5763>. [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description Protocol (SDP) Grouping Framework", RFC 5888, DOI 10.17487/RFC5888, June 2010, <http://www.rfc-editor.org/info/rfc5888>. [RFC5939] Andreasen, F., "Session Description Protocol (SDP) Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939, September 2010, <http://www.rfc-editor.org/info/rfc5939>. [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in the Session Description Protocol", RFC 5956, DOI 10.17487/ RFC5956, September 2010, <http://www.rfc-editor.org/info/rfc5956>. [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions Defined for 3GPP Packet-Switched Streaming Service and Multimedia Broadcast/Multicast Service", RFC 6064, DOI 10.17487/RFC6064, January 2011, <http://www.rfc-editor.org/info/rfc6064>. [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- Specific Multicast (SSM) Sessions", RFC 6128, DOI 10.17487/RFC6128, February 2011, <http://www.rfc-editor.org/info/rfc6128>. [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: Media Path Key Agreement for Unicast Secure RTP", RFC 6189, DOI 10.17487/RFC6189, April 2011, <http://www.rfc-editor.org/info/rfc6189>. Nandakumar Expires March 26, 2017 [Page 93]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for the Internet Key Exchange Protocol (IKE) in the Session Description Protocol (SDP)", RFC 6193, DOI 10.17487/ RFC6193, April 2011, <http://www.rfc-editor.org/info/rfc6193>. [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media Control Channel Framework", RFC 6230, DOI 10.17487/ RFC6230, May 2011, <http://www.rfc-editor.org/info/rfc6230>. [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, <http://www.rfc-editor.org/info/rfc6236>. [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping between Unicast and Multicast RTP Sessions", RFC 6284, DOI 10.17487/RFC6284, June 2011, <http://www.rfc-editor.org/info/rfc6284>. [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, "Unicast-Based Rapid Acquisition of Multicast RTP Sessions", RFC 6285, DOI 10.17487/RFC6285, June 2011, <http://www.rfc-editor.org/info/rfc6285>. [RFC6364] Begen, A., "Session Description Protocol Elements for the Forward Error Correction (FEC) Framework", RFC 6364, DOI 10.17487/RFC6364, October 2011, <http://www.rfc-editor.org/info/rfc6364>. [RFC6642] Wu, Q., Ed., Xia, F., and R. Even, "RTP Control Protocol (RTCP) Extension for a Third-Party Loss Report", RFC 6642, DOI 10.17487/RFC6642, June 2012, <http://www.rfc-editor.org/info/rfc6642>. [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., and K. Carlberg, "Explicit Congestion Notification (ECN) for RTP over UDP", RFC 6679, DOI 10.17487/RFC6679, August 2012, <http://www.rfc-editor.org/info/rfc6679>. [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection Establishment for Media Anchoring (CEMA) for the Message Session Relay Protocol (MSRP)", RFC 6714, DOI 10.17487/ RFC6714, August 2012, <http://www.rfc-editor.org/info/rfc6714>. Nandakumar Expires March 26, 2017 [Page 94]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A Datagram Congestion Control Protocol UDP Encapsulation for NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November 2012, <http://www.rfc-editor.org/info/rfc6773>. [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control Protocol Version 2 (MRCPv2)", RFC 6787, DOI 10.17487/ RFC6787, November 2012, <http://www.rfc-editor.org/info/rfc6787>. [RFC6849] Kaplan, H., Ed., Hedayat, K., Venna, N., Jones, P., and N. Stratton, "An Extension to the Session Description Protocol (SDP) and Real-time Transport Protocol (RTP) for Media Loopback", RFC 6849, DOI 10.17487/RFC6849, February 2013, <http://www.rfc-editor.org/info/rfc6849>. [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session Description Protocol (SDP) Media Capabilities Negotiation", RFC 6871, DOI 10.17487/RFC6871, February 2013, <http://www.rfc-editor.org/info/rfc6871>. [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S. Veikkolainen, "The Session Description Protocol (SDP) Alternate Connectivity (ALTC) Attribute", RFC 6947, DOI 10.17487/RFC6947, May 2013, <http://www.rfc-editor.org/info/rfc6947>. [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman, "Miscellaneous Capabilities Negotiation in the Session Description Protocol (SDP)", RFC 7006, DOI 10.17487/ RFC7006, September 2013, <http://www.rfc-editor.org/info/rfc7006>. [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping Semantics in the Session Description Protocol", RFC 7104, DOI 10.17487/RFC7104, January 2014, <http://www.rfc-editor.org/info/rfc7104>. [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session Description Protocol (SDP) Extension for Setting Audio and Video Media Streams over Circuit-Switched Bearers in the Public Switched Telephone Network (PSTN)", RFC 7195, DOI 10.17487/RFC7195, May 2014, <http://www.rfc-editor.org/info/rfc7195>. Nandakumar Expires March 26, 2017 [Page 95]
Internet-Draft SDP Attribute Multiplexing September 2016 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay Attribute in the Session Description Protocol", RFC 7197, DOI 10.17487/RFC7197, April 2014, <http://www.rfc-editor.org/info/rfc7197>. [RFC7266] Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Mean Opinion Score (MOS) Metric Reporting", RFC 7266, DOI 10.17487/RFC7266, June 2014, <http://www.rfc-editor.org/info/rfc7266>. [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O., Boronat, F., Montagud, M., and K. Gross, "Inter- Destination Media Synchronization (IDMS) Using the RTP Control Protocol (RTCP)", RFC 7272, DOI 10.17487/RFC7272, June 2014, <http://www.rfc-editor.org/info/rfc7272>. [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H. Stokking, "RTP Clock Source Signalling", RFC 7273, DOI 10.17487/RFC7273, June 2014, <http://www.rfc-editor.org/info/rfc7273>. [RFC7657] Black, D., Ed. and P. Jones, "Differentiated Services (Diffserv) and Real-Time Communication", RFC 7657, DOI 10.17487/RFC7657, November 2015, <http://www.rfc-editor.org/info/rfc7657>. [T.38] "Procedures for real-time Group 3 facsimile communication over IP networks", <http://www.itu.int/rec/T-REC-T.38/e>. Author's Address Suhas Nandakumar Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: snandaku@cisco.com Nandakumar Expires March 26, 2017 [Page 96]