--- 1/draft-ietf-mmusic-sdp-mux-attributes-05.txt 2014-12-11 02:14:49.623869243 -0800 +++ 2/draft-ietf-mmusic-sdp-mux-attributes-06.txt 2014-12-11 02:14:49.811873841 -0800 @@ -1,52 +1,53 @@ Network Working Group S. Nandakumar Internet-Draft Cisco -Intended status: Standards Track November 26, 2014 -Expires: May 30, 2015 +Intended status: Standards Track December 11, 2014 +Expires: June 14, 2015 A Framework for SDP Attributes when Multiplexing - draft-ietf-mmusic-sdp-mux-attributes-05 + draft-ietf-mmusic-sdp-mux-attributes-06 Abstract The Session Description Protocol (SDP) provides mechanisms to describe attributes of multimedia sessions and of individual media streams (e.g., Real-time Transport Protocol (RTP) sessions) within a - multimedia session. In the RTCWEB WG, there is a need to use a - single 5-tuple for sending and receiving media associated with - multiple media descriptions ("m=" lines). Such a requirement has - raised concerns over the semantic implications of the SDP attributes - associated with the RTP Media Streams multiplexed over a single - underlying transport layer flow. + multimedia session. [I-D.ietf-mmusic-sdp-bundle-negotiation] + provides SDP extensions to negotiate the usage of single 5-tuple for + sending and receiving media associated with multiple media + descriptions ("m=" lines). Such a mechanism has made it necessary to + understand the semantic implications of the SDP attributes associated + with the RTP Media Streams multiplexed over a single underlying + transport layer flow. - The scope of this specification is to provide a framework for + The purpose of this specification is to provide a framework for analyzing the multiplexing characteristics of SDP attributes. 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 May 30, 2015. + This Internet-Draft will expire on June 14, 2015. Copyright Notice Copyright (c) 2014 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 @@ -66,210 +67,210 @@ outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 6 + 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 7 4.1. Category: NORMAL . . . . . . . . . . . . . . . . . . . . 7 - 4.2. Category: NOT RECOMMENDED . . . . . . . . . . . . . . . . 7 + 4.2. Category: NOT RECOMMENDED . . . . . . . . . . . . . . . . 8 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 + 4.7. Category: IDENTICAL-PER-PT . . . . . . . . . . . . . . . 11 + 4.8. Category: SPECIAL . . . . . . . . . . . . . . . . . . . . 12 + 4.9. Category: TBD . . . . . . . . . . . . . . . . . . . . . . 12 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 12 - 5.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 12 + 5.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 13 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 - Interactive Connectivity Establishment (ICE) . 19 + 5.3. RFC5761 - Multiplexing RTP and RTCP . . . . . . . . . . . 15 + 5.4. RFC3312 - Integration of Resource Management and (SIP) . 15 + 5.5. RFC4574 - SDP Label Attribute . . . . . . . . . . . . . . 16 + 5.6. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 16 + 5.7. RFC4568 - SDP Security Descriptions . . . . . . . . . . . 17 + 5.8. RFC5762 - RTP over DCCP . . . . . . . . . . . . . . . . . 17 + 5.9. RFC6773 - DCCP-UDP Encapsulation . . . . . . . . . . . . 18 + 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile . . . . . . . 19 + 5.11. RFC6787 - Media Resource Control Protocol Version 2 . . . 19 + 5.12. RFC5245 - Interactive Connectivity Establishment (ICE) . 20 5.13. RFC5285 - RTP Header Extensions . . . . . . . . . . . . . 21 - 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 . . . . . . 23 - 5.19. RFC7266 - RTCP XR Blocks for MOS Metric Reporting . . . 23 - 5.20. RFC6285 - Rapid Acquisition of Multicast RTP Sessions . . 24 - 5.21. RFC6230 - Media Control Channel Framework . . . . . . . . 24 - 5.22. RFC6364 - SDP Elements for FEC Framework . . . . . . . . 25 - 5.23. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 25 - 5.24. RFC3407 - SDP Simple Capability Declaration . . . . . . . 26 + 5.14. RFC3605 - RTCP attribute in SDP . . . . . . . . . . . . . 22 + 5.15. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 22 + 5.16. RFC7273 - RTP Clock Source Signalling . . . . . . . . . . 23 + 5.17. RFC6236 - Image Attributes in SDP . . . . . . . . . . . . 24 + 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 . . 25 + 5.21. RFC6230 - Media Control Channel Framework . . . . . . . . 25 + 5.22. RFC6364 - SDP Elements for FEC Framework . . . . . . . . 26 + 5.23. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 26 + 5.24. RFC3407 - SDP Simple Capability Declaration . . . . . . . 27 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP - Sessions . . . . . . . . . . . . . . . . . . . . . . . . 26 - 5.26. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 27 - 5.27. RFC4583 - SDP Format for BFCP Streams . . . . . . . . . . 27 - 5.28. RFC5547 - SDP Offer/Answer for File Transfer . . . . . . 28 - 5.29. RFC6849 - SDP and RTP Media Loopback Extension . . . . . 28 - 5.30. RFC5760 - RTCP with Unicast Feedback . . . . . . . . . . 29 - 5.31. RFC3611 - RTCP XR . . . . . . . . . . . . . . . . . . . . 29 - 5.32. RFC5939 - SDP Capability Negotiation . . . . . . . . . . 29 - 5.33. RFC6871- SDP Media Capabilities Negotiation . . . . . . . 30 - 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP . . 31 - 5.35. RFC4567 - Key Management Extensions for SDP and RTSP . . 32 - 5.36. RFC4572 - Comedia over TLS in SDP . . . . . . . . . . . . 33 - 5.37. RFC4570 - SDP Source Filters . . . . . . . . . . . . . . 33 - 5.38. RFC6128 - RTCP Port for Multicast Sessions . . . . . . . 34 - 5.39. RFC6189 - ZRTP . . . . . . . . . . . . . . . . . . . . . 34 + Sessions . . . . . . . . . . . . . . . . . . . . . . . . 27 + 5.26. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 28 + 5.27. RFC4583 - SDP Format for BFCP Streams . . . . . . . . . . 28 + 5.28. RFC5547 - SDP Offer/Answer for File Transfer . . . . . . 29 + 5.29. RFC6849 - SDP and RTP Media Loopback Extension . . . . . 29 + 5.30. RFC5760 - RTCP with Unicast Feedback . . . . . . . . . . 30 + 5.31. RFC3611 - RTCP XR . . . . . . . . . . . . . . . . . . . . 30 + 5.32. RFC5939 - SDP Capability Negotiation . . . . . . . . . . 30 + 5.33. RFC6871- SDP Media Capabilities Negotiation . . . . . . . 31 + 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP . . 32 + 5.35. RFC4567 - Key Management Extensions for SDP and RTSP . . 33 + 5.36. RFC4572 - Comedia over TLS in SDP . . . . . . . . . . . . 34 + 5.37. RFC4570 - SDP Source Filters . . . . . . . . . . . . . . 34 + 5.38. RFC6128 - RTCP Port for Multicast Sessions . . . . . . . 35 + 5.39. RFC6189 - ZRTP . . . . . . . . . . . . . . . . . . . . . 35 5.40. RFC4145 - Connection-Oriented Media . . . . . . . . . . . 35 - 5.41. RFC6947 - The SDP ALTC Attribute . . . . . . . . . . . . 35 + 5.41. RFC6947 - The SDP ALTC Attribute . . . . . . . . . . . . 36 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers - in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) . . 36 - 5.44. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . 36 - 5.45. RFC6193 - Media Description for IKE in SDP . . . . . . . 37 - 5.46. RFC2326 - Real Time Streaming Protocol . . . . . . . . . 38 - 5.47. RFC6064 - SDP and RTSP Extensions for 3GPP . . . . . . . 38 - 5.48. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 41 - 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 42 - 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 43 - 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 43 - 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 44 - 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 44 - 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 45 - 5.55. ITU-T-REC.Q1970 . . . . . . . . . . . . . . . . . . . . . 46 - 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 47 - 5.57. RFC4975 - The Message Session Relay Protocol . . . . . . 47 - 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 48 - 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 48 - 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 48 - 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . 49 - 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . 49 - 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 50 - 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 50 - 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 51 - 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . 52 - 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 52 - 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 53 - 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 54 - 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 54 - 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . 54 + in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 36 + 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) . . 37 + 5.44. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . 37 + 5.45. RFC6193 - Media Description for IKE in SDP . . . . . . . 38 + 5.46. RFC2326 - Real Time Streaming Protocol . . . . . . . . . 39 + 5.47. RFC6064 - SDP and RTSP Extensions for 3GPP . . . . . . . 39 + 5.48. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 42 + 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 45 + 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 45 + 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 45 + 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 46 + 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 46 + 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 47 + 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 48 + 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 49 + 5.57. RFC4975 - The Message Session Relay Protocol . . . . . . 50 + 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 50 + 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 50 + 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 51 + 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . 51 + 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . 52 + 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 52 + 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 52 + 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 53 + 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . 54 + 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 54 + 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 55 + 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 56 + 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 56 + 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . 56 8.2. RFC3524 - Mapping Media Streams to Resource - Reservation Flows . . . . . . . . . . . . . . . . . . . . 55 - 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . 55 - 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 55 - 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . 56 - 8.6. RFC7104 - Duplication Grouping Semantics in the SDP . . 56 - 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 57 - 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 57 - 9.2. RFC7104 - Duplication Grouping Semantics in the SDP . . . 57 - 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 57 - 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 57 - 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 58 - 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . 58 - 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 58 - 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 58 - 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 59 - 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . 59 - 14. Multiplexing Considerations for Encapsulating Attributes . . 59 - 14.1. RFC3407 - cpar Attribute Analysis . . . . . . . . . . . 60 - 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 60 + Reservation Flows . . . . . . . . . . . . . . . . . . . . 57 + 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . 57 + 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 58 + 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . 58 + 8.6. RFC7104 - Duplication Grouping Semantics in the SDP . . 59 + 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 59 + 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 59 + 9.2. RFC7104 - Duplication Grouping Semantics in the SDP . . . 59 + 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 60 + 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 60 + 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 60 + 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . 60 + 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 61 + 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 61 + 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 61 + 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . 61 + 14. Multiplexing Considerations for Encapsulating Attributes . . 62 + 14.1. RFC3407 - cpar Attribute Analysis . . . . . . . . . . . 62 + 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 63 14.2.1. Recommendation - Procedures for Potential - Configuration Pairing . . . . . . . . . . . . . . . 61 - 14.2.1.1. Example: Transport Capability Multiplexing . . . 62 - 14.2.1.2. Example: Attribute Capability Multiplexing . . . 63 - 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 64 - 14.3.1. Recommendation: Dealing with Payload Type Numbers . 64 + Configuration Pairing . . . . . . . . . . . . . . . 64 + 14.2.1.1. Example: Transport Capability Multiplexing . . . 65 + 14.2.1.2. Example: Attribute Capability Multiplexing . . . 66 + 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 66 + 14.3.1. Recommendation: Dealing with Payload Type Numbers . 66 14.3.1.1. Example: Attribute Capability Under Shared - Payload Type . . . . . . . . . . . . . . . . . . 64 - 14.3.2. Recommendation: Dealing with Latent Configurations . 65 - 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 66 - 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 66 - 15.2. 'Mux Category' column for subregistries . . . . . . . . 67 - 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 67 - 15.2.2. Table: att-field (session level) . . . . . . . . . . 67 - 15.2.3. Table: att-field (both session and media level) . . 68 - 15.2.4. Table: att-field (media level only) . . . . . . . . 70 - 15.2.5. Table: att-field (source level) . . . . . . . . . . 73 - 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 73 - 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 74 - 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 74 - 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 75 - 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 75 - 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 75 - 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 76 - 15.2.13. Table: SDP/RTSP key management protocol identifiers 76 - 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 76 - 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 77 - 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 77 - 15.2.17. Table: Timestamp Reference Clock Source Parameters . 77 - 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 78 - 16. Security Considerations . . . . . . . . . . . . . . . . . . . 78 - 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 78 - 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 79 - 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 81 - 19.1. Normative References . . . . . . . . . . . . . . . . . . 81 - 19.2. Informative References . . . . . . . . . . . . . . . . . 81 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 88 + Payload Type . . . . . . . . . . . . . . . . . . 67 -1. Introduction + 14.3.2. Recommendation: Dealing with Latent Configurations . 68 + 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 68 + 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 68 + 15.2. 'Mux Category' column for subregistries . . . . . . . . 69 + 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 69 + 15.2.2. Table: att-field (session level) . . . . . . . . . . 70 + 15.2.3. Table: att-field (both session and media level) . . 71 + 15.2.4. Table: att-field (media level only) . . . . . . . . 72 + 15.2.5. Table: att-field (source level) . . . . . . . . . . 75 + 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 76 + 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 76 + 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 77 + 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 77 + 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 77 + 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 78 + 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 78 + 15.2.13. Table: SDP/RTSP key management protocol identifiers 78 + 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 79 + 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 79 + 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 79 + 15.2.17. Table: Timestamp Reference Clock Source Parameters . 80 + 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 80 + 16. Security Considerations . . . . . . . . . . . . . . . . . . . 81 + 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 81 + 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 81 + 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 84 + 19.1. Normative References . . . . . . . . . . . . . . . . . . 84 + 19.2. Informative References . . . . . . . . . . . . . . . . . 84 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 90 - Real-Time Communication in WEB-browsers (Rtcweb) framework requires - Real-time Transport Protocol (RTP) as the media transport protocol - and Session Description Protocol (SDP) [RFC4566] for describing and - negotiating multi-media communication sessions. +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 + (audio, video, etc.) described using different media descriptions represent separate RTP Sessions that are carried over individual - transport layer flows. However in the IETF RTCWEB WG, a need to use - a single 5-tuple for sending and receiving media associated with - multiple SDP media descriptions ("m=" lines) has been identified. - This would for e.g. allow the usage of a single set of Interactive - Connectivity Establishment (ICE) [RFC5245] candidates for multiple - media descriptions. This in turn has made necessary to understand - the interpretation and usage of the SDP attributes defined for the - multiplexed media descriptions. + 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 e.g. + allow the usage of a single set of ICE [RFC5245] candidates for + multiple media descriptions. This in turn has made 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 generic future-proof 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 applies 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. + The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Motivation The time and complications of setting up ICE [RFC5245] and DTLS-SRTP [RFC5763] transports for use by RTP, and conservation of ports, forms an 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 - these SDP attributes as they are defined today. + 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. @@ -299,21 +300,21 @@ With the above semantic grouping as a reference, the proposed framework classifies each attribute into one of the following categories: 4.1. Category: NORMAL Attributes that can be independently specified when multiplexing and retain their original semantics. In the example given below, the direction and label attributes are - independently specified for audio and video m=lines. These + 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 @@ -334,36 +335,34 @@ complicate the handling of multiplexed streams or might fail multiplexing altogether. 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 3456 RTP/AVP 97 // with zrtp a=rtpmap:97 iLBC/8000 - a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2 df881ae642c371ba46df - m=video 34567 RTP/AVP 31 //without zrtp a=rtpmap:31 H261/90000 4.3. Category: IDENTICAL - Attributes that MUST be identical across all the media descriptions - being multiplexed. + Attributes and their associated values (if any) that MUST be + identical across all the media descriptions being multiplexed. 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. + 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 @@ -389,30 +388,30 @@ 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 Attributes that can be set normally for multiple items in a multiplexed group but the software MUST pick just one of the - attribute of the given type for use. The one chosen is the attribute - associated with the "m=" line that represents the information being - used for the transport of the RTP. + attributes of the given type for use. The one chosen is the + attribute associated with the "m=" line that represents the + information being used for the transport of the RTP. 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 + 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 + 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 @@ -468,21 +467,21 @@ 4.7. Category: IDENTICAL-PER-PT Attributes that 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. 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: + all the video "m=" lines and all the payload specific parameters (ex: rtpmap, fmtp) are identical. 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 @@ -496,25 +495,25 @@ 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 - Attributes where the text in the source draft must be consulted for - further handling when multiplexed. + Attributes where the text in the specification defining the attribute + must be consulted for further handling when multiplexed. As an example, for the attribute extmap, the specification defining - the extension MUST be referred to understand the multiplexing + the extension must be referred to understand the multiplexing implications. 4.9. Category: TBD Attributes that have not been analyzed under the proposed multiplexing framework yet. For the purposes of implementations it is advised to consider "NOT RECOMMENDED" as the category when multiplexing these attributes. 5. Analysis of Existing Attributes @@ -538,21 +536,21 @@ details regarding the assigned category, wherever necessary. 5.1. RFC4566 - SDP: Session Description Protocol [RFC4566] defines the Session Description Protocol (SDP) that is intended for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. +-----------------+---------------------+-------+-------------------+ - | Attr Name | Notes | Level | Mux Category | + | 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 | @@ -613,29 +611,28 @@ RFC4566 Attribute Analysis 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. +----------+----------------------------+-------+-------------------+ - | Attr | Notes | Level | Mux Category | - | Name | | | | + | 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. | | | + | | multiplexed "m=" lines. | | | | | | | | +----------+----------------------------+-------+-------------------+ 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 @@ -754,67 +751,67 @@ | Name | Notes | Current | Mux Category | +--------------------+---------------------+---------+--------------+ | dccp-service-code | If RFC6773 is not | M | NOT | | | being used in | | RECOMMENDED | | | addition to | | | | | RFC5762, the port | | | | | in the "m=" line is | | | | | a DCCP port. DCCP | | | | | being a connection | | | | | oriented protocol, | | | - | | does not allow | | | + | | it does not allow | | | | | multiple | | | | | connections on the | | | - | | same 5-tuple. | | | + | | same 5-tuple | | | | | | | | +--------------------+---------------------+---------+--------------+ RFC5762 Attribute Analysis If RFC6773 is being used in addition to RFC5762 and provided that DCCP-in-UDP layer has additional demultiplexing, then it may 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 - multiplexing MUST NOT be performed even in this alternate scenario. + multiplexing must not be performed even in this alternate scenario. 5.9. RFC6773 - DCCP-UDP Encapsulation [RFC6773] document specifies an alternative encapsulation of the Datagram Congestion Control Protocol (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 MUST NOT be | M | NOT | + | dccp-port | Multiplexing must not be | M | NOT | | | performed due to potential | | RECOMMENDED | | | conflict between the port | | | | | used for DCCP | | | - | | en/decapsulation and the RTP. | | | + | | en/decapsulation and the RTP | | | | | | | | +------------+-------------------------------+-------+--------------+ RFC6773 Attribute Analysis - Since RFC6773 is about tunneling DCCP in UDP, with the UDP port being - the port of the DCCP en-/de-capsulation service. This encapsulation + RFC6773 is about tunneling DCCP in UDP, with the UDP port being the + port of the DCCP en-/de-capsulation service. This encapsulation allows arbitrary DCCP packets to be encapsulated and the DCCP port - chosen MAY conflict with the port chosen for the RTP traffic. + chosen may 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 MAY or MAY NOT work depending on the - nature of DCCP encapsulations and ports choses thus rendering it to + DCCP port spaces together. This may or may not work depending on the + nature of DCCP encapsulations 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 Real-time Transport Protocol (RTCP) packets to be transmitted with reduced size. +-------------+--------------------------------+-------+------------+ | Name | Notes | Level | Mux | @@ -870,85 +867,83 @@ +--------------------+-------------------------+-------+------------+ | 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 | + | ice-pwd | ice-pwd must be the one | B | TRANSPORT | | | that corresponds to the | | | - | | m=line chosen for | | | + | | "m=" line chosen for | | | | | setting up the | | | | | underlying transport | | | | | flow | | | | | | | | - | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | + | ice-ufrag | ice-ufrag must be the | B | TRANSPORT | | | one that corresponds to | | | - | | the m=line chosen for | | | - | | setting up the | | | + | | the "m=" line chosen | | | + | | for setting up the | | | | | underlying transport | | | | | flow | | | | | | | | - | candidate | ice candidate MUST be | M | TRANSPORT | + | candidate | ice candidate must be | M | TRANSPORT | | | the one that | | | - | | corresponds to the | | | - | | m=line chosen for | | | - | | setting up the | | | - | | underlying transport | | | - | | flow | | | + | | 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 | | | + | | must be the one that | | | + | | corresponds to the "m=" | | | + | | line chosen for setting | | | + | | up the underlying | | | + | | transport flow | | | | | | | | +--------------------+-------------------------+-------+------------+ RFC5245 Attribute Analysis 5.13. RFC5285 - RTP Header Extensions [RFC5285] provides a general mechanism to use the header extension feature of RTP (the Real-Time Transport Protocol). 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 extensions in use in a session are signaled in the setup information for that session. +---------+-------------------------------------+-------+-----------+ | Name | Notes | Level | Mux | | | | | Category | +---------+-------------------------------------+-------+-----------+ | extmap | Specific RTP extension document | B | SPECIAL | - | | MUST be referred | | | + | | must be referred | | | | | | | | +---------+-------------------------------------+-------+-----------+ 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 | Identical attribute value MUST be | M | IDENTICAL | + | rtcp | Identical attribute value must be | M | IDENTICAL | | | used since the RTCP port affects the | | | | | entire RTP session. | | | | | | | | +-------+--------------------------------------+-------+------------+ RFC3605 Attribute Analysis 5.15. RFC5576 - Source-Specific SDP Attributes [RFC5576] defines a mechanism to describe RTP media sources, which @@ -974,22 +969,22 @@ | | | | | | fmtp | The attribute value | SR | IDENTICAL-PER-PT | | | must be same for a | | | | | given codec | | | | | configuration | | | | | | | | +----------------+----------------------+-------+-------------------+ RFC5576 Attribute Analysis - If SSRCs are repeated across m=lines being multiplexed, they MUST all - represent the same underlying RTP Source. + 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 Session Description Protocol (SDP) signalling that identifies timestamp reference clock sources and SDP signalling that identifies the media clock sources in a multimedia session. +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ @@ -1079,26 +1074,26 @@ [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 the Session Initiation Protocol (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 Applicable | M | NORMAL | + +---------+---------------+-------+--------------+ + | cfw-id | Not Impacted | M | NORMAL | | | | | | - +---------+-----------------+-------+--------------+ + +---------+---------------+-------+--------------+ RFC6230 Attribute Analysis 5.22. RFC6364 - SDP Elements for FEC Framework [RFC6364] specifies the use of the Session Description Protocol (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 @@ -1218,22 +1213,22 @@ [RFC4583] document specifies how to describe Binary Floor Control Protocol (BFCP) streams in Session Description Protocol (SDP) descriptions. User agents using the offer/answer model to establish BFCP streams use this format in their offers and answers. +------------+---------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +------------+---------------------------------+-------+------------+ - | floorctrl | Must be repeated across all the | M | IDENTICAL | - | | multiplexed m=lines | | | + | floorctrl | must be repeated across all the | M | IDENTICAL | + | | multiplexed "m=" lines | | | | | | | | | confid | Not Impacted | M | NORMAL | | | | | | | userid | Not Impacted | M | NORMAL | | | | | | | floorid | The floorid MUST be globally | M | NORMAL | | | unique | | | | | | | | +------------+---------------------------------+-------+------------+ @@ -1261,21 +1256,21 @@ +----------------------+---------------+-------+--------------+ RFC5547 Attribute Analysis 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 VoIP, Real-time Text and Video over IP performance metrics. + advanced VoIP, Real-time Text, and Video over IP performance metrics. +---------------------------+----------------+-------+--------------+ | Name | Notes | Level | Mux Category | +---------------------------+----------------+-------+--------------+ | loopback rtp-pkt-loopback | Not Impacted | M | NORMAL | | | | | | | loopback rtp-media- | Not Impacted | M | NORMAL | | loopback | | | | | | | | | | loopback-source | Not Impacted | M | NORMAL | @@ -1292,23 +1287,23 @@ Protocol (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. +---------------+------------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +---------------+------------------------------+-------+------------+ - | rtcp-unicast | The attribute MUST be | M | IDENTICAL | - | | reported across all m=lines | | | - | | multiplexed | | | + | rtcp-unicast | The attribute must be | M | IDENTICAL | + | | reported across all "m=" | | | + | | lines multiplexed | | | | | | | | +---------------+------------------------------+-------+------------+ RFC5760 Attribute Analysis 5.31. RFC3611 - RTCP XR [RFC3611] defines the Extended Report (XR) packet type for the RTP Control Protocol (RTCP), and defines how the use of XR packets can be signaled by an application if it employs the Session Description @@ -1400,25 +1395,25 @@ +----------+-----------------------------------+-------+------------+ | 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 | + | ccap | The connection address type must | B | IDENTICAL | | | be identical across all the | | | - | | multiplexed m= lines. | | | + | | multiplexed "m=" lines | | | | | | | | - | ccap-v0 | Not Impacted. | B | NORMAL | + | ccap-v0 | Not Impacted | B | NORMAL | | | | | | | icap | Not Impacted | B | NORMAL | | | | | | | icap-v0 | Not Impacted | B | NORMAL | | | | | | +----------+-----------------------------------+-------+------------+ RFC7006 - Attribute Analysis 5.35. RFC4567 - Key Management Extensions for SDP and RTSP @@ -1427,25 +1422,27 @@ (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 | | | + | 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 | | | + | mikey | Key management protocol must be | B | IDENTICAL | + | | identical across all the "m=" | | | + | | lines | | | | | | | | +-----------+----------------------------------+-------+------------+ RFC4567 Attribute Analysis 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 the Session Description Protocol (SDP). It defines a new SDP @@ -1454,21 +1451,21 @@ 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 | | | + | | "m=" line defining the | | | | | underlying transport is | | | | | chosen | | | | | | | | +--------------+-------------------------------+-------+------------+ RFC4572 Attribute Analysis 5.37. RFC4570 - SDP Source Filters [RFC4570] describes how to adapt the Session Description Protocol @@ -1477,23 +1474,23 @@ 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 | | | + | source-filter | The attribute must be | B | IDENTICAL | + | | repeated across all "m=" | | | + | | lines multiplexed | | | | | | | | +----------------+-----------------------------+-------+------------+ RFC4570 Attribute Analysis 5.38. RFC6128 - RTCP Port for Multicast Sessions The Session Description Protocol (SDP) has an attribute that allows RTP applications to specify an address and a port associated with the RTP Control Protocol (RTCP) traffic. In RTP-based source-specific @@ -1503,123 +1500,122 @@ 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 | + | multicast-rtcp | Multicast RTCP port must | B | IDENTICAL | | | be identical across all | | | - | | the m=lines | | | + | | the "m=" lines | | | | | | | | +-----------------+----------------------------+-------+------------+ 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 Secure Real-time Transport Protocol (SRTP) sessions for Voice over IP (VoIP) applications. +------------+-------------------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+-------------------------------+-------+--------------+ - | zrtp-hash | Complicates if all the | M | NOT | - | | m=lines are not authenticated | | RECOMMENDED | - | | as given in the example below | | | + | zrtp-hash | Complicates if all the "m=" | M | NOT | + | | lines are not authenticated | | RECOMMENDED | | | | | | +------------+-------------------------------+-------+--------------+ RFC6189 Attribute Analysis 5.40. RFC4145 - Connection-Oriented Media [RFC4145] describes how to express media transport over TCP using the Session Description Protocol (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 | MUST be identical across all | B | IDENTICAL | - | | m=lines | | | + | setup | must be identical across all | B | IDENTICAL | + | | "m=" lines | | | | | | | | - | connection | MUST be identical across all | B | IDENTICAL | - | | m=lines | | | + | connection | must be identical across all | B | IDENTICAL | + | | "m=" lines | | | | | | | | +-------------+--------------------------------+-------+------------+ 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. | | | + | | one that corresponds to the "m=" | | | + | | line chosen for setting up the | | | + | | underlying transport flow | | | | | | | | +-------+--------------------------------------+-------+------------+ RFC6947 Attribute Analysis 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers in PSTN [RFC7195] describes use cases, requirements, and protocol extensions for using the Session Description Protocol (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 | Not Impacted. | M | NORMAL | + +--------------------------+---------------+-------+--------------+ + | cs-correlation:callerid | Not Impacted | M | NORMAL | | | | | | - | cs-correlation:uuie | Not Impacted. | M | NORMAL | + | cs-correlation:uuie | Not Impacted | M | NORMAL | | | | | | - | cs-correlation:dtmf | Not Impacted. | M | NORMAL | + | cs-correlation:dtmf | Not Impacted | M | NORMAL | | | | | | - | cs-correlation:external | Not Impacted. | M | NORMAL | + | cs-correlation:external | Not Impacted | M | NORMAL | | | | | | - +--------------------------+----------------+-------+--------------+ + +--------------------------+---------------+-------+--------------+ RFC7195 Attribute Analysis 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) [RFC7272] defines a new RTP Control Protocol (RTCP) Packet Type and an RTCP Extended Report (XR) Block Type to be used for achieving Inter-Destination Media Synchronization (IDMS). - +------------+----------------+-------+--------------+ + +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | - +------------+----------------+-------+--------------+ - | rtcp-idms | Not Impacted. | M | NORMAL | + +------------+---------------+-------+--------------+ + | rtcp-idms | Not Impacted | M | NORMAL | | | | | | - +------------+----------------+-------+--------------+ + +------------+---------------+-------+--------------+ RFC7272 Attribute Analysis 5.44. RFC5159 - OMA BCAST SDP Attributes [RFC5159] provides descriptions of Session Description Protocol (SDP) attributes used by the Open Mobile Alliance's Broadcast Service and Content Protection specification. +---------------------+---------------+-------+--------------+ @@ -1643,42 +1639,43 @@ 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 the Session Description Protocol (SDP) so that it can negotiate use of the Internet Key Exchange Protocol (IKE) for media sessions in the SDP offer/answer model. +-------------------+--------------------------+-------+------------+ | Name | Notes | Level | Mux | | | | | Category | +-------------------+--------------------------+-------+------------+ - | ike-setup | Attribute MUST be | B | IDENTICAL | + | ike-setup | Attribute must be | B | IDENTICAL | | | identical across all the | | | - | | m=lines | | | + | | "m=" lines | | | | | | | | - | psk-fingerprint | Attribute MUST be | B | IDENTICAL | + | psk-fingerprint | Attribute must be | B | IDENTICAL | | | identical across all the | | | - | | m=lines | | | + | | "m=" lines | | | | | | | | - | ike-esp | Attribute MUST be | B | IDENTICAL | + | ike-esp | Attribute must be | B | IDENTICAL | | | identical across all the | | | - | | m=lines | | | + | | "m=" lines | | | | | | | | - | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL | + | ike-esp-udpencap | Attribute must be | B | IDENTICAL | | | identical across all the | | | - | | m=lines | | | + | | "m=" lines | | | | | | | | +-------------------+--------------------------+-------+------------+ RFC6193 Attribute Analysis With the above SDP constraints, a session multiplexed with multiple - m=lines will use only one IPSec association for all of the m= lines. + "m=" lines will use only one IPSec association for all of the "m=" + lines. 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. +----------+---------------------------------+-------+--------------+ @@ -1693,20 +1690,25 @@ | control | RTSP is not supported for RTP | B | NOT | | | Stream multiplexing | | RECOMMENDED | | | | | | | mtag | RTSP is not supported for RTP | B | NOT | | | Stream multiplexing | | RECOMMENDED | | | | | | +----------+---------------------------------+-------+--------------+ RFC2326 Attribute Analysis + [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 the Session Description Protocol (SDP) and Real Time Streaming Protocol (RTSP) with some extensions. [RFC6064] provides information about these extensions and registers the RTSP and SDP extensions with IANA. +-------------------------------+------------+-------+--------------+ | Name | Notes | Level | Mux Category | @@ -1827,95 +1829,141 @@ RFC6064 Attribute Analysis [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 [RFC3108] describes conventions for using the Session - Description Protocol (SDP) described for controlling ATM Bearer - Connections, and any associated ATM Adaptation Layer (AAL). + [RFC3108] describes conventions for using the Session Description + Protocol (SDP) described for controlling ATM Bearer Connections, and + any associated ATM Adaptation Layer (AAL). - +------------------------+--------------+-------+--------------+ + +------------------------+------------------+-------+---------------+ | Name | Notes | Level | Mux Category | - +------------------------+--------------+-------+--------------+ - | aalType | Not Impacted | B | NORMAL | - | eecid | Not Impacted | B | NORMAL | - | aalType | Not Impacted | B | NORMAL | - | capability | Not Impacted | B | NORMAL | - | qosClass | Not Impacted | B | NORMAL | - | bcob | Not Impacted | B | NORMAL | - | stc | Not Impacted | B | NORMAL | - | upcc | Not Impacted | B | NORMAL | - | atmQOSparms | Not Impacted | B | NORMAL | - | atmTrfcDesc | Not Impacted | B | NORMAL | - | abrParms | Not Impacted | B | NORMAL | - | abrSetup | Not Impacted | B | NORMAL | - | bearerType | Not Impacted | B | NORMAL | - | lij | Not Impacted | B | NORMAL | - | anycast | Not Impacted | B | NORMAL | - | cache | Not Impacted | B | NORMAL | - | bearerSigIE | Not Impacted | B | NORMAL | - | aalApp | Not Impacted | B | NORMAL | - | cbrRate | Not Impacted | B | NORMAL | - | sbc | Not Impacted | B | NORMAL | - | clkrec | Not Impacted | B | NORMAL | - | fec | Not Impacted | B | NORMAL | - | prtfl | Not Impacted | B | NORMAL | - | structure | Not Impacted | B | NORMAL | - | cpsSDUsize | Not Impacted | B | NORMAL | - | aal2CPS | Not Impacted | B | NORMAL | - | aal2CPSSDUrate | Not Impacted | B | NORMAL | - | aal2sscs3661unassured | Not Impacted | B | NORMAL | - | aal2sscs3661assured | Not Impacted | B | NORMAL | - | aal2sscs3662 | Not Impacted | B | NORMAL | - | aal5sscop | Not Impacted | B | NORMAL | - | atmmap | Not Impacted | B | NORMAL | - | silenceSupp | Not Impacted | B | NORMAL | - | ecan | Not Impacted | B | NORMAL | - | gc | Not Impacted | B | NORMAL | - | profileDesc | Not Impacted | B | NORMAL | - | vsel | Not Impacted | B | NORMAL | - | dsel | Not Impacted | B | NORMAL | - | fsel | Not Impacted | B | NORMAL | - | onewaySel | Not Impacted | B | NORMAL | - | codecconfig | Not Impacted | B | NORMAL | - | isup_usi | Not Impacted | B | NORMAL | - | uiLayer1_Prot | Not Impacted | B | NORMAL | - | chain | Not Impacted | B | NORMAL | + +------------------------+------------------+-------+---------------+ + | aalType | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | eecid | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | capability | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | qosClass | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | bcob | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | stc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | upcc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | atmQOSparms | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | atmTrfcDesc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | abrParms | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | abrSetup | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | bearerType | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | lij | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | anycast | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | cache | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | bearerSigIE | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aalApp | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | cbrRate | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | sbc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | clkrec | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | fec | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | prtfl | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | structure | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | cpsSDUsize | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal2CPS | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal2CPSSDUrate | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal2sscs3661unassured | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal2sscs3661assured | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal2sscs3662 | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | aal5sscop | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | atmmap | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | silenceSupp | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | ecan | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | gc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | profileDesc | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | vsel | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | dsel | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | fsel | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | onewaySel | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | codecconfig | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | isup_usi | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | uiLayer1_Prot | Refer to notes | B | NOT | + | | below | | RECOMMENDED | + | chain | Refer to notes | B | NOT | + | | below | | RECOMMENDED | | | | | | - +------------------------+--------------+-------+--------------+ + +------------------------+------------------+-------+---------------+ RFC3108 Attribute Analysis RFC3108 describes conventions for using the Session Description Protocol (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 may be multiplexed into a bearer connection. For all adaptation types (AAL1, AAL2 and AAL5), bearer connections may 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 may carry one or more real-time (e.g. VoIP) media sessions with a life-cycle different from that of the underlying ATM transport. + [I-D.ietf-mmusic-sdp-bundle-negotiation] is applicable only for + nettypes IN and address types "IP4" or "IP6". + 5.49. 3GPP TS 26.114 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and interaction + +----------------------+-------------------------+-------+----------+ | 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 | | | | | | | | @@ -1921,33 +1969,32 @@ | | | | | +----------------------+-------------------------+-------+----------+ 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 | Not-Applicable | NORMAL | + +---------------------+---------------+-------+--------------+ + | Name | Notes | Level | Mux Category | + +---------------------+---------------+-------+--------------+ + | PSCid | Not Impacted | S | NORMAL | | | | | | - | bc_service | Not Impacted | Not-Applicable | NORMAL | + | bc_service | Not Impacted | S | NORMAL | | | | | | - | bc_program | Not Impacted | Not-Applicable | NORMAL | + | bc_program | Not Impacted | S | NORMAL | | | | | | - | bc_service_package | Not Impacted | Not-Applicable | NORMAL | + | bc_service_package | Not Impacted | S | NORMAL | | | | | | - +---------------------+--------------+----------------+-------------+ + +---------------------+---------------+-------+--------------+ 3GPP TS 183.063 Attribute Analysis 5.51. 3GPP TS 24.182 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting tones +-------------+---------------------------------+-------+-----------+ | Name | Notes | Level | Mux | | | | | Category | @@ -1979,29 +2026,29 @@ [R3GPPTS24.229] specifies IP multimedia call control protocol based on Session Initial protocol and Session Description Protocol. +------------------+---------------------------+-------+------------+ | 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. | | | + | | to the "m=" line chosen | | | + | | for setting up the | | | + | | underlying transport flow | | | | | | | | | visited-realm | visited-realm must be | M | TRANSPORT | | | the one that corresponds | | | - | | to the m=line chosen for | | | - | | setting up the underlying | | | - | | transport flow. | | | + | | 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 | @@ -2050,32 +2097,38 @@ | | | | | | T38VendorInfo | Not Impacted | S | NORMAL | | | | | | +------------------------+---------------+-------+--------------+ ITU T.38 Attribute Analysis The ITU T.38 attributes are clearly unaffected by multiplexing and are specific to the working of the fax protocol itself. -5.55. ITU-T-REC.Q1970 +5.55. ITU-T Q.1970 - [ITU-T-REC.Q1970] defines BICC IP bearer control protocol. + [Q.1970] defines BICC IP bearer control protocol. - +--------+---------------+-------+--------------+ - | Name | Notes | Level | Mux Category | - +--------+---------------+-------+--------------+ - | ipbcp | Not Impacted | S | NORMAL | + +--------+---------------------------------------+-------+----------+ + | Name | Notes | Level | Mux | + | | | | Category | + +--------+---------------------------------------+-------+----------+ + | ipbcp | ipbcp version identifies type of | S | SPECIAL | + | | IPBCP message used in BICC (ITU-T | | | + | | Q.1901) environment which are limited | | | + | | to single media payload. Pertinent | | | + | | ITU.T specifications needs to be | | | + | | referred while multiplexing | | | | | | | | - +--------+---------------+-------+--------------+ + +--------+---------------------------------------+-------+----------+ - ITU-T-REC.Q1970 Attribute Analysis + 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 +-----------+------------------------------------+-------+----------+ | Name | Notes | Level | Mux | | | | | Category | +-----------+------------------------------------+-------+----------+ @@ -2090,21 +2143,21 @@ | | 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. | | | + | | a gateway | | | | | | | | +-----------+------------------------------------+-------+----------+ 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 @@ -2124,48 +2177,52 @@ | | | | | +-----------------------+---------------+-------+--------------+ RFC4975 Attribute Analysis 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 | Not-Applicable | NOT RECOMMENDED | - | | attributes. | | | + +----------+----------------------+-------+------------------+ + | rtpred1 | Historic attributes | M | NOT RECOMMENDED | | | | | | - | rtpred2 | Historic | Not-Applicable | NOT RECOMMENDED | - | | attributes. | | | + | rtpred2 | Historic attributes | M | NOT RECOMMENDED | | | | | | - +----------+---------------------+----------------+-----------------+ + +----------+----------------------+-------+------------------+ Historical Attribute Analysis 6. bwtype Attribute Analysis This section specifies handling of specific bandwidth attributes when used in multiplexing scenarios. 6.1. RFC4566 - SDP: Session Description Protocol + + [RFC4566] defines the Session Description Protocol (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. | | | + | | values is considered | | | | | | | | +------------+-----------------------------------+-------+----------+ RFC4566 bwtype Analysis 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth [RFC3556] defines an extension to the Session Description Protocol (SDP) to specify two additional modifiers for the bandwidth attribute. These modifiers may be used to specify the bandwidth @@ -2214,100 +2271,107 @@ | | defined under multiplexing | | | | | | | | +------------------+-----------------------------+-------+----------+ RFC3890 bwtype Analysis 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. + 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. +----------+----------------------------+-------+-------------------+ - | Attr | Notes | Level | Mux Category | - | Name | | | | + | 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 | + | 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 | + | 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 | | | | | | | | +----------+----------------------------+-------+-------------------+ 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. - +-------+-------------------------------+-------+-------------------+ - | Attr | Notes | Level | Mux Category | - | Name | | | | - +-------+-------------------------------+-------+-------------------+ + +------+--------------------------------+-------+-------------------+ + | Name | Notes | Level | Mux Category | + +------+--------------------------------+-------+-------------------+ | ccm | The attribute value must be | M | IDENTICAL-PER-PT | | | same for a given codec | | | | | configuration | | | | | | | | - +-------+-------------------------------+-------+-------------------+ + +------+--------------------------------+-------+-------------------+ RFC5104 Attribute Analysis 7.3. RFC6285 - Unicast-Based RAMS + [RFC6285] describes a method using the existing RTP and RTP Control + Protocol (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 | | | | | | | | +-------+-------------------------------+-------+-------------------+ RFC6285 Attribute Analysis @@ -2364,23 +2428,28 @@ | nack | The attribute value must be | M | IDENTICAL-PER-PT | | pslei | same for a given codec | | | | | configuration | | | | | | | | +--------+------------------------------+-------+-------------------+ RFC6642 Attribute Analysis 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. + +--------+------------------------------+-------+-------------------+ - | Attr | Notes | Level | Mux Category | - | Name | | | | + | 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 | @@ -2390,21 +2459,21 @@ | ccm | The attribute value must be | M | IDENTICAL-PER-PT | | vbcm | same for a given codec | | | | | configuration | | | | | | | | +--------+------------------------------+-------+-------------------+ RFC5104 Attribute Analysis 8. group Attribute Analysis - This section analyzes SDP "group" semantics. + This section analyzes SDP "group" attribute semantics. 8.1. RFC5888 - SDP Grouping Framework [RFC5888] defines a framework to group "m" lines in the Session Description Protocol (SDP) for different purposes. +------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+---------------+-------+--------------+ | group:LS | Not Impacted | S | NORMAL | @@ -2511,81 +2580,107 @@ +------------+---------------+-------+--------------+ 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-groupFEC-FR | Not Impacted | SR | NORMAL | | | | | | +-------------------+---------------+-------+--------------+ RFC5576 Attribute Analysis 9.2. RFC7104 - Duplication Grouping Semantics in the SDP + [RFC7104] defines the semantics for grouping redundant streams in the + Session Description Protocol (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. + +-----------------+---------------+-------+--------------+ | Name | Notes | Level | Mux Category | +-----------------+---------------+-------+--------------+ | ssrc-group:DUP | Not Impacted | SR | NORMAL | | | | | | +-----------------+---------------+-------+--------------+ RFC7104 Attribute Analysis 10. QoS Mechanism Token Analysis This section analyzes QoS tokes specified with SDP. 10.1. RFC5432 - QoS Mechanism Selection in SDP - +-------+---------------------------------------+-------+-----------+ - | Name | Notes | Level | Mux | - | | | | Category | - +-------+---------------------------------------+-------+-----------+ - | rsvp | Not Impacted, since QOS mechanisms | B | NORMAL | - | | are applied per flow. | | | + + [RFC5432] defines procedures to negotiate QOS mechanisms using the + Session Description Protocol (SDP) offer/answer model. + + +-------+---------------+-------+--------------+ + | Name | Notes | Level | Mux Category | + +-------+---------------+-------+--------------+ + | rsvp | Not Impacted | B | NORMAL | | | | | | - | nsis | Not Impacted, since QOS mechanisms | B | NORMAL | - | | are applied per flow. | | | + | nsis | Not Impacted | B | NORMAL | | | | | | - +-------+---------------------------------------+-------+-----------+ + +-------+---------------+-------+--------------+ RFC5432 Attribute Analysis 11. k= Attribute Analysis 11.1. RFC4566 SDP: Session Description Protocol + [RFC4566] defines the Session Description Protocol (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 | NOT | | | attribute | | RECOMMENDED | | | | | | +------+------------------------------------+-------+---------------+ RFC4566 Attribute Analysis 12. content Attribute Analysis 12.1. RFC4796 + [RFC4796] defines a new Session Description Protocol (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 | @@ -2625,24 +2720,20 @@ | | reuse of SSRCs | | | | | | | | | application/ulpfec | Not recommended for | M | NOT | | | multiplexing due to | | RECOMMENDED | | | reuse of SSRCs | | | | | | | | +---------------------+----------------------+-------+--------------+ RFC5109 Payload Format Analysis - Draft draft-lennox-payload-ulp-ssrc-mux proposes a simple fix to make - it possible to use ULP with multiplexing and ULP is allowed when used - with that. - 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 @@ -2667,22 +2758,22 @@ 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. + 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 @@ -2717,49 +2808,49 @@ 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 bundled media descriptions. + 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 ensuring right multiplexing behavior. Although it is possible to analyze the various potential - configurations in bundled media descriptions to find combinations + 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 group, we provide a simple rule for constructing potential - configurations:- + 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 + 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 @@ -2836,32 +2928,32 @@ 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 + 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 mutliplexing. + under multiplexing. 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; @@ -2880,41 +2972,41 @@ 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 97. This implies that both the media capability 2 - and 4 along with their media format capabilities MUST refer to the + 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 bundled 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 of - latent configurations, or combinations of latent and potential - configurations with bundled 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. + 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 + 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.] The IANA is requested to add a new column named "Mux Category" to several of the subregistries in the "Session Description Protocol (SDP) Parameters" registry. Section 15.1 defines a new subregistry for identifying the initial registrations for various multiplexing @@ -3000,21 +3093,21 @@ | 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 | NORMAL | + | ipbcp | SPECIAL | | group | NORMAL | | ice-lite | NORMAL | | ice-options | NORMAL | | bcastversion | NORMAL | | 3GPP-Integrity-Key | NOT RECOMMENDED | | 3GPP-SDP-Auth | NOT RECOMMENDED | | alt-group | NOT RECOMMENDED | | PSCid | NORMAL | | bc_service | NORMAL | | bc_program | NORMAL | @@ -3127,63 +3220,63 @@ | maxptime | IDENTICAL-PER-PT | | des | NOT RECOMMENDED | | curr | NOT RECOMMENDED | | conf | NOT RECOMMENDED | | mid | NORMAL | | rtcp | IDENTICAL | | rtcp-fb | IDENTICAL-PER-PT | | label | NORMAL | | T38VendorInfo | NORMAL | | crypto | TRANSPORT | - | eecid | NORMAL | - | aalType | NORMAL | - | capability | NORMAL | - | qosClass | NORMAL | - | bcob | NORMAL | - | stc | NORMAL | - | upcc | NORMAL | - | atmQOSparms | NORMAL | - | atmTrfcDesc | NORMAL | - | abrParms | NORMAL | - | abrSetup | NORMAL | - | bearerType | NORMAL | - | lij | NORMAL | - | anycast | NORMAL | - | cache | NORMAL | - | bearerSigIE | NORMAL | - | aalApp | NORMAL | - | cbrRate | NORMAL | - | sbc | NORMAL | - | clkrec | NORMAL | - | fec | NORMAL | - | prtfl | NORMAL | - | structure | NORMAL | - | cpsSDUsize | NORMAL | - | all2CPS | NORMAL | - | all2CPSSDUrate | NORMAL | - | aal2sscs3661unassured | NORMAL | - | aal2sscs3661assured | NORMAL | - | aal2sscs3662 | NORMAL | - | aal5sscop | NORMAL | - | atmmap | NORMAL | - | silenceSupp | NORMAL | - | ecan | NORMAL | - | gc | NORMAL | - | profileDesc | NORMAL | - | vsel | NORMAL | - | dsel | NORMAL | - | fsel | NORMAL | - | onewaySel | NORMAL | - | codecConfig | NORMAL | - | isup_usi | NORMAL | - | uiLayer1_Prot | NORMAL | - | chain | NORMAL | + | eecid | NOT RECOMMENDED | + | aalType | NOT RECOMMENDED | + | capability | NOT RECOMMENDED | + | qosClass | NOT RECOMMENDED | + | bcob | NOT RECOMMENDED | + | stc | NOT RECOMMENDED | + | upcc | NOT RECOMMENDED | + | atmQOSparms | NOT RECOMMENDED | + | atmTrfcDesc | NOT RECOMMENDED | + | abrParms | NOT RECOMMENDED | + | abrSetup | NOT RECOMMENDED | + | bearerType | NOT RECOMMENDED | + | lij | NOT RECOMMENDED | + | anycast | NOT RECOMMENDED | + | cache | NOT RECOMMENDED | + | bearerSigIE | NOT RECOMMENDED | + | aalApp | NOT RECOMMENDED | + | cbrRate | NOT RECOMMENDED | + | sbc | NOT RECOMMENDED | + | clkrec | NOT RECOMMENDED | + | fec | NOT RECOMMENDED | + | prtfl | NOT RECOMMENDED | + | structure | NOT RECOMMENDED | + | cpsSDUsize | NOT RECOMMENDED | + | all2CPS | NOT RECOMMENDED | + | all2CPSSDUrate | NOT RECOMMENDED | + | aal2sscs3661unassured | NOT RECOMMENDED | + | aal2sscs3661assured | NOT RECOMMENDED | + | aal2sscs3662 | NOT RECOMMENDED | + | aal5sscop | NOT RECOMMENDED | + | atmmap | NOT RECOMMENDED | + | silenceSupp | NOT RECOMMENDED | + | ecan | NOT RECOMMENDED | + | gc | NOT RECOMMENDED | + | profileDesc | NOT RECOMMENDED | + | vsel | NOT RECOMMENDED | + | dsel | NOT RECOMMENDED | + | fsel | NOT RECOMMENDED | + | onewaySel | NOT RECOMMENDED | + | codecConfig | NOT RECOMMENDED | + | isup_usi | NOT RECOMMENDED | + | uiLayer1_Prot | NOT RECOMMENDED | + | chain | NOT RECOMMENDED | | floorctrl | IDENTICAL | | confid | NORMAL | | userid | NORMAL | | floorid | NORMAL | | FEC | NORMAL | | accept-types | NORMAL | | accept-wrapped-types | NORMAL | | max-size | NORMAL | | path | NORMAL | | dccp-service-code | NOT RECOMMENDED | @@ -3486,54 +3579,62 @@ | Name | Mux Category | +-----------+--------------+ | sender | NORMAL | | direct | NORMAL | | IEEE1722 | NORMAL | +-----------+--------------+ 16. Security Considerations This document does not add any new security considerations beyond the - existing considerations in the RFC for protocols that are being + existing considerations in the RFCs for protocols that are being multiplexed together. The ways that SRTP streams are keyed is not believed to create any two-time pad vulnerability for the currently defined SRTP keying mechanism. 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, and Dan Wing on suggesting structural - changes helping improve the document readability. + 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 + 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). + Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves + (5.48,5.55) 18. Change Log [RFC EDITOR NOTE: Please remove this section when publishing] + 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 @@ -3651,22 +3753,21 @@ [I.D-draft-ietf-dart-dscp-rtp] Black, D. and P. Jones, "The Session Description Protocol (SDP) Content Attribute", draft-ietf-dart-dscp-rtp-07 (work in progress), September 2014. [IANA] "Session Description Protocol (SDP) Parameters", . - [ITU-T-REC.Q1970] - "Q.1970 : BICC IP bearer control protocol", + [Q.1970] "Q.1970 : BICC IP bearer control protocol", . [R3GPPTS183.063] "TISPAN - IMS based ITPV Stage 3 specification.", . [R3GPPTS24.182] "IP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT); Protocol specification", @@ -3681,20 +3782,23 @@ "IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP);", . [R3GPPTS26.114] "IP multimedia Subsystem : Media Handling and interaction", . + [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time + Streaming Protocol (RTSP)", RFC 2326, April 1998. + [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the Session Description Protocol (SDP) for ATM Bearer Connections", RFC 3108, May 2001. [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, "Integration of Resource Management and Session Initiation