idnits 2.17.1 draft-ietf-mmusic-sdp-mux-attributes-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 5 instances of lines with non-RFC2606-compliant FQDNs in the document. == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. -- The document has examples using IPv4 documentation addresses according to RFC6890, but does not use any IPv6 documentation addresses. Maybe there should be IPv6 examples, too? Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords -- however, there's a paragraph with a matching beginning. Boilerplate error? (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: 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. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: +------------+-------------------------------+-------+--------------+ | Name | Notes | Level | Mux Category | +------------+-------------------------------+-------+--------------+ | 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 | | | | | | | | +------------+-------------------------------+-------+--------------+ == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 16, 2015) is 3381 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-54) exists of draft-ietf-mmusic-sdp-bundle-negotiation-12 ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) -- Obsolete informational reference (is this intentional?): RFC 2326 (Obsoleted by RFC 7826) -- Obsolete informational reference (is this intentional?): RFC 4091 (Obsoleted by RFC 5245) -- Obsolete informational reference (is this intentional?): RFC 4572 (Obsoleted by RFC 8122) -- Obsolete informational reference (is this intentional?): RFC 4583 (Obsoleted by RFC 8856) -- Obsolete informational reference (is this intentional?): RFC 5245 (Obsoleted by RFC 8445, RFC 8839) -- Obsolete informational reference (is this intentional?): RFC 5285 (Obsoleted by RFC 8285) Summary: 1 error (**), 0 flaws (~~), 8 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Nandakumar 3 Internet-Draft Cisco 4 Intended status: Standards Track January 16, 2015 5 Expires: July 20, 2015 7 A Framework for SDP Attributes when Multiplexing 8 draft-ietf-mmusic-sdp-mux-attributes-07 10 Abstract 12 The Session Description Protocol (SDP) provides mechanisms to 13 describe attributes of multimedia sessions and of individual media 14 streams (e.g., Real-time Transport Protocol (RTP) sessions) within a 15 multimedia session. Typically media associated with individual media 16 descriptions ("m=" lines) represent seperate RTP Sessions and thus 17 carried over individual underlying transport layer flows. For 18 scenarios where SDP is used to negotiate the usage of single 5-tuple 19 for sending and receiving media associated with multiple media 20 descriptions, it is required to understand the semantic implications 21 of the SDP attributes associated with the RTP Media Streams 22 multiplexed over a single underlying transport layer flow. 24 The purpose of this specification is to provide a framework for 25 analyzing the multiplexing characteristics of SDP attributes. This 26 specification also categorizes the existing SDP attributes based on 27 the framework described herein. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on July 20, 2015. 46 Copyright Notice 48 Copyright (c) 2015 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 This document may contain material from IETF Documents or IETF 62 Contributions published or made publicly available before November 63 10, 2008. The person(s) controlling the copyright in some of this 64 material may not have granted the IETF Trust the right to allow 65 modifications of such material outside the IETF Standards Process. 66 Without obtaining an adequate license from the person(s) controlling 67 the copyright in such materials, this document may not be modified 68 outside the IETF Standards Process, and derivative works of it may 69 not be created outside the IETF Standards Process, except to format 70 it for publication as an RFC or to translate it into languages other 71 than English. 73 Table of Contents 75 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 76 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 77 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 6 78 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 7 79 4.1. Category: NORMAL . . . . . . . . . . . . . . . . . . . . 7 80 4.2. Category: NOT RECOMMENDED . . . . . . . . . . . . . . . . 8 81 4.3. Category: IDENTICAL . . . . . . . . . . . . . . . . . . . 8 82 4.4. Category: SUM . . . . . . . . . . . . . . . . . . . . . . 8 83 4.5. Category: TRANSPORT . . . . . . . . . . . . . . . . . . . 9 84 4.6. Category: INHERIT . . . . . . . . . . . . . . . . . . . . 10 85 4.7. Category: IDENTICAL-PER-PT . . . . . . . . . . . . . . . 11 86 4.8. Category: SPECIAL . . . . . . . . . . . . . . . . . . . . 12 87 4.9. Category: TBD . . . . . . . . . . . . . . . . . . . . . . 12 88 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 12 89 5.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 13 90 5.2. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 14 91 5.3. RFC5761 - Multiplexing RTP and RTCP . . . . . . . . . . . 15 92 5.4. RFC3312 - Integration of Resource Management and (SIP) . 15 93 5.5. RFC4574 - SDP Label Attribute . . . . . . . . . . . . . . 16 94 5.6. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 16 95 5.7. RFC4568 - SDP Security Descriptions . . . . . . . . . . . 17 96 5.8. RFC5762 - RTP over DCCP . . . . . . . . . . . . . . . . . 17 97 5.9. RFC6773 - DCCP-UDP Encapsulation . . . . . . . . . . . . 18 98 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile . . . . . . . 19 99 5.11. RFC6787 - Media Resource Control Protocol Version 2 . . . 19 100 5.12. RFC5245 - Interactive Connectivity Establishment (ICE) . 20 101 5.13. RFC5285 - RTP Header Extensions . . . . . . . . . . . . . 21 102 5.14. RFC3605 - RTCP attribute in SDP . . . . . . . . . . . . . 22 103 5.15. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 22 104 5.16. RFC7273 - RTP Clock Source Signalling . . . . . . . . . . 23 105 5.17. RFC6236 - Image Attributes in SDP . . . . . . . . . . . . 24 106 5.18. RFC7197 - Duplication Delay Attribute in SDP . . . . . . 24 107 5.19. RFC7266 - RTCP XR Blocks for MOS Metric Reporting . . . 24 108 5.20. RFC6285 - Rapid Acquisition of Multicast RTP Sessions . . 25 109 5.21. RFC6230 - Media Control Channel Framework . . . . . . . . 25 110 5.22. RFC6364 - SDP Elements for FEC Framework . . . . . . . . 26 111 5.23. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 26 112 5.24. RFC3407 - SDP Simple Capability Declaration . . . . . . . 27 113 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP 114 Sessions . . . . . . . . . . . . . . . . . . . . . . . . 27 115 5.26. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 28 116 5.27. RFC4583 - SDP Format for BFCP Streams . . . . . . . . . . 28 117 5.28. RFC5547 - SDP Offer/Answer for File Transfer . . . . . . 29 118 5.29. RFC6849 - SDP and RTP Media Loopback Extension . . . . . 29 119 5.30. RFC5760 - RTCP with Unicast Feedback . . . . . . . . . . 30 120 5.31. RFC3611 - RTCP XR . . . . . . . . . . . . . . . . . . . . 30 121 5.32. RFC5939 - SDP Capability Negotiation . . . . . . . . . . 30 122 5.33. RFC6871- SDP Media Capabilities Negotiation . . . . . . . 31 123 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP . . 32 124 5.35. RFC4567 - Key Management Extensions for SDP and RTSP . . 33 125 5.36. RFC4572 - Comedia over TLS in SDP . . . . . . . . . . . . 34 126 5.37. RFC4570 - SDP Source Filters . . . . . . . . . . . . . . 34 127 5.38. RFC6128 - RTCP Port for Multicast Sessions . . . . . . . 35 128 5.39. RFC6189 - ZRTP . . . . . . . . . . . . . . . . . . . . . 35 129 5.40. RFC4145 - Connection-Oriented Media . . . . . . . . . . . 35 130 5.41. RFC6947 - The SDP ALTC Attribute . . . . . . . . . . . . 36 131 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers 132 in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 36 133 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) . . 37 134 5.44. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . 37 135 5.45. RFC6193 - Media Description for IKE in SDP . . . . . . . 38 136 5.46. RFC2326 - Real Time Streaming Protocol . . . . . . . . . 39 137 5.47. RFC6064 - SDP and RTSP Extensions for 3GPP . . . . . . . 39 138 5.48. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 42 139 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 45 140 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 45 141 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 45 142 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 46 143 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 46 144 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 47 145 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 48 146 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 49 147 5.57. RFC4975 - The Message Session Relay Protocol . . . . . . 50 148 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 50 149 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 50 150 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 51 151 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . 51 152 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . 52 153 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 52 154 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 52 155 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 53 156 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . 54 157 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 54 158 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 55 159 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 56 160 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 56 161 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . 56 162 8.2. RFC3524 - Mapping Media Streams to Resource 163 Reservation Flows . . . . . . . . . . . . . . . . . . . . 57 164 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . 57 165 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 58 166 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . 58 167 8.6. RFC7104 - Duplication Grouping Semantics in the SDP . . 59 168 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 59 169 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 59 170 9.2. RFC7104 - Duplication Grouping Semantics in the SDP . . . 59 171 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 60 172 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 60 173 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 60 174 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . 60 175 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 61 176 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 61 177 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 61 178 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . 61 179 14. Multiplexing Considerations for Encapsulating Attributes . . 62 180 14.1. RFC3407 - cpar Attribute Analysis . . . . . . . . . . . 62 181 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 63 182 14.2.1. Recommendation - Procedures for Potential 183 Configuration Pairing . . . . . . . . . . . . . . . 64 184 14.2.1.1. Example: Transport Capability Multiplexing . . . 65 185 14.2.1.2. Example: Attribute Capability Multiplexing . . . 66 186 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 66 187 14.3.1. Recommendation: Dealing with Payload Type Numbers . 66 188 14.3.1.1. Example: Attribute Capability Under Shared 189 Payload Type . . . . . . . . . . . . . . . . . . 67 191 14.3.2. Recommendation: Dealing with Latent Configurations . 68 192 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 68 193 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 68 194 15.2. 'Mux Category' column for subregistries . . . . . . . . 69 195 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 69 196 15.2.2. Table: att-field (session level) . . . . . . . . . . 70 197 15.2.3. Table: att-field (both session and media level) . . 71 198 15.2.4. Table: att-field (media level only) . . . . . . . . 72 199 15.2.5. Table: att-field (source level) . . . . . . . . . . 75 200 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 76 201 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 76 202 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 77 203 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 77 204 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 77 205 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 78 206 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 78 207 15.2.13. Table: SDP/RTSP key management protocol identifiers 78 208 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 79 209 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 79 210 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 79 211 15.2.17. Table: Timestamp Reference Clock Source Parameters . 80 212 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 80 213 16. Security Considerations . . . . . . . . . . . . . . . . . . . 81 214 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 81 215 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 81 216 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 84 217 19.1. Normative References . . . . . . . . . . . . . . . . . . 84 218 19.2. Informative References . . . . . . . . . . . . . . . . . 84 219 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 90 221 1. Introduction 223 SDP defines several attributes for capturing characteristics that 224 apply to the individual media descriptions (described by "m=" lines") 225 and the overall multimedia session. Typically different media types 226 (audio, video, etc.) described using different media descriptions 227 represent separate RTP Sessions that are carried over individual 228 transport layer flows. However 229 [I-D.ietf-mmusic-sdp-bundle-negotiation] defines a way to use a 230 single address:port combination (BUNDLE address) for receiving media 231 associated with multiple SDP media descriptions. This would for e.g. 232 allow the usage of a single set of ICE [RFC5245] candidates for 233 multiple media descriptions. This in turn has made necessary to 234 understand the interpretation and usage of the SDP attributes defined 235 for the multiplexed media descriptions. 237 Given the number of SDP attributes registered with the [IANA] and 238 possibility of new attributes being defined in the future, there is 239 need for generic future-proof framework to analyze these attributes 240 for their applicability in the transport multiplexing use-cases. 242 The document starts with providing the motivation for requiring such 243 a framework. This is followed by introduction to the SDP attribute 244 analysis framework/procedures, following which several sections 245 applies the framework to the SDP attributes registered with the 246 [IANA]. 248 2. Terminology 250 5-tuple: A collection of the following values: source address, source 251 port, destination address, destination port, and transport-layer 252 protocol. 254 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", 255 "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be 256 interpreted as described in [RFC2119]. 258 3. Motivation 260 The time and complications of setting up ICE [RFC5245] and DTLS-SRTP 261 [RFC5763] transports for use by RTP, and conservation of ports, forms 262 an requirement to try and reduce the number of transport level flows 263 needed. This has resulted in the definition of ways, such as, 264 [I-D.ietf-mmusic-sdp-bundle-negotiation] to multiplex RTP over a 265 single transport flow in order to preserve network resources such as 266 port numbers. This imposes further restrictions on applicability of 267 the SDP attributes as they are defined today. 269 The specific problem is that there are attribute combinations which 270 make sense when specified on independent "m= " lines -- as with 271 classical SDP -- that do not make sense when those "m=" lines are 272 then multiplexed over the same transport. To give an obvious 273 example, ICE permits each "m=" line to have an independently 274 specified ice-ufrag attribute. However, if the media from multiple 275 "m=" lines is multiplexed over the same ICE component, then the 276 meaning of media-level ice-ufrag attributes becomes muddled. 278 As of today there are close to 250 SDP attributes registered with the 279 [IANA] and more will be added in the future. There is no clearly 280 defined procedure to establish the validity/applicability of these 281 attribute when used with transport multiplexing. 283 4. SDP Attribute Analysis Framework 285 Attributes in an SDP session description can be defined at the 286 session-level and media-level. These attributes could be 287 semantically grouped as noted below. 289 o Attributes related to media content such as media type, encoding 290 schemes, payload types. 292 o Attributes specifying media transport characteristics like RTP/ 293 RTCP port numbers, network addresses, QOS. 295 o Metadata description attributes capturing session timing and 296 origin information. 298 o Attributes establishing relationships between media streams such 299 as grouping framework 301 With the above semantic grouping as a reference, the proposed 302 framework classifies each attribute into one of the following 303 categories: 305 4.1. Category: NORMAL 307 Attributes that can be independently specified when multiplexing and 308 retain their original semantics. 310 In the example given below, the direction and label attributes are 311 independently specified for audio and video "m=" lines. These 312 attributes are not impacted by multiplexing these media streams over 313 a single transport layer flow. 315 v=0 316 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 317 s= 318 c=IN IP4 host.atlanta.example.com 319 t=0 0 320 m=audio 49172 RTP/AVP 99 321 a=sendonly 322 a=label:1 323 a=rtpmap:99 iLBC/8000 324 m=video 49172 RTP/AVP 31 325 a=recvonly 326 a=label:2 327 a=rtpmap:31 H261/90000 329 4.2. Category: NOT RECOMMENDED 331 Attributes that are recommended against multiplexing since their 332 usage under multiplexing might lead to incorrect behavior. 334 Example: Multiplexing media descriptions having attribute zrtp-hash 335 defined with the media descriptions lacking it, would either 336 complicate the handling of multiplexed streams or might fail 337 multiplexing altogether. 339 v=0 340 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 341 s= 342 c=IN IP4 client.biloxi.example.com 343 t=0 0 344 m=audio 3456 RTP/AVP 97 // with zrtp 345 a=rtpmap:97 iLBC/8000 346 a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2 347 df881ae642c371ba46df 348 m=video 34567 RTP/AVP 31 //without zrtp 349 a=rtpmap:31 H261/90000 351 4.3. Category: IDENTICAL 353 Attributes and their associated values (if any) that MUST be 354 identical across all the media descriptions being multiplexed. 356 Attributes such as rtcp-mux fall into this category. Since RTCP 357 reporting is done per RTP Session, RTCP Multiplexing MUST be enabled 358 for both the audio and video "m=" lines if they are transported over 359 a single 5-tuple. 361 v=0 362 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 363 s= 364 c=IN IP4 client.biloxi.example.com 365 t=0 0 366 m=audio 34567 RTP/AVP 97 367 a=rtcp-mux 368 m=video 34567 RTP/AVP 31 369 a=rtpmap:31 H261/90000 370 a=rtcp-mux 372 4.4. Category: SUM 374 Attributes can be set as they are normally used but software using 375 them in the multiplexing scenario, MUST apply the sum of all the 376 attributes being multiplexed instead of trying to use them 377 independently. This is typically used for bandwidth or other rate 378 limiting attributes to the underlying transport. 380 The software parsing the SDP sample below, should use the aggregate 381 Application Specific (AS) bandwidth value from the individual media 382 descriptions to determine the AS value for the multiplexed session. 383 Thus the calculated AS value would be 256+64 kilobits per second for 384 the given example. 386 v=0 387 o=test 2890844526 2890842807 IN IP4 126.16.64.4 388 c=IN IP4 client.biloxi.example.com 389 t=0 0 390 m=audio 49170 RTP/AVP 0 391 b=AS:64 392 m=video 51372 RTP/AVP 31 393 b=AS:256 395 4.5. Category: TRANSPORT 397 Attributes that can be set normally for multiple items in a 398 multiplexed group but the software MUST pick just one of the 399 attributes of the given type for use. The one chosen is the 400 attribute associated with the "m=" line that represents the 401 information being used for the transport of the RTP. 403 In the example below, "a=crypto" attribute is defined for both the 404 audio and the video "m=" lines. The video media line's a=crypto 405 attribute is chosen since its mid value (bar) appears first in the 406 a=group:BUNDLE line. This is due to BUNDLE grouping semantic 407 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values 408 from "m=" line corresponding to the mid appearing first on the 409 a=group:BUNDLE line to be considered for setting up the RTP 410 Transport. 412 v=0 413 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 414 s= 415 c=IN IP4 host.atlanta.example.com 416 t=0 0 417 a=group:BUNDLE bar foo 418 m=audio 49172 RTP/AVP 99 419 a=mid:foo 420 a=crypto:1 AES_CM_128_HMAC_SHA1_80 421 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 422 a=rtpmap:99 iLBC/8000 423 m=video 51374 RTP/AVP 31 424 a=mid:bar 425 a=crypto:1 AES_CM_128_HMAC_SHA1_80 426 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 427 a=rtpmap:96 H261/90000 429 4.6. Category: INHERIT 431 Attributes that encapsulate other SDP attributes or parameters. 432 These attributes inherit their multiplexing characteristics from the 433 attributes or parameters they encapsulate. Such attributes as of 434 today, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of a 435 generic framework for indicating and negotiating transport, media and 436 media format related capabilities in the SDP. 438 The inheritance manifests itself when the encapsulated attribute or 439 parameter is being leveraged. In the case of SDP Capability 440 Negotiation [RFC5939] for example, this occurs when a capability 441 (encapsulating attribute) is used as part of a configuration; the 442 configuration inherits the multiplexing category of each of its 443 constituent (encapsulated) attributes and parameters. This in turn 444 MAY place constraints on what constitutes a valid configuration from 445 a multiplexing point of view, e.g. because some attributes MUST be 446 IDENTICAL (see Section 14 for further details). 448 v=0 449 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 450 s= 451 c=IN IP4 host.atlanta.example.com 452 t=0 0 453 m=video 3456 RTP/AVP 100 454 a=rtpmap:100 VP8/90000 455 a=fmtp:100 max-fr=30;max-fs=8040 456 a=sqn: 0 457 a=cdsc: 1 video RTP/AVP 100 458 a=cpar: a=rtcp-mux 459 m=video 3456 RTP/AVP 101 460 a=rtpmap:101 VP8/90000 461 a=fmtp:100 max-fr=15;max-fs=1200 462 a=cdsc: 2 video RTP/AVP 101 463 a=cpar: a=rtcp-mux 465 In the above example, the category IDENTICAL is inherited for the 466 cpar encapsulated rtcp-mux attribute. 468 4.7. Category: IDENTICAL-PER-PT 470 Attributes that define the RTP payload configuration on per Payload 471 Type basis and MUST have identical values across all the media 472 descriptions for a given RTP Payload Type when repeated. These 473 Payload Types identify the same codec configuration as defined in the 474 Section 10.1.2 of [I-D.ietf-mmusic-sdp-bundle-negotiation] under this 475 context. 477 In the SDP example below, Payload Types 96 and 97 are repeated across 478 all the video "m=" lines and all the payload specific parameters (ex: 479 rtpmap, fmtp) are identical. 481 v=0 482 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 483 s= 484 c=IN IP4 host.atlanta.example.com 485 t=0 0 486 a=group:BUNDLE cam1, cam2 487 m= video 96 97 488 a=mid:cam1 489 a=rtpmap:96 H264/90000 490 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 491 max-mbps=108000; max-br=1000 492 a=rtpmap:97 H264/90000 493 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 494 max-mbps=7200; max-br=200 495 m= video 96 97 496 a=mid:cam2 497 a=rtpmap:96 H264/90000 498 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 499 max-mbps=108000; max-br=1000 500 a=rtpmap:97 H264/90000 501 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 502 max-mbps=7200; max-br=200 504 4.8. Category: SPECIAL 506 Attributes where the text in the specification defining the attribute 507 MUST be consulted for further handling when multiplexed. 509 As an example, for the attribute extmap, the specification defining 510 the extension needs to be referred to understand the multiplexing 511 implications. 513 4.9. Category: TBD 515 Attributes that have not been analyzed under the proposed 516 multiplexing framework yet. For the purposes of implementations it 517 is advised to consider "NOT RECOMMENDED" as the category when 518 multiplexing these attributes. 520 5. Analysis of Existing Attributes 522 This section analyzes attributes listed in [IANA], grouped under the 523 IETF document that defines them. 525 The "Level" column indicates whether the attribute is currently 526 specified as: 528 o S -- Session level 529 o M -- Media level 531 o B -- Both 533 o SR -- Source-level (for a single SSRC) 535 The "Mux Category" column identifies multiplexing category assigned 536 per attribute and the "Notes" column captures additional informative 537 details regarding the assigned category, wherever necessary. 539 5.1. RFC4566 - SDP: Session Description Protocol 541 [RFC4566] defines the Session Description Protocol (SDP) that is 542 intended for describing multimedia sessions for the purposes of 543 session announcement, session invitation, and other forms of 544 multimedia session initiation. 546 +-----------------+---------------------+-------+-------------------+ 547 | Name | Notes | Level | Mux Category | 548 +-----------------+---------------------+-------+-------------------+ 549 | sendrecv | Not impacted | B | NORMAL | 550 | | | | | 551 | sendonly | Not impacted | B | NORMAL | 552 | | | | | 553 | recvonly | Not impacted | B | NORMAL | 554 | | | | | 555 | inactive | Not impacted | B | NORMAL | 556 | | | | | 557 | cat | Not impacted | S | NORMAL | 558 | | | | | 559 | ptime | The attribute value | M | IDENTICAL-PER-PT | 560 | | MUST be same for a | | | 561 | | given codec | | | 562 | | configuration | | | 563 | | | | | 564 | maxptime | The attribute value | M | IDENTICAL-PER-PT | 565 | | MUST be same for a | | | 566 | | given codec | | | 567 | | configuration | | | 568 | | | | | 569 | orient | Not Impacted | M | NORMAL | 570 | | | | | 571 | framerate | The attribute value | M | IDENTICAL-PER-PT | 572 | | MUST be same for a | | | 573 | | given codec | | | 574 | | configuration | | | 575 | | | | | 576 | quality | Not Impacted | M | NORMAL | 577 | | | | | 578 | rtpmap | The attribute value | M | IDENTICAL-PER-PT | 579 | | MUST be same for a | | | 580 | | given codec | | | 581 | | configuration | | | 582 | | | | | 583 | fmtp | The attribute value | M | IDENTICAL-PER-PT | 584 | | MUST be same for a | | | 585 | | given codec | | | 586 | | configuration | | | 587 | | | | | 588 | keywds | Not impacted | S | NORMAL | 589 | | | | | 590 | type | Not Impacted | S | NORMAL | 591 | | | | | 592 | type:broadcast | Not Impacted | S | NORMAL | 593 | | | | | 594 | type:H332 | Not Impacted | S | NORMAL | 595 | | | | | 596 | type:meeting | Not Impacted | S | NORMAL | 597 | | | | | 598 | type:moderated | Not Impacted | S | NORMAL | 599 | | | | | 600 | type:test | Not Impacted | S | NORMAL | 601 | | | | | 602 | tool | Not Impacted | S | NORMAL | 603 | | | | | 604 | charset | Not Impacted | S | NORMAL | 605 | | | | | 606 | sdplang | Not Impacted | B | NORMAL | 607 | | | | | 608 | lang | Not Impacted | B | NORMAL | 609 | | | | | 610 +-----------------+---------------------+-------+-------------------+ 612 RFC4566 Attribute Analysis 614 5.2. RFC4585 - RTP/AVPF 616 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 617 enables receivers to provide, statistically, more immediate feedback 618 to the senders and thus allows for short-term adaptation and 619 efficient feedback-based repair mechanisms to be implemented. 621 +----------+----------------------------+-------+-------------------+ 622 | Name | Notes | Level | Mux Category | 623 +----------+----------------------------+-------+-------------------+ 624 | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT | 625 | | attributes are Payload | | | 626 | | Type (PT) scoped, their | | | 627 | | values MUST be identical | | | 628 | | for a given PT across the | | | 629 | | multiplexed "m=" lines. | | | 630 | | | | | 631 +----------+----------------------------+-------+-------------------+ 633 RFC4585 Attribute Analysis 635 5.3. RFC5761 - Multiplexing RTP and RTCP 637 [RFC5761] discusses issues that arise when multiplexing RTP data 638 packets and RTP Control Protocol (RTCP) packets on a single UDP port. 639 It describes when such multiplexing is and is not appropriate, and it 640 explains how the Session Description Protocol (SDP) can be used to 641 signal multiplexed sessions. 643 +-----------+----------------------------------+-------+------------+ 644 | Name | Notes | Level | Mux | 645 | | | | Category | 646 +-----------+----------------------------------+-------+------------+ 647 | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL | 648 | | affects the entire RTP Session | | | 649 | | | | | 650 +-----------+----------------------------------+-------+------------+ 652 RFC5761 Attribute Analysis 654 5.4. RFC3312 - Integration of Resource Management and (SIP) 656 [RFC3312] defines a generic framework for preconditions, which are 657 extensible through IANA registration. This document also discusses 658 how network quality of service can be made a precondition for 659 establishment of sessions initiated by the Session Initiation 660 Protocol (SIP). These preconditions require that the participant 661 reserve network resources before continuing with the session. 663 +-------+-----------------------+-------+------------------+ 664 | Name | Notes | Level | Mux Category | 665 +-------+-----------------------+-------+------------------+ 666 | des | Refer to notes below | M | NOT RECOMMENDED | 667 | | | | | 668 | conf | Refer to notes below | M | NOT RECOMMENDED | 669 | | | | | 670 | curr | Refer to notes below | M | NOT RECOMMENDED | 671 | | | | | 672 +-------+-----------------------+-------+------------------+ 674 RFC3312 Attribute Analysis 676 A mismatched set of preconditions across media descriptions results 677 in Session establishment failures due to inability in meeting the 678 right resource reservations requested. 680 5.5. RFC4574 - SDP Label Attribute 682 [RFC4574] defines a new Session Description Protocol (SDP) media- 683 level attribute: "label". The "label" attribute carries a pointer to 684 a media stream in the context of an arbitrary network application 685 that uses SDP. The sender of the SDP document can attach the "label" 686 attribute to a particular media stream or streams. The application 687 can then use the provided pointer to refer to each particular media 688 stream in its context. 690 +--------+---------------+-------+--------------+ 691 | Name | Notes | Level | Mux Category | 692 +--------+---------------+-------+--------------+ 693 | label | Not Impacted | M | NORMAL | 694 | | | | | 695 +--------+---------------+-------+--------------+ 697 RFC4574 Attribute Analysis 699 5.6. RFC5432 - QoS Mechanism Selection in SDP 701 [RFC5432] defines procedures to negotiate QOS mechanisms using the 702 Session Description Protocol (SDP) offer/answer model. 704 +----------------+------------------------+-------+--------------+ 705 | Name | Notes | Level | Mux Category | 706 +----------------+------------------------+-------+--------------+ 707 | qos-mech-send | Refer to notes below | B | NORMAL | 708 | | | | | 709 | qos-mech-recv | Refer to notes below. | B | NORMAL | 710 | | | | | 711 +----------------+------------------------+-------+--------------+ 713 RFC5432 Attribute Analysis 715 A single DSCP code point per flow being multiplexed doesn't impact 716 multiplexing since QOS mechanisms are signaled/scoped per flow. For 717 scenarios that involves having different DSCP code points for packets 718 being transmitted over the same 5-tuple, issues as discussed in 719 [I.D-draft-ietf-dart-dscp-rtp] needs to be taken into consideration. 721 5.7. RFC4568 - SDP Security Descriptions 723 [RFC4568] defines a Session Description Protocol (SDP) cryptographic 724 attribute for unicast media streams. The attribute describes a 725 cryptographic key and other parameters that serve to configure 726 security for a unicast media stream in either a single message or a 727 roundtrip exchange. 729 +---------+------------------------------------+-------+------------+ 730 | Name | Notes | Level | Mux | 731 | | | | Category | 732 +---------+------------------------------------+-------+------------+ 733 | crypto | crypto attribute MUST be the one | M | TRANSPORT | 734 | | that corresponds to the "m=" line | | | 735 | | chosen for setting up the | | | 736 | | underlying transport flow | | | 737 | | | | | 738 +---------+------------------------------------+-------+------------+ 740 RFC4568 Attribute Analysis 742 5.8. RFC5762 - RTP over DCCP 744 The Real-time Transport Protocol (RTP) is a widely used transport for 745 real-time multimedia on IP networks. The Datagram Congestion Control 746 Protocol (DCCP) is a transport protocol that provides desirable 747 services for real-time applications. [RFC5762] specifies a mapping 748 of RTP onto DCCP, along with associated signaling, such that real- 749 time applications can make use of the services provided by DCCP. 751 +--------------------+---------------------+---------+--------------+ 752 | Name | Notes | Current | Mux Category | 753 +--------------------+---------------------+---------+--------------+ 754 | dccp-service-code | If RFC6773 is not | M | NOT | 755 | | being used in | | RECOMMENDED | 756 | | addition to | | | 757 | | RFC5762, the port | | | 758 | | in the "m=" line is | | | 759 | | a DCCP port. DCCP | | | 760 | | being a connection | | | 761 | | oriented protocol, | | | 762 | | it does not allow | | | 763 | | multiple | | | 764 | | connections on the | | | 765 | | same 5-tuple | | | 766 | | | | | 767 +--------------------+---------------------+---------+--------------+ 769 RFC5762 Attribute Analysis 771 If RFC6773 is being used in addition to RFC5762 and provided that 772 DCCP-in-UDP layer has additional demultiplexing, then it may be 773 possible to use different DCCP service codes for each DCCP flow, 774 given each uses a different DCCP port. Although doing so might 775 conflict with the media type of the "m=" line. None of this is 776 standardized yet and it wouldn't work as explained. Hence 777 multiplexing MUST not be performed even in this alternate scenario. 779 5.9. RFC6773 - DCCP-UDP Encapsulation 781 [RFC6773] document specifies an alternative encapsulation of the 782 Datagram Congestion Control Protocol (DCCP), referred to as DCCP-UDP. 783 This encapsulation allows DCCP to be carried through the current 784 generation of Network Address Translation (NAT) middle boxes without 785 modification of those middle boxes. 787 +------------+-------------------------------+-------+--------------+ 788 | Name | Notes | Level | Mux Category | 789 +------------+-------------------------------+-------+--------------+ 790 | dccp-port | Multiplexing MUST not be | M | NOT | 791 | | performed due to potential | | RECOMMENDED | 792 | | conflict between the port | | | 793 | | used for DCCP | | | 794 | | en/decapsulation and the RTP | | | 795 | | | | | 796 +------------+-------------------------------+-------+--------------+ 798 RFC6773 Attribute Analysis 800 RFC6773 is about tunneling DCCP in UDP, with the UDP port being the 801 port of the DCCP en-/de-capsulation service. This encapsulation 802 allows arbitrary DCCP packets to be encapsulated and the DCCP port 803 chosen MAY conflict with the port chosen for the RTP traffic. 805 For multiplexing several DCCP-in-UDP encapsulations on the same UDP 806 port, with no RTP traffic on the same port implies collapsing several 807 DCCP port spaces together. This may or may not work depending on the 808 nature of DCCP encapsulations and ports choices thus rendering it to 809 be very application dependent. 811 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile 813 [RFC5506] discusses benefits and issues that arise when allowing 814 Real-time Transport Protocol (RTCP) packets to be transmitted with 815 reduced size. 817 +-------------+--------------------------------+-------+------------+ 818 | Name | Notes | Level | Mux | 819 | | | | Category | 820 +-------------+--------------------------------+-------+------------+ 821 | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL | 822 | | entire RTP Session | | | 823 | | | | | 824 +-------------+--------------------------------+-------+------------+ 826 RFC5506 Attribute Analysis 828 5.11. RFC6787 - Media Resource Control Protocol Version 2 830 The Media Resource Control Protocol Version 2 (MRCPv2) allows client 831 hosts to control media service resources such as speech synthesizers, 832 recognizers, verifiers, and identifiers residing in servers on the 833 network. MRCPv2 is not a "stand-alone" protocol -- it relies on 834 other protocols, such as the Session Initiation Protocol (SIP), to 835 coordinate MRCPv2 clients and servers and manage sessions between 836 them, and the Session Description Protocol (SDP) to describe, 837 discover, and exchange capabilities. It also depends on SIP and SDP 838 to establish the media sessions and associated parameters between the 839 media source or sink and the media server. Once this is done, the 840 MRCPv2 exchange operates over the control session established above, 841 allowing the client to control the media processing resources on the 842 speech resource server. [RFC6787] defines attributes for this 843 purpose. 845 +-----------+---------------+-------+--------------+ 846 | Name | Notes | Level | Mux Category | 847 +-----------+---------------+-------+--------------+ 848 | resource | Not Impacted | M | NORMAL | 849 | | | | | 850 | channel | Not Impacted | M | NORMAL | 851 | | | | | 852 | cmid | Not Impacted | M | NORMAL | 853 | | | | | 854 +-----------+---------------+-------+--------------+ 856 RFC6787 Attribute Analysis 858 5.12. RFC5245 - Interactive Connectivity Establishment (ICE) 860 [RFC5245] describes a protocol for Network Address Translator(NAT) 861 traversal for UDP-based multimedia sessions established with the 862 offer/answer model. This protocol is called Interactive Connectivity 863 Establishment (ICE). ICE makes use of the Session Traversal 864 Utilities for NAT (STUN) protocol and its extension,Traversal Using 865 Relay NAT (TURN). ICE can be used by any protocol utilizing the 866 offer/answer model, such as the Session Initiation Protocol (SIP). 868 +--------------------+-------------------------+-------+------------+ 869 | Name | Notes | Level | Mux | 870 | | | | Category | 871 +--------------------+-------------------------+-------+------------+ 872 | ice-lite | Not Impacted | S | NORMAL | 873 | | | | | 874 | ice-options | Not Impacted | S | NORMAL | 875 | | | | | 876 | ice-mismatch | Not Impacted | S | NORMAL | 877 | | | | | 878 | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT | 879 | | that corresponds to the | | | 880 | | "m=" line chosen for | | | 881 | | setting up the | | | 882 | | underlying transport | | | 883 | | flow | | | 884 | | | | | 885 | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | 886 | | one that corresponds to | | | 887 | | the "m=" line chosen | | | 888 | | for setting up the | | | 889 | | underlying transport | | | 890 | | flow | | | 891 | | | | | 892 | candidate | ice candidate MUST be | M | TRANSPORT | 893 | | the one that | | | 894 | | corresponds to the "m=" | | | 895 | | line chosen for setting | | | 896 | | up the underlying | | | 897 | | transport flow | | | 898 | | | | | 899 | remote-candidates | ice remote candidate | M | TRANSPORT | 900 | | MUST be the one that | | | 901 | | corresponds to the "m=" | | | 902 | | line chosen for setting | | | 903 | | up the underlying | | | 904 | | transport flow | | | 905 | | | | | 906 +--------------------+-------------------------+-------+------------+ 908 RFC5245 Attribute Analysis 910 5.13. RFC5285 - RTP Header Extensions 912 [RFC5285] provides a general mechanism to use the header extension 913 feature of RTP (the Real-Time Transport Protocol). It provides the 914 option to use a small number of small extensions in each RTP packet, 915 where the universe of possible extensions is large and registration 916 is de-centralized. The actual extensions in use in a session are 917 signaled in the setup information for that session. 919 +---------+-------------------------------------+-------+-----------+ 920 | Name | Notes | Level | Mux | 921 | | | | Category | 922 +---------+-------------------------------------+-------+-----------+ 923 | extmap | Specific RTP extension document | B | SPECIAL | 924 | | MUST be referred | | | 925 | | | | | 926 +---------+-------------------------------------+-------+-----------+ 928 RFC5285 Attribute Analysis 930 5.14. RFC3605 - RTCP attribute in SDP 932 Originally, SDP assumed that RTP and RTCP were carried on consecutive 933 ports. However, this is not always true when NATs are involved. 934 [RFC3605] specifies an early mechanism to indicate the RTCP port. 936 +-------+--------------------------------------+-------+------------+ 937 | Name | Notes | Level | Mux | 938 | | | | Category | 939 +-------+--------------------------------------+-------+------------+ 940 | rtcp | RTCP Port MUST be the one that | M | TRANSPORT | 941 | | corresponds to the "m=" line chosen | | | 942 | | for setting up the underlying | | | 943 | | transport flow. | | | 944 | | | | | 945 +-------+--------------------------------------+-------+------------+ 947 RFC3605 Attribute Analysis 949 5.15. RFC5576 - Source-Specific SDP Attributes 951 [RFC5576] defines a mechanism to describe RTP media sources, which 952 are identified by their synchronization source (SSRC) identifiers, in 953 SDP, to associate attributes with these sources, and to express 954 relationships among sources. It also defines several source-level 955 attributes that can be used to describe properties of media sources. 957 +----------------+----------------------+-------+-------------------+ 958 | Name | Notes | Level | Mux Category | 959 +----------------+----------------------+-------+-------------------+ 960 | ssrc | Refer to Notes below | M | NORMAL | 961 | | | | | 962 | ssrc-group | Refer to section | M | NORMAL | 963 | | Section 9 for | | | 964 | | specific analysis of | | | 965 | | the grouping | | | 966 | | semantics | | | 967 | | | | | 968 | cname | Not Impacted | SR | NORMAL | 969 | | | | | 970 | previous-ssrc | Refer to notes below | SR | NORMAL | 971 | | | | | 972 | fmtp | The attribute value | SR | IDENTICAL-PER-PT | 973 | | MUST be same for a | | | 974 | | given codec | | | 975 | | configuration | | | 976 | | | | | 977 +----------------+----------------------+-------+-------------------+ 979 RFC5576 Attribute Analysis 981 If SSRCs are repeated across "m=" lines being multiplexed, they MUST 982 all represent the same underlying RTP Source. 984 5.16. RFC7273 - RTP Clock Source Signalling 986 [RFC7273] specifies Session Description Protocol (SDP) signalling 987 that identifies timestamp reference clock sources and SDP signalling 988 that identifies the media clock sources in a multimedia session. 990 +------------+---------------+-------+--------------+ 991 | Name | Notes | Level | Mux Category | 992 +------------+---------------+-------+--------------+ 993 | ts-refclk | Not Impacted | B | NORMAL | 994 | | | | | 995 | mediaclk | Not Impacted | B | NORMAL | 996 | | | | | 997 +------------+---------------+-------+--------------+ 999 RFC7273 Attribute Analysis 1001 5.17. RFC6236 - Image Attributes in SDP 1003 [RFC6236] proposes a new generic session setup attribute to make it 1004 possible to negotiate different image attributes such as image size. 1005 A possible use case is to make it possible for a low-end hand-held 1006 terminal to display video without the need to rescale the 1007 image,something that may consume large amounts of memory and 1008 processing power. The document also helps to maintain an optimal 1009 bitrate for video as only the image size that is desired by the 1010 receiver is transmitted. 1012 +------------+--------------------------+-------+-------------------+ 1013 | Name | Notes | Level | Mux Category | 1014 +------------+--------------------------+-------+-------------------+ 1015 | imageattr | The attribute value MUST | M | IDENTICAL-PER-PT | 1016 | | be same for a given | | | 1017 | | codec configuration | | | 1018 | | | | | 1019 +------------+--------------------------+-------+-------------------+ 1021 RFC6236 Attribute Analysis 1023 5.18. RFC7197 - Duplication Delay Attribute in SDP 1025 [RFC7197] defines an attribute to indicate the presence of temporally 1026 redundant media streams and the duplication delay in the Session 1027 Description Protocol. 1029 +--------------------+---------------+-------+--------------+ 1030 | Name | Notes | Level | Mux Category | 1031 +--------------------+---------------+-------+--------------+ 1032 | duplication-delay | Not Impacted | B | NORMAL | 1033 | | | | | 1034 +--------------------+---------------+-------+--------------+ 1036 RFC7197 Attribute Analysis 1038 5.19. RFC7266 - RTCP XR Blocks for MOS Metric Reporting 1040 [RFC7266] defines an RTP Control Protocol (RTCP) Extended Report (XR) 1041 Block including two new segment types and associated Session 1042 Description Protocol (SDP) parameters that allow the reporting of 1043 mean opinion score (MOS) Metrics for use in a range of RTP 1044 applications. 1046 +-------------+---------------+-------+--------------+ 1047 | Name | Notes | Level | Mux Category | 1048 +-------------+---------------+-------+--------------+ 1049 | calgextmap | Not Impacted | B | NORMAL | 1050 | | | | | 1051 +-------------+---------------+-------+--------------+ 1053 RFC7266 Attribute Analysis 1055 5.20. RFC6285 - Rapid Acquisition of Multicast RTP Sessions 1057 [RFC6285] describes a method using the existing RTP and RTP Control 1058 Protocol (RTCP) machinery that reduces the acquisition delay. In 1059 this method, an auxiliary unicast RTP session carrying the Reference 1060 Information to the receiver precedes or accompanies the multicast 1061 stream. This unicast RTP flow can be transmitted at a faster than 1062 natural bitrate to further accelerate the acquisition. The 1063 motivating use case for this capability is multicast applications 1064 that carry real-time compressed audio and video. 1066 +---------------+-------------------+-------+------------------+ 1067 | Name | Notes | Level | Mux Category | 1068 +---------------+-------------------+-------+------------------+ 1069 | rams-updates | Not recommended | M | NOT RECOMMENDED | 1070 | | | | | 1071 +---------------+-------------------+-------+------------------+ 1073 RFC6285 Attribute Analysis 1075 5.21. RFC6230 - Media Control Channel Framework 1077 [RFC6230] describes a framework and protocol for application 1078 deployment where the application programming logic and media 1079 processing are distributed. This implies that application 1080 programming logic can seamlessly gain access to appropriate resources 1081 that are not co-located on the same physical network entity. The 1082 framework uses the Session Initiation Protocol (SIP) to establish an 1083 application-level control mechanism between application servers and 1084 associated external servers such as media servers. 1086 +---------+---------------+-------+--------------+ 1087 | Name | Notes | Level | Mux Category | 1088 +---------+---------------+-------+--------------+ 1089 | cfw-id | Not Impacted | M | NORMAL | 1090 | | | | | 1091 +---------+---------------+-------+--------------+ 1093 RFC6230 Attribute Analysis 1095 5.22. RFC6364 - SDP Elements for FEC Framework 1097 [RFC6364] specifies the use of the Session Description Protocol (SDP) 1098 to describe the parameters required to signal the Forward Error 1099 Correction (FEC) Framework Configuration Information between the 1100 sender(s) and receiver(s). This document also provides examples that 1101 show the semantics for grouping multiple source and repair flows 1102 together for the applications that simultaneously use multiple 1103 instances of the FEC Framework. 1105 +------------------+-----------------------------+-------+----------+ 1106 | Name | Notes | Level | Mux | 1107 | | | | Category | 1108 +------------------+-----------------------------+-------+----------+ 1109 | fec-source-flow | Specific FEC scheme | M | SPECIAL | 1110 | | document needs to be | | | 1111 | | referred | | | 1112 | | | | | 1113 | fec-repair-flow | Specific FEC scheme | M | SPECIAL | 1114 | | document needs to be | | | 1115 | | referred | | | 1116 | | | | | 1117 | repair-window | Specific FEC scheme | M | SPECIAL | 1118 | | document needs to be | | | 1119 | | referred | | | 1120 | | | | | 1121 +------------------+-----------------------------+-------+----------+ 1123 RFC6364 Attribute Analysis 1125 5.23. RFC4796 - Content Attribute 1127 [RFC4796] defines a new Session Description Protocol (SDP) media- 1128 level attribute, 'content'. The 'content' attribute defines the 1129 content of the media stream to a more detailed level than the media 1130 description line. The sender of an SDP session description can 1131 attach the 'content' attribute to one or more media streams. The 1132 receiving application can then treat each media stream differently 1133 (e.g., show it on a big or small screen) based on its content. 1135 +----------+---------------+-------+--------------+ 1136 | Name | Notes | Level | Mux Category | 1137 +----------+---------------+-------+--------------+ 1138 | content | Not Impacted | M | NORMAL | 1139 | | | | | 1140 +----------+---------------+-------+--------------+ 1142 RFC4796 Attribute Analysis 1144 5.24. RFC3407 - SDP Simple Capability Declaration 1146 [RFC3407] defines a set of Session Description Protocol (SDP) 1147 attributes that enables SDP to provide a minimal and backwards 1148 compatible capability declaration mechanism. 1150 +----------+------------------------+-------+--------------+ 1151 | Name | Notes | Level | Mux Category | 1152 +----------+------------------------+-------+--------------+ 1153 | sqn | Not Impacted | B | NORMAL | 1154 | | | | | 1155 | cdsc | Not Impacted. | B | NORMAL | 1156 | | | | | 1157 | cpar | Refer to Section 14 | B | INHERIT | 1158 | | | | | 1159 | cparmin | Refer to notes below | B | SPECIAL | 1160 | | | | | 1161 | cparmax | Refer to notes below | B | SPECIAL | 1162 | | | | | 1163 +----------+------------------------+-------+--------------+ 1165 RFC3407 Attribute Analysis 1167 Since the attributes (a=cparmin and a=cparmax) define minimum and 1168 maximum numerical values associated with the attributes described in 1169 a=cpar, it is recommended to consult the document defining the 1170 attribute. 1172 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP Sessions 1174 [RFC6284] presents a port mapping solution that allows RTP receivers 1175 to choose their own ports for an auxiliary unicast session in RTP 1176 applications using both unicast and multicast services. The solution 1177 provides protection against denial-of-service or packet amplification 1178 attacks that could be used to cause one or more RTP packets to be 1179 sent to a victim client. 1181 +------------------+-------------------------+-------+--------------+ 1182 | Name | Notes | Level | Mux Category | 1183 +------------------+-------------------------+-------+--------------+ 1184 | portmapping-req | Not recommended, if | M | NOT | 1185 | | port mapping is | | RECOMMENDED | 1186 | | required by the | | | 1187 | | application | | | 1188 | | | | | 1189 +------------------+-------------------------+-------+--------------+ 1191 RFC6284 Attribute Analysis 1193 5.26. RFC6714 - MSRP-CEMA 1195 [RFC6714] defines a Message Session Relay Protocol (MSRP) extension, 1196 Connection Establishment for Media Anchoring (CEMA). Support of this 1197 extension is OPTIONAL. The extension allows middle boxes to anchor 1198 the MSRP connection, without the need for middle boxes to modify the 1199 MSRP messages; thus, it also enables secure end-to-end MSRP 1200 communication in networks where such middle boxes are deployed. This 1201 document also defines a Session Description Protocol (SDP) attribute, 1202 'msrp-cema', that MSRP endpoints use to indicate support of the CEMA 1203 extension. 1205 +------------+---------------+-------+--------------+ 1206 | Name | Notes | Level | Mux Category | 1207 +------------+---------------+-------+--------------+ 1208 | msrp-cema | Not Impacted | M | NORMAL | 1209 | | | | | 1210 +------------+---------------+-------+--------------+ 1212 RFC6714 Attribute Analysis 1214 5.27. RFC4583 - SDP Format for BFCP Streams 1216 [RFC4583] document specifies how to describe Binary Floor Control 1217 Protocol (BFCP) streams in Session Description Protocol (SDP) 1218 descriptions. User agents using the offer/answer model to establish 1219 BFCP streams use this format in their offers and answers. 1221 +------------+---------------------------------+-------+------------+ 1222 | Name | Notes | Level | Mux | 1223 | | | | Category | 1224 +------------+---------------------------------+-------+------------+ 1225 | floorctrl | The attribute MUST be repeated | M | IDENTICAL | 1226 | | across all the multiplexed "m=" | | | 1227 | | lines | | | 1228 | | | | | 1229 | confid | Not Impacted | M | NORMAL | 1230 | | | | | 1231 | userid | Not Impacted | M | NORMAL | 1232 | | | | | 1233 | floorid | The floorid MUST be globally | M | NORMAL | 1234 | | unique | | | 1235 | | | | | 1236 +------------+---------------------------------+-------+------------+ 1238 RFC4583 Attribute Analysis 1240 5.28. RFC5547 - SDP Offer/Answer for File Transfer 1242 [RFC5547] provides a mechanism to negotiate the transfer of one or 1243 more files between two endpoints by using the Session Description 1244 Protocol (SDP) offer/answer model specified in [RFC3264]. 1246 +----------------------+---------------+-------+--------------+ 1247 | Name | Notes | Level | Mux Category | 1248 +----------------------+---------------+-------+--------------+ 1249 | file-selector | Not Impacted | M | NORMAL | 1250 | | | | | 1251 | file-transfer-id | Not Impacted | M | NORMAL | 1252 | | | | | 1253 | file-disposition | Not Impacted | M | NORMAL | 1254 | | | | | 1255 | file-date | Not Impacted | M | NORMAL | 1256 | | | | | 1257 | file-iconfile-range | Not Impacted | M | NORMAL | 1258 | | | | | 1259 +----------------------+---------------+-------+--------------+ 1261 RFC5547 Attribute Analysis 1263 5.29. RFC6849 - SDP and RTP Media Loopback Extension 1265 [RFC6849] adds new SDP media types and attributes, which enable 1266 establishment of media sessions where the media is looped back to the 1267 transmitter. Such media sessions will serve as monitoring and 1268 troubleshooting tools by providing the means for measurement of more 1269 advanced VoIP, Real-time Text, and Video over IP performance metrics. 1271 +---------------------------+----------------+-------+--------------+ 1272 | Name | Notes | Level | Mux Category | 1273 +---------------------------+----------------+-------+--------------+ 1274 | loopback rtp-pkt-loopback | Not Impacted | M | NORMAL | 1275 | | | | | 1276 | loopback rtp-media- | Not Impacted | M | NORMAL | 1277 | loopback | | | | 1278 | | | | | 1279 | loopback-source | Not Impacted | M | NORMAL | 1280 | | | | | 1281 | loopback-mirror | Not Impacted | M | NORMAL | 1282 | | | | | 1283 +---------------------------+----------------+-------+--------------+ 1285 RFC6849 Analysis 1287 5.30. RFC5760 - RTCP with Unicast Feedback 1289 [RFC5760] specifies an extension to the Real-time Transport Control 1290 Protocol (RTCP) to use unicast feedback to a multicast sender. The 1291 proposed extension is useful for single-source multicast sessions 1292 such as Source-Specific Multicast (SSM) communication where the 1293 traditional model of many-to-many group communication is either not 1294 available or not desired. 1296 +---------------+------------------------------+-------+------------+ 1297 | Name | Notes | Level | Mux | 1298 | | | | Category | 1299 +---------------+------------------------------+-------+------------+ 1300 | rtcp-unicast | The attribute MUST be | M | IDENTICAL | 1301 | | reported across all "m=" | | | 1302 | | lines multiplexed | | | 1303 | | | | | 1304 +---------------+------------------------------+-------+------------+ 1306 RFC5760 Attribute Analysis 1308 5.31. RFC3611 - RTCP XR 1310 [RFC3611] defines the Extended Report (XR) packet type for the RTP 1311 Control Protocol (RTCP), and defines how the use of XR packets can be 1312 signaled by an application if it employs the Session Description 1313 Protocol (SDP). 1315 +----------+---------------+-------+--------------+ 1316 | Name | Notes | Level | Mux Category | 1317 +----------+---------------+-------+--------------+ 1318 | rtcp-xr | Not Impacted | B | NORMAL | 1319 | | | | | 1320 +----------+---------------+-------+--------------+ 1322 RFC3611 Attribute Analysis 1324 5.32. RFC5939 - SDP Capability Negotiation 1326 [RFC5939] defines a general SDP Capability Negotiation framework. It 1327 also specifies how to provide attributes and transport protocols as 1328 capabilities and negotiate them using the framework. Extensions for 1329 other types of capabilities (e.g., media types and media formats) may 1330 be provided in other documents. 1332 +---------+-------------------------------+-------+--------------+ 1333 | Name | Notes | Level | Mux Category | 1334 +---------+-------------------------------+-------+--------------+ 1335 | pcfg | Refer to Section Section 14 | M | SPECIAL | 1336 | | | | | 1337 | acfg | Refer to Section Section 14 | M | SPECIAL | 1338 | | | | | 1339 | csup | Not Impacted | B | NORMAL | 1340 | | | | | 1341 | creq | Not Impacted | B | NORMAL | 1342 | | | | | 1343 | acap | Refer to section Section 14 | B | INHERIT | 1344 | | | | | 1345 | tcap | Refer to section Section 14 | B | INHERIT | 1346 | | | | | 1347 | cap-v0 | Not Impacted | B | NORMAL | 1348 | | | | | 1349 +---------+-------------------------------+-------+--------------+ 1351 RFC5939 Attribute Analysis 1353 5.33. RFC6871- SDP Media Capabilities Negotiation 1355 Session Description Protocol (SDP) capability negotiation provides a 1356 general framework for indicating and negotiating capabilities in SDP. 1357 The base framework defines only capabilities for negotiating 1358 transport protocols and attributes. [RFC6871] extends the framework 1359 by defining media capabilities that can be used to negotiate media 1360 types and their associated parameters. 1362 +---------+-----------------------------+-------+-------------------+ 1363 | Name | Notes | Level | Mux Category | 1364 +---------+-----------------------------+-------+-------------------+ 1365 | rmcap | Refer to Section Section 14 | B | IDENTICAL-PER-PT | 1366 | | | | | 1367 | omcap | Not Impacted | B | NORMAL | 1368 | | | | | 1369 | mfcap | Refer to Section Section 14 | B | IDENTICAL-PER-PT | 1370 | | | | | 1371 | mscap | Refer to Section Section 14 | B | INHERIT | 1372 | | | | | 1373 | lcfg | Refer to Section Section 14 | B | SPECIAL | 1374 | | | | | 1375 | sescap | Refer to notes below | S | NOT RECOMMENDED | 1376 | | | | | 1377 | med-v0 | Not Impacted | S | NORMAL | 1378 | | | | | 1379 +---------+-----------------------------+-------+-------------------+ 1381 RFC6871 - Attribute Analysis 1383 The "sescap" attribute is NOT RECOMMENDED for use with multiplexing. 1384 The reason is that it requires the use of unique configuration 1385 numbers across the entire SDP (per [RFC6871]) as opposed to within a 1386 media description only (per [RFC5939]). As described in Section 14, 1387 the use of identical configuration numbers between multiplexed 1388 (bundled) media descriptions is the default way of indicating 1389 compatible configurations in a bundle. 1391 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP 1393 [RFC7006] extends the SDP capability negotiation framework to allow 1394 endpoints to negotiate three additional SDP capabilities. In 1395 particular, this memo provides a mechanism to negotiate bandwidth 1396 ("b=" line), connection data ("c=" line), and session or media titles 1397 ("i=" line for each session or media). 1399 +----------+-----------------------------------+-------+------------+ 1400 | Name | Notes | Level | Mux | 1401 | | | | Category | 1402 +----------+-----------------------------------+-------+------------+ 1403 | bcap | Inherit the category SUM as | B | INHERIT | 1404 | | applicable to b= attribute | | | 1405 | | | | | 1406 | bcap-v0 | Not Impacted | B | NORMAL | 1407 | | | | | 1408 | ccap | The connection address type MUST | B | IDENTICAL | 1409 | | be identical across all the | | | 1410 | | multiplexed "m=" lines | | | 1411 | | | | | 1412 | ccap-v0 | Not Impacted | B | NORMAL | 1413 | | | | | 1414 | icap | Not Impacted | B | NORMAL | 1415 | | | | | 1416 | icap-v0 | Not Impacted | B | NORMAL | 1417 | | | | | 1418 +----------+-----------------------------------+-------+------------+ 1420 RFC7006 - Attribute Analysis 1422 5.35. RFC4567 - Key Management Extensions for SDP and RTSP 1424 [RFC4567] defines general extensions for Session Description Protocol 1425 (SDP) and Real Time Streaming Protocol (RTSP) to carry messages, as 1426 specified by a key management protocol, in order to secure the media. 1427 These extensions are presented as a framework, to be used by one or 1428 more key management protocols. As such, their use is meaningful only 1429 when complemented by an appropriate key management protocol. 1431 +-----------+----------------------------------+-------+------------+ 1432 | Name | Notes | Level | Mux | 1433 | | | | Category | 1434 +-----------+----------------------------------+-------+------------+ 1435 | key-mgmt | Key management protocol MUST be | B | IDENTICAL | 1436 | | identical across all the "m=" | | | 1437 | | lines | | | 1438 | | | | | 1439 | mikey | Key management protocol MUST be | B | IDENTICAL | 1440 | | identical across all the "m=" | | | 1441 | | lines | | | 1442 | | | | | 1443 +-----------+----------------------------------+-------+------------+ 1445 RFC4567 Attribute Analysis 1447 5.36. RFC4572 - Comedia over TLS in SDP 1449 [RFC4572] specifies how to establish secure connection-oriented media 1450 transport sessions over the Transport Layer Security (TLS) protocol 1451 using the Session Description Protocol (SDP). It defines a new SDP 1452 protocol identifier, 'TCP/TLS'. It also defines the syntax and 1453 semantics for an SDP 'fingerprint' attribute that identifies the 1454 certificate that will be presented for the TLS session. This 1455 mechanism allows media transport over TLS connections to be 1456 established securely, so long as the integrity of session 1457 descriptions is assured. 1459 +--------------+-------------------------------+-------+------------+ 1460 | Name | Notes | Level | Mux | 1461 | | | | Category | 1462 +--------------+-------------------------------+-------+------------+ 1463 | fingerprint | fingerprint value from the | B | TRANSPORT | 1464 | | "m=" line defining the | | | 1465 | | underlying transport is | | | 1466 | | chosen | | | 1467 | | | | | 1468 +--------------+-------------------------------+-------+------------+ 1470 RFC4572 Attribute Analysis 1472 5.37. RFC4570 - SDP Source Filters 1474 [RFC4570] describes how to adapt the Session Description Protocol 1475 (SDP) to express one or more source addresses as a source filter for 1476 one or more destination "connection" addresses. It defines the 1477 syntax and semantics for an SDP "source-filter" attribute that may 1478 reference either IPv4 or IPv6 address(es) as either an inclusive or 1479 exclusive source list for either multicast or unicast destinations. 1480 In particular, an inclusive source-filter can be used to specify a 1481 Source-Specific Multicast (SSM) session. 1483 +----------------+-----------------------------+-------+------------+ 1484 | Name | Notes | Level | Mux | 1485 | | | | Category | 1486 +----------------+-----------------------------+-------+------------+ 1487 | source-filter | The attribute MUST be | B | IDENTICAL | 1488 | | repeated across all "m=" | | | 1489 | | lines multiplexed | | | 1490 | | | | | 1491 +----------------+-----------------------------+-------+------------+ 1493 RFC4570 Attribute Analysis 1495 5.38. RFC6128 - RTCP Port for Multicast Sessions 1497 The Session Description Protocol (SDP) has an attribute that allows 1498 RTP applications to specify an address and a port associated with the 1499 RTP Control Protocol (RTCP) traffic. In RTP-based source-specific 1500 multicast (SSM) sessions, the same attribute is used to designate the 1501 address and the RTCP port of the Feedback Target in the SDP 1502 description. However, the RTCP port associated with the SSM session 1503 itself cannot be specified by the same attribute to avoid ambiguity, 1504 and thus, is required to be derived from the "m=" line of the media 1505 description. Deriving the RTCP port from the "m=" line imposes an 1506 unnecessary restriction. [RFC6128] removes this restriction by 1507 introducing a new SDP attribute. 1509 +-----------------+----------------------------+-------+------------+ 1510 | Name | Notes | Level | Mux | 1511 | | | | Category | 1512 +-----------------+----------------------------+-------+------------+ 1513 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | 1514 | | be identical across all | | | 1515 | | the "m=" lines | | | 1516 | | | | | 1517 +-----------------+----------------------------+-------+------------+ 1519 RFC6128 Attribute Analysis 1521 5.39. RFC6189 - ZRTP 1523 [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman 1524 exchange to agree on a session key and parameters for establishing 1525 unicast Secure Real-time Transport Protocol (SRTP) sessions for Voice 1526 over IP (VoIP) applications. 1528 +------------+-------------------------------+-------+--------------+ 1529 | Name | Notes | Level | Mux Category | 1530 +------------+-------------------------------+-------+--------------+ 1531 | zrtp-hash | Complicates if all the "m=" | M | NOT | 1532 | | lines are not authenticated | | RECOMMENDED | 1533 | | | | | 1534 +------------+-------------------------------+-------+--------------+ 1536 RFC6189 Attribute Analysis 1538 5.40. RFC4145 - Connection-Oriented Media 1540 [RFC4145] describes how to express media transport over TCP using the 1541 Session Description Protocol (SDP). It defines the SDP 'TCP' 1542 protocol identifier, the SDP 'setup' attribute, which describes the 1543 connection setup procedure, and the SDP 'connection' attribute, which 1544 handles connection reestablishment. 1546 +-------------+--------------------------------+-------+------------+ 1547 | Name | Notes | Level | Mux | 1548 | | | | Category | 1549 +-------------+--------------------------------+-------+------------+ 1550 | setup | The attribute MUST be | B | IDENTICAL | 1551 | | identical across all "m=" | | | 1552 | | lines | | | 1553 | | | | | 1554 | connection | Thee attribute MUST be | B | IDENTICAL | 1555 | | identical across all "m=" | | | 1556 | | lines | | | 1557 | | | | | 1558 +-------------+--------------------------------+-------+------------+ 1560 RFC4145 Attribute Analysis 1562 5.41. RFC6947 - The SDP ALTC Attribute 1564 [RFC6947] proposes a mechanism that allows the same SDP offer to 1565 carry multiple IP addresses of different address families (e.g., IPv4 1566 and IPv6). The proposed attribute, the "altc" attribute, solves the 1567 backward-compatibility problem that plagued Alternative Network 1568 Address Types (ANAT) due to their syntax. 1570 +-------+--------------------------------------+-------+------------+ 1571 | Name | Notes | Level | Mux | 1572 | | | | Category | 1573 +-------+--------------------------------------+-------+------------+ 1574 | altc | The IP Address and port MUST be the | M | TRANSPORT | 1575 | | one that corresponds to the "m=" | | | 1576 | | line chosen for setting up the | | | 1577 | | underlying transport flow | | | 1578 | | | | | 1579 +-------+--------------------------------------+-------+------------+ 1581 RFC6947 Attribute Analysis 1583 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers in PSTN 1585 [RFC7195] describes use cases, requirements, and protocol extensions 1586 for using the Session Description Protocol (SDP) offer/answer model 1587 for establishing audio and video media streams over circuit-switched 1588 bearers in the Public Switched Telephone Network (PSTN). 1590 +--------------------------+---------------+-------+--------------+ 1591 | Name | Notes | Level | Mux Category | 1592 +--------------------------+---------------+-------+--------------+ 1593 | cs-correlation:callerid | Not Impacted | M | NORMAL | 1594 | | | | | 1595 | cs-correlation:uuie | Not Impacted | M | NORMAL | 1596 | | | | | 1597 | cs-correlation:dtmf | Not Impacted | M | NORMAL | 1598 | | | | | 1599 | cs-correlation:external | Not Impacted | M | NORMAL | 1600 | | | | | 1601 +--------------------------+---------------+-------+--------------+ 1603 RFC7195 Attribute Analysis 1605 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) 1607 [RFC7272] defines a new RTP Control Protocol (RTCP) Packet Type and 1608 an RTCP Extended Report (XR) Block Type to be used for achieving 1609 Inter-Destination Media Synchronization (IDMS). 1611 +------------+---------------+-------+--------------+ 1612 | Name | Notes | Level | Mux Category | 1613 +------------+---------------+-------+--------------+ 1614 | rtcp-idms | Not Impacted | M | NORMAL | 1615 | | | | | 1616 +------------+---------------+-------+--------------+ 1618 RFC7272 Attribute Analysis 1620 5.44. RFC5159 - OMA BCAST SDP Attributes 1622 [RFC5159] provides descriptions of Session Description Protocol (SDP) 1623 attributes used by the Open Mobile Alliance's Broadcast Service and 1624 Content Protection specification. 1626 +---------------------+---------------+-------+--------------+ 1627 | Name | Notes | Level | Mux Category | 1628 +---------------------+---------------+-------+--------------+ 1629 | bcastversion | Not Impacted | S | NORMAL | 1630 | | | | | 1631 | stkmstream | Not Impacted | B | NORMAL | 1632 | | | | | 1633 | SRTPAuthentication | Not Impacted | M | NORMAL | 1634 | | | | | 1635 | SRTPROCTxRate | Not Impacted | M | NORMAL | 1636 | | | | | 1637 +---------------------+---------------+-------+--------------+ 1639 RFC5159 Attribute Analysis 1641 5.45. RFC6193 - Media Description for IKE in SDP 1643 [RFC6193] specifies how to establish a media session that represents 1644 a virtual private network using the Session Initiation Protocol for 1645 the purpose of on-demand media/application sharing between peers. It 1646 extends the protocol identifier of the Session Description Protocol 1647 (SDP) so that it can negotiate use of the Internet Key Exchange 1648 Protocol (IKE) for media sessions in the SDP offer/answer model. 1650 +-------------------+--------------------------+-------+------------+ 1651 | Name | Notes | Level | Mux | 1652 | | | | Category | 1653 +-------------------+--------------------------+-------+------------+ 1654 | ike-setup | Attribute MUST be | B | IDENTICAL | 1655 | | identical across all the | | | 1656 | | "m=" lines | | | 1657 | | | | | 1658 | psk-fingerprint | Attribute MUST be | B | IDENTICAL | 1659 | | identical across all the | | | 1660 | | "m=" lines | | | 1661 | | | | | 1662 | ike-esp | Attribute MUST be | B | IDENTICAL | 1663 | | identical across all the | | | 1664 | | "m=" lines | | | 1665 | | | | | 1666 | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL | 1667 | | identical across all the | | | 1668 | | "m=" lines | | | 1669 | | | | | 1670 +-------------------+--------------------------+-------+------------+ 1672 RFC6193 Attribute Analysis 1674 With the above SDP constraints, a session multiplexed with multiple 1675 "m=" lines will use only one IPSec association for all of the "m=" 1676 lines. 1678 5.46. RFC2326 - Real Time Streaming Protocol 1680 The Real Time Streaming Protocol, or RTSP, is an application-level 1681 protocol for control over the delivery of data with real-time 1682 properties. RTSP provides an extensible framework to enable 1683 controlled, on-demand delivery of real-time data, such as audio and 1684 video. 1686 +----------+---------------------------------+-------+--------------+ 1687 | Name | Notes | Level | Mux Category | 1688 +----------+---------------------------------+-------+--------------+ 1689 | etag | RTSP is not supported for RTP | B | NOT | 1690 | | Stream multiplexing | | RECOMMENDED | 1691 | | | | | 1692 | range | RTSP is not supported for RTP | B | NOT | 1693 | | Stream multiplexing | | RECOMMENDED | 1694 | | | | | 1695 | control | RTSP is not supported for RTP | B | NOT | 1696 | | Stream multiplexing | | RECOMMENDED | 1697 | | | | | 1698 | mtag | RTSP is not supported for RTP | B | NOT | 1699 | | Stream multiplexing | | RECOMMENDED | 1700 | | | | | 1701 +----------+---------------------------------+-------+--------------+ 1703 RFC2326 Attribute Analysis 1705 [RFC2326] defines SDP attributes that are applicable in the 1706 declarative usage of SDP alone. For purposes of this document, only 1707 the Offer/Answer usage of SDP is considered as mandated by 1708 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1710 5.47. RFC6064 - SDP and RTSP Extensions for 3GPP 1712 The Packet-switched Streaming Service (PSS) and the Multimedia 1713 Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session 1714 Description Protocol (SDP) and Real Time Streaming Protocol (RTSP) 1715 with some extensions. [RFC6064] provides information about these 1716 extensions and registers the RTSP and SDP extensions with IANA. 1718 +-------------------------------+------------+-------+--------------+ 1719 | Name | Notes | Level | Mux Category | 1720 +-------------------------------+------------+-------+--------------+ 1721 | X-predecbufsize | Refer to | M | NOT | 1722 | | notes | | RECOMMENDED | 1723 | | below | | | 1724 | | | | | 1725 | X-initpredecbufperiod | Refer to | M | NOT | 1726 | | notes | | RECOMMENDED | 1727 | | below | | | 1728 | | | | | 1729 | X-initpostdecbufperiod | Refer to | M | NOT | 1730 | | notes | | RECOMMENDED | 1731 | | below | | | 1732 | | | | | 1733 | X-decbyterate | Refer to | M | NOT | 1734 | | notes | | RECOMMENDED | 1735 | | below | | | 1736 | | | | | 1737 | 3gpp-videopostdecbufsize | Refer to | M | NOT | 1738 | | notes | | RECOMMENDED | 1739 | | below | | | 1740 | | | | | 1741 | framesize | Refer to | M | NOT | 1742 | | notes | | RECOMMENDED | 1743 | | below | | | 1744 | | | | | 1745 | 3GPP-Integrity-Key | Refer to | S | NOT | 1746 | | notes | | RECOMMENDED | 1747 | | below | | | 1748 | | | | | 1749 | 3GPP-SDP-Auth | Refer to | S | NOT | 1750 | | notes | | RECOMMENDED | 1751 | | below | | | 1752 | | | | | 1753 | 3GPP-SRTP-Config | Refer to | M | NOT | 1754 | | notes | | RECOMMENDED | 1755 | | below | | | 1756 | | | | | 1757 | alt | Refer to | M | NOT | 1758 | | notes | | RECOMMENDED | 1759 | | below | | | 1760 | | | | | 1761 | alt-default-id | Refer to | M | NOT | 1762 | | notes | | RECOMMENDED | 1763 | | below | | | 1764 | | | | | 1765 | alt-group | Refer to | M | NOT | 1766 | | notes | | RECOMMENDED | 1767 | | below | | | 1768 | | | | | 1769 | 3GPP-Adaptation-Support | Refer to | M | NOT | 1770 | | notes | | RECOMMENDED | 1771 | | below | | | 1772 | | | | | 1773 | 3GPP-Asset-Information | Refer to | B | NOT | 1774 | | notes | | RECOMMENDED | 1775 | | below | | | 1776 | | | | | 1777 | mbms-mode | Refer to | B | NOT | 1778 | | notes | | RECOMMENDED | 1779 | | below | | | 1780 | | | | | 1781 | mbms-flowid | Refer to | M | NOT | 1782 | | notes | | RECOMMENDED | 1783 | | below | | | 1784 | | | | | 1785 | mbms-repair | Refer to | B | NOT | 1786 | | notes | | RECOMMENDED | 1787 | | below | | | 1788 | | | | | 1789 | 3GPP-QoE-Metrics | Refer to | M | NOT | 1790 | | notes | | RECOMMENDED | 1791 | | below | | | 1792 | | | | | 1793 | 3GPP-QoE-Metrics:Corruption | Refer to | M | NOT | 1794 | duration | notes | | RECOMMENDED | 1795 | | below | | | 1796 | | | | | 1797 | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | NOT | 1798 | duration | notes | | RECOMMENDED | 1799 | | below | | | 1800 | | | | | 1801 | 3GPP-QoE-Metrics:Initial | Refer to | M | NOT | 1802 | buffering duration | notes | | RECOMMENDED | 1803 | | below | | | 1804 | | | | | 1805 | 3GPP-QoE-Metrics:Successive | Refer to | M | NOT | 1806 | loss of RTP packets | notes | | RECOMMENDED | 1807 | | below | | | 1808 | | | | | 1809 | 3GPP-QoE-Metrics:Frame rate | Refer to | M | NOT | 1810 | deviation | notes | | RECOMMENDED | 1811 | | below | | | 1812 | | | | | 1813 | 3GPP-QoE-Metrics:Jitter | Refer to | M | NOT | 1814 | duration | notes | | RECOMMENDED | 1815 | | below | | | 1816 | | | | | 1817 | 3GPP-QoE-Metrics:Content | Refer to | B | NOT | 1818 | Switch Time | notes | | RECOMMENDED | 1819 | | below | | | 1820 | | | | | 1821 | 3GPP-QoE-Metrics:Average | Refer to | M | NOT | 1822 | Codec Bitrate | notes | | RECOMMENDED | 1823 | | below | | | 1824 | | | | | 1825 | 3GPP-QoE-Metrics:Codec | Refer to | M | NOT | 1826 | Information | notes | | RECOMMENDED | 1827 | | below | | | 1828 | | | | | 1829 | 3GPP-QoE-Metrics:Buffer | Refer to | M | NOT | 1830 | Status | notes | | RECOMMENDED | 1831 | | below | | | 1832 | | | | | 1833 +-------------------------------+------------+-------+--------------+ 1835 RFC6064 Attribute Analysis 1837 [RFC6064] defines SDP attributes that are applicable in the 1838 declarative usage of SDP alone. For purposes of this document, only 1839 the Offer/Answer usage of SDP is considered as mandated by 1840 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1842 5.48. RFC3108 - ATM SDP 1844 [RFC3108] describes conventions for using the Session Description 1845 Protocol (SDP) described for controlling ATM Bearer Connections, and 1846 any associated ATM Adaptation Layer (AAL). 1848 +------------------------+------------------+-------+---------------+ 1849 | Name | Notes | Level | Mux Category | 1850 +------------------------+------------------+-------+---------------+ 1851 | aalType | Refer to notes | B | NOT | 1852 | | below | | RECOMMENDED | 1853 | eecid | Refer to notes | B | NOT | 1854 | | below | | RECOMMENDED | 1855 | capability | Refer to notes | B | NOT | 1856 | | below | | RECOMMENDED | 1857 | qosClass | Refer to notes | B | NOT | 1858 | | below | | RECOMMENDED | 1859 | bcob | Refer to notes | B | NOT | 1860 | | below | | RECOMMENDED | 1861 | stc | Refer to notes | B | NOT | 1862 | | below | | RECOMMENDED | 1863 | upcc | Refer to notes | B | NOT | 1864 | | below | | RECOMMENDED | 1865 | atmQOSparms | Refer to notes | B | NOT | 1866 | | below | | RECOMMENDED | 1867 | atmTrfcDesc | Refer to notes | B | NOT | 1868 | | below | | RECOMMENDED | 1869 | abrParms | Refer to notes | B | NOT | 1870 | | below | | RECOMMENDED | 1871 | abrSetup | Refer to notes | B | NOT | 1872 | | below | | RECOMMENDED | 1873 | bearerType | Refer to notes | B | NOT | 1874 | | below | | RECOMMENDED | 1875 | lij | Refer to notes | B | NOT | 1876 | | below | | RECOMMENDED | 1877 | anycast | Refer to notes | B | NOT | 1878 | | below | | RECOMMENDED | 1879 | cache | Refer to notes | B | NOT | 1880 | | below | | RECOMMENDED | 1881 | bearerSigIE | Refer to notes | B | NOT | 1882 | | below | | RECOMMENDED | 1883 | aalApp | Refer to notes | B | NOT | 1884 | | below | | RECOMMENDED | 1885 | cbrRate | Refer to notes | B | NOT | 1886 | | below | | RECOMMENDED | 1887 | sbc | Refer to notes | B | NOT | 1888 | | below | | RECOMMENDED | 1889 | clkrec | Refer to notes | B | NOT | 1890 | | below | | RECOMMENDED | 1891 | fec | Refer to notes | B | NOT | 1892 | | below | | RECOMMENDED | 1893 | prtfl | Refer to notes | B | NOT | 1894 | | below | | RECOMMENDED | 1895 | structure | Refer to notes | B | NOT | 1896 | | below | | RECOMMENDED | 1897 | cpsSDUsize | Refer to notes | B | NOT | 1898 | | below | | RECOMMENDED | 1899 | aal2CPS | Refer to notes | B | NOT | 1900 | | below | | RECOMMENDED | 1901 | aal2CPSSDUrate | Refer to notes | B | NOT | 1902 | | below | | RECOMMENDED | 1903 | aal2sscs3661unassured | Refer to notes | B | NOT | 1904 | | below | | RECOMMENDED | 1905 | aal2sscs3661assured | Refer to notes | B | NOT | 1906 | | below | | RECOMMENDED | 1907 | aal2sscs3662 | Refer to notes | B | NOT | 1908 | | below | | RECOMMENDED | 1909 | aal5sscop | Refer to notes | B | NOT | 1910 | | below | | RECOMMENDED | 1911 | atmmap | Refer to notes | B | NOT | 1912 | | below | | RECOMMENDED | 1913 | silenceSupp | Refer to notes | B | NOT | 1914 | | below | | RECOMMENDED | 1915 | ecan | Refer to notes | B | NOT | 1916 | | below | | RECOMMENDED | 1917 | gc | Refer to notes | B | NOT | 1918 | | below | | RECOMMENDED | 1919 | profileDesc | Refer to notes | B | NOT | 1920 | | below | | RECOMMENDED | 1921 | vsel | Refer to notes | B | NOT | 1922 | | below | | RECOMMENDED | 1923 | dsel | Refer to notes | B | NOT | 1924 | | below | | RECOMMENDED | 1925 | fsel | Refer to notes | B | NOT | 1926 | | below | | RECOMMENDED | 1927 | onewaySel | Refer to notes | B | NOT | 1928 | | below | | RECOMMENDED | 1929 | codecconfig | Refer to notes | B | NOT | 1930 | | below | | RECOMMENDED | 1931 | isup_usi | Refer to notes | B | NOT | 1932 | | below | | RECOMMENDED | 1933 | uiLayer1_Prot | Refer to notes | B | NOT | 1934 | | below | | RECOMMENDED | 1935 | chain | Refer to notes | B | NOT | 1936 | | below | | RECOMMENDED | 1937 | | | | | 1938 +------------------------+------------------+-------+---------------+ 1940 RFC3108 Attribute Analysis 1942 RFC3108 describes conventions for using the Session Description 1943 Protocol (SDP) for characterizing ATM bearer connections using an 1944 AAL1, AAL2 or AAL5 adaptation layers. For AAL1, AAL2 and AAL5, 1945 bearer connections can be used to transport single media streams. In 1946 addition, for AAL1 and AAL2, multiple media streams MAY be 1947 multiplexed into a bearer connection. For all adaptation types 1948 (AAL1, AAL2 and AAL5), bearer connections MAY be bundled into a 1949 single media group. In all cases addressed by RFC3108, a real-time 1950 media stream (voice, video, voiceband data, pseudo-wire and others) 1951 or a multiplex of media streams is mapped directly into an ATM 1952 connection. RFC3108 does not address cases where ATM serves as a 1953 low-level transport pipe for IP packets which in turn MAY carry one 1954 or more real-time (e.g. VoIP) media sessions with a life-cycle 1955 different from that of the underlying ATM transport. 1957 [I-D.ietf-mmusic-sdp-bundle-negotiation] is applicable only for 1958 nettypes IN and address types "IP4" or "IP6". 1960 5.49. 3GPP TS 26.114 1962 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and 1963 interaction 1965 +----------------------+-------------------------+-------+----------+ 1966 | Name | Notes | Level | Mux | 1967 | | | | Category | 1968 +----------------------+-------------------------+-------+----------+ 1969 | 3gpp_sync_info | Usage defined for the | M | NORMAL | 1970 | | IP Multimedia Subsystem | | | 1971 | | | | | 1972 | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL | 1973 | | IP Multimedia Subsystem | | | 1974 | | | | | 1975 +----------------------+-------------------------+-------+----------+ 1977 3GPP TS 26.114 Attribute Analysis 1979 5.50. 3GPP TS 183.063 1981 [R3GPPTS183.063] Telecommunications and Internet converged Services 1982 and Protocols for Advanced Networking (TISPAN); 1984 +---------------------+---------------+-------+--------------+ 1985 | Name | Notes | Level | Mux Category | 1986 +---------------------+---------------+-------+--------------+ 1987 | PSCid | Not Impacted | S | NORMAL | 1988 | | | | | 1989 | bc_service | Not Impacted | S | NORMAL | 1990 | | | | | 1991 | bc_program | Not Impacted | S | NORMAL | 1992 | | | | | 1993 | bc_service_package | Not Impacted | S | NORMAL | 1994 | | | | | 1995 +---------------------+---------------+-------+--------------+ 1997 3GPP TS 183.063 Attribute Analysis 1999 5.51. 3GPP TS 24.182 2001 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting 2002 tones 2003 +-------------+---------------------------------+-------+-----------+ 2004 | Name | Notes | Level | Mux | 2005 | | | | Category | 2006 +-------------+---------------------------------+-------+-----------+ 2007 | g.3gpp.cat | Usage defined for the IP | M | NORMAL | 2008 | | Multimedia Subsystem | | | 2009 | | | | | 2010 +-------------+---------------------------------+-------+-----------+ 2012 3GPP TS 24.182 Attribute Analysis 2014 5.52. 3GPP TS 24.183 2016 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing 2017 Signal 2019 +-------------+---------------------------------+-------+-----------+ 2020 | Name | Notes | Level | Mux | 2021 | | | | Category | 2022 +-------------+---------------------------------+-------+-----------+ 2023 | g.3gpp.crs | Usage defined for the IP | M | NORMAL | 2024 | | Multimedia Subsystem | | | 2025 | | | | | 2026 +-------------+---------------------------------+-------+-----------+ 2028 3GPP TS 24.183 Attribute Analysis 2030 5.53. 3GPP TS 24.229 2032 [R3GPPTS24.229] specifies IP multimedia call control protocol based 2033 on Session Initial protocol and Session Description Protocol. 2035 +------------------+---------------------------+-------+------------+ 2036 | Name | Notes | Level | Mux | 2037 | | | | Category | 2038 +------------------+---------------------------+-------+------------+ 2039 | secondary-realm | secondary-realm MUST be | M | TRANSPORT | 2040 | | the one that corresponds | | | 2041 | | to the "m=" line chosen | | | 2042 | | for setting up the | | | 2043 | | underlying transport flow | | | 2044 | | | | | 2045 | visited-realm | visited-realm MUST be the | M | TRANSPORT | 2046 | | one that corresponds to | | | 2047 | | the "m=" line chosen for | | | 2048 | | setting up the underlying | | | 2049 | | transport flow | | | 2050 | | | | | 2051 | omr-m-cksum | Not Impacted | M | NORMAL | 2052 | | | | | 2053 | omr-s-cksum | Not Impacted | M | NORMAL | 2054 | | | | | 2055 | omr-m-att | Not Impacted | M | NORMAL | 2056 | | | | | 2057 | omr-s-att | Not Impacted | M | NORMAL | 2058 | | | | | 2059 | omr-m-bw | Not Impacted | M | NORMAL | 2060 | | | | | 2061 | omr-s-bw | Not Impacted | M | NORMAL | 2062 | | | | | 2063 | omr-codecs | Not Impacted | M | NORMAL | 2064 | | | | | 2065 +------------------+---------------------------+-------+------------+ 2067 3GPP TS 24.229 Attribute Analysis 2069 5.54. ITU T.38 2071 [T.38] defines procedures for real-time Group 3 facsimile 2072 communications over IP networks. 2074 +------------------------+---------------+-------+--------------+ 2075 | Name | Notes | Level | Mux Category | 2076 +------------------------+---------------+-------+--------------+ 2077 | T38FaxVersion | Not Impacted | S | NORMAL | 2078 | | | | | 2079 | T38MaxBitRate | Not Impacted | S | NORMAL | 2080 | | | | | 2081 | T38FaxFillBitRemoval | Not Impacted | S | NORMAL | 2082 | | | | | 2083 | T38FaxTranscodingMMR | Not Impacted | S | NORMAL | 2084 | | | | | 2085 | T38FaxTranscodingJBIG | Not Impacted | S | NORMAL | 2086 | | | | | 2087 | T38FaxRateManagement | Not Impacted | S | NORMAL | 2088 | | | | | 2089 | T38FaxMaxBuffer | Not Impacted | S | NORMAL | 2090 | | | | | 2091 | T38FaxMaxDatagram | Not Impacted | S | NORMAL | 2092 | | | | | 2093 | T38FaxUdpEC | Not Impacted | S | NORMAL | 2094 | | | | | 2095 | T38FaxMaxIFP | Not Impacted | S | NORMAL | 2096 | | | | | 2097 | T38FaxUdpECDepth | Not Impacted | S | NORMAL | 2098 | | | | | 2099 | T38FaxUdpFECMaxSpan | Not Impacted | S | NORMAL | 2100 | | | | | 2101 | T38ModemType | Not Impacted | S | NORMAL | 2102 | | | | | 2103 | T38VendorInfo | Not Impacted | S | NORMAL | 2104 | | | | | 2105 +------------------------+---------------+-------+--------------+ 2107 ITU T.38 Attribute Analysis 2109 The ITU T.38 attributes are clearly unaffected by multiplexing and 2110 are specific to the working of the fax protocol itself. 2112 5.55. ITU-T Q.1970 2114 [Q.1970] defines BICC IP bearer control protocol. 2116 +--------+---------------------------------------+-------+----------+ 2117 | Name | Notes | Level | Mux | 2118 | | | | Category | 2119 +--------+---------------------------------------+-------+----------+ 2120 | ipbcp | ipbcp version identifies type of | S | SPECIAL | 2121 | | IPBCP message used in BICC (ITU-T | | | 2122 | | Q.1901) environment which are limited | | | 2123 | | to single media payload. Pertinent | | | 2124 | | ITU.T specifications needs to be | | | 2125 | | referred while multiplexing | | | 2126 | | | | | 2127 +--------+---------------------------------------+-------+----------+ 2129 ITU-T Q.1970 Attribute Analysis 2131 5.56. ITU-T H.248.15 2133 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 2134 package attribute 2136 +-----------+------------------------------------+-------+----------+ 2137 | Name | Notes | Level | Mux | 2138 | | | | Category | 2139 +-----------+------------------------------------+-------+----------+ 2140 | h248item | It is only applicable for | B | SPECIAL | 2141 | | signaling the inclusion of H.248 | | | 2142 | | extension packages to a gateway | | | 2143 | | via the local and remote | | | 2144 | | descriptors. The attribute itself | | | 2145 | | is unaffected by multiplexing, but | | | 2146 | | the packaged referenced in a | | | 2147 | | specific use of the attribute may | | | 2148 | | be impacted. Further analysis of | | | 2149 | | each package is needed to | | | 2150 | | determine if there is an issue. | | | 2151 | | This is only a concern in | | | 2152 | | environments using a decomposed | | | 2153 | | server/gateway with H.248 signaled | | | 2154 | | between them. The ITU-T will need | | | 2155 | | to do further analysis of various | | | 2156 | | packages when they specify how to | | | 2157 | | signal the use of multiplexing to | | | 2158 | | a gateway | | | 2159 | | | | | 2160 +-----------+------------------------------------+-------+----------+ 2162 ITU-T H.248.15 Attribute Analysis 2164 5.57. RFC4975 - The Message Session Relay Protocol 2166 [RFC4975] the Message Session Relay Protocol, a protocol for 2167 transmitting a series of related instant messages in the context of a 2168 session. Message sessions are treated like any other media stream 2169 when set up via a rendezvous or session creation protocol such as the 2170 Session Initiation Protocol. 2172 +-----------------------+---------------+-------+--------------+ 2173 | Name | Notes | Level | Mux Category | 2174 +-----------------------+---------------+-------+--------------+ 2175 | accept-types | Not Impacted | M | NORMAL | 2176 | | | | | 2177 | accept-wrapped-types | Not Impacted | M | NORMAL | 2178 | | | | | 2179 | max-size | Not Impacted | M | NORMAL | 2180 | | | | | 2181 | path | Not Impacted | M | NORMAL | 2182 | | | | | 2183 +-----------------------+---------------+-------+--------------+ 2185 RFC4975 Attribute Analysis 2187 5.58. Historical Attributes 2189 This section specifies analysis for the attributes that are included 2190 for historic usage alone by the [IANA]. 2192 +----------+----------------------+-------+------------------+ 2193 | Name | Notes | Level | Mux Category | 2194 +----------+----------------------+-------+------------------+ 2195 | rtpred1 | Historic attributes | M | NOT RECOMMENDED | 2196 | | | | | 2197 | rtpred2 | Historic attributes | M | NOT RECOMMENDED | 2198 | | | | | 2199 +----------+----------------------+-------+------------------+ 2201 Historical Attribute Analysis 2203 6. bwtype Attribute Analysis 2205 This section specifies handling of specific bandwidth attributes when 2206 used in multiplexing scenarios. 2208 6.1. RFC4566 - SDP: Session Description Protocol 2210 [RFC4566] defines the Session Description Protocol (SDP) that is 2211 intended for describing multimedia sessions for the purposes of 2212 session announcement, session invitation, and other forms of 2213 multimedia session initiation. 2215 +------------+-----------------------------------+-------+----------+ 2216 | Name | Notes | Level | Mux | 2217 | | | | Category | 2218 +------------+-----------------------------------+-------+----------+ 2219 | bwtype:CT | Not Impacted | S | NORMAL | 2220 | | | | | 2221 | bwtype:AS | For the media level usage, the | B | SUM | 2222 | | aggregate of individual bandwidth | | | 2223 | | values is considered | | | 2224 | | | | | 2225 +------------+-----------------------------------+-------+----------+ 2227 RFC4566 bwtype Analysis 2229 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth 2231 [RFC3556] defines an extension to the Session Description Protocol 2232 (SDP) to specify two additional modifiers for the bandwidth 2233 attribute. These modifiers may be used to specify the bandwidth 2234 allowed for RTP Control Protocol (RTCP) packets in a Real-time 2235 Transport Protocol (RTP) session. 2237 +------------+-----------------------------------+-------+----------+ 2238 | Name | Notes | Level | Mux | 2239 | | | | Category | 2240 +------------+-----------------------------------+-------+----------+ 2241 | bwtype:RS | Session level usage represents | B | SUM | 2242 | | session aggregate and media level | | | 2243 | | usage indicates SUM of the | | | 2244 | | individual values while | | | 2245 | | multiplexing | | | 2246 | | | | | 2247 | bwtype:RR | Session level usage represents | B | SUM | 2248 | | session aggregate and media level | | | 2249 | | usage indicates SUM of the | | | 2250 | | individual values while | | | 2251 | | multiplexing | | | 2252 | | | | | 2253 +------------+-----------------------------------+-------+----------+ 2255 RFC3556 bwtype Analysis 2257 6.3. RFC3890 - Bandwidth Modifier for SDP 2259 [RFC3890] defines a Session Description Protocol (SDP) Transport 2260 Independent Application Specific Maximum (TIAS) bandwidth modifier 2261 that does not include transport overhead; instead an additional 2262 packet rate attribute is defined. The transport independent bit-rate 2263 value together with the maximum packet rate can then be used to 2264 calculate the real bit-rate over the transport actually used. 2266 +------------------+-----------------------------+-------+----------+ 2267 | Name | Notes | Level | Mux | 2268 | | | | Category | 2269 +------------------+-----------------------------+-------+----------+ 2270 | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL | 2271 | | clearly defined | | | 2272 | | Offer/Answer usage. | | | 2273 | | | | | 2274 | bwtype:maxprate | The usage of TIAS and | B | SPECIAL | 2275 | | maxprate is not well | | | 2276 | | defined under multiplexing | | | 2277 | | | | | 2278 +------------------+-----------------------------+-------+----------+ 2280 RFC3890 bwtype Analysis 2282 The intention of TIAS is that the media level bit-rate is multiplied 2283 with the known per-packet overhead for the selected transport and the 2284 maxprate value to determine the worst case bit-rate from the 2285 transport to more accurately capture the required usage. Summing 2286 TIAS values independently across "m=" lines and multiplying the 2287 computed sum with maxprate and the per-packet overhead would inflate 2288 the value significantly. Instead performing multiplication and 2289 adding the individual values is a more appropriate usage. 2291 7. rtcp-fb Attribute Analysis 2293 This section analyzes rtcp-fb SDP attributes. 2295 7.1. RFC4585 - RTP/AVPF 2297 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 2298 enables receivers to provide, statistically, more immediate feedback 2299 to the senders and thus allows for short-term adaptation and 2300 efficient feedback-based repair mechanisms to be implemented. 2302 +----------+----------------------------+-------+-------------------+ 2303 | Name | Notes | Level | Mux Category | 2304 +----------+----------------------------+-------+-------------------+ 2305 | ack rpsi | The attribute value MUST | M | IDENTICAL-PER-PT | 2306 | | be same for a given codec | | | 2307 | | configuration | | | 2308 | | | | | 2309 | ack app | Feedback parameters MUST | M | SPECIAL | 2310 | | be handled in the app | | | 2311 | | specific way when | | | 2312 | | multiplexed | | | 2313 | | | | | 2314 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2315 | | be same for a given codec | | | 2316 | | configuration | | | 2317 | | | | | 2318 | nack pli | The attribute value MUST | M | IDENTICAL-PER-PT | 2319 | | be same for a given codec | | | 2320 | | configuration | | | 2321 | | | | | 2322 | nack sli | The attribute value MUST | M | IDENTICAL-PER-PT | 2323 | | be same for a given codec | | | 2324 | | configuration | | | 2325 | | | | | 2326 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2327 | rpsi | be same for a given codec | | | 2328 | | configuration | | | 2329 | | | | | 2330 | nack app | Feedback parameters MUST | M | SPECIAL | 2331 | | be handled in the app | | | 2332 | | specific way when | | | 2333 | | multiplexed | | | 2334 | | | | | 2335 | trr-int | The attribute value MUST | M | IDENTICAL-PER-PT | 2336 | | be same for a given codec | | | 2337 | | configuration | | | 2338 | | | | | 2339 +----------+----------------------------+-------+-------------------+ 2341 RFC4585 Attribute Analysis 2343 7.2. RFC5104 - Codec Control Messages in AVPF 2345 [RFC5104] specifies a few extensions to the messages defined in the 2346 Audio-Visual Profile with Feedback (AVPF). They are helpful 2347 primarily in conversational multimedia scenarios where centralized 2348 multipoint functionalities are in use. However, some are also usable 2349 in smaller multicast environments and point-to-point calls. 2351 +------+--------------------------------+-------+-------------------+ 2352 | Name | Notes | Level | Mux Category | 2353 +------+--------------------------------+-------+-------------------+ 2354 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2355 | | same for a given codec | | | 2356 | | configuration | | | 2357 | | | | | 2358 +------+--------------------------------+-------+-------------------+ 2360 RFC5104 Attribute Analysis 2362 7.3. RFC6285 - Unicast-Based RAMS 2364 [RFC6285] describes a method using the existing RTP and RTP Control 2365 Protocol (RTCP) machinery that reduces the acquisition delay. In 2366 this method, an auxiliary unicast RTP session carrying the Reference 2367 Information to the receiver precedes or accompanies the multicast 2368 stream. This unicast RTP flow can be transmitted at a faster than 2369 natural bitrate to further accelerate the acquisition. The 2370 motivating use case for this capability is multicast applications 2371 that carry real-time compressed audio and video. 2373 +-------+-------------------------------+-------+-------------------+ 2374 | Name | Notes | Level | Mux Category | 2375 +-------+-------------------------------+-------+-------------------+ 2376 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2377 | rai | same for a given codec | | | 2378 | | configuration | | | 2379 | | | | | 2380 +-------+-------------------------------+-------+-------------------+ 2382 RFC6285 Attribute Analysis 2384 7.4. RFC6679 - ECN for RTP over UDP/IP 2386 [RFC6679] specifies how Explicit Congestion Notification (ECN) can be 2387 used with the Real-time Transport Protocol (RTP) running over UDP, 2388 using the RTP Control Protocol (RTCP) as a feedback mechanism. It 2389 defines a new RTCP Extended Report (XR) block for periodic ECN 2390 feedback, a new RTCP transport feedback message for timely reporting 2391 of congestion events, and a Session Traversal Utilities for NAT 2392 (STUN) extension used in the optional initialization method using 2393 Interactive Connectivity Establishment (ICE). 2395 +------------------+---------------------------+-------+------------+ 2396 | Name | Notes | Level | Mux | 2397 | | | | Category | 2398 +------------------+---------------------------+-------+------------+ 2399 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | 2400 | | the RTP Session level | | | 2401 | | | | | 2402 | nack ecn | This attribute enables | M | IDENTICAL | 2403 | | ECN at the RTP session | | | 2404 | | level | | | 2405 | | | | | 2406 +------------------+---------------------------+-------+------------+ 2408 RFC6679 Attribute Analysis 2410 7.5. RFC6642 - Third-Party Loss Report 2412 In a large RTP session using the RTP Control Protocol (RTCP) feedback 2413 mechanism defined in [RFC4585], a feedback target may experience 2414 transient overload if some event causes a large number of receivers 2415 to send feedback at once. This overload is usually avoided by 2416 ensuring that feedback reports are forwarded to all receivers, 2417 allowing them to avoid sending duplicate feedback reports. However, 2418 there are cases where it is not recommended to forward feedback 2419 reports, and this may allow feedback implosion. [RFC6642] memo 2420 discusses these cases and defines a new RTCP Third-Party Loss Report 2421 that can be used to inform receivers that the feedback target is 2422 aware of some loss event, allowing them to suppress feedback. 2423 Associated Session Description Protocol (SDP) signaling is also 2424 defined. 2426 +--------+------------------------------+-------+-------------------+ 2427 | Name | Notes | Level | Mux Category | 2428 +--------+------------------------------+-------+-------------------+ 2429 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2430 | tllei | same for a given codec | | | 2431 | | configuration | | | 2432 | | | | | 2433 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2434 | pslei | same for a given codec | | | 2435 | | configuration | | | 2436 | | | | | 2437 +--------+------------------------------+-------+-------------------+ 2439 RFC6642 Attribute Analysis 2441 7.6. RFC5104 - Codec Control Messages in AVPF 2443 [RFC5104] specifies a few extensions to the messages defined in the 2444 Audio-Visual Profile with Feedback (AVPF). They are helpful 2445 primarily in conversational multimedia scenarios where centralized 2446 multipoint functionalities are in use. However, some are also usable 2447 in smaller multicast environments and point-to-point calls. 2449 +--------+------------------------------+-------+-------------------+ 2450 | Name | Notes | Level | Mux Category | 2451 +--------+------------------------------+-------+-------------------+ 2452 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2453 | fir | same for a given codec | | | 2454 | | configuration | | | 2455 | | | | | 2456 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2457 | tmmbr | same for a given codec | | | 2458 | | configuration | | | 2459 | | | | | 2460 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2461 | tstr | same for a given codec | | | 2462 | | configuration | | | 2463 | | | | | 2464 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2465 | vbcm | same for a given codec | | | 2466 | | configuration | | | 2467 | | | | | 2468 +--------+------------------------------+-------+-------------------+ 2470 RFC5104 Attribute Analysis 2472 8. group Attribute Analysis 2474 This section analyzes SDP "group" attribute semantics. 2476 8.1. RFC5888 - SDP Grouping Framework 2478 [RFC5888] defines a framework to group "m" lines in the Session 2479 Description Protocol (SDP) for different purposes. 2481 +------------+---------------+-------+--------------+ 2482 | Name | Notes | Level | Mux Category | 2483 +------------+---------------+-------+--------------+ 2484 | group:LS | Not Impacted | S | NORMAL | 2485 | | | | | 2486 | group:FID | Not Impacted | S | NORMAL | 2487 | | | | | 2488 +------------+---------------+-------+--------------+ 2490 RFC5888 Attribute Analysis 2492 8.2. RFC3524 - Mapping Media Streams to Resource Reservation Flows 2494 [RFC3524] defines an extension to the Session Description Protocol 2495 (SDP) grouping framework. It allows requesting a group of media 2496 streams to be mapped into a single resource reservation flow. The 2497 SDP syntax needed is defined, as well as a new "semantics" attribute 2498 called Single Reservation Flow (SRF). 2500 +------------+---------------+-------+--------------+ 2501 | Name | Notes | Level | Mux Category | 2502 +------------+---------------+-------+--------------+ 2503 | group:SRF | Not Impacted | S | NORMAL | 2504 | | | | | 2505 +------------+---------------+-------+--------------+ 2507 RFC3524 Attribute Analysis 2509 8.3. RFC4091 - ANAT Semantics 2511 [RFC4091] defines the Alternative Network Address Types (ANAT) 2512 semantics for the Session Description Protocol (SDP) grouping 2513 framework. The ANAT semantics allow alternative types of network 2514 addresses to establish a particular media stream. 2516 +-------------+---------------------------+-------+-----------------+ 2517 | Name | Notes | Level | Mux Category | 2518 +-------------+---------------------------+-------+-----------------+ 2519 | group:ANAT | ANAT semantics is | S | NOT RECOMMENDED | 2520 | | obseleted | | | 2521 | | | | | 2522 +-------------+---------------------------+-------+-----------------+ 2524 RFC4091 Attribute Analysis 2526 8.4. RFC5956 - FEC Grouping Semantics in SDP 2528 [RFC5956] defines the semantics for grouping the associated source 2529 and FEC-based (Forward Error Correction) repair flows in the Session 2530 Description Protocol (SDP). The semantics defined in the document 2531 are to be used with the SDP Grouping Framework (RFC 5888). These 2532 semantics allow the description of grouping relationships between the 2533 source and repair flows when one or more source and/or repair flows 2534 are associated in the same group, and they provide support for 2535 additive repair flows. SSRC-level (Synchronization Source) grouping 2536 semantics are also defined in this document for Real-time Transport 2537 Protocol (RTP) streams using SSRC multiplexing. 2539 +---------------+---------------+-------+--------------+ 2540 | Name | Notes | Level | Mux Category | 2541 +---------------+---------------+-------+--------------+ 2542 | group:FEC-FR | Not Impacted | S | NORMAL | 2543 | | | | | 2544 +---------------+---------------+-------+--------------+ 2546 RFC5956 Attribute Analysis 2548 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP 2550 [RFC5583] defines semantics that allow for signaling the decoding 2551 dependency of different media descriptions with the same media type 2552 in the Session Description Protocol (SDP). This is required, for 2553 example, if media data is separated and transported in different 2554 network streams as a result of the use of a layered or multiple 2555 descriptive media coding process. 2557 +--------+------------------------------+-------+-------------------+ 2558 | Name | Notes | Level | Mux Category | 2559 +--------+------------------------------+-------+-------------------+ 2560 | depend | The attribute value MUST be | M | IDENTICAL-PER-PT | 2561 | lay | same for a given codec | | | 2562 | | configuration | | | 2563 | | | | | 2564 | depend | The attribute value MUST be | M | IDENTICAL-PER-PT | 2565 | mdc | same for a given codec | | | 2566 | | configuration | | | 2567 | | | | | 2568 +--------+------------------------------+-------+-------------------+ 2570 RFC5583 Attribute Analysis 2572 8.6. RFC7104 - Duplication Grouping Semantics in the SDP 2574 [RFC7104] defines the semantics for grouping redundant streams in the 2575 Session Description Protocol (SDP). The semantics defined in this 2576 document are to be used with the SDP Grouping Framework. Grouping 2577 semantics at the Synchronization Source (SSRC) level are also defined 2578 in this document for RTP streams using SSRC multiplexing. 2580 +------------+---------------+-------+--------------+ 2581 | Name | Notes | Level | Mux Category | 2582 +------------+---------------+-------+--------------+ 2583 | group:DUP | Not Impacted | S | NORMAL | 2584 | | | | | 2585 +------------+---------------+-------+--------------+ 2587 RFC7104 Attribute Analysis 2589 9. ssrc-group Attribute Analysis 2591 This section analyzes "ssrc-group" semantics. 2593 9.1. RFC5576 - Source-Specific SDP Attributes 2595 [RFC5576] defines a mechanism to describe RTP media sources, which 2596 are identified by their synchronization source (SSRC) identifiers, in 2597 SDP, to associate attributes with these sources, and to express 2598 relationships among sources. It also defines several source-level 2599 attributes that can be used to describe properties of media sources. 2601 +-------------------+---------------+-------+--------------+ 2602 | Name | Notes | Level | Mux Category | 2603 +-------------------+---------------+-------+--------------+ 2604 | ssrc-group:FID | Not Impacted | SR | NORMAL | 2605 | | | | | 2606 | ssrc-group:FEC | Not Impacted | SR | NORMAL | 2607 | | | | | 2608 | ssrc-groupFEC-FR | Not Impacted | SR | NORMAL | 2609 | | | | | 2610 +-------------------+---------------+-------+--------------+ 2612 RFC5576 Attribute Analysis 2614 9.2. RFC7104 - Duplication Grouping Semantics in the SDP 2616 [RFC7104] defines the semantics for grouping redundant streams in the 2617 Session Description Protocol (SDP). The semantics defined in this 2618 document are to be used with the SDP Grouping Framework. Grouping 2619 semantics at the Synchronization Source (SSRC) level are also defined 2620 in this document for RTP streams using SSRC multiplexing. 2622 +-----------------+---------------+-------+--------------+ 2623 | Name | Notes | Level | Mux Category | 2624 +-----------------+---------------+-------+--------------+ 2625 | ssrc-group:DUP | Not Impacted | SR | NORMAL | 2626 | | | | | 2627 +-----------------+---------------+-------+--------------+ 2629 RFC7104 Attribute Analysis 2631 10. QoS Mechanism Token Analysis 2633 This section analyzes QoS tokes specified with SDP. 2635 10.1. RFC5432 - QoS Mechanism Selection in SDP 2637 [RFC5432] defines procedures to negotiate QOS mechanisms using the 2638 Session Description Protocol (SDP) offer/answer model. 2640 +-------+---------------+-------+--------------+ 2641 | Name | Notes | Level | Mux Category | 2642 +-------+---------------+-------+--------------+ 2643 | rsvp | Not Impacted | B | NORMAL | 2644 | | | | | 2645 | nsis | Not Impacted | B | NORMAL | 2646 | | | | | 2647 +-------+---------------+-------+--------------+ 2649 RFC5432 Attribute Analysis 2651 11. k= Attribute Analysis 2653 11.1. RFC4566 SDP: Session Description Protocol 2655 [RFC4566] defines the Session Description Protocol (SDP) that is 2656 intended for describing multimedia sessions for the purposes of 2657 session announcement, session invitation, and other forms of 2658 multimedia session initiation. 2660 +------+------------------------------------+-------+---------------+ 2661 | Name | Notes | Level | Mux Category | 2662 +------+------------------------------------+-------+---------------+ 2663 | k= | It is NOT recommended to use this | S | NOT | 2664 | | attribute | | RECOMMENDED | 2665 | | | | | 2666 +------+------------------------------------+-------+---------------+ 2668 RFC4566 Attribute Analysis 2670 12. content Attribute Analysis 2672 12.1. RFC4796 2674 [RFC4796] defines a new Session Description Protocol (SDP) media- 2675 level attribute, 'content'. The 'content' attribute defines the 2676 content of the media stream to a more detailed level than the media 2677 description line. The sender of an SDP session description can 2678 attach the 'content' attribute to one or more media streams. The 2679 receiving application can then treat each media stream differently 2680 (e.g., show it on a big or small screen) based on its content. 2682 +------------------+---------------+-------+--------------+ 2683 | Name | Notes | Level | Mux Category | 2684 +------------------+---------------+-------+--------------+ 2685 | content:slides | Not Impacted | M | NORMAL | 2686 | | | | | 2687 | content:speaker | Not Impacted | M | NORMAL | 2688 | | | | | 2689 | content:main | Not Impacted | M | NORMAL | 2690 | | | | | 2691 | content:sl | Not Impacted | M | NORMAL | 2692 | | | | | 2693 | content:alt | Not Impacted | M | NORMAL | 2694 | | | | | 2695 +------------------+---------------+-------+--------------+ 2697 RFC4796 Attribute Analysis 2699 13. Payload Formats 2701 13.1. RFC5109 - RTP Payload Format for Generic FEC 2703 [RFC5109] describes a payload format for generic Forward Error 2704 Correction (FEC) for media data encapsulated in RTP. It is based on 2705 the exclusive-or (parity) operation. The payload format allows end 2706 systems to apply protection using various protection lengths and 2707 levels, in addition to using various protection group sizes to adapt 2708 to different media and channel characteristics. It enables complete 2709 recovery of the protected packets or partial recovery of the critical 2710 parts of the payload depending on the packet loss situation. 2712 +---------------------+----------------------+-------+--------------+ 2713 | Name | Notes | Level | Mux Category | 2714 +---------------------+----------------------+-------+--------------+ 2715 | audio/ulpfec | Not recommended for | M | NOT | 2716 | | multiplexing due to | | RECOMMENDED | 2717 | | reuse of SSRCs | | | 2718 | | | | | 2719 | video/ulpfec | Not recommended for | M | NOT | 2720 | | multiplexing due to | | RECOMMENDED | 2721 | | reuse of SSRCs | | | 2722 | | | | | 2723 | text/ulpfec | Not recommended for | M | NOT | 2724 | | multiplexing due to | | RECOMMENDED | 2725 | | reuse of SSRCs | | | 2726 | | | | | 2727 | application/ulpfec | Not recommended for | M | NOT | 2728 | | multiplexing due to | | RECOMMENDED | 2729 | | reuse of SSRCs | | | 2730 | | | | | 2731 +---------------------+----------------------+-------+--------------+ 2733 RFC5109 Payload Format Analysis 2735 14. Multiplexing Considerations for Encapsulating Attributes 2737 This sections deals with recommendations for defining the 2738 multiplexing characteristics of the SDP attributes that encapsulate 2739 other SDP attributes/parameters. Such attributes as of today, for 2740 example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of 2741 a generic framework for indicating and negotiating transport, media 2742 and media format related capabilities in the SDP. 2744 The behavior of such attributes under multiplexing is in turn defined 2745 by the multiplexing behavior of the attributes they encapsulate which 2746 are made known once the Offer/Answer negotiation process is 2747 completed. 2749 14.1. RFC3407 - cpar Attribute Analysis 2751 [RFC3407] capability parameter attribute (a=cpar) encapsulates b= 2752 (bandwidth) or an a= attribute. For bandwidth attribute 2753 encapsulation, the category SUM is inherited. For the case of a= 2754 attribute, the category corresponding to the SDP attribute being 2755 encapsulated is inherited. 2757 v=0 2758 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2759 s= 2760 c=IN IP4 host.atlanta.example.com 2761 t=0 0 2762 m=video 3456 RTP/AVP 100 2763 a=rtpmap:100 VP8/90000 2764 a=sqn: 0 2765 a=cdsc: 1 video RTP/AVP 100 2766 a=cpar: a=rtcp-mux 2767 m=video 3456 RTP/AVP 101 2768 a=rtpmap:101 VP8/90000 2769 a=fmtp:100 max-fr=15;max-fs=1200 2770 a=cdsc: 2 video RTP/AVP 101 2771 a=cpar: a=rtcp-mux 2773 In the above example,the category IDENTICAL is inherited for the cpar 2774 encapsulated rtcp-mux attribute. 2776 14.2. RFC5939 Analysis 2778 [RFC5939] defines a general SDP capability negotiation framework. It 2779 also specifies how to provide transport protocols and SDP attributes 2780 as capabilities and negotiate them using the framework. 2782 For this purpose, [RFC5939] defines the following 2784 o A set of capabilities for the session and its associated media 2785 stream components, supported by each side. The attribute 2786 ("a=acap") defines how to list an attribute name and its 2787 associated value (if any) as a capability. The attribute 2788 ("a=tcap") defines how to list transport protocols (e.g., "RTP/ 2789 AVP") as capabilities. 2791 o A set of potential configurations ("a=pcfg") provided by the 2792 offerer to indicate whcich combination of those capabilities can 2793 be used for the session and its associated media stream 2794 components. Potential configurations are not ready for use until 2795 fully negotiated. They provide an alternative that MAY be used, 2796 subject to SDP capability negotiation procedures. In particular 2797 the answerer MAY choose one of the potential configurations for 2798 use as part of the current Offer/Answer exchange. 2800 o An actual configuration ("a=acfg") for the session and its 2801 associated media stream components. The actual configuration 2802 identifies the potential configuration that was negotiated for 2803 use. Use of an actual configuration does not require any further 2804 negotiation. 2806 o A negotiation process that takes the current actual and the set of 2807 potential configurations (combinations of capabilities) as input 2808 and provides the negotiated actual configurations as output. In 2809 [RFC5939] the negotiation process is done independently for each 2810 media description. 2812 14.2.1. Recommendation - Procedures for Potential Configuration Pairing 2814 This section provides recommendations for entities generating and 2815 processing SDP under the generic capability negotiation framework as 2816 defined in [RFC5939] under the context of media stream multiplexing. 2818 These recommendations are provided for the purposes of enabling the 2819 Offerer to make sure that the generated potential configurations 2820 between the multiplexed streams can (easily) be negotiated to be 2821 consistent between those streams. In particular, the procedures aim 2822 to simplify Answerer's procedure to choose potential configurations 2823 that are consistent across all the multiplexed media descriptions. 2825 A potential configuration selects a set of attributes and parameters 2826 that become part of the media description when negotiated. When 2827 multiplexing media descriptions with potential configurations 2828 specified, there MAY be a need for coordinating this selection 2829 between multiplexed media descriptions ensuring right multiplexing 2830 behavior. 2832 Although it is possible to analyze the various potential 2833 configurations in multiplexed media descriptions to find combinations 2834 that satisfy such constraints, it can quickly become complicated to 2835 do so. 2837 The procedures defined in [RFC5939] state that each potential 2838 configuration in the SDP has a unique configuration number, however 2839 the scope of uniqueness is limited to each media description. To 2840 make it simple for the answerer to chose valid combinations of 2841 potential configurations across media descriptions in a given bundle 2842 group, we provide a simple rule for constructing potential 2843 configurations 2845 o Let m-bundle be the set of media descriptions that form a given 2846 bundle . 2848 o Let m-bundle-pcfg be the set of media descriptions in m-bundle 2849 that include one or more potential configurations. 2851 o Each media description in m-bundle-pcfg MUST have at least one 2852 potential configuration with the same configuration number (e.g. 2853 "1"). 2855 o For each potential configuration with configuration number x in m- 2856 bundle-pcfg, the offerer MUST ensure that if the answerer chooses 2857 configuration number x in each of the media descriptions in m- 2858 bundle-pcfg, then the resulting SDP will have all multiplexing 2859 constraints satisfied for those media descriptions. 2861 o Since it is nearly impossible to define a generic mechanism for 2862 various capability extensions, this document does't provide 2863 procedures for dealing with the capability extension attributes. 2864 However, Section 14.3 provide analysis of media capability 2865 extension attributes as defined in [RFC6871]. 2867 The above allows the answerer to easily find multiplexing compatible 2868 combinations of potential configurations:- The answerer simply choses 2869 a potential configuration (number) that is present in all of the 2870 media descriptions with potential configurations in the bundle. 2872 Note that it is still possible for the offerer to provide additional 2873 potential configurations with independent configuration numbers. The 2874 answerer will have to perform more complicated analysis to determine 2875 valid multiplexed combinations of those. 2877 14.2.1.1. Example: Transport Capability Multiplexing 2879 v=0 2880 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2881 s= 2882 c=IN IP4 host.atlanta.example.com 2883 t=0 0 2884 a=tcap:1 RTP/SAVPF 2885 a=tcap:2 RTP/SAVP 2886 a=group:BUNDLE audio video 2887 m= audio 2888 a=mid:audio 2889 a=pcfg:1 t=1 2890 a=pcfg:2 2891 m= video 2892 a=mid:video 2893 a=pcfg:1 t=1 2894 a=pcfg:2 t=2 2896 In the example above, the potential configurations that offer 2897 transport protocol capability of RTP/SAVPF has the same configuration 2898 number "1" in both the audio and video media descriptions. 2900 14.2.1.2. Example: Attribute Capability Multiplexing 2902 v=0 2903 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2904 s= 2905 c=IN IP4 host.atlanta.example.com 2906 t=0 0 2907 a=acap:1 a=rtcp-mux 2908 a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80 2909 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 2910 a=group:BUNDLE audio video 2911 m= audio 49172 RTP/AVP 99 2912 a=mid:audio 2913 a=pcfg:1 a=1 2914 a=pcfg:2 2915 m= video 560024 RTP/AVP 100 2916 a=mid:video 2917 a=pcfg:1 a=1 2918 a=pcfg:2 a=2 2920 In the example above, the potential configuration number "1" is 2921 repeated while referring to attribute capability a=rtcp-mux, since 2922 the behavior is IDENTICAL for the attribute a=rtcp-mux under 2923 multiplexing. 2925 14.3. RFC6871 Analysis 2927 [RFC6871] extends capability negotiation framework described in 2928 [RFC5939] by defining media capabilities that can be used to indicate 2929 and negotiate media types and their associated format parameters. It 2930 also allows indication of latent configurations and session 2931 capabilities. 2933 14.3.1. Recommendation: Dealing with Payload Type Numbers 2935 [RFC6871] defines a new payload type ("pt") parameter to be used with 2936 the potential, actual and latent configuration parameters. The 2937 parameter associates RTP payload type numbers with the referenced 2938 RTP-based media format capabilities ("a=rmcap") defined in [RFC6871] 2939 and is appropriate only when the transport protocol uses RTP. This 2940 means that the same payload type number can be assigned as part of 2941 potential or actual configurations in different media descriptions in 2942 a bundle. There are rules for the usage of identical Payload Type 2943 values across multiplexed "m=" lines as described in 2944 [I-D.ietf-mmusic-sdp-bundle-negotiation], which MUST be followed here 2945 as well. As described in Section 14.2.1, the use of identical 2946 configuration numbers for compatible configurations in different 2947 media descriptions that are part of the bundle provides a way to 2948 ensure that the answerer can easily pick compatible configurations 2949 here as well. 2951 14.3.1.1. Example: Attribute Capability Under Shared Payload Type 2953 The attributes (a=rmcap, a=mfcap) follow the above recommendations 2954 under multiplexing. 2956 v=0 2957 o=- 25678 753849 IN IP4 192.0.2.1 2958 s= 2959 c=IN IP4 192.0.2.1 2960 t=0 0 2961 a=creq:med-v0 2962 m=audio 54322 RTP/AVP 96 2963 a=rtpmap:96 AMR-WB/16000/1 2964 a=fmtp:96 mode-change-capability=1; max-red=220; 2965 mode-set=0,2,4,7 2966 a=rmcap:1,3 audio AMR-WB/16000/1 2967 a=rmcap:2 audio AMR/8000/1 2968 a=mfcap:1,2 mode-change-capability=1 2969 a=mfcap:3 mode-change-capability=2 2970 a=pcfg:1 m=1 pt=1:96 2971 a=pcfg:2 m=2 pt=2:97 2972 a=pcfg:3 m=3 pt=3:98 2973 m=audio 54322 RTP/AVP 96 2974 a=rtpmap:96 AMR-WB/16000/1 2975 a=fmtp:96 mode-change-capability=1; max-red=220; 2976 mode-set=0,2,4,7 2977 a=rmcap:4 audio AMR/8000/1 2978 a=rmcap:5 audio OPUS/48000/2 2979 a=mfcap:5 minptime=40 2980 a=mfcap:4 mode-change-capability=1 2981 a=pcfg:1 m=4 pt=4:97 2982 a=pcfg:4 m=5 pt=5:101 2984 In the example above, the potential configuration number "1" is 2985 repeated when referring to media and media format capability used for 2986 the Payload Type 97. This implies that both the media capability 2 2987 and 4 along with their media format capabilities MUST refer to the 2988 same codec configuration, as per the definition of IDENTICAL-PER-PT. 2990 14.3.2. Recommendation: Dealing with Latent Configurations 2992 [RFC6871] adds the notion of a latent configurations, which provides 2993 configuration information that may be used to guide a subsequent 2994 offer/exchange, e.g. by adding another media stream or use 2995 alternative codec combinations not currently offered. Latent 2996 configurations have configuration numbers which cannot overlap with 2997 the potential configuration numbers [RFC6871]. Supported 2998 combinations of potential and latent configurations are indicated by 2999 use of the "a=sescap" attribute, however use of this attribute is not 3000 recommended with multiplexed media, since it requires the use of 3001 unique configuration numbers across the SDP. Taken together, this 3002 means there is no well-defined way to indicate supported combinations 3003 of latent configurations, or combinations of latent and potential 3004 configurations with multiplexed media. It is still allowed to use 3005 the latent configuration attribute, however the limitations above 3006 will apply. To determine valid combinations, actual negotiation will 3007 have to be attempted subsequently instead. 3009 15. IANA Considerations 3011 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this 3012 document.] 3014 The IANA is requested to add a new column named "Mux Category" to 3015 several of the subregistries in the "Session Description Protocol 3016 (SDP) Parameters" registry. Section 15.1 defines a new subregistry 3017 for identifying the initial registrations for various multiplexing 3018 categories applicable, as proposed in this document. 3020 The tables in Section 15.2 identify name of an entry in the existing 3021 subregistry and specify the value to put in the new "Mux Category" 3022 column of the associated IANA registry. Any entries in the existing 3023 tables that do not have a value for the "Mux Category" specified in 3024 this RFC will get a value of "TBD". Future specifications can change 3025 the "TBD" entries to the correct value. 3027 15.1. New 'Multiplexing Categories' subregistry 3029 A new sub-registry needs to be defined called the "Multiplexing 3030 Categories", with the following registrations created initially: 3031 "NORMAL", "NOT RECOMMENDED", "IDENTICAL", "TRANSPORT", "SUM", 3032 "INHERIT", "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this 3033 document. 3035 Initial value registration for "Multiplexing Categories". 3037 +-------------------------+-----------+ 3038 | Multiplexing Categories | Reference | 3039 +-------------------------+-----------+ 3040 | NORMAL | RFCXXXX | 3041 | NOT RECOMMENDED | RFCXXXX | 3042 | IDENTICAL | RFCXXXX | 3043 | TRANSPORT | RFCXXXX | 3044 | SUM | RFCXXXX | 3045 | INHERIT | RFCXXXX | 3046 | IDENTICAL-PER-PT | RFCXXXX | 3047 | SPECIAL | RFCXXXX | 3048 | TBD | RFCXXXX | 3049 +-------------------------+-----------+ 3051 Further entries may be registered on a first-come first-serve basis. 3052 Each registration needs to indicate the multiplexing category value 3053 to be added to the "Multiplexing Categories" subregistry as defined 3054 in this section. 3056 Such a registration MUST also indicate the applicability of the newly 3057 defined multiplexing category value to various subregistries defined 3058 at "Session Description Protocol (SDP) Parameters". 3060 The general registration procedures of [RFC4566] apply. 3062 15.2. 'Mux Category' column for subregistries 3064 Each sub-section identifies a subregistry in the "Session Description 3065 Protocol (SDP) Parameters" registry. The tables list the column that 3066 identifies the SDP attribute name/Token/Value from the corresponding 3067 subregistries and the values to be used for the new "Mux Category" 3068 column to be added. 3070 15.2.1. Table: SDP bwtype 3072 The following values are to be added to the 'SDP bwtype' subregistry 3073 in the "Session Description Protocol (SDP) Parameters" registry. The 3074 references should be updated to point at this RFC as well as the 3075 previous references. 3077 +----------+--------------+ 3078 | SDP Name | Mux Category | 3079 +----------+--------------+ 3080 | CT | NORMAL | 3081 | AS | SUM | 3082 | RS | SUM | 3083 | RR | SUM | 3084 | TIAS | SPECIAL | 3085 +----------+--------------+ 3087 15.2.2. Table: att-field (session level) 3089 The following values are to be added to the "att-field (session 3090 level)" subregistry in the "Session Description Protocol (SDP) 3091 Parameters" registry. The references should be updated to point at 3092 this RFC as well as the previous references. 3094 +---------------------+------------------+ 3095 | SDP Name | Mux Category | 3096 +---------------------+------------------+ 3097 | cat | NORMAL | 3098 | keywds | NORMAL | 3099 | type | NORMAL | 3100 | type:broadcast | NORMAL | 3101 | type:H332 | NORMAL | 3102 | type:meeting | NORMAL | 3103 | type:moderated | NORMAL | 3104 | type:test | NORMAL | 3105 | charset | NORMAL | 3106 | charset:iso8895-1 | NORMAL | 3107 | tool | NORMAL | 3108 | ipbcp | SPECIAL | 3109 | group | NORMAL | 3110 | ice-lite | NORMAL | 3111 | ice-options | NORMAL | 3112 | bcastversion | NORMAL | 3113 | 3GPP-Integrity-Key | NOT RECOMMENDED | 3114 | 3GPP-SDP-Auth | NOT RECOMMENDED | 3115 | alt-group | NOT RECOMMENDED | 3116 | PSCid | NORMAL | 3117 | bc_service | NORMAL | 3118 | bc_program | NORMAL | 3119 | bc_service_package | NORMAL | 3120 | sescap | NOT RECOMMENDED | 3121 | rtsp-ice-d-m | NOT RECOMMENDED | 3122 +---------------------+------------------+ 3124 15.2.3. Table: att-field (both session and media level) 3126 The following values are to be added to the "att-field (both session 3127 and media level)" subregistry in the "Session Description Protocol 3128 (SDP) Parameters" registry. The references should be updated to 3129 point at this RFC as well as the previous references. 3131 +-------------------------+-------------------+ 3132 | SDP Name | Mux Category | 3133 +-------------------------+-------------------+ 3134 | recvonly | NORMAL | 3135 | sendrecv | NORMAL | 3136 | sendonly | NORMAL | 3137 | sdplang | NORMAL | 3138 | lang | NORMAL | 3139 | h248item | SPECIAL | 3140 | sqn | NORMAL | 3141 | cdsc | NORMAL | 3142 | cpar | INHERIT | 3143 | cparmin | SPECIAL | 3144 | cparmax | SPECIAL | 3145 | rtcp-xr | NORMAL | 3146 | maxprate | SPECIAL | 3147 | setup | IDENTICAL | 3148 | connection | IDENTICAL | 3149 | key-mgmt | IDENTICAL | 3150 | source-filter | IDENTICAL | 3151 | inactive | NORMAL | 3152 | fingerprint | TRANSPORT | 3153 | flute-tsi | TBD | 3154 | flute-ch | TBD | 3155 | FEC-declaration | TBD | 3156 | FEC-OTI-extension | TBD | 3157 | content-desc | TBD | 3158 | ice-pwd | TRANSPORT | 3159 | ice-ufrag | TRANSPORT | 3160 | stkmstream | NORMAL | 3161 | extmap | SPECIAL | 3162 | qos-mech-send | NORMAL | 3163 | qos-mech-recv | NORMAL | 3164 | csup | NORMAL | 3165 | creq | NORMAL | 3166 | acap | INHERIT | 3167 | tcap | INHERIT | 3168 | 3GPP-QoE-Metrics | NOT RECOMMENDED | 3169 | 3GPP-Asset-Information | NOT RECOMMENDED | 3170 | mbms-mode | NOT RECOMMENDED | 3171 | mbms-repair | NOT RECOMMENDED | 3172 | ike-setup | IDENTICAL | 3173 | psk-fingerprint | IDENTICAL | 3174 | multicast-rtcp | IDENTICAL | 3175 | rmcap | IDENTICAL-PER-PT | 3176 | omcap | NORMAL | 3177 | mfcap | IDENTICAL-PER-PT | 3178 | mscap | INHERIT | 3179 | 3gpp.iut.replication | TBD | 3180 | bcap | INHERIT | 3181 | ccap | IDENTICAL | 3182 | icap | NORMAL | 3183 | 3gpp_sync_info | NORMAL | 3184 | 3gpp_MaxRecvSDUSize | NORMAL | 3185 | etag | NOT RECOMMENDED | 3186 | duplication-delay | NORMAL | 3187 | range | NOT RECOMMENDED | 3188 | control | NOT RECOMMENDED | 3189 | mtag | NOT RECOMMENDED | 3190 | ts-refclk | NORMAL | 3191 | mediaclk | NORMAL | 3192 | calgextmap | NORMAL | 3193 +-------------------------+-------------------+ 3195 15.2.4. Table: att-field (media level only) 3197 The following values are to be added to the "att-field (media level 3198 only)" registry in the "Session Description Protocol (SDP) 3199 Parameters" registry. The references should be updated to point at 3200 this RFC as well as the previous references. 3202 +---------------------------+-------------------+ 3203 | SDP Name | Mux Category | 3204 +---------------------------+-------------------+ 3205 | ptime | IDENTICAL-PER-PT | 3206 | orient | NORMAL | 3207 | orient:portrait | NORMAL | 3208 | orient:landscape | NORMAL | 3209 | orient:seascape | NORMAL | 3210 | framerate | IDENTICAL-PER-PT | 3211 | quality | NORMAL | 3212 | rtpmap | IDENTICAL-PER-PT | 3213 | fmtp | IDENTICAL-PER-PT | 3214 | rtpred1 | NOT RECOMMENDED | 3215 | rtpred2 | NOT RECOMMENDED | 3216 | T38FaxVersion | NORMAL | 3217 | T38MaxBitRate | NORMAL | 3218 | T38FaxFillBitRemoval | NORMAL | 3219 | T38FaxTranscodingMMR | NORMAL | 3220 | T38FaxTranscodingJBIG | NORMAL | 3221 | T38FaxRateManagement | NORMAL | 3222 | T38FaxMaxBuffer | NORMAL | 3223 | T38FaxMaxDatagram | NORMAL | 3224 | T38FaxUdpEC | NORMAL | 3225 | maxptime | IDENTICAL-PER-PT | 3226 | des | NOT RECOMMENDED | 3227 | curr | NOT RECOMMENDED | 3228 | conf | NOT RECOMMENDED | 3229 | mid | NORMAL | 3230 | rtcp | TRANSPORT | 3231 | rtcp-fb | IDENTICAL-PER-PT | 3232 | label | NORMAL | 3233 | T38VendorInfo | NORMAL | 3234 | crypto | TRANSPORT | 3235 | eecid | NOT RECOMMENDED | 3236 | aalType | NOT RECOMMENDED | 3237 | capability | NOT RECOMMENDED | 3238 | qosClass | NOT RECOMMENDED | 3239 | bcob | NOT RECOMMENDED | 3240 | stc | NOT RECOMMENDED | 3241 | upcc | NOT RECOMMENDED | 3242 | atmQOSparms | NOT RECOMMENDED | 3243 | atmTrfcDesc | NOT RECOMMENDED | 3244 | abrParms | NOT RECOMMENDED | 3245 | abrSetup | NOT RECOMMENDED | 3246 | bearerType | NOT RECOMMENDED | 3247 | lij | NOT RECOMMENDED | 3248 | anycast | NOT RECOMMENDED | 3249 | cache | NOT RECOMMENDED | 3250 | bearerSigIE | NOT RECOMMENDED | 3251 | aalApp | NOT RECOMMENDED | 3252 | cbrRate | NOT RECOMMENDED | 3253 | sbc | NOT RECOMMENDED | 3254 | clkrec | NOT RECOMMENDED | 3255 | fec | NOT RECOMMENDED | 3256 | prtfl | NOT RECOMMENDED | 3257 | structure | NOT RECOMMENDED | 3258 | cpsSDUsize | NOT RECOMMENDED | 3259 | all2CPS | NOT RECOMMENDED | 3260 | all2CPSSDUrate | NOT RECOMMENDED | 3261 | aal2sscs3661unassured | NOT RECOMMENDED | 3262 | aal2sscs3661assured | NOT RECOMMENDED | 3263 | aal2sscs3662 | NOT RECOMMENDED | 3264 | aal5sscop | NOT RECOMMENDED | 3265 | atmmap | NOT RECOMMENDED | 3266 | silenceSupp | NOT RECOMMENDED | 3267 | ecan | NOT RECOMMENDED | 3268 | gc | NOT RECOMMENDED | 3269 | profileDesc | NOT RECOMMENDED | 3270 | vsel | NOT RECOMMENDED | 3271 | dsel | NOT RECOMMENDED | 3272 | fsel | NOT RECOMMENDED | 3273 | onewaySel | NOT RECOMMENDED | 3274 | codecConfig | NOT RECOMMENDED | 3275 | isup_usi | NOT RECOMMENDED | 3276 | uiLayer1_Prot | NOT RECOMMENDED | 3277 | chain | NOT RECOMMENDED | 3278 | floorctrl | IDENTICAL | 3279 | confid | NORMAL | 3280 | userid | NORMAL | 3281 | floorid | NORMAL | 3282 | FEC | NORMAL | 3283 | accept-types | NORMAL | 3284 | accept-wrapped-types | NORMAL | 3285 | max-size | NORMAL | 3286 | path | NORMAL | 3287 | dccp-service-code | NOT RECOMMENDED | 3288 | rtcp-mux | IDENTICAL | 3289 | candidate | TRANSPORT | 3290 | ice-mismatch | NORMAL | 3291 | remote-candidates | TRANSPORT | 3292 | SRTPAuthentication | NORMAL | 3293 | SRTPROCTxRate | NORMAL | 3294 | rtcp-rsize | IDENTICAL | 3295 | file-selector | NORMAL | 3296 | file-transfer-id | NORMAL | 3297 | file-disposition | NORMAL | 3298 | file-date | NORMAL | 3299 | file-icon | NORMAL | 3300 | file-range | NORMAL | 3301 | depend | IDENTICAL-PER-PT | 3302 | ssrc | NORMAL | 3303 | ssrc-group | NORMAL | 3304 | rtcp-unicast | IDENTICAL | 3305 | pcfg | SPECIAL | 3306 | acfg | SPECIAL | 3307 | zrtp-hash | NOT RECOMMENDED | 3308 | X-predecbufsize | NOT RECOMMENDED | 3309 | X-initpredecbufperiod | NOT RECOMMENDED | 3310 | X-initpostdecbufperiod | NOT RECOMMENDED | 3311 | X-decbyterate | NOT RECOMMENDED | 3312 | 3gpp-videopostdecbufsize | NOT RECOMMENDED | 3313 | framesize | NOT RECOMMENDED | 3314 | 3GPP-SRTP-Config | NOT RECOMMENDED | 3315 | alt | NOT RECOMMENDED | 3316 | alt-default-id | NOT RECOMMENDED | 3317 | 3GPP-Adaption-Support | NOT RECOMMENDED | 3318 | mbms-flowid | NOT RECOMMENDED | 3319 | fec-source-flow | SPECIAL | 3320 | fec-repair-flow | SPECIAL | 3321 | repair-window | SPECIAL | 3322 | rams-updates | NOT RECOMMENDED | 3323 | imageattr | IDENTICAL-PER-PT | 3324 | cfw-id | NORMAL | 3325 | portmapping-req | NOT RECOMMENDED | 3326 | g.3gpp.cat | NORMAL | 3327 | g.3gpp.crs | NORMAL | 3328 | ecn-capable-rtp | IDENTICAL | 3329 | visited-realm | TRANSPORT | 3330 | secondary-realm | TRANSPORT | 3331 | omr-s-cksum | NORMAL | 3332 | omr-m-cksum | NORMAL | 3333 | omr-codecs | NORMAL | 3334 | omr-m-att | NORMAL | 3335 | omr-s-att | NORMAL | 3336 | omr-m-bw | NORMAL | 3337 | omr-s-bw | NORMAL | 3338 | msrp-cema | NORMAL | 3339 | dccp-port | NOT RECOMMENDED | 3340 | resource | NORMAL | 3341 | channel | NORMAL | 3342 | cmid | NORMAL | 3343 | content | NORMAL | 3344 | lcfg | SPECIAL | 3345 | loopback | NORMAL | 3346 | loopback-source | NORMAL | 3347 | loopback-mirror | NORMAL | 3348 | chatroom | TBD | 3349 | altc | TRANSPORT | 3350 | T38FaxMaxIFP | NORMAL | 3351 | T38FaxUdpECDepth | NORMAL | 3352 | T38FaxUdpFECMaxSpan | NORMAL | 3353 | T38ModemType | NORMAL | 3354 | cs-correlation | NORMAL | 3355 | rtcp-idms | NORMAL | 3356 +---------------------------+-------------------+ 3358 15.2.5. Table: att-field (source level) 3360 The following values are to be added to the "att-field (source 3361 level)" registry in the "Session Description Protocol (SDP) 3362 Parameters" registry. The references should be updated to point at 3363 this RFC as well as the previous references. 3365 +----------------+-------------------+ 3366 | SDP Name | Mux Category | 3367 +----------------+-------------------+ 3368 | cname | NORMAL | 3369 | previous-ssrc | NORMAL | 3370 | fmtp | IDENTICAL-PER-PT | 3371 | ts-refclk | NORMAL | 3372 | mediaclk | NORMAL | 3373 +----------------+-------------------+ 3375 15.2.6. Table: content SDP Parameters 3377 The following values are to be added to the "content SDP Parameters" 3378 subregistry in the "Session Description Protocol (SDP) Parameters" 3379 registry. The references should be updated to point at this RFC as 3380 well as the previous references. 3382 +----------+--------------+ 3383 | SDP Name | Mux Category | 3384 +----------+--------------+ 3385 | slides | NORMAL | 3386 | speaker | NORMAL | 3387 | sl | NORMAL | 3388 | main | NORMAL | 3389 | alt | NORMAL | 3390 +----------+--------------+ 3392 15.2.7. Table: Semantics for the 'group' SDP Attribute 3394 The following values are to be added to the "Semantics for the 3395 "group" SDP Attribute" subregistry in the "Session Description 3396 Protocol (SDP) Parameters" registry. The references should be 3397 updated to point at this RFC as well as the previous references. 3399 +---------+------------------+ 3400 | Token | Mux Category | 3401 +---------+------------------+ 3402 | LS | NORMAL | 3403 | FID | NORMAL | 3404 | SRF | NORMAL | 3405 | ANAT | NOT RECOMMENDED | 3406 | FEC | NORMAL | 3407 | FEC-FR | NORMAL | 3408 | CS | NORMAL | 3409 | DDP | NORMAL | 3410 | DUP | NORMAL | 3411 +---------+------------------+ 3413 15.2.8. Table: 'rtcp-fb' Attribute Values 3415 The following values are to be added to the " 'rtcp-fb' Attribute 3416 Values" subregistry in the "Session Description Protocol (SDP) 3417 Parameters" registry. The references should be updated to point at 3418 this RFC as well as the previous references. 3420 +------------+-------------------+ 3421 | Value Name | Mux Category | 3422 +------------+-------------------+ 3423 | ack | IDENTICAL-PER-PT | 3424 | app | SPECIAL | 3425 | ccm | IDENTICAL-PER-PT | 3426 | nack | IDENTICAL-PER-PT | 3427 | trr-int | IDENTICAL-PER-PT | 3428 +------------+-------------------+ 3430 15.2.9. Table: 'ack' and 'nack' Attribute Values 3432 The following values are to be added to the " 'ack' and 'nack' 3433 Attribute Values" subregistry in the "Session Description Protocol 3434 (SDP) Parameters" registry. The references should be updated to 3435 point at this RFC as well as the previous references. 3437 +------------+-------------------+ 3438 | Value Name | Mux Category | 3439 +------------+-------------------+ 3440 | sli | IDENTICAL-PER-PT | 3441 | pli | IDENTICAL-PER-PT | 3442 | rpsi | IDENTICAL-PER-PT | 3443 | app | SPECIAL | 3444 | rai | IDENTICAL-PER-PT | 3445 | tllei | IDENTICAL-PER-PT | 3446 | pslei | IDENTICAL-PER-PT | 3447 | ecn | IDENTICAL | 3448 +------------+-------------------+ 3450 15.2.10. Table: 'depend' SDP Attribute Values 3452 The following values are to be added to the " 'depend' SDP Attribute 3453 Values" subregistry in the "Session Description Protocol (SDP) 3454 Parameters" registry. The references should be updated to point at 3455 this RFC as well as the previous references. 3457 +-------+-------------------+ 3458 | Token | Mux Category | 3459 +-------+-------------------+ 3460 | lay | IDENTICAL-PER-PT | 3461 | mdc | IDENTICAL-PER-PT | 3462 +-------+-------------------+ 3464 15.2.11. Table: 'cs-correlation' Attribute Values 3466 The following values are to be added to the " "cs-correlation" 3467 Attribute Values" subregistry in the "Session Description Protocol 3468 (SDP) Parameters" registry. The references should be updated to 3469 point at this RFC as well as the previous references. 3471 +-----------+--------------+ 3472 | Value | Mux Category | 3473 +-----------+--------------+ 3474 | callerid | NORMAL | 3475 | uuie | NORMAL | 3476 | dtmf | NORMAL | 3477 | external | NORMAL | 3478 +-----------+--------------+ 3480 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 3482 The following values are to be added to the Semantics for the 3483 "Semantics for the "ssrc-group" SDP Attribute" subregistry in the 3484 "Session Description Protocol (SDP) Parameters" registry. The 3485 references should be updated to point at this RFC as well as the 3486 previous references. 3488 +---------+--------------+ 3489 | Token | Mux Category | 3490 +---------+--------------+ 3491 | FID | NORMAL | 3492 | FEC | NORMAL | 3493 | FEC-FR | NORMAL | 3494 | DUP | NORMAL | 3495 +---------+--------------+ 3497 15.2.13. Table: SDP/RTSP key management protocol identifiers 3499 The following values are to be added to the "SDP/RTSP key management 3500 protocol identifiers" subregistry in the "Session Description 3501 Protocol (SDP) Parameters" registry. The references should be 3502 updated to point at this RFC as well as the previous references. 3504 +------------+--------------+ 3505 | Value Name | Mux Category | 3506 +------------+--------------+ 3507 | mikey | IDENTICAL | 3508 +------------+--------------+ 3510 15.2.14. Table: Codec Control Messages 3512 The following values are to be added to the "Codec Control Messages" 3513 subregistry in the "Session Description Protocol (SDP) Parameters" 3514 registry. The references should be updated to point at this RFC as 3515 well as the previous references. 3517 +------------+-------------------+ 3518 | Value Name | Mux Category | 3519 +------------+-------------------+ 3520 | fir | IDENTICAL-PER-PT | 3521 | tmmbr | IDENTICAL-PER-PT | 3522 | tstr | IDENTICAL-PER-PT | 3523 | vbcm | IDENTICAL-PER-PT | 3524 +------------+-------------------+ 3526 15.2.15. Table: QoS Mechanism Tokens 3528 The following values are to be added to the "QoS Mechanism Tokens" 3529 subregistry in the "Session Description Protocol (SDP) Parameters" 3530 registry. The references should be updated to point at this RFC as 3531 well as the previous references. 3533 +---------------+--------------+ 3534 | QoS Mechanism | Mux Category | 3535 +---------------+--------------+ 3536 | rsvp | NORMAL | 3537 | nsis | NORMAL | 3538 +---------------+--------------+ 3540 15.2.16. Table: SDP Capability Negotiation Option Tags 3542 The following values are to be added to the "SDP Capability 3543 Negotiation Option Tags" subregistry in the "Session Description 3544 Protocol (SDP) Parameters" registry. The references should be 3545 updated to point at this RFC as well as the previous references. 3547 +---------------+--------------+ 3548 | QoS Mechanism | Mux Category | 3549 +---------------+--------------+ 3550 | cap-v0 | NORMAL | 3551 | med-v0 | NORMAL | 3552 | bcap-v0 | NORMAL | 3553 | ccap-v0 | NORMAL | 3554 | icap-v0 | NORMAL | 3555 +---------------+--------------+ 3557 15.2.17. Table: Timestamp Reference Clock Source Parameters 3559 The following values are to be added to the "Timestamp Reference 3560 Clock Source Parameters" subregistry in the "Session Description 3561 Protocol (SDP) Parameters" registry. The references should be 3562 updated to point at this RFC as well as the previous references. 3564 +----------+--------------+ 3565 | Name | Mux Category | 3566 +----------+--------------+ 3567 | ntp | NORMAL | 3568 | ptp | NORMAL | 3569 | gps | NORMAL | 3570 | gal | NORMAL | 3571 | glonass | NORMAL | 3572 | local | NORMAL | 3573 | private | NORMAL | 3574 +----------+--------------+ 3576 15.2.18. Table: Media Clock Source Parameters 3578 The following values are to be added to the "Media Clock Source 3579 Parameters" subegistry in the "Session Description Protocol (SDP) 3580 Parameters" registry. The references should be updated to point at 3581 this RFC as well as the previous references. 3583 +-----------+--------------+ 3584 | Name | Mux Category | 3585 +-----------+--------------+ 3586 | sender | NORMAL | 3587 | direct | NORMAL | 3588 | IEEE1722 | NORMAL | 3589 +-----------+--------------+ 3591 16. Security Considerations 3593 This document does not add any new security considerations beyond the 3594 existing considerations in the RFCs for protocols that are being 3595 multiplexed together. 3597 The ways that SRTP streams are keyed is not believed to create any 3598 two-time pad vulnerability for the currently defined SRTP keying 3599 mechanism. 3601 17. Acknowledgments 3603 I would like to thank Cullen Jennings, Flemming Andreasen for 3604 suggesting the categories, contributing text and reviewing the draft. 3605 I would also link to thank Magnus Westerlund, Christer Holmberg, 3606 Jonathan Lennox, Bo Burman, Ari Keranen, and Dan Wing on suggesting 3607 structural changes helping improve the document readability. 3609 I would like also to thank following experts on their inputs and 3610 reviews as listed - Flemming Andreasen(5.24,5.32,5.33,14), Rohan 3611 Mahy(5.57), Eric Burger(5.26),Christian Huitema(5.14), Christer 3612 Holmberg(5.21,5.26,5.51,5.52), Richard Ejzak (5.44,5.53,5.54), Colin 3613 Perkins(5.7,5.8,5.9,5.58), Magnus 3614 Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Roni 3615 Evens(5.12,5.27,8.4), Subha Dhesikan(5.6,10), Dan 3616 Wing(5.7,5.12,5.35,5.39,5.45), Cullen Jennings (5.40), Ali C 3617 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 3618 (7.2,7.6), Charles Eckel(5.15,5.27,5.28,9.1,8.5), Paul Kyzivat(5.24), 3619 Ian Johansson(5.15), Saravanan Shanmugham(5.11), Paul E Jones(5.30), 3620 Rajesh Kumar(5.48), Jonathan Lennox(5.36,5,15,9.1,11.1), Mo 3621 Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Christian Huitema (5.14), Qin 3622 Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves 3623 (5.48,5.55), Thomas Stach. 3625 18. Change Log 3627 [RFC EDITOR NOTE: Please remove this section when publishing] 3629 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 3631 o Incorporated last call review comments from Thomas Stach and Ari 3632 Keranen. 3634 o Fixed more nits to prep for the LastCall. 3636 Changes from draft-ietf-mmusic-sdp-mux-attributes-05 3637 o Incorporated review comments from Christian Grooves and Ari 3638 Keranen. 3640 o Fixed more nits to prep for the LastCall. 3642 Changes from draft-ietf-mmusic-sdp-mux-attributes-04 3644 o Fixed minor nits overall. 3646 o Updated Acknowledgement Sections 3648 o Last Call Version. 3650 Changes from draft-ietf-mmusic-sdp-mux-attributes-03 3652 o More re-work on the IANA section. 3654 o Clean ups preparing for the last call. 3656 Changes from draft-ietf-mmusic-sdp-mux-attributes-02 3658 o Incorporated suggestions from Flemming on Capability Negotiation. 3660 o Closed open issues from IETF90 3662 o Added IANA section to list the categories for all the SDP 3663 attributes anlayzed 3665 o Lots of cleanup 3667 o Reformatted Refernces section to use short-form notation 3669 Changes from draft-ietf-mmusic-sdp-mux-attributes-01 3671 o Updated section 15 to provide detailed recommendation on dealing 3672 with encapsulating attributes. Also updated sections 5.20, 5.28, 3673 5.29 to refer to Section 15. 3675 o Added new categories IDENTICAL-PER-PT and INHERIT 3677 o Updated Sections 16 to add the new categories. 3679 o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the 3680 category IDENTICAL-PER-PT. 3682 o Reformatted section 4 to add individual categories to their own 3683 sections. 3685 Changes from draft-ietf-mmusic-sdp-mux-attributes-00 3687 o Added Section 15 to provide recommendations on multiplexing SDP 3688 encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 3689 to refer to Section 15. 3691 o Updated Section 5.38 to incorporate PM-dir review inputs from Qin 3692 Wu 3694 o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more 3695 clarity. 3697 o Fixed few nits regarding sentence clarity and fill-in the NOTES 3698 section where information was lacking. 3700 Changes from draft-nandakumar-mmusic-mux-attributes-05 3702 o Renamed the document to be a WG document. 3704 o Added Section 14. 3706 o Updated Open Issues based on IETF88 discussions. 3708 Changes from draft-nandakumar-mmusic-mux-attributes-04 3710 o Added few OPEN ISSUES that needs to be discussed. 3712 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 3713 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 3715 o Updated Table Column name Current to Level and improved TRANSPORT 3716 category explanation on suggestions form Dan Wing. 3718 o Grouped all the rtcp-fb attribute analysis under a single section 3719 as suggested by Magnus/ 3721 Changes from draft-nandakumar-mmusic-mux-attributes-03 3723 o Maintenance change to clean up grammatical nits and wordings. 3725 Changes from draft-nandakumar-mmusic-mux-attributes-02 3727 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 3728 5.37,5.40,5.41,5.42,5.43,5.44,5.45,6.1,6.2,6.3,8,3,12.1 based on 3729 the inputs from the respective RFC Authors. 3731 Changes from draft-nandakumar-mmusic-mux-attributes-01 3732 o Replaced Category BAD with NOT RECOMMENDED. 3734 o Added Category TBD. 3736 o Updated IANA Consideration Section. 3738 Changes from draft-nandakumar-mmusic-mux-attributes-00 3740 o Added new section for dealing with FEC payload types. 3742 19. References 3744 19.1. Normative References 3746 [I-D.ietf-mmusic-sdp-bundle-negotiation] 3747 Holmberg, C., Alvestrand, H., and C. Jennings, 3748 "Negotiating Media Multiplexing Using the Session 3749 Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- 3750 negotiation-12 (work in progress), October 2014. 3752 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3753 Requirement Levels", BCP 14, RFC 2119, March 1997. 3755 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 3756 Description Protocol", RFC 4566, July 2006. 3758 19.2. Informative References 3760 [H.248.15] 3761 "Gateway control protocol: SDP H.248 package attribute", 3762 . 3764 [I.D-draft-ietf-dart-dscp-rtp] 3765 Black, D. and P. Jones, "The Session Description Protocol 3766 (SDP) Content Attribute", draft-ietf-dart-dscp-rtp-07 3767 (work in progress), September 2014. 3769 [IANA] "Session Description Protocol (SDP) Parameters", 3770 . 3773 [Q.1970] "Q.1970 : BICC IP bearer control protocol", 3774 . 3776 [R3GPPTS183.063] 3777 "TISPAN - IMS based ITPV Stage 3 specification.", 3778 . 3781 [R3GPPTS24.182] 3782 "IP Multimedia Subsystem (IMS) Customized Alerting Tones 3783 (CAT); Protocol specification", 3784 . 3786 [R3GPPTS24.183] 3787 "IP Multimedia Subsystem (IMS) Customized Ringing Signal 3788 (CRS); Protocol specification", 3789 . 3791 [R3GPPTS24.229] 3792 "IP multimedia call control protocol based on Session 3793 Initiation Protocol (SIP) and Session Description Protocol 3794 (SDP);", 3795 . 3797 [R3GPPTS26.114] 3798 "IP multimedia Subsystem : Media Handling and 3799 interaction", 3800 . 3802 [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time 3803 Streaming Protocol (RTSP)", RFC 2326, April 1998. 3805 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the 3806 Session Description Protocol (SDP) for ATM Bearer 3807 Connections", RFC 3108, May 2001. 3809 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 3810 with Session Description Protocol (SDP)", RFC 3264, June 3811 2002. 3813 [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, 3814 "Integration of Resource Management and Session Initiation 3815 Protocol (SIP)", RFC 3312, October 2002. 3817 [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple 3818 Capability Declaration", RFC 3407, October 2002. 3820 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to 3821 Resource Reservation Flows", RFC 3524, April 2003. 3823 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth 3824 Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3825 3556, July 2003. 3827 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute 3828 in Session Description Protocol (SDP)", RFC 3605, October 3829 2003. 3831 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 3832 Protocol Extended Reports (RTCP XR)", RFC 3611, November 3833 2003. 3835 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth 3836 Modifier for the Session Description Protocol (SDP)", RFC 3837 3890, September 2004. 3839 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network 3840 Address Types (ANAT) Semantics for the Session Description 3841 Protocol (SDP) Grouping Framework", RFC 4091, June 2005. 3843 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 3844 the Session Description Protocol (SDP)", RFC 4145, 3845 September 2005. 3847 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. 3848 Carrara, "Key Management Extensions for Session 3849 Description Protocol (SDP) and Real Time Streaming 3850 Protocol (RTSP)", RFC 4567, July 2006. 3852 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session 3853 Description Protocol (SDP) Security Descriptions for Media 3854 Streams", RFC 4568, July 2006. 3856 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol 3857 (SDP) Source Filters", RFC 4570, July 2006. 3859 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the 3860 Transport Layer Security (TLS) Protocol in the Session 3861 Description Protocol (SDP)", RFC 4572, July 2006. 3863 [RFC4574] Levin, O. and G. Camarillo, "The Session Description 3864 Protocol (SDP) Label Attribute", RFC 4574, August 2006. 3866 [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format 3867 for Binary Floor Control Protocol (BFCP) Streams", RFC 3868 4583, November 2006. 3870 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 3871 "Extended RTP Profile for Real-time Transport Control 3872 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 3873 2006. 3875 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description 3876 Protocol (SDP) Content Attribute", RFC 4796, February 3877 2007. 3879 [RFC4975] Campbell, B., Mahy, R., and C. Jennings, "The Message 3880 Session Relay Protocol (MSRP)", RFC 4975, September 2007. 3882 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 3883 "Codec Control Messages in the RTP Audio-Visual Profile 3884 with Feedback (AVPF)", RFC 5104, February 2008. 3886 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 3887 Correction", RFC 5109, December 2007. 3889 [RFC5159] Dondeti, L. and A. Jerichow, "Session Description Protocol 3890 (SDP) Attributes for Open Mobile Alliance (OMA) Broadcast 3891 (BCAST) Service and Content Protection", RFC 5159, March 3892 2008. 3894 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 3895 (ICE): A Protocol for Network Address Translator (NAT) 3896 Traversal for Offer/Answer Protocols", RFC 5245, April 3897 2010. 3899 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP 3900 Header Extensions", RFC 5285, July 2008. 3902 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of 3903 Service (QoS) Mechanism Selection in the Session 3904 Description Protocol (SDP)", RFC 5432, March 2009. 3906 [RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size 3907 Real-Time Transport Control Protocol (RTCP): Opportunities 3908 and Consequences", RFC 5506, April 2009. 3910 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., 3911 and P. Kyzivat, "A Session Description Protocol (SDP) 3912 Offer/Answer Mechanism to Enable File Transfer", RFC 5547, 3913 May 2009. 3915 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific 3916 Media Attributes in the Session Description Protocol 3917 (SDP)", RFC 5576, June 2009. 3919 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding 3920 Dependency in the Session Description Protocol (SDP)", RFC 3921 5583, July 2009. 3923 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 3924 Protocol (RTCP) Extensions for Single-Source Multicast 3925 Sessions with Unicast Feedback", RFC 5760, February 2010. 3927 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and 3928 Control Packets on a Single Port", RFC 5761, April 2010. 3930 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control 3931 Protocol (DCCP)", RFC 5762, April 2010. 3933 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework 3934 for Establishing a Secure Real-time Transport Protocol 3935 (SRTP) Security Context Using Datagram Transport Layer 3936 Security (DTLS)", RFC 5763, May 2010. 3938 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description 3939 Protocol (SDP) Grouping Framework", RFC 5888, June 2010. 3941 [RFC5939] Andreasen, F., "Session Description Protocol (SDP) 3942 Capability Negotiation", RFC 5939, September 2010. 3944 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in 3945 the Session Description Protocol", RFC 5956, September 3946 2010. 3948 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions 3949 Defined for 3GPP Packet-Switched Streaming Service and 3950 Multimedia Broadcast/Multicast Service", RFC 6064, January 3951 2011. 3953 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- 3954 Specific Multicast (SSM) Sessions", RFC 6128, February 3955 2011. 3957 [RFC6189] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media 3958 Path Key Agreement for Unicast Secure RTP", RFC 6189, 3959 April 2011. 3961 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for 3962 the Internet Key Exchange Protocol (IKE) in the Session 3963 Description Protocol (SDP)", RFC 6193, April 2011. 3965 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media 3966 Control Channel Framework", RFC 6230, May 2011. 3968 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image 3969 Attributes in the Session Description Protocol (SDP)", RFC 3970 6236, May 2011. 3972 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping 3973 between Unicast and Multicast RTP Sessions", RFC 6284, 3974 June 2011. 3976 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, 3977 "Unicast-Based Rapid Acquisition of Multicast RTP 3978 Sessions", RFC 6285, June 2011. 3980 [RFC6364] Begen, A., "Session Description Protocol Elements for the 3981 Forward Error Correction (FEC) Framework", RFC 6364, 3982 October 2011. 3984 [RFC6642] Wu, Q., Xia, F., and R. Even, "RTP Control Protocol (RTCP) 3985 Extension for a Third-Party Loss Report", RFC 6642, June 3986 2012. 3988 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., 3989 and K. Carlberg, "Explicit Congestion Notification (ECN) 3990 for RTP over UDP", RFC 6679, August 2012. 3992 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection 3993 Establishment for Media Anchoring (CEMA) for the Message 3994 Session Relay Protocol (MSRP)", RFC 6714, August 2012. 3996 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A 3997 Datagram Congestion Control Protocol UDP Encapsulation for 3998 NAT Traversal", RFC 6773, November 2012. 4000 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control 4001 Protocol Version 2 (MRCPv2)", RFC 6787, November 2012. 4003 [RFC6849] Kaplan, H., Hedayat, K., Venna, N., Jones, P., and N. 4004 Stratton, "An Extension to the Session Description 4005 Protocol (SDP) and Real-time Transport Protocol (RTP) for 4006 Media Loopback", RFC 6849, February 2013. 4008 [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session 4009 Description Protocol (SDP) Media Capabilities 4010 Negotiation", RFC 6871, February 2013. 4012 [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S. 4013 Veikkolainen, "The Session Description Protocol (SDP) 4014 Alternate Connectivity (ALTC) Attribute", RFC 6947, May 4015 2013. 4017 [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman, 4018 "Miscellaneous Capabilities Negotiation in the Session 4019 Description Protocol (SDP)", RFC 7006, September 2013. 4021 [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping 4022 Semantics in the Session Description Protocol", RFC 7104, 4023 January 2014. 4025 [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session 4026 Description Protocol (SDP) Extension for Setting Audio and 4027 Video Media Streams over Circuit-Switched Bearers in the 4028 Public Switched Telephone Network (PSTN)", RFC 7195, May 4029 2014. 4031 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay 4032 Attribute in the Session Description Protocol", RFC 7197, 4033 April 2014. 4035 [RFC7266] Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control 4036 Protocol (RTCP) Extended Report (XR) Blocks for Mean 4037 Opinion Score (MOS) Metric Reporting", RFC 7266, June 4038 2014. 4040 [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O., 4041 Boronat, F., Montagud, M., and K. Gross, "Inter- 4042 Destination Media Synchronization (IDMS) Using the RTP 4043 Control Protocol (RTCP)", RFC 7272, June 2014. 4045 [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H. 4046 Stokking, "RTP Clock Source Signalling", RFC 7273, June 4047 2014. 4049 [T.38] "Procedures for real-time Group 3 facsimile communication 4050 over IP networks", . 4052 Author's Address 4054 Suhas Nandakumar 4055 Cisco 4056 170 West Tasman Drive 4057 San Jose, CA 95134 4058 USA 4060 Email: snandaku@cisco.com