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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. 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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 July 5, 2015 5 Expires: January 6, 2016 7 A Framework for SDP Attributes when Multiplexing 8 draft-ietf-mmusic-sdp-mux-attributes-09 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 RTP sessions and are thus carried 17 over individual underlying transport layer flows. For scenarios 18 where SDP is used to negotiate the usage of single 5-tuple for 19 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 January 6, 2016. 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 . . . . . . . . . . . . . . . . . . . . . . 9 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 . . . . . . . . . . . . 23 106 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 . . . . . . . . 25 111 5.23. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 26 112 5.24. RFC3407 - SDP Simple Capability Declaration . . . . . . . 26 113 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP 114 Sessions . . . . . . . . . . . . . . . . . . . . . . . . 27 115 5.26. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 27 116 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 . . . . . . . . . . . . . . . . . . . . 31 121 5.32. RFC5939 - SDP Capability Negotiation . . . . . . . . . . 31 122 5.33. RFC6871- SDP Media Capabilities Negotiation . . . . . . . 32 123 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 . . . . . . . . . . . 36 130 5.41. RFC6947 - The SDP ALTC Attribute . . . . . . . . . . . . 36 131 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers 132 in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 37 133 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) . . 37 134 5.44. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . 38 135 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 . . . . . . . 40 138 5.48. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 43 139 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 45 140 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 46 141 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 46 142 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 47 143 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 47 144 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 48 145 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 50 146 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 50 147 5.57. RFC4975 - The Message Session Relay Protocol . . . . . . 51 148 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 52 149 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 52 150 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 53 151 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . 53 152 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . 54 153 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 54 154 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 54 155 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 55 156 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . 56 157 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 56 158 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 57 159 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 58 160 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 58 161 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . 58 162 8.2. RFC3524 - Mapping Media Streams to Resource 163 Reservation Flows . . . . . . . . . . . . . . . . . . . . 59 164 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . 59 165 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 60 166 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . 60 167 8.6. RFC7104 - Duplication Grouping Semantics in the SDP . . 61 168 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 61 169 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 61 170 9.2. RFC7104 - Duplication Grouping Semantics in the SDP . . . 61 171 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 62 172 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 62 173 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 63 174 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . 63 175 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 63 176 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 63 177 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 64 178 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . 64 179 14. Multiplexing Considerations for Encapsulating Attributes . . 64 180 14.1. RFC3407 - cpar Attribute Analysis . . . . . . . . . . . 65 181 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 65 182 14.2.1. Recommendation - Procedures for Potential 183 Configuration Pairing . . . . . . . . . . . . . . . 66 184 14.2.1.1. Example: Transport Capability Multiplexing . . . 67 185 14.2.1.2. Example: Attribute Capability Multiplexing . . . 68 186 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 69 187 14.3.1. Recommendation: Dealing with Payload Type Numbers . 69 188 14.3.1.1. Example: Attribute Capability Under Shared 189 Payload Type . . . . . . . . . . . . . . . . . . 69 191 14.3.2. Recommendation: Dealing with Latent Configurations . 70 192 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 71 193 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 71 194 15.2. 'Mux Category' column for subregistries . . . . . . . . 72 195 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 72 196 15.2.2. Table: att-field (session level) . . . . . . . . . . 72 197 15.2.3. Table: att-field (both session and media level) . . 73 198 15.2.4. Table: att-field (media level only) . . . . . . . . 75 199 15.2.5. Table: att-field (source level) . . . . . . . . . . 78 200 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 79 201 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 79 202 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 79 203 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 80 204 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 80 205 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 81 206 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 81 207 15.2.13. Table: SDP/RTSP key management protocol identifiers 81 208 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 82 209 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 82 210 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 82 211 15.2.17. Table: Timestamp Reference Clock Source Parameters . 83 212 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 83 213 16. Security Considerations . . . . . . . . . . . . . . . . . . . 83 214 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 84 215 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 84 216 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 87 217 19.1. Normative References . . . . . . . . . . . . . . . . . . 87 218 19.2. Informative References . . . . . . . . . . . . . . . . . 87 219 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 93 221 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 apply 245 the framework to the SDP attributes registered with the [IANA]. 247 2. Terminology 249 5-tuple: A collection of the following values: source address, source 250 port, destination address, destination port, and transport-layer 251 protocol. 253 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", 254 "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be 255 interpreted as described in [RFC2119]. 257 3. Motivation 259 The time and complications of setting up ICE [RFC5245] and DTLS-SRTP 260 [RFC5763] transports for use by RTP, and conservation of ports (to 261 avoid maintaining large number of NAT bindings open, reduce time/ 262 ports needed for ICE to detect connectivity), forms a requirement to 263 try and reduce the number of transport level flows needed. This has 264 resulted in the definition of ways, such as, 265 [I-D.ietf-mmusic-sdp-bundle-negotiation] to multiplex RTP over a 266 single transport flow in order to preserve network resources such as 267 port numbers. This imposes further restrictions on applicability of 268 the SDP attributes as they are defined today. 270 The specific problem is that there are attribute combinations which 271 make sense when specified on independent "m=" lines -- as with 272 classical SDP -- that do not make sense when those "m=" lines are 273 then multiplexed over the same transport. To give an obvious 274 example, ICE permits each "m=" line to have an independently 275 specified ice-ufrag attribute. However, if the media from multiple 276 "m=" lines is multiplexed over the same ICE component, then the 277 meaning of media-level ice-ufrag attributes becomes muddled. 279 At the time of writing this document there are close to 250 SDP 280 attributes registered with the [IANA] and more will be added in the 281 future. There is no clearly defined procedure to establish the 282 validity/applicability of these attributes when used with transport 283 multiplexing. 285 4. SDP Attribute Analysis Framework 287 Attributes in an SDP session description can be defined at the 288 session-level and media-level. Informally, these attributes could be 289 semantically grouped as noted below. 291 o Attributes related to media content such as media type, encoding 292 schemes, payload types. 294 o Attributes specifying media transport characteristics like RTP/ 295 RTCP port numbers, network addresses, QOS. 297 o Metadata description attributes capturing session timing and 298 origin information. 300 o Attributes establishing relationships between media descriptions 301 such as grouping framework [RFC5888] 303 With the above semantic grouping as a reference, the proposed 304 framework classifies each attribute into one of the following 305 categories: 307 4.1. Category: NORMAL 309 Attributes that can be independently specified when multiplexing and 310 retain their original semantics. 312 In the example given below, the direction and label attributes are 313 independently specified for audio and video "m=" lines. These 314 attributes are not impacted by multiplexing these media streams over 315 a single transport layer flow. 317 v=0 318 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 319 s= 320 c=IN IP4 host.atlanta.example.com 321 t=0 0 322 m=audio 49172 RTP/AVP 99 323 a=sendonly 324 a=label:1 325 a=rtpmap:99 iLBC/8000 326 m=video 49172 RTP/AVP 31 327 a=recvonly 328 a=label:2 329 a=rtpmap:31 H261/90000 331 4.2. Category: NOT RECOMMENDED 333 Attributes that are not recommended for multiplexing since their 334 usage under multiplexing might lead to incorrect behavior. 336 Example: Multiplexing media descriptions over a single DCCP transport 337 [RFC5762] is NOT RECOMMENDED since DCCP being a connection oriented 338 protocol doesn't allow multiple connections on the same 5-tuple. 340 v=0 341 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 342 s= 343 c=IN IP4 client.biloxi.example.com 344 t=0 0 345 m=video 5004 DCCP/RTP/AVP 99 346 a=rtpmap:99 h261/9000 347 a=dccp-service-code:SC=x52545056 348 a=setup:passive 349 a=connection:new 350 m=video 5004 DCCP/RTP/AVP 100 351 a=rtpmap:100 h261/9000 352 a=dccp-service-code:SC=x5254504f 353 a=setup:passive 354 a=connection:new 356 4.3. Category: IDENTICAL 358 Attributes and their associated values (if any) that MUST be 359 identical across all the media descriptions being multiplexed. 361 Attributes such as rtcp-mux fall into this category. Since RTCP 362 reporting is done per RTP session, RTCP Multiplexing MUST be enabled 363 for both the audio and video "m=" lines if they are transported over 364 a single 5-tuple. 366 v=0 367 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 368 s= 369 c=IN IP4 client.biloxi.example.com 370 t=0 0 371 m=audio 34567 RTP/AVP 97 372 a=rtcp-mux 373 m=video 34567 RTP/AVP 31 374 a=rtpmap:31 H261/90000 375 a=rtcp-mux 377 4.4. Category: SUM 379 Attributes can be set as they are normally used but software using 380 them in the multiplexing scenario, MUST apply the sum of all the 381 attributes being multiplexed instead of trying to use them 382 independently. This is typically used for bandwidth or other rate 383 limiting attributes to the underlying transport. 385 The software parsing the SDP sample below, should use the aggregate 386 Application Specific (AS) bandwidth value from the individual media 387 descriptions to determine the AS value for the multiplexed session. 388 Thus the calculated AS value would be 256+64 kilobits per second for 389 the given example. 391 v=0 392 o=test 2890844526 2890842807 IN IP4 126.16.64.4 393 c=IN IP4 client.biloxi.example.com 394 t=0 0 395 m=audio 49170 RTP/AVP 0 396 b=AS:64 397 m=video 51372 RTP/AVP 31 398 b=AS:256 400 4.5. Category: TRANSPORT 402 Attributes that can be set normally for multiple items in a 403 multiplexed group but the software MUST pick the one that's 404 associated with the "m=" line whose information is used for setting 405 up the underlying transport. 407 In the example below, "a=crypto" attribute is defined for both the 408 audio and the video "m=" lines. The video media line's a=crypto 409 attribute is chosen since its mid value (bar) appears first in the 410 a=group:BUNDLE line. This is due to BUNDLE grouping semantic 411 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values 412 from "m=" line corresponding to the mid appearing first on the 413 a=group:BUNDLE line to be considered for setting up the RTP 414 Transport. 416 v=0 417 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 418 s= 419 c=IN IP4 host.atlanta.example.com 420 t=0 0 421 a=group:BUNDLE bar foo 422 m=audio 49172 RTP/AVP 99 423 a=mid:foo 424 a=crypto:1 AES_CM_128_HMAC_SHA1_80 425 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 426 a=rtpmap:99 iLBC/8000 427 m=video 51374 RTP/AVP 31 428 a=mid:bar 429 a=crypto:1 AES_CM_128_HMAC_SHA1_80 430 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 431 a=rtpmap:96 H261/90000 433 4.6. Category: INHERIT 435 Attributes that encapsulate other SDP attributes or parameters. 436 These attributes inherit their multiplexing characteristics from the 437 attributes or parameters they encapsulate. Such attributes are 438 defined in [RFC3407], [RFC5939] and [RFC6871] as part of a generic 439 framework for indicating and negotiating transport, media and media 440 format related capabilities in the SDP. 442 The inheritance manifests itself when the encapsulated attribute or 443 parameter is being leveraged. In the case of SDP Capability 444 Negotiation [RFC5939] for example, this occurs when a capability 445 (encapsulating attribute) is used as part of a configuration; the 446 configuration inherits the multiplexing category of each of its 447 constituent (encapsulated) attributes and parameters. This in turn 448 MAY place constraints on what constitutes a valid configuration from 449 a multiplexing point of view, e.g. because some attributes MUST be 450 IDENTICAL (see Section 14 for further details). 452 v=0 453 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 454 s= 455 c=IN IP4 host.atlanta.example.com 456 t=0 0 457 m=video 3456 RTP/AVP 100 458 a=rtpmap:100 VP8/90000 459 a=fmtp:100 max-fr=30;max-fs=8040 460 a=sqn: 0 461 a=cdsc: 1 video RTP/AVP 100 462 a=cpar: a=rtcp-mux 463 m=video 3456 RTP/AVP 101 464 a=rtpmap:101 VP8/90000 465 a=fmtp:100 max-fr=15;max-fs=1200 466 a=cdsc: 2 video RTP/AVP 101 467 a=cpar: a=rtcp-mux 469 In the above example, the category IDENTICAL is inherited for the 470 cpar encapsulated rtcp-mux attribute. 472 4.7. Category: IDENTICAL-PER-PT 474 Attributes that define the RTP payload configuration on per Payload 475 Type basis and MUST have identical values across all the media 476 descriptions for a given RTP Payload Type when repeated. These 477 Payload Types identify the same codec configuration as defined in the 478 Section 10.1.2 of [I-D.ietf-mmusic-sdp-bundle-negotiation] under this 479 context. 481 In the SDP example below, Payload Types 96 and 97 are repeated across 482 all the video "m=" lines and all the payload specific parameters (ex: 483 rtpmap, fmtp) are identical (Note: some line breaks included are due 484 to formatting only). 486 v=0 487 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 488 s= 489 c=IN IP4 host.atlanta.example.com 490 t=0 0 491 a=group:BUNDLE cam1 cam2 492 m=video 96 97 493 a=mid:cam1 494 a=rtpmap:96 H264/90000 495 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 496 max-mbps=108000; max-br=1000 497 a=rtpmap:97 H264/90000 498 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 499 max-mbps=7200; max-br=200 500 m=video 96 97 501 a=mid:cam2 502 a=rtpmap:96 H264/90000 503 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 504 max-mbps=108000; max-br=1000 505 a=rtpmap:97 H264/90000 506 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 507 max-mbps=7200; max-br=200 509 4.8. Category: SPECIAL 511 Attributes where the text in the specification defining the attribute 512 MUST be consulted for further handling when multiplexed. 514 As an example, for the attribute extmap [RFC5285], the specification 515 defining the extension needs to be referred to understand the 516 multiplexing implications. 518 4.9. Category: TBD 520 Attributes that have not been analyzed under the proposed 521 multiplexing framework. For the purposes of implementations it is 522 advised to consider "NOT RECOMMENDED" as the category when 523 multiplexing these attributes. 525 5. Analysis of Existing Attributes 527 This section analyzes attributes listed in [IANA], grouped under the 528 IETF document that defines them. 530 The "Level" column indicates whether the attribute is currently 531 specified as: 533 o S -- Session level 534 o M -- Media level 536 o B -- Both 538 o SR -- Source-level (for a single SSRC) [RFC5576] 540 The "Mux Category" column identifies multiplexing category assigned 541 per attribute and the "Notes" column captures additional informative 542 details regarding the assigned category, wherever necessary. 544 5.1. RFC4566 - SDP: Session Description Protocol 546 [RFC4566] defines the Session Description Protocol (SDP) that is 547 intended for describing multimedia sessions for the purposes of 548 session announcement, session invitation, and other forms of 549 multimedia session initiation. 551 +-----------------+---------------------+-------+-------------------+ 552 | Name | Notes | Level | Mux Category | 553 +-----------------+---------------------+-------+-------------------+ 554 | sendrecv | Not impacted | B | NORMAL | 555 | | | | | 556 | sendonly | Not impacted | B | NORMAL | 557 | | | | | 558 | recvonly | Not impacted | B | NORMAL | 559 | | | | | 560 | inactive | Not impacted | B | NORMAL | 561 | | | | | 562 | cat | Not impacted | S | NORMAL | 563 | | | | | 564 | ptime | The attribute value | M | IDENTICAL-PER-PT | 565 | | MUST be same for a | | | 566 | | given codec | | | 567 | | configuration | | | 568 | | | | | 569 | maxptime | The attribute value | M | IDENTICAL-PER-PT | 570 | | MUST be same for a | | | 571 | | given codec | | | 572 | | configuration | | | 573 | | | | | 574 | orient | Not Impacted | M | NORMAL | 575 | | | | | 576 | framerate | The attribute value | M | IDENTICAL-PER-PT | 577 | | MUST be same for a | | | 578 | | given codec | | | 579 | | configuration | | | 580 | | | | | 581 | quality | Not Impacted | M | NORMAL | 582 | | | | | 583 | rtpmap | The attribute value | M | IDENTICAL-PER-PT | 584 | | MUST be same for a | | | 585 | | given codec | | | 586 | | configuration | | | 587 | | | | | 588 | fmtp | The attribute value | M | IDENTICAL-PER-PT | 589 | | MUST be same for a | | | 590 | | given codec | | | 591 | | configuration | | | 592 | | | | | 593 | keywds | Not impacted | S | NORMAL | 594 | | | | | 595 | type | Not Impacted | S | NORMAL | 596 | | | | | 597 | type:broadcast | Not Impacted | S | NORMAL | 598 | | | | | 599 | type:H332 | Not Impacted | S | NORMAL | 600 | | | | | 601 | type:meeting | Not Impacted | S | NORMAL | 602 | | | | | 603 | type:moderated | Not Impacted | S | NORMAL | 604 | | | | | 605 | type:test | Not Impacted | S | NORMAL | 606 | | | | | 607 | tool | Not Impacted | S | NORMAL | 608 | | | | | 609 | charset | Not Impacted | S | NORMAL | 610 | | | | | 611 | sdplang | Not Impacted | B | NORMAL | 612 | | | | | 613 | lang | Not Impacted | B | NORMAL | 614 | | | | | 615 +-----------------+---------------------+-------+-------------------+ 617 RFC4566 Attribute Analysis 619 5.2. RFC4585 - RTP/AVPF 621 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 622 enables receivers to provide, statistically, more immediate feedback 623 to the senders and thus allows for short-term adaptation and 624 efficient feedback-based repair mechanisms to be implemented. 626 +----------+----------------------------+-------+-------------------+ 627 | Name | Notes | Level | Mux Category | 628 +----------+----------------------------+-------+-------------------+ 629 | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT | 630 | | attributes are Payload | | | 631 | | Type (PT) scoped, their | | | 632 | | values MUST be identical | | | 633 | | for a given PT across the | | | 634 | | multiplexed "m=" lines. | | | 635 | | | | | 636 +----------+----------------------------+-------+-------------------+ 638 RFC4585 Attribute Analysis 640 5.3. RFC5761 - Multiplexing RTP and RTCP 642 [RFC5761] discusses issues that arise when multiplexing RTP data 643 packets and RTP Control Protocol (RTCP) packets on a single UDP port. 644 It describes when such multiplexing is and is not appropriate, and it 645 explains how the Session Description Protocol (SDP) can be used to 646 signal multiplexed sessions. 648 +-----------+----------------------------------+-------+------------+ 649 | Name | Notes | Level | Mux | 650 | | | | Category | 651 +-----------+----------------------------------+-------+------------+ 652 | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL | 653 | | affects the entire RTP session | | | 654 | | | | | 655 +-----------+----------------------------------+-------+------------+ 657 RFC5761 Attribute Analysis 659 5.4. RFC3312 - Integration of Resource Management and (SIP) 661 [RFC3312] defines a generic framework for preconditions, which are 662 extensible through IANA registration. This document also discusses 663 how network quality of service can be made a precondition for 664 establishment of sessions initiated by the Session Initiation 665 Protocol (SIP). These preconditions require that the participant 666 reserve network resources before continuing with the session. 668 +-------+-----------------------+-------+------------------+ 669 | Name | Notes | Level | Mux Category | 670 +-------+-----------------------+-------+------------------+ 671 | des | Refer to notes below | M | NOT RECOMMENDED | 672 | | | | | 673 | conf | Refer to notes below | M | NOT RECOMMENDED | 674 | | | | | 675 | curr | Refer to notes below | M | NOT RECOMMENDED | 676 | | | | | 677 +-------+-----------------------+-------+------------------+ 679 RFC3312 Attribute Analysis 681 NOTE: A mismatched set of preconditions across media descriptions 682 results in Session establishment failures due to inability in meeting 683 the right resource reservations requested. 685 5.5. RFC4574 - SDP Label Attribute 687 [RFC4574] defines a new Session Description Protocol (SDP) media- 688 level attribute: "label". The "label" attribute carries a pointer to 689 a media stream in the context of an arbitrary network application 690 that uses SDP. The sender of the SDP document can attach the "label" 691 attribute to a particular media stream or streams. The application 692 can then use the provided pointer to refer to each particular media 693 stream in its context. 695 +--------+---------------+-------+--------------+ 696 | Name | Notes | Level | Mux Category | 697 +--------+---------------+-------+--------------+ 698 | label | Not Impacted | M | NORMAL | 699 | | | | | 700 +--------+---------------+-------+--------------+ 702 RFC4574 Attribute Analysis 704 5.6. RFC5432 - QoS Mechanism Selection in SDP 706 [RFC5432] defines procedures to negotiate QOS mechanisms using the 707 Session Description Protocol (SDP) offer/answer model. 709 +----------------+----------------------------+-------+-------------+ 710 | Name | Notes | Level | Mux | 711 | | | | Category | 712 +----------------+----------------------------+-------+-------------+ 713 | qos-mech-send | Refer to section Section | B | TRANSPORT | 714 | | 10 | | | 715 | | | | | 716 | qos-mech-recv | Refer to section Section | B | TRANSPORT | 717 | | 10 | | | 718 | | | | | 719 +----------------+----------------------------+-------+-------------+ 721 RFC5432 Attribute Analysis 723 5.7. RFC4568 - SDP Security Descriptions 725 [RFC4568] defines a Session Description Protocol (SDP) cryptographic 726 attribute for unicast media streams. The attribute describes a 727 cryptographic key and other parameters that serve to configure 728 security for a unicast media stream in either a single message or a 729 roundtrip exchange. 731 +---------+------------------------------------+-------+------------+ 732 | Name | Notes | Level | Mux | 733 | | | | Category | 734 +---------+------------------------------------+-------+------------+ 735 | crypto | crypto attribute MUST be the one | M | TRANSPORT | 736 | | that corresponds to the "m=" line | | | 737 | | chosen for setting up the | | | 738 | | underlying transport flow | | | 739 | | | | | 740 +---------+------------------------------------+-------+------------+ 742 RFC4568 Attribute Analysis 744 5.8. RFC5762 - RTP over DCCP 746 The Real-time Transport Protocol (RTP) is a widely used transport for 747 real-time multimedia on IP networks. The Datagram Congestion Control 748 Protocol (DCCP) is a transport protocol that provides desirable 749 services for real-time applications. [RFC5762] specifies a mapping 750 of RTP onto DCCP, along with associated signaling, such that real- 751 time applications can make use of the services provided by DCCP. 753 +--------------------+---------------------+---------+--------------+ 754 | Name | Notes | Current | Mux Category | 755 +--------------------+---------------------+---------+--------------+ 756 | dccp-service-code | If RFC6773 is not | M | NOT | 757 | | being used in | | RECOMMENDED | 758 | | addition to | | | 759 | | RFC5762, the port | | | 760 | | in the "m=" line is | | | 761 | | a DCCP port. DCCP | | | 762 | | being a connection | | | 763 | | oriented protocol, | | | 764 | | it does not allow | | | 765 | | multiple | | | 766 | | connections on the | | | 767 | | same 5-tuple | | | 768 | | | | | 769 +--------------------+---------------------+---------+--------------+ 771 RFC5762 Attribute Analysis 773 If RFC6773 is being used in addition to RFC5762 and provided that 774 DCCP-in-UDP layer has additional demultiplexing, then it may be 775 possible to use different DCCP service codes for each DCCP flow, 776 given each uses a different DCCP port. Although doing so might 777 conflict with the media type of the "m=" line. None of this is 778 standardized yet and it wouldn't work as explained. Hence 779 multiplexing MUST not be performed even in this alternate scenario. 781 5.9. RFC6773 - DCCP-UDP Encapsulation 783 [RFC6773] document specifies an alternative encapsulation of the 784 Datagram Congestion Control Protocol (DCCP), referred to as DCCP-UDP. 785 This encapsulation allows DCCP to be carried through the current 786 generation of Network Address Translation (NAT) middle boxes without 787 modification of those middle boxes. 789 +------------+-------------------------------+-------+--------------+ 790 | Name | Notes | Level | Mux Category | 791 +------------+-------------------------------+-------+--------------+ 792 | dccp-port | Multiplexing MUST not be | M | NOT | 793 | | performed due to potential | | RECOMMENDED | 794 | | conflict between the port | | | 795 | | used for DCCP | | | 796 | | en/decapsulation and the RTP | | | 797 | | | | | 798 +------------+-------------------------------+-------+--------------+ 800 RFC6773 Attribute Analysis 802 NOTE: RFC6773 is about tunneling DCCP in UDP, with the UDP port being 803 the port of the DCCP en-/de-capsulation service. This encapsulation 804 allows arbitrary DCCP packets to be encapsulated and the DCCP port 805 chosen MAY conflict with the port chosen for the RTP traffic. For 806 multiplexing several DCCP-in-UDP encapsulations on the same UDP port, 807 with no RTP traffic on the same port implies collapsing several DCCP 808 port spaces together. This may or may not work depending on the 809 nature of DCCP encapsulation and ports choices thus rendering it to 810 be very application dependent. 812 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile 814 [RFC5506] discusses benefits and issues that arise when allowing 815 Real-time Transport Protocol (RTCP) packets to be transmitted with 816 reduced size. 818 +-------------+--------------------------------+-------+------------+ 819 | Name | Notes | Level | Mux | 820 | | | | Category | 821 +-------------+--------------------------------+-------+------------+ 822 | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL | 823 | | entire RTP session | | | 824 | | | | | 825 +-------------+--------------------------------+-------+------------+ 827 RFC5506 Attribute Analysis 829 5.11. RFC6787 - Media Resource Control Protocol Version 2 831 The Media Resource Control Protocol Version 2 (MRCPv2) allows client 832 hosts to control media service resources such as speech synthesizers, 833 recognizers, verifiers, and identifiers residing in servers on the 834 network. MRCPv2 is not a "stand-alone" protocol -- it relies on 835 other protocols, such as the Session Initiation Protocol (SIP), to 836 coordinate MRCPv2 clients and servers and manage sessions between 837 them, and the Session Description Protocol (SDP) to describe, 838 discover, and exchange capabilities. It also depends on SIP and SDP 839 to establish the media sessions and associated parameters between the 840 media source or sink and the media server. Once this is done, the 841 MRCPv2 exchange operates over the control session established above, 842 allowing the client to control the media processing resources on the 843 speech resource server. [RFC6787] defines attributes for this 844 purpose. 846 +-----------+---------------+-------+--------------+ 847 | Name | Notes | Level | Mux Category | 848 +-----------+---------------+-------+--------------+ 849 | resource | Not Impacted | M | NORMAL | 850 | | | | | 851 | channel | Not Impacted | M | NORMAL | 852 | | | | | 853 | cmid | Not Impacted | M | NORMAL | 854 | | | | | 855 +-----------+---------------+-------+--------------+ 857 RFC6787 Attribute Analysis 859 5.12. RFC5245 - Interactive Connectivity Establishment (ICE) 861 [RFC5245] describes a protocol for Network Address Translator(NAT) 862 traversal for UDP-based multimedia sessions established with the 863 offer/answer model. This protocol is called Interactive Connectivity 864 Establishment (ICE). ICE makes use of the Session Traversal 865 Utilities for NAT (STUN) protocol and its extension,Traversal Using 866 Relay NAT (TURN). ICE can be used by any protocol utilizing the 867 offer/answer model, such as the Session Initiation Protocol (SIP). 869 +--------------------+-------------------------+-------+------------+ 870 | Name | Notes | Level | Mux | 871 | | | | Category | 872 +--------------------+-------------------------+-------+------------+ 873 | ice-lite | Not Impacted | S | NORMAL | 874 | | | | | 875 | ice-options | Not Impacted | S | NORMAL | 876 | | | | | 877 | ice-mismatch | Not Impacted | S | NORMAL | 878 | | | | | 879 | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT | 880 | | that corresponds to the | | | 881 | | "m=" line chosen for | | | 882 | | setting up the | | | 883 | | underlying transport | | | 884 | | flow | | | 885 | | | | | 886 | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | 887 | | one that corresponds to | | | 888 | | the "m=" line chosen | | | 889 | | for setting up the | | | 890 | | underlying transport | | | 891 | | flow | | | 892 | | | | | 893 | candidate | ice candidate MUST be | M | TRANSPORT | 894 | | the one that | | | 895 | | corresponds to the "m=" | | | 896 | | line chosen for setting | | | 897 | | up the underlying | | | 898 | | transport flow | | | 899 | | | | | 900 | remote-candidates | ice remote candidate | M | TRANSPORT | 901 | | MUST be the one that | | | 902 | | corresponds to the "m=" | | | 903 | | line chosen for setting | | | 904 | | up the underlying | | | 905 | | transport flow | | | 906 | | | | | 907 +--------------------+-------------------------+-------+------------+ 909 RFC5245 Attribute Analysis 911 5.13. RFC5285 - RTP Header Extensions 913 [RFC5285] provides a general mechanism to use the header extension 914 feature of RTP (the Real-Time Transport Protocol). It provides the 915 option to use a small number of small extensions in each RTP packet, 916 where the universe of possible extensions is large and registration 917 is de-centralized. The actual extensions in use in a session are 918 signaled in the setup information for that session. 920 +---------+-------------------------------------+-------+-----------+ 921 | Name | Notes | Level | Mux | 922 | | | | Category | 923 +---------+-------------------------------------+-------+-----------+ 924 | extmap | Specific RTP extension document | B | SPECIAL | 925 | | MUST be referred | | | 926 | | | | | 927 +---------+-------------------------------------+-------+-----------+ 929 RFC5285 Attribute Analysis 931 5.14. RFC3605 - RTCP attribute in SDP 933 Originally, SDP assumed that RTP and RTCP were carried on consecutive 934 ports. However, this is not always true when NATs are involved. 935 [RFC3605] specifies an early mechanism to indicate the RTCP port. 937 +-------+--------------------------------------+-------+------------+ 938 | Name | Notes | Level | Mux | 939 | | | | Category | 940 +-------+--------------------------------------+-------+------------+ 941 | rtcp | RTCP Port MUST be the one that | M | TRANSPORT | 942 | | corresponds to the "m=" line chosen | | | 943 | | for setting up the underlying | | | 944 | | transport flow. | | | 945 | | | | | 946 +-------+--------------------------------------+-------+------------+ 948 RFC3605 Attribute Analysis 950 5.15. RFC5576 - Source-Specific SDP Attributes 952 [RFC5576] defines a mechanism to describe RTP media sources, which 953 are identified by their synchronization source (SSRC) identifiers, in 954 SDP, to associate attributes with these sources, and to express 955 relationships among sources. It also defines several source-level 956 attributes that can be used to describe properties of media sources. 958 +----------------+----------------------+-------+-------------------+ 959 | Name | Notes | Level | Mux Category | 960 +----------------+----------------------+-------+-------------------+ 961 | ssrc | Refer to Notes below | M | NORMAL | 962 | | | | | 963 | ssrc-group | Refer to Section 9 | M | NORMAL | 964 | | for specific | | | 965 | | analysis of the | | | 966 | | grouping 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 NOTE: If SSRCs are repeated across "m=" lines being multiplexed, they 982 MUST 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 NOTE: Since the attributes (a=cparmin and a=cparmax) define minimum 1168 and maximum numerical values associated with the attributes described 1169 in 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 | Refer to notes below | M | TBD | 1209 | | | | | 1210 +------------+-----------------------+-------+--------------+ 1212 RFC6714 Attribute Analysis 1214 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1215 there exists no publicly available specification that defines 1216 procedures for multiplexing/demultiplexing MRSP flows over a single 1217 5-tuple. Once such a specification is available, the multiplexing 1218 categories assignments for the attributes in this section MUST be 1219 revisited. 1221 5.27. RFC4583 - SDP Format for BFCP Streams 1223 [RFC4583] document specifies how to describe Binary Floor Control 1224 Protocol (BFCP) streams in Session Description Protocol (SDP) 1225 descriptions. User agents using the offer/answer model to establish 1226 BFCP streams use this format in their offers and answers. 1228 +------------+---------------------------------+-------+------------+ 1229 | Name | Notes | Level | Mux | 1230 | | | | Category | 1231 +------------+---------------------------------+-------+------------+ 1232 | floorctrl | The attribute MUST be repeated | M | IDENTICAL | 1233 | | across all the multiplexed "m=" | | | 1234 | | lines | | | 1235 | | | | | 1236 | confid | Not Impacted | M | NORMAL | 1237 | | | | | 1238 | userid | Not Impacted | M | NORMAL | 1239 | | | | | 1240 | floorid | The floorid MUST be globally | M | NORMAL | 1241 | | unique | | | 1242 | | | | | 1243 +------------+---------------------------------+-------+------------+ 1245 RFC4583 Attribute Analysis 1247 5.28. RFC5547 - SDP Offer/Answer for File Transfer 1249 [RFC5547] provides a mechanism to negotiate the transfer of one or 1250 more files between two endpoints by using the Session Description 1251 Protocol (SDP) offer/answer model specified in [RFC3264]. 1253 +-------------------+-----------------------+-------+--------------+ 1254 | Name | Notes | Level | Mux Category | 1255 +-------------------+-----------------------+-------+--------------+ 1256 | file-selector | Refer to notes below | M | TBD | 1257 | | | | | 1258 | file-transfer-id | Refer to notes below | M | TBD | 1259 | | | | | 1260 | file-disposition | Refer to notes below | M | TBD | 1261 | | | | | 1262 | file-date | Refer to notes below | M | TBD | 1263 | | | | | 1264 | file-icon | Refer to notes below | M | TBD | 1265 | | | | | 1266 | file-range | Refer to notes below | M | TBD | 1267 | | | | | 1268 +-------------------+-----------------------+-------+--------------+ 1270 RFC5547 Attribute Analysis 1272 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1273 there exists no publicly available specification that defines 1274 procedures for multiplexing/demultiplexing MRSP flows over a single 1275 5-tuple. Once such a specification is available, the multiplexing 1276 categories assignments for attributes in this section MUST be 1277 revisited. 1279 5.29. RFC6849 - SDP and RTP Media Loopback Extension 1281 [RFC6849] adds new SDP media types and attributes, which enable 1282 establishment of media sessions where the media is looped back to the 1283 transmitter. Such media sessions will serve as monitoring and 1284 troubleshooting tools by providing the means for measurement of more 1285 advanced VoIP, Real-time Text, and Video over IP performance metrics. 1287 +---------------------+-----------------+-------+-------------------+ 1288 | Name | Notes | Level | Mux Category | 1289 +---------------------+-----------------+-------+-------------------+ 1290 | loopback rtp-pkt- | The attribute | M | IDENTICAL-PER-PT | 1291 | loopback | value MUST be | | | 1292 | | same for a | | | 1293 | | given codec | | | 1294 | | configuration | | | 1295 | | | | | 1296 | loopback rtp-media- | The attribute | M | IDENTICAL-PER-PT | 1297 | loopback | value MUST be | | | 1298 | | same for a | | | 1299 | | given codec | | | 1300 | | configuration | | | 1301 | | | | | 1302 | loopback-source | Not Impacted | M | NORMAL | 1303 | | | | | 1304 | loopback-mirror | Not Impacted | M | NORMAL | 1305 | | | | | 1306 +---------------------+-----------------+-------+-------------------+ 1308 RFC6849 Analysis 1310 5.30. RFC5760 - RTCP with Unicast Feedback 1312 [RFC5760] specifies an extension to the Real-time Transport Control 1313 Protocol (RTCP) to use unicast feedback to a multicast sender. The 1314 proposed extension is useful for single-source multicast sessions 1315 such as Source-Specific Multicast (SSM) communication where the 1316 traditional model of many-to-many group communication is either not 1317 available or not desired. 1319 +---------------+------------------------------+-------+------------+ 1320 | Name | Notes | Level | Mux | 1321 | | | | Category | 1322 +---------------+------------------------------+-------+------------+ 1323 | rtcp-unicast | The attribute MUST be | M | IDENTICAL | 1324 | | reported across all "m=" | | | 1325 | | lines multiplexed | | | 1326 | | | | | 1327 +---------------+------------------------------+-------+------------+ 1329 RFC5760 Attribute Analysis 1331 5.31. RFC3611 - RTCP XR 1333 [RFC3611] defines the Extended Report (XR) packet type for the RTP 1334 Control Protocol (RTCP), and defines how the use of XR packets can be 1335 signaled by an application if it employs the Session Description 1336 Protocol (SDP). 1338 +----------+---------------+-------+--------------+ 1339 | Name | Notes | Level | Mux Category | 1340 +----------+---------------+-------+--------------+ 1341 | rtcp-xr | Not Impacted | B | NORMAL | 1342 | | | | | 1343 +----------+---------------+-------+--------------+ 1345 RFC3611 Attribute Analysis 1347 5.32. RFC5939 - SDP Capability Negotiation 1349 [RFC5939] defines a general SDP Capability Negotiation framework. It 1350 also specifies how to provide attributes and transport protocols as 1351 capabilities and negotiate them using the framework. Extensions for 1352 other types of capabilities (e.g., media types and media formats) may 1353 be provided in other documents. 1355 +---------+-----------------------+-------+--------------+ 1356 | Name | Notes | Level | Mux Category | 1357 +---------+-----------------------+-------+--------------+ 1358 | pcfg | Refer to Section 14 | M | SPECIAL | 1359 | | | | | 1360 | acfg | Refer to Section 14 | M | SPECIAL | 1361 | | | | | 1362 | csup | Not Impacted | B | NORMAL | 1363 | | | | | 1364 | creq | Not Impacted | B | NORMAL | 1365 | | | | | 1366 | acap | Refer to Section 14 | B | INHERIT | 1367 | | | | | 1368 | tcap | Refer to Section 14 | B | INHERIT | 1369 | | | | | 1370 | cap-v0 | Not Impacted | B | NORMAL | 1371 | | | | | 1372 +---------+-----------------------+-------+--------------+ 1374 RFC5939 Attribute Analysis 1376 5.33. RFC6871- SDP Media Capabilities Negotiation 1378 Session Description Protocol (SDP) capability negotiation provides a 1379 general framework for indicating and negotiating capabilities in SDP. 1380 The base framework defines only capabilities for negotiating 1381 transport protocols and attributes. [RFC6871] extends the framework 1382 by defining media capabilities that can be used to negotiate media 1383 types and their associated parameters. 1385 +---------+-----------------------+-------+-------------------+ 1386 | Name | Notes | Level | Mux Category | 1387 +---------+-----------------------+-------+-------------------+ 1388 | rmcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1389 | | | | | 1390 | omcap | Not Impacted | B | NORMAL | 1391 | | | | | 1392 | mfcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1393 | | | | | 1394 | mscap | Refer to Section 14 | B | INHERIT | 1395 | | | | | 1396 | lcfg | Refer to Section 14 | B | SPECIAL | 1397 | | | | | 1398 | sescap | Refer to notes below | S | NOT RECOMMENDED | 1399 | | | | | 1400 | med-v0 | Not Impacted | S | NORMAL | 1401 | | | | | 1402 +---------+-----------------------+-------+-------------------+ 1404 RFC6871 - Attribute Analysis 1406 NOTE: The "sescap" attribute is NOT RECOMMENDED for use with 1407 multiplexing. The reason is that it requires the use of unique 1408 configuration numbers across the entire SDP (per [RFC6871]) as 1409 opposed to within a media description only (per [RFC5939]). As 1410 described in Section 14, the use of identical configuration numbers 1411 between multiplexed (bundled) media descriptions is the default way 1412 of indicating compatible configurations in a bundle. 1414 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP 1416 [RFC7006] extends the SDP capability negotiation framework to allow 1417 endpoints to negotiate three additional SDP capabilities. In 1418 particular, this memo provides a mechanism to negotiate bandwidth 1419 ("b=" line), connection data ("c=" line), and session or media titles 1420 ("i=" line for each session or media). 1422 +----------+-----------------------------------+-------+------------+ 1423 | Name | Notes | Level | Mux | 1424 | | | | Category | 1425 +----------+-----------------------------------+-------+------------+ 1426 | bcap | Inherit the category SUM as | B | INHERIT | 1427 | | applicable to b= attribute | | | 1428 | | | | | 1429 | bcap-v0 | Not Impacted | B | NORMAL | 1430 | | | | | 1431 | ccap | The connection address type MUST | B | IDENTICAL | 1432 | | be identical across all the | | | 1433 | | multiplexed "m=" lines | | | 1434 | | | | | 1435 | ccap-v0 | Not Impacted | B | NORMAL | 1436 | | | | | 1437 | icap | Not Impacted | B | NORMAL | 1438 | | | | | 1439 | icap-v0 | Not Impacted | B | NORMAL | 1440 | | | | | 1441 +----------+-----------------------------------+-------+------------+ 1443 RFC7006 - Attribute Analysis 1445 5.35. RFC4567 - Key Management Extensions for SDP and RTSP 1447 [RFC4567] defines general extensions for Session Description Protocol 1448 (SDP) and Real Time Streaming Protocol (RTSP) to carry messages, as 1449 specified by a key management protocol, in order to secure the media. 1450 These extensions are presented as a framework, to be used by one or 1451 more key management protocols. As such, their use is meaningful only 1452 when complemented by an appropriate key management protocol. 1454 +-----------+----------------------------------+-------+------------+ 1455 | Name | Notes | Level | Mux | 1456 | | | | Category | 1457 +-----------+----------------------------------+-------+------------+ 1458 | key-mgmt | Key management protocol MUST be | B | IDENTICAL | 1459 | | identical across all the "m=" | | | 1460 | | lines | | | 1461 | | | | | 1462 | mikey | Key management protocol MUST be | B | IDENTICAL | 1463 | | identical across all the "m=" | | | 1464 | | lines | | | 1465 | | | | | 1466 +-----------+----------------------------------+-------+------------+ 1468 RFC4567 Attribute Analysis 1470 5.36. RFC4572 - Comedia over TLS in SDP 1472 [RFC4572] specifies how to establish secure connection-oriented media 1473 transport sessions over the Transport Layer Security (TLS) protocol 1474 using the Session Description Protocol (SDP). It defines a new SDP 1475 protocol identifier, 'TCP/TLS'. It also defines the syntax and 1476 semantics for an SDP 'fingerprint' attribute that identifies the 1477 certificate that will be presented for the TLS session. This 1478 mechanism allows media transport over TLS connections to be 1479 established securely, so long as the integrity of session 1480 descriptions is assured. 1482 +--------------+-------------------------------+-------+------------+ 1483 | Name | Notes | Level | Mux | 1484 | | | | Category | 1485 +--------------+-------------------------------+-------+------------+ 1486 | fingerprint | fingerprint value from the | B | TRANSPORT | 1487 | | "m=" line defining the | | | 1488 | | underlying transport is | | | 1489 | | chosen | | | 1490 | | | | | 1491 +--------------+-------------------------------+-------+------------+ 1493 RFC4572 Attribute Analysis 1495 5.37. RFC4570 - SDP Source Filters 1497 [RFC4570] describes how to adapt the Session Description Protocol 1498 (SDP) to express one or more source addresses as a source filter for 1499 one or more destination "connection" addresses. It defines the 1500 syntax and semantics for an SDP "source-filter" attribute that may 1501 reference either IPv4 or IPv6 address(es) as either an inclusive or 1502 exclusive source list for either multicast or unicast destinations. 1503 In particular, an inclusive source-filter can be used to specify a 1504 Source-Specific Multicast (SSM) session. 1506 +----------------+-----------------------------+-------+------------+ 1507 | Name | Notes | Level | Mux | 1508 | | | | Category | 1509 +----------------+-----------------------------+-------+------------+ 1510 | source-filter | The attribute MUST be | B | IDENTICAL | 1511 | | repeated across all "m=" | | | 1512 | | lines multiplexed | | | 1513 | | | | | 1514 +----------------+-----------------------------+-------+------------+ 1516 RFC4570 Attribute Analysis 1518 5.38. RFC6128 - RTCP Port for Multicast Sessions 1520 The Session Description Protocol (SDP) has an attribute that allows 1521 RTP applications to specify an address and a port associated with the 1522 RTP Control Protocol (RTCP) traffic. In RTP-based source-specific 1523 multicast (SSM) sessions, the same attribute is used to designate the 1524 address and the RTCP port of the Feedback Target in the SDP 1525 description. However, the RTCP port associated with the SSM session 1526 itself cannot be specified by the same attribute to avoid ambiguity, 1527 and thus, is required to be derived from the "m=" line of the media 1528 description. Deriving the RTCP port from the "m=" line imposes an 1529 unnecessary restriction. [RFC6128] removes this restriction by 1530 introducing a new SDP attribute. 1532 +-----------------+----------------------------+-------+------------+ 1533 | Name | Notes | Level | Mux | 1534 | | | | Category | 1535 +-----------------+----------------------------+-------+------------+ 1536 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | 1537 | | be identical across all | | | 1538 | | the "m=" lines | | | 1539 | | | | | 1540 +-----------------+----------------------------+-------+------------+ 1542 RFC6128 Attribute Analysis 1544 5.39. RFC6189 - ZRTP 1546 [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman 1547 exchange to agree on a session key and parameters for establishing 1548 unicast Secure Real-time Transport Protocol (SRTP) sessions for Voice 1549 over IP (VoIP) applications. 1551 +------------+---------------------------------+-------+------------+ 1552 | Name | Notes | Level | Mux | 1553 | | | | Category | 1554 +------------+---------------------------------+-------+------------+ 1555 | zrtp-hash | zrtp-hash attribute MUST be the | M | TRANSPORT | 1556 | | one that corresponds to the | | | 1557 | | "m=" line chosen for setting up | | | 1558 | | the underlying transport flow | | | 1559 | | | | | 1560 +------------+---------------------------------+-------+------------+ 1562 RFC6189 Attribute Analysis 1564 5.40. RFC4145 - Connection-Oriented Media 1566 [RFC4145] describes how to express media transport over TCP using the 1567 Session Description Protocol (SDP). It defines the SDP 'TCP' 1568 protocol identifier, the SDP 'setup' attribute, which describes the 1569 connection setup procedure, and the SDP 'connection' attribute, which 1570 handles connection reestablishment. 1572 +-------------+--------------------------------+-------+------------+ 1573 | Name | Notes | Level | Mux | 1574 | | | | Category | 1575 +-------------+--------------------------------+-------+------------+ 1576 | setup | The attribute MUST be | B | IDENTICAL | 1577 | | identical across all "m=" | | | 1578 | | lines | | | 1579 | | | | | 1580 | connection | Thee attribute MUST be | B | IDENTICAL | 1581 | | identical across all "m=" | | | 1582 | | lines | | | 1583 | | | | | 1584 +-------------+--------------------------------+-------+------------+ 1586 RFC4145 Attribute Analysis 1588 5.41. RFC6947 - The SDP ALTC Attribute 1590 [RFC6947] proposes a mechanism that allows the same SDP offer to 1591 carry multiple IP addresses of different address families (e.g., IPv4 1592 and IPv6). The proposed attribute, the "altc" attribute, solves the 1593 backward-compatibility problem that plagued Alternative Network 1594 Address Types (ANAT) due to their syntax. 1596 +-------+--------------------------------------+-------+------------+ 1597 | Name | Notes | Level | Mux | 1598 | | | | Category | 1599 +-------+--------------------------------------+-------+------------+ 1600 | altc | The IP Address and port MUST be the | M | TRANSPORT | 1601 | | one that corresponds to the "m=" | | | 1602 | | line chosen for setting up the | | | 1603 | | underlying transport flow | | | 1604 | | | | | 1605 +-------+--------------------------------------+-------+------------+ 1607 RFC6947 Attribute Analysis 1609 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers in PSTN 1611 [RFC7195] describes use cases, requirements, and protocol extensions 1612 for using the Session Description Protocol (SDP) offer/answer model 1613 for establishing audio and video media streams over circuit-switched 1614 bearers in the Public Switched Telephone Network (PSTN). 1616 +--------------------------+-------------------+-------+------------+ 1617 | Name | Notes | Level | Mux | 1618 | | | | Category | 1619 +--------------------------+-------------------+-------+------------+ 1620 | cs-correlation:callerid | Refer to notes | M | TBD | 1621 | | below | | | 1622 | | | | | 1623 | cs-correlation:uuie | Refer to notes | M | TBD | 1624 | | below | | | 1625 | | | | | 1626 | cs-correlation:dtmf | Refer to notes | M | TBD | 1627 | | below | | | 1628 | | | | | 1629 | cs-correlation:external | Refer to notes | M | TBD | 1630 | | below | | | 1631 | | | | | 1632 +--------------------------+-------------------+-------+------------+ 1634 RFC7195 Attribute Analysis 1636 NOTE: [RFC7195] defines SDP attributes for establishing audio and 1637 video media streams over circuit-switched bearers by defining a new 1638 nettype value "PSTN". However, section 7.2 of 1639 [I-D.ietf-mmusic-sdp-bundle-negotiation] requires the "c=" line 1640 nettype value of 'IN'. If in future there exists a specification 1641 that defines procedures to multiplex media streams over nettype 1642 "PSTN", the multiplexing categories for attributes in this section 1643 MUST be revisited. 1645 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) 1647 [RFC7272] defines a new RTP Control Protocol (RTCP) Packet Type and 1648 an RTCP Extended Report (XR) Block Type to be used for achieving 1649 Inter-Destination Media Synchronization (IDMS). 1651 +------------+---------------+-------+--------------+ 1652 | Name | Notes | Level | Mux Category | 1653 +------------+---------------+-------+--------------+ 1654 | rtcp-idms | Not Impacted | M | NORMAL | 1655 | | | | | 1656 +------------+---------------+-------+--------------+ 1658 RFC7272 Attribute Analysis 1660 5.44. RFC5159 - OMA BCAST SDP Attributes 1662 [RFC5159] provides descriptions of Session Description Protocol (SDP) 1663 attributes used by the Open Mobile Alliance's Broadcast Service and 1664 Content Protection specification. 1666 +---------------------+-----------------------+-------+-------------+ 1667 | Name | Notes | Level | Mux | 1668 | | | | Category | 1669 +---------------------+-----------------------+-------+-------------+ 1670 | bcastversion | Not Impacted | S | NORMAL | 1671 | | | | | 1672 | stkmstream | Not Impacted | B | NORMAL | 1673 | | | | | 1674 | SRTPAuthentication | Needs further | M | TBD | 1675 | | analysis | | | 1676 | | | | | 1677 | SRTPROCTxRate | Needs further | M | TBD | 1678 | | analysis | | | 1679 | | | | | 1680 +---------------------+-----------------------+-------+-------------+ 1682 RFC5159 Attribute Analysis 1684 5.45. RFC6193 - Media Description for IKE in SDP 1686 [RFC6193] specifies how to establish a media session that represents 1687 a virtual private network using the Session Initiation Protocol for 1688 the purpose of on-demand media/application sharing between peers. It 1689 extends the protocol identifier of the Session Description Protocol 1690 (SDP) so that it can negotiate use of the Internet Key Exchange 1691 Protocol (IKE) for media sessions in the SDP offer/answer model. 1693 +-------------------+--------------------------+-------+------------+ 1694 | Name | Notes | Level | Mux | 1695 | | | | Category | 1696 +-------------------+--------------------------+-------+------------+ 1697 | ike-setup | Attribute MUST be | B | IDENTICAL | 1698 | | identical across all the | | | 1699 | | "m=" lines | | | 1700 | | | | | 1701 | psk-fingerprint | Attribute MUST be | B | IDENTICAL | 1702 | | identical across all the | | | 1703 | | "m=" lines | | | 1704 | | | | | 1705 | ike-esp | Attribute MUST be | B | IDENTICAL | 1706 | | identical across all the | | | 1707 | | "m=" lines | | | 1708 | | | | | 1709 | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL | 1710 | | identical across all the | | | 1711 | | "m=" lines | | | 1712 | | | | | 1713 +-------------------+--------------------------+-------+------------+ 1715 RFC6193 Attribute Analysis 1717 NOTE: With the above SDP constraints, a session multiplexed with 1718 multiple "m=" lines will use only one IPSec association for all of 1719 the "m=" lines. 1721 5.46. RFC2326 - Real Time Streaming Protocol 1723 The Real Time Streaming Protocol, or RTSP, is an application-level 1724 protocol for control over the delivery of data with real-time 1725 properties. RTSP provides an extensible framework to enable 1726 controlled, on-demand delivery of real-time data, such as audio and 1727 video. 1729 +----------+---------------------------------+-------+--------------+ 1730 | Name | Notes | Level | Mux Category | 1731 +----------+---------------------------------+-------+--------------+ 1732 | etag | RTSP is not supported for RTP | B | NOT | 1733 | | Stream multiplexing | | RECOMMENDED | 1734 | | | | | 1735 | range | RTSP is not supported for RTP | B | NOT | 1736 | | Stream multiplexing | | RECOMMENDED | 1737 | | | | | 1738 | control | RTSP is not supported for RTP | B | NOT | 1739 | | Stream multiplexing | | RECOMMENDED | 1740 | | | | | 1741 | mtag | RTSP is not supported for RTP | B | NOT | 1742 | | Stream multiplexing | | RECOMMENDED | 1743 | | | | | 1744 +----------+---------------------------------+-------+--------------+ 1746 RFC2326 Attribute Analysis 1748 NOTE: [RFC2326] defines SDP attributes that are applicable in the 1749 declarative usage of SDP alone. For purposes of this document, only 1750 the Offer/Answer usage of SDP is considered as mandated by 1751 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1753 5.47. RFC6064 - SDP and RTSP Extensions for 3GPP 1755 The Packet-switched Streaming Service (PSS) and the Multimedia 1756 Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session 1757 Description Protocol (SDP) and Real Time Streaming Protocol (RTSP) 1758 with some extensions. [RFC6064] provides information about these 1759 extensions and registers the RTSP and SDP extensions with IANA. 1761 +-------------------------------+------------+-------+--------------+ 1762 | Name | Notes | Level | Mux Category | 1763 +-------------------------------+------------+-------+--------------+ 1764 | X-predecbufsize | Refer to | M | NOT | 1765 | | notes | | RECOMMENDED | 1766 | | below | | | 1767 | | | | | 1768 | X-initpredecbufperiod | Refer to | M | NOT | 1769 | | notes | | RECOMMENDED | 1770 | | below | | | 1771 | | | | | 1772 | X-initpostdecbufperiod | Refer to | M | NOT | 1773 | | notes | | RECOMMENDED | 1774 | | below | | | 1775 | | | | | 1776 | X-decbyterate | Refer to | M | NOT | 1777 | | notes | | RECOMMENDED | 1778 | | below | | | 1779 | | | | | 1780 | 3gpp-videopostdecbufsize | Refer to | M | NOT | 1781 | | notes | | RECOMMENDED | 1782 | | below | | | 1783 | | | | | 1784 | framesize | Refer to | M | NOT | 1785 | | notes | | RECOMMENDED | 1786 | | below | | | 1787 | | | | | 1788 | 3GPP-Integrity-Key | Refer to | S | NOT | 1789 | | notes | | RECOMMENDED | 1790 | | below | | | 1791 | | | | | 1792 | 3GPP-SDP-Auth | Refer to | S | NOT | 1793 | | notes | | RECOMMENDED | 1794 | | below | | | 1795 | | | | | 1796 | 3GPP-SRTP-Config | Refer to | M | NOT | 1797 | | notes | | RECOMMENDED | 1798 | | below | | | 1799 | | | | | 1800 | alt | Refer to | M | NOT | 1801 | | notes | | RECOMMENDED | 1802 | | below | | | 1803 | | | | | 1804 | alt-default-id | Refer to | M | NOT | 1805 | | notes | | RECOMMENDED | 1806 | | below | | | 1807 | | | | | 1808 | alt-group | Refer to | M | NOT | 1809 | | notes | | RECOMMENDED | 1810 | | below | | | 1811 | | | | | 1812 | 3GPP-Adaptation-Support | Refer to | M | NOT | 1813 | | notes | | RECOMMENDED | 1814 | | below | | | 1815 | | | | | 1816 | 3GPP-Asset-Information | Refer to | B | NOT | 1817 | | notes | | RECOMMENDED | 1818 | | below | | | 1819 | | | | | 1820 | mbms-mode | Refer to | B | NOT | 1821 | | notes | | RECOMMENDED | 1822 | | below | | | 1823 | | | | | 1824 | mbms-flowid | Refer to | M | NOT | 1825 | | notes | | RECOMMENDED | 1826 | | below | | | 1827 | | | | | 1828 | mbms-repair | Refer to | B | NOT | 1829 | | notes | | RECOMMENDED | 1830 | | below | | | 1831 | | | | | 1832 | 3GPP-QoE-Metrics | Refer to | M | NOT | 1833 | | notes | | RECOMMENDED | 1834 | | below | | | 1835 | | | | | 1836 | 3GPP-QoE-Metrics:Corruption | Refer to | M | NOT | 1837 | duration | notes | | RECOMMENDED | 1838 | | below | | | 1839 | | | | | 1840 | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | NOT | 1841 | duration | notes | | RECOMMENDED | 1842 | | below | | | 1843 | | | | | 1844 | 3GPP-QoE-Metrics:Initial | Refer to | M | NOT | 1845 | buffering duration | notes | | RECOMMENDED | 1846 | | below | | | 1847 | | | | | 1848 | 3GPP-QoE-Metrics:Successive | Refer to | M | NOT | 1849 | loss of RTP packets | notes | | RECOMMENDED | 1850 | | below | | | 1851 | | | | | 1852 | 3GPP-QoE-Metrics:Frame rate | Refer to | M | NOT | 1853 | deviation | notes | | RECOMMENDED | 1854 | | below | | | 1855 | | | | | 1856 | 3GPP-QoE-Metrics:Jitter | Refer to | M | NOT | 1857 | duration | notes | | RECOMMENDED | 1858 | | below | | | 1859 | | | | | 1860 | 3GPP-QoE-Metrics:Content | Refer to | B | NOT | 1861 | Switch Time | notes | | RECOMMENDED | 1862 | | below | | | 1863 | | | | | 1864 | 3GPP-QoE-Metrics:Average | Refer to | M | NOT | 1865 | Codec Bitrate | notes | | RECOMMENDED | 1866 | | below | | | 1867 | | | | | 1868 | 3GPP-QoE-Metrics:Codec | Refer to | M | NOT | 1869 | Information | notes | | RECOMMENDED | 1870 | | below | | | 1871 | | | | | 1872 | 3GPP-QoE-Metrics:Buffer | Refer to | M | NOT | 1873 | Status | notes | | RECOMMENDED | 1874 | | below | | | 1875 | | | | | 1876 +-------------------------------+------------+-------+--------------+ 1878 RFC6064 Attribute Analysis 1880 NOTE: [RFC6064] defines SDP attributes that are applicable in the 1881 declarative usage of SDP alone. For purposes of this document, only 1882 the Offer/Answer usage of SDP is considered as mandated by 1883 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1885 5.48. RFC3108 - ATM SDP 1887 [RFC3108] describes conventions for using the Session Description 1888 Protocol (SDP) described for controlling ATM Bearer Connections, and 1889 any associated ATM Adaptation Layer (AAL). 1891 +------------------------+------------------+-------+---------------+ 1892 | Name | Notes | Level | Mux Category | 1893 +------------------------+------------------+-------+---------------+ 1894 | aalType | Refer to notes | B | NOT | 1895 | | below | | RECOMMENDED | 1896 | eecid | Refer to notes | B | NOT | 1897 | | below | | RECOMMENDED | 1898 | capability | Refer to notes | B | NOT | 1899 | | below | | RECOMMENDED | 1900 | qosClass | Refer to notes | B | NOT | 1901 | | below | | RECOMMENDED | 1902 | bcob | Refer to notes | B | NOT | 1903 | | below | | RECOMMENDED | 1904 | stc | Refer to notes | B | NOT | 1905 | | below | | RECOMMENDED | 1906 | upcc | Refer to notes | B | NOT | 1907 | | below | | RECOMMENDED | 1908 | atmQOSparms | Refer to notes | B | NOT | 1909 | | below | | RECOMMENDED | 1910 | atmTrfcDesc | Refer to notes | B | NOT | 1911 | | below | | RECOMMENDED | 1912 | abrParms | Refer to notes | B | NOT | 1913 | | below | | RECOMMENDED | 1914 | abrSetup | Refer to notes | B | NOT | 1915 | | below | | RECOMMENDED | 1916 | bearerType | Refer to notes | B | NOT | 1917 | | below | | RECOMMENDED | 1918 | lij | Refer to notes | B | NOT | 1919 | | below | | RECOMMENDED | 1920 | anycast | Refer to notes | B | NOT | 1921 | | below | | RECOMMENDED | 1922 | cache | Refer to notes | B | NOT | 1923 | | below | | RECOMMENDED | 1924 | bearerSigIE | Refer to notes | B | NOT | 1925 | | below | | RECOMMENDED | 1926 | aalApp | Refer to notes | B | NOT | 1927 | | below | | RECOMMENDED | 1928 | cbrRate | Refer to notes | B | NOT | 1929 | | below | | RECOMMENDED | 1930 | sbc | Refer to notes | B | NOT | 1931 | | below | | RECOMMENDED | 1932 | clkrec | Refer to notes | B | NOT | 1933 | | below | | RECOMMENDED | 1934 | fec | Refer to notes | B | NOT | 1935 | | below | | RECOMMENDED | 1936 | prtfl | Refer to notes | B | NOT | 1937 | | below | | RECOMMENDED | 1938 | structure | Refer to notes | B | NOT | 1939 | | below | | RECOMMENDED | 1940 | cpsSDUsize | Refer to notes | B | NOT | 1941 | | below | | RECOMMENDED | 1942 | aal2CPS | Refer to notes | B | NOT | 1943 | | below | | RECOMMENDED | 1944 | aal2CPSSDUrate | Refer to notes | B | NOT | 1945 | | below | | RECOMMENDED | 1946 | aal2sscs3661unassured | Refer to notes | B | NOT | 1947 | | below | | RECOMMENDED | 1948 | aal2sscs3661assured | Refer to notes | B | NOT | 1949 | | below | | RECOMMENDED | 1950 | aal2sscs3662 | Refer to notes | B | NOT | 1951 | | below | | RECOMMENDED | 1952 | aal5sscop | Refer to notes | B | NOT | 1953 | | below | | RECOMMENDED | 1954 | atmmap | Refer to notes | B | NOT | 1955 | | below | | RECOMMENDED | 1956 | silenceSupp | Refer to notes | B | NOT | 1957 | | below | | RECOMMENDED | 1958 | ecan | Refer to notes | B | NOT | 1959 | | below | | RECOMMENDED | 1960 | gc | Refer to notes | B | NOT | 1961 | | below | | RECOMMENDED | 1962 | profileDesc | Refer to notes | B | NOT | 1963 | | below | | RECOMMENDED | 1964 | vsel | Refer to notes | B | NOT | 1965 | | below | | RECOMMENDED | 1966 | dsel | Refer to notes | B | NOT | 1967 | | below | | RECOMMENDED | 1968 | fsel | Refer to notes | B | NOT | 1969 | | below | | RECOMMENDED | 1970 | onewaySel | Refer to notes | B | NOT | 1971 | | below | | RECOMMENDED | 1972 | codecconfig | Refer to notes | B | NOT | 1973 | | below | | RECOMMENDED | 1974 | isup_usi | Refer to notes | B | NOT | 1975 | | below | | RECOMMENDED | 1976 | uiLayer1_Prot | Refer to notes | B | NOT | 1977 | | below | | RECOMMENDED | 1978 | chain | Refer to notes | B | NOT | 1979 | | below | | RECOMMENDED | 1980 | | | | | 1981 +------------------------+------------------+-------+---------------+ 1983 RFC3108 Attribute Analysis 1985 NOTE: RFC3108 describes conventions for using the Session Description 1986 Protocol (SDP) for characterizing ATM bearer connections using an 1987 AAL1, AAL2 or AAL5 adaptation layers. For AAL1, AAL2 and AAL5, 1988 bearer connections can be used to transport single media streams. In 1989 addition, for AAL1 and AAL2, multiple media streams MAY be 1990 multiplexed into a bearer connection. For all adaptation types 1991 (AAL1, AAL2 and AAL5), bearer connections MAY be bundled into a 1992 single media group. In all cases addressed by RFC3108, a real-time 1993 media stream (voice, video, voiceband data, pseudo-wire and others) 1994 or a multiplex of media streams is mapped directly into an ATM 1995 connection. RFC3108 does not address cases where ATM serves as a 1996 low-level transport pipe for IP packets which in turn MAY carry one 1997 or more real-time (e.g. VoIP) media sessions with a life-cycle 1998 different from that of the underlying ATM transport. 2000 5.49. 3GPP TS 26.114 2002 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and 2003 interaction 2004 +----------------------+-------------------------+-------+----------+ 2005 | Name | Notes | Level | Mux | 2006 | | | | Category | 2007 +----------------------+-------------------------+-------+----------+ 2008 | 3gpp_sync_info | Usage defined for the | M | NORMAL | 2009 | | IP Multimedia Subsystem | | | 2010 | | | | | 2011 | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL | 2012 | | IP Multimedia Subsystem | | | 2013 | | | | | 2014 +----------------------+-------------------------+-------+----------+ 2016 3GPP TS 26.114 Attribute Analysis 2018 5.50. 3GPP TS 183.063 2020 [R3GPPTS183.063] Telecommunications and Internet converged Services 2021 and Protocols for Advanced Networking (TISPAN); 2023 +---------------------+---------------+-------+--------------+ 2024 | Name | Notes | Level | Mux Category | 2025 +---------------------+---------------+-------+--------------+ 2026 | PSCid | Not Impacted | S | NORMAL | 2027 | | | | | 2028 | bc_service | Not Impacted | S | NORMAL | 2029 | | | | | 2030 | bc_program | Not Impacted | S | NORMAL | 2031 | | | | | 2032 | bc_service_package | Not Impacted | S | NORMAL | 2033 | | | | | 2034 +---------------------+---------------+-------+--------------+ 2036 3GPP TS 183.063 Attribute Analysis 2038 5.51. 3GPP TS 24.182 2040 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting 2041 tones 2042 +-------------+---------------------------------+-------+-----------+ 2043 | Name | Notes | Level | Mux | 2044 | | | | Category | 2045 +-------------+---------------------------------+-------+-----------+ 2046 | g.3gpp.cat | Usage defined for the IP | M | NORMAL | 2047 | | Multimedia Subsystem | | | 2048 | | | | | 2049 +-------------+---------------------------------+-------+-----------+ 2051 3GPP TS 24.182 Attribute Analysis 2053 5.52. 3GPP TS 24.183 2055 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing 2056 Signal 2058 +-------------+---------------------------------+-------+-----------+ 2059 | Name | Notes | Level | Mux | 2060 | | | | Category | 2061 +-------------+---------------------------------+-------+-----------+ 2062 | g.3gpp.crs | Usage defined for the IP | M | NORMAL | 2063 | | Multimedia Subsystem | | | 2064 | | | | | 2065 +-------------+---------------------------------+-------+-----------+ 2067 3GPP TS 24.183 Attribute Analysis 2069 5.53. 3GPP TS 24.229 2071 [R3GPPTS24.229] specifies IP multimedia call control protocol based 2072 on Session Initial protocol and Session Description Protocol. 2074 +------------------+---------------------------+-------+------------+ 2075 | Name | Notes | Level | Mux | 2076 | | | | Category | 2077 +------------------+---------------------------+-------+------------+ 2078 | secondary-realm | secondary-realm MUST be | M | TRANSPORT | 2079 | | the one that corresponds | | | 2080 | | to the "m=" line chosen | | | 2081 | | for setting up the | | | 2082 | | underlying transport flow | | | 2083 | | | | | 2084 | visited-realm | visited-realm MUST be the | M | TRANSPORT | 2085 | | one that corresponds to | | | 2086 | | the "m=" line chosen for | | | 2087 | | setting up the underlying | | | 2088 | | transport flow | | | 2089 | | | | | 2090 | omr-m-cksum | Not Impacted | M | NORMAL | 2091 | | | | | 2092 | omr-s-cksum | Not Impacted | M | NORMAL | 2093 | | | | | 2094 | omr-m-att | Not Impacted | M | NORMAL | 2095 | | | | | 2096 | omr-s-att | Not Impacted | M | NORMAL | 2097 | | | | | 2098 | omr-m-bw | Not Impacted | M | NORMAL | 2099 | | | | | 2100 | omr-s-bw | Not Impacted | M | NORMAL | 2101 | | | | | 2102 | omr-codecs | Not Impacted | M | NORMAL | 2103 | | | | | 2104 +------------------+---------------------------+-------+------------+ 2106 3GPP TS 24.229 Attribute Analysis 2108 5.54. ITU T.38 2110 [T.38] defines procedures for real-time Group 3 facsimile 2111 communications over IP networks. 2113 +------------------------+--------------------+-------+-------------+ 2114 | Name | Notes | Level | Mux | 2115 | | | | Category | 2116 +------------------------+--------------------+-------+-------------+ 2117 | T38FaxVersion | Refer to notes | S | TBD | 2118 | | below | | | 2119 | | | | | 2120 | T38MaxBitRate | Refer to notes | S | TBD | 2121 | | below | | | 2122 | | | | | 2123 | T38FaxFillBitRemoval | Refer to notes | S | TBD | 2124 | | below | | | 2125 | | | | | 2126 | T38FaxTranscodingMMR | Refer to notes | S | TBD | 2127 | | below | | | 2128 | | | | | 2129 | T38FaxTranscodingJBIG | Refer to notes | S | TBD | 2130 | | below | | | 2131 | | | | | 2132 | T38FaxRateManagement | Refer to notes | S | TBD | 2133 | | below | | | 2134 | | | | | 2135 | T38FaxMaxBuffer | Refer to notes | S | TBD | 2136 | | below | | | 2137 | | | | | 2138 | T38FaxMaxDatagram | Refer to notes | S | TBD | 2139 | | below | | | 2140 | | | | | 2141 | T38FaxUdpEC | Refer to notes | S | TBD | 2142 | | below | | | 2143 | | | | | 2144 | T38FaxMaxIFP | Refer to notes | S | TBD | 2145 | | below | | | 2146 | | | | | 2147 | T38FaxUdpECDepth | Refer to notes | S | TBD | 2148 | | below | | | 2149 | | | | | 2150 | T38FaxUdpFECMaxSpan | Refer to notes | S | TBD | 2151 | | below | | | 2152 | | | | | 2153 | T38ModemType | Refer to notes | S | TBD | 2154 | | below | | | 2155 | | | | | 2156 | T38VendorInfo | Refer to notes | S | TBD | 2157 | | below | | | 2158 | | | | | 2159 +------------------------+--------------------+-------+-------------+ 2161 ITU T.38 Attribute Analysis 2163 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2164 there exists no publicly available specification that defines 2165 procedures for multiplexing/demultiplexing fax protocols flows over a 2166 single 5-tuple. Once such a specification is available, the 2167 multiplexing category assignments for the attributes in this section 2168 MUST be revisited. 2170 5.55. ITU-T Q.1970 2172 [Q.1970] defines BICC IP bearer control protocol. 2174 +--------+---------------------------------------+-------+----------+ 2175 | Name | Notes | Level | Mux | 2176 | | | | Category | 2177 +--------+---------------------------------------+-------+----------+ 2178 | ipbcp | ipbcp version identifies type of | S | SPECIAL | 2179 | | IPBCP message used in BICC (ITU-T | | | 2180 | | Q.1901) environment which are limited | | | 2181 | | to single media payload. Pertinent | | | 2182 | | ITU.T specifications needs to be | | | 2183 | | referred while multiplexing | | | 2184 | | | | | 2185 +--------+---------------------------------------+-------+----------+ 2187 ITU-T Q.1970 Attribute Analysis 2189 5.56. ITU-T H.248.15 2191 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 2192 package attribute 2193 +-----------+------------------------------------+-------+----------+ 2194 | Name | Notes | Level | Mux | 2195 | | | | Category | 2196 +-----------+------------------------------------+-------+----------+ 2197 | h248item | It is only applicable for | B | SPECIAL | 2198 | | signaling the inclusion of H.248 | | | 2199 | | extension packages to a gateway | | | 2200 | | via the local and remote | | | 2201 | | descriptors. The attribute itself | | | 2202 | | is unaffected by multiplexing, but | | | 2203 | | the packaged referenced in a | | | 2204 | | specific use of the attribute may | | | 2205 | | be impacted. Further analysis of | | | 2206 | | each package is needed to | | | 2207 | | determine if there is an issue. | | | 2208 | | This is only a concern in | | | 2209 | | environments using a decomposed | | | 2210 | | server/gateway with H.248 signaled | | | 2211 | | between them. The ITU-T will need | | | 2212 | | to do further analysis of various | | | 2213 | | packages when they specify how to | | | 2214 | | signal the use of multiplexing to | | | 2215 | | a gateway | | | 2216 | | | | | 2217 +-----------+------------------------------------+-------+----------+ 2219 ITU-T H.248.15 Attribute Analysis 2221 5.57. RFC4975 - The Message Session Relay Protocol 2223 [RFC4975] the Message Session Relay Protocol, a protocol for 2224 transmitting a series of related instant messages in the context of a 2225 session. Message sessions are treated like any other media stream 2226 when set up via a rendezvous or session creation protocol such as the 2227 Session Initiation Protocol. 2229 +-----------------------+---------------------+-------+-------------+ 2230 | Name | Notes | Level | Mux | 2231 | | | | Category | 2232 +-----------------------+---------------------+-------+-------------+ 2233 | accept-types | Refer to notes | M | TBD | 2234 | | below | | | 2235 | | | | | 2236 | accept-wrapped-types | Refer to notes | M | TBD | 2237 | | below | | | 2238 | | | | | 2239 | max-size | Refer to notes | M | TBD | 2240 | | below | | | 2241 | | | | | 2242 | path | Refer to notes | M | TBD | 2243 | | below | | | 2244 | | | | | 2245 +-----------------------+---------------------+-------+-------------+ 2247 RFC4975 Attribute Analysis 2249 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2250 there exists no publicly available specification that defines 2251 procedures for multiplexing/demultiplexing MRSP flows over a single 2252 5-tuple. Once such a specification is available, the multiplexing 2253 categories assignments for the attributes in this section MUST be 2254 revisited. 2256 5.58. Historical Attributes 2258 This section specifies analysis for the attributes that are included 2259 for historic usage alone by the [IANA]. 2261 +----------+----------------------+-------+------------------+ 2262 | Name | Notes | Level | Mux Category | 2263 +----------+----------------------+-------+------------------+ 2264 | rtpred1 | Historic attributes | M | NOT RECOMMENDED | 2265 | | | | | 2266 | rtpred2 | Historic attributes | M | NOT RECOMMENDED | 2267 | | | | | 2268 +----------+----------------------+-------+------------------+ 2270 Historical Attribute Analysis 2272 6. bwtype Attribute Analysis 2274 This section specifies handling of specific bandwidth attributes when 2275 used in multiplexing scenarios. 2277 6.1. RFC4566 - SDP: Session Description Protocol 2279 [RFC4566] defines the Session Description Protocol (SDP) that is 2280 intended for describing multimedia sessions for the purposes of 2281 session announcement, session invitation, and other forms of 2282 multimedia session initiation. 2284 +------------+-----------------------------------+-------+----------+ 2285 | Name | Notes | Level | Mux | 2286 | | | | Category | 2287 +------------+-----------------------------------+-------+----------+ 2288 | bwtype:CT | Not Impacted | S | NORMAL | 2289 | | | | | 2290 | bwtype:AS | For the media level usage, the | B | SUM | 2291 | | aggregate of individual bandwidth | | | 2292 | | values is considered | | | 2293 | | | | | 2294 +------------+-----------------------------------+-------+----------+ 2296 RFC4566 bwtype Analysis 2298 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth 2300 [RFC3556] defines an extension to the Session Description Protocol 2301 (SDP) to specify two additional modifiers for the bandwidth 2302 attribute. These modifiers may be used to specify the bandwidth 2303 allowed for RTP Control Protocol (RTCP) packets in a Real-time 2304 Transport Protocol (RTP) session. 2306 +------------+-----------------------------------+-------+----------+ 2307 | Name | Notes | Level | Mux | 2308 | | | | Category | 2309 +------------+-----------------------------------+-------+----------+ 2310 | bwtype:RS | Session level usage represents | B | SUM | 2311 | | session aggregate and media level | | | 2312 | | usage indicates SUM of the | | | 2313 | | individual values while | | | 2314 | | multiplexing | | | 2315 | | | | | 2316 | bwtype:RR | Session level usage represents | B | SUM | 2317 | | session aggregate and media level | | | 2318 | | usage indicates SUM of the | | | 2319 | | individual values while | | | 2320 | | multiplexing | | | 2321 | | | | | 2322 +------------+-----------------------------------+-------+----------+ 2324 RFC3556 bwtype Analysis 2326 6.3. RFC3890 - Bandwidth Modifier for SDP 2328 [RFC3890] defines a Session Description Protocol (SDP) Transport 2329 Independent Application Specific Maximum (TIAS) bandwidth modifier 2330 that does not include transport overhead; instead an additional 2331 packet rate attribute is defined. The transport independent bit-rate 2332 value together with the maximum packet rate can then be used to 2333 calculate the real bit-rate over the transport actually used. 2335 +--------------+---------------------------------+-------+----------+ 2336 | Name | Notes | Level | Mux | 2337 | | | | Category | 2338 +--------------+---------------------------------+-------+----------+ 2339 | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL | 2340 | | clearly defined Offer/Answer | | | 2341 | | usage. | | | 2342 | | | | | 2343 | maxprate | The usage of TIAS and maxprate | B | SPECIAL | 2344 | | is not well defined under | | | 2345 | | multiplexing | | | 2346 | | | | | 2347 +--------------+---------------------------------+-------+----------+ 2349 RFC3890 bwtype Analysis 2351 NOTE: The intention of TIAS is that the media level bit-rate is 2352 multiplied with the known per-packet overhead for the selected 2353 transport and the maxprate value to determine the worst case bit-rate 2354 from the transport to more accurately capture the required usage. 2355 Summing TIAS values independently across "m=" lines and multiplying 2356 the computed sum with maxprate and the per-packet overhead would 2357 inflate the value significantly. Instead performing multiplication 2358 and adding the individual values is a more appropriate usage. 2360 7. rtcp-fb Attribute Analysis 2362 This section analyzes rtcp-fb SDP attributes. 2364 7.1. RFC4585 - RTP/AVPF 2366 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 2367 enables receivers to provide, statistically, more immediate feedback 2368 to the senders and thus allows for short-term adaptation and 2369 efficient feedback-based repair mechanisms to be implemented. 2371 +----------+----------------------------+-------+-------------------+ 2372 | Name | Notes | Level | Mux Category | 2373 +----------+----------------------------+-------+-------------------+ 2374 | ack rpsi | The attribute value MUST | M | IDENTICAL-PER-PT | 2375 | | be same for a given codec | | | 2376 | | configuration | | | 2377 | | | | | 2378 | ack app | Feedback parameters MUST | M | SPECIAL | 2379 | | be handled in the app | | | 2380 | | specific way when | | | 2381 | | multiplexed | | | 2382 | | | | | 2383 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2384 | | be same for a given codec | | | 2385 | | configuration | | | 2386 | | | | | 2387 | nack pli | The attribute value MUST | M | IDENTICAL-PER-PT | 2388 | | be same for a given codec | | | 2389 | | configuration | | | 2390 | | | | | 2391 | nack sli | The attribute value MUST | M | IDENTICAL-PER-PT | 2392 | | be same for a given codec | | | 2393 | | configuration | | | 2394 | | | | | 2395 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2396 | rpsi | be same for a given codec | | | 2397 | | configuration | | | 2398 | | | | | 2399 | nack app | Feedback parameters MUST | M | SPECIAL | 2400 | | be handled in the app | | | 2401 | | specific way when | | | 2402 | | multiplexed | | | 2403 | | | | | 2404 | trr-int | The attribute value MUST | M | IDENTICAL-PER-PT | 2405 | | be same for a given codec | | | 2406 | | configuration | | | 2407 | | | | | 2408 +----------+----------------------------+-------+-------------------+ 2410 RFC4585 Attribute Analysis 2412 7.2. RFC5104 - Codec Control Messages in AVPF 2414 [RFC5104] specifies a few extensions to the messages defined in the 2415 Audio-Visual Profile with Feedback (AVPF). They are helpful 2416 primarily in conversational multimedia scenarios where centralized 2417 multipoint functionalities are in use. However, some are also usable 2418 in smaller multicast environments and point-to-point calls. 2420 +------+--------------------------------+-------+-------------------+ 2421 | Name | Notes | Level | Mux Category | 2422 +------+--------------------------------+-------+-------------------+ 2423 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2424 | | same for a given codec | | | 2425 | | configuration | | | 2426 | | | | | 2427 +------+--------------------------------+-------+-------------------+ 2429 RFC5104 Attribute Analysis 2431 7.3. RFC6285 - Unicast-Based RAMS 2433 [RFC6285] describes a method using the existing RTP and RTP Control 2434 Protocol (RTCP) machinery that reduces the acquisition delay. In 2435 this method, an auxiliary unicast RTP session carrying the Reference 2436 Information to the receiver precedes or accompanies the multicast 2437 stream. This unicast RTP flow can be transmitted at a faster than 2438 natural bitrate to further accelerate the acquisition. The 2439 motivating use case for this capability is multicast applications 2440 that carry real-time compressed audio and video. 2442 +-------+-------------------------------+-------+-------------------+ 2443 | Name | Notes | Level | Mux Category | 2444 +-------+-------------------------------+-------+-------------------+ 2445 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2446 | rai | same for a given codec | | | 2447 | | configuration | | | 2448 | | | | | 2449 +-------+-------------------------------+-------+-------------------+ 2451 RFC6285 Attribute Analysis 2453 7.4. RFC6679 - ECN for RTP over UDP/IP 2455 [RFC6679] specifies how Explicit Congestion Notification (ECN) can be 2456 used with the Real-time Transport Protocol (RTP) running over UDP, 2457 using the RTP Control Protocol (RTCP) as a feedback mechanism. It 2458 defines a new RTCP Extended Report (XR) block for periodic ECN 2459 feedback, a new RTCP transport feedback message for timely reporting 2460 of congestion events, and a Session Traversal Utilities for NAT 2461 (STUN) extension used in the optional initialization method using 2462 Interactive Connectivity Establishment (ICE). 2464 +------------------+---------------------------+-------+------------+ 2465 | Name | Notes | Level | Mux | 2466 | | | | Category | 2467 +------------------+---------------------------+-------+------------+ 2468 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | 2469 | | the RTP session level | | | 2470 | | | | | 2471 | nack ecn | This attribute enables | M | IDENTICAL | 2472 | | ECN at the RTP session | | | 2473 | | level | | | 2474 | | | | | 2475 +------------------+---------------------------+-------+------------+ 2477 RFC6679 Attribute Analysis 2479 7.5. RFC6642 - Third-Party Loss Report 2481 In a large RTP session using the RTP Control Protocol (RTCP) feedback 2482 mechanism defined in [RFC4585], a feedback target may experience 2483 transient overload if some event causes a large number of receivers 2484 to send feedback at once. This overload is usually avoided by 2485 ensuring that feedback reports are forwarded to all receivers, 2486 allowing them to avoid sending duplicate feedback reports. However, 2487 there are cases where it is not recommended to forward feedback 2488 reports, and this may allow feedback implosion. [RFC6642] memo 2489 discusses these cases and defines a new RTCP Third-Party Loss Report 2490 that can be used to inform receivers that the feedback target is 2491 aware of some loss event, allowing them to suppress feedback. 2492 Associated Session Description Protocol (SDP) signaling is also 2493 defined. 2495 +--------+------------------------------+-------+-------------------+ 2496 | Name | Notes | Level | Mux Category | 2497 +--------+------------------------------+-------+-------------------+ 2498 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2499 | tllei | same for a given codec | | | 2500 | | configuration | | | 2501 | | | | | 2502 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2503 | pslei | same for a given codec | | | 2504 | | configuration | | | 2505 | | | | | 2506 +--------+------------------------------+-------+-------------------+ 2508 RFC6642 Attribute Analysis 2510 7.6. RFC5104 - Codec Control Messages in AVPF 2512 [RFC5104] specifies a few extensions to the messages defined in the 2513 Audio-Visual Profile with Feedback (AVPF). They are helpful 2514 primarily in conversational multimedia scenarios where centralized 2515 multipoint functionalities are in use. However, some are also usable 2516 in smaller multicast environments and point-to-point calls. 2518 +--------+------------------------------+-------+-------------------+ 2519 | Name | Notes | Level | Mux Category | 2520 +--------+------------------------------+-------+-------------------+ 2521 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2522 | fir | same for a given codec | | | 2523 | | configuration | | | 2524 | | | | | 2525 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2526 | tmmbr | same for a given codec | | | 2527 | | configuration | | | 2528 | | | | | 2529 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2530 | tstr | same for a given codec | | | 2531 | | configuration | | | 2532 | | | | | 2533 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2534 | vbcm | same for a given codec | | | 2535 | | configuration | | | 2536 | | | | | 2537 +--------+------------------------------+-------+-------------------+ 2539 RFC5104 Attribute Analysis 2541 8. group Attribute Analysis 2543 This section analyzes SDP "group" attribute semantics [RFC5888]. 2545 8.1. RFC5888 - SDP Grouping Framework 2547 [RFC5888] defines a framework to group "m" lines in the Session 2548 Description Protocol (SDP) for different purposes. 2550 +------------+---------------+-------+--------------+ 2551 | Name | Notes | Level | Mux Category | 2552 +------------+---------------+-------+--------------+ 2553 | group:LS | Not Impacted | S | NORMAL | 2554 | | | | | 2555 | group:FID | Not Impacted | S | NORMAL | 2556 | | | | | 2557 +------------+---------------+-------+--------------+ 2559 RFC5888 Attribute Analysis 2561 8.2. RFC3524 - Mapping Media Streams to Resource Reservation Flows 2563 [RFC3524] defines an extension to the Session Description Protocol 2564 (SDP) grouping framework. It allows requesting a group of media 2565 streams to be mapped into a single resource reservation flow. The 2566 SDP syntax needed is defined, as well as a new "semantics" attribute 2567 called Single Reservation Flow (SRF). 2569 +------------+---------------+-------+--------------+ 2570 | Name | Notes | Level | Mux Category | 2571 +------------+---------------+-------+--------------+ 2572 | group:SRF | Not Impacted | S | NORMAL | 2573 | | | | | 2574 +------------+---------------+-------+--------------+ 2576 RFC3524 Attribute Analysis 2578 8.3. RFC4091 - ANAT Semantics 2580 [RFC4091] defines the Alternative Network Address Types (ANAT) 2581 semantics for the Session Description Protocol (SDP) grouping 2582 framework. The ANAT semantics allow alternative types of network 2583 addresses to establish a particular media stream. 2585 +-------------+---------------------------+-------+-----------------+ 2586 | Name | Notes | Level | Mux Category | 2587 +-------------+---------------------------+-------+-----------------+ 2588 | group:ANAT | ANAT semantics is | S | NOT RECOMMENDED | 2589 | | obseleted | | | 2590 | | | | | 2591 +-------------+---------------------------+-------+-----------------+ 2593 RFC4091 Attribute Analysis 2595 8.4. RFC5956 - FEC Grouping Semantics in SDP 2597 [RFC5956] defines the semantics for grouping the associated source 2598 and FEC-based (Forward Error Correction) repair flows in the Session 2599 Description Protocol (SDP). The semantics defined in the document 2600 are to be used with the SDP Grouping Framework (RFC 5888). These 2601 semantics allow the description of grouping relationships between the 2602 source and repair flows when one or more source and/or repair flows 2603 are associated in the same group, and they provide support for 2604 additive repair flows. SSRC-level (Synchronization Source) grouping 2605 semantics are also defined in this document for Real-time Transport 2606 Protocol (RTP) streams using SSRC multiplexing. 2608 +---------------+---------------+-------+--------------+ 2609 | Name | Notes | Level | Mux Category | 2610 +---------------+---------------+-------+--------------+ 2611 | group:FEC-FR | Not Impacted | S | NORMAL | 2612 | | | | | 2613 +---------------+---------------+-------+--------------+ 2615 RFC5956 Attribute Analysis 2617 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP 2619 [RFC5583] defines semantics that allow for signaling the decoding 2620 dependency of different media descriptions with the same media type 2621 in the Session Description Protocol (SDP). This is required, for 2622 example, if media data is separated and transported in different 2623 network streams as a result of the use of a layered or multiple 2624 descriptive media coding process. 2626 +--------+------------------------------+-------+-------------------+ 2627 | Name | Notes | Level | Mux Category | 2628 +--------+------------------------------+-------+-------------------+ 2629 | depend | The attribute value MUST be | M | IDENTICAL-PER-PT | 2630 | lay | same for a given codec | | | 2631 | | configuration | | | 2632 | | | | | 2633 | depend | The attribute value MUST be | M | IDENTICAL-PER-PT | 2634 | mdc | same for a given codec | | | 2635 | | configuration | | | 2636 | | | | | 2637 +--------+------------------------------+-------+-------------------+ 2639 RFC5583 Attribute Analysis 2641 8.6. RFC7104 - Duplication Grouping Semantics in the SDP 2643 [RFC7104] defines the semantics for grouping redundant streams in the 2644 Session Description Protocol (SDP). The semantics defined in this 2645 document are to be used with the SDP Grouping Framework. Grouping 2646 semantics at the Synchronization Source (SSRC) level are also defined 2647 in this document for RTP streams using SSRC multiplexing. 2649 +------------+---------------+-------+--------------+ 2650 | Name | Notes | Level | Mux Category | 2651 +------------+---------------+-------+--------------+ 2652 | group:DUP | Not Impacted | S | NORMAL | 2653 | | | | | 2654 +------------+---------------+-------+--------------+ 2656 RFC7104 Attribute Analysis 2658 9. ssrc-group Attribute Analysis 2660 This section analyzes "ssrc-group" semantics. 2662 9.1. RFC5576 - Source-Specific SDP Attributes 2664 [RFC5576] defines a mechanism to describe RTP media sources, which 2665 are identified by their synchronization source (SSRC) identifiers, in 2666 SDP, to associate attributes with these sources, and to express 2667 relationships among sources. It also defines several source-level 2668 attributes that can be used to describe properties of media sources. 2670 +-------------------+---------------+-------+--------------+ 2671 | Name | Notes | Level | Mux Category | 2672 +-------------------+---------------+-------+--------------+ 2673 | ssrc-group:FID | Not Impacted | SR | NORMAL | 2674 | | | | | 2675 | ssrc-group:FEC | Not Impacted | SR | NORMAL | 2676 | | | | | 2677 | ssrc-groupFEC-FR | Not Impacted | SR | NORMAL | 2678 | | | | | 2679 +-------------------+---------------+-------+--------------+ 2681 RFC5576 Attribute Analysis 2683 9.2. RFC7104 - Duplication Grouping Semantics in the SDP 2685 [RFC7104] defines the semantics for grouping redundant streams in the 2686 Session Description Protocol (SDP). The semantics defined in this 2687 document are to be used with the SDP Grouping Framework. Grouping 2688 semantics at the Synchronization Source (SSRC) level are also defined 2689 in this document for RTP streams using SSRC multiplexing. 2691 +-----------------+---------------+-------+--------------+ 2692 | Name | Notes | Level | Mux Category | 2693 +-----------------+---------------+-------+--------------+ 2694 | ssrc-group:DUP | Not Impacted | SR | NORMAL | 2695 | | | | | 2696 +-----------------+---------------+-------+--------------+ 2698 RFC7104 Attribute Analysis 2700 10. QoS Mechanism Token Analysis 2702 This section analyzes QoS tokes specified with SDP. 2704 10.1. RFC5432 - QoS Mechanism Selection in SDP 2706 [RFC5432] defines procedures to negotiate QOS mechanisms using the 2707 Session Description Protocol (SDP) offer/answer model. 2709 +-------+--------------------------------------+-------+------------+ 2710 | Name | Notes | Level | Mux | 2711 | | | | Category | 2712 +-------+--------------------------------------+-------+------------+ 2713 | rsvp | rsvp attribute MUST be the one that | B | TRANSPORT | 2714 | | corresponds to the "m=" line chosen | | | 2715 | | for setting up the underlying | | | 2716 | | transport flow | | | 2717 | | | | | 2718 | nsis | rsvp attribute MUST be the one that | B | TRANSPORT | 2719 | | corresponds to the "m=" line chosen | | | 2720 | | for setting up the underlying | | | 2721 | | transport | | | 2722 | | | | | 2723 +-------+--------------------------------------+-------+------------+ 2725 RFC5432 Attribute Analysis 2727 NOTE: A single DSCP code point per flow being multiplexed doesn't 2728 impact multiplexing since QOS mechanisms are signaled/scoped per 2729 flow. For scenarios that involve having different DSCP code points 2730 for packets being transmitted over the same 5-tuple, issues as 2731 discussed in [I.D-draft-ietf-dart-dscp-rtp] need to be taken into 2732 consideration. 2734 11. k= Attribute Analysis 2736 11.1. RFC4566 SDP: Session Description Protocol 2738 [RFC4566] defines the Session Description Protocol (SDP) that is 2739 intended for describing multimedia sessions for the purposes of 2740 session announcement, session invitation, and other forms of 2741 multimedia session initiation. 2743 +------+------------------------------------+-------+---------------+ 2744 | Name | Notes | Level | Mux Category | 2745 +------+------------------------------------+-------+---------------+ 2746 | k= | It is NOT recommended to use this | S | NOT | 2747 | | attribute | | RECOMMENDED | 2748 | | | | | 2749 +------+------------------------------------+-------+---------------+ 2751 RFC4566 Attribute Analysis 2753 12. content Attribute Analysis 2755 12.1. RFC4796 2757 [RFC4796] defines a new Session Description Protocol (SDP) media- 2758 level attribute, 'content'. The 'content' attribute defines the 2759 content of the media stream to a more detailed level than the media 2760 description line. The sender of an SDP session description can 2761 attach the 'content' attribute to one or more media streams. The 2762 receiving application can then treat each media stream differently 2763 (e.g., show it on a big or small screen) based on its content. 2765 +------------------+---------------+-------+--------------+ 2766 | Name | Notes | Level | Mux Category | 2767 +------------------+---------------+-------+--------------+ 2768 | content:slides | Not Impacted | M | NORMAL | 2769 | | | | | 2770 | content:speaker | Not Impacted | M | NORMAL | 2771 | | | | | 2772 | content:main | Not Impacted | M | NORMAL | 2773 | | | | | 2774 | content:sl | Not Impacted | M | NORMAL | 2775 | | | | | 2776 | content:alt | Not Impacted | M | NORMAL | 2777 | | | | | 2778 +------------------+---------------+-------+--------------+ 2780 RFC4796 Attribute Analysis 2782 13. Payload Formats 2784 13.1. RFC5109 - RTP Payload Format for Generic FEC 2786 [RFC5109] describes a payload format for generic Forward Error 2787 Correction (FEC) for media data encapsulated in RTP. It is based on 2788 the exclusive-or (parity) operation. The payload format allows end 2789 systems to apply protection using various protection lengths and 2790 levels, in addition to using various protection group sizes to adapt 2791 to different media and channel characteristics. It enables complete 2792 recovery of the protected packets or partial recovery of the critical 2793 parts of the payload depending on the packet loss situation. 2795 +---------------------+----------------------+-------+--------------+ 2796 | Name | Notes | Level | Mux Category | 2797 +---------------------+----------------------+-------+--------------+ 2798 | audio/ulpfec | Not recommended for | M | NOT | 2799 | | multiplexing due to | | RECOMMENDED | 2800 | | reuse of SSRCs | | | 2801 | | | | | 2802 | video/ulpfec | Not recommended for | M | NOT | 2803 | | multiplexing due to | | RECOMMENDED | 2804 | | reuse of SSRCs | | | 2805 | | | | | 2806 | text/ulpfec | Not recommended for | M | NOT | 2807 | | multiplexing due to | | RECOMMENDED | 2808 | | reuse of SSRCs | | | 2809 | | | | | 2810 | application/ulpfec | Not recommended for | M | NOT | 2811 | | multiplexing due to | | RECOMMENDED | 2812 | | reuse of SSRCs | | | 2813 | | | | | 2814 +---------------------+----------------------+-------+--------------+ 2816 RFC5109 Payload Format Analysis 2818 14. Multiplexing Considerations for Encapsulating Attributes 2820 This sections deals with recommendations for defining the 2821 multiplexing characteristics of the SDP attributes that encapsulate 2822 other SDP attributes/parameters. Such attributes as of today, for 2823 example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of 2824 a generic framework for indicating and negotiating transport, media 2825 and media format related capabilities in the SDP. 2827 The behavior of such attributes under multiplexing is in turn defined 2828 by the multiplexing behavior of the attributes they encapsulate which 2829 are made known once the Offer/Answer negotiation process is 2830 completed. 2832 14.1. RFC3407 - cpar Attribute Analysis 2834 [RFC3407] capability parameter attribute (a=cpar) encapsulates b= 2835 (bandwidth) or an a= attribute. For bandwidth attribute 2836 encapsulation, the category SUM is inherited. For the case of a= 2837 attribute, the category corresponding to the SDP attribute being 2838 encapsulated is inherited. 2840 v=0 2841 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2842 s= 2843 c=IN IP4 host.atlanta.example.com 2844 t=0 0 2845 m=video 3456 RTP/AVP 100 2846 a=rtpmap:100 VP8/90000 2847 a=sqn: 0 2848 a=cdsc: 1 video RTP/AVP 100 2849 a=cpar: a=rtcp-mux 2850 m=video 3456 RTP/AVP 101 2851 a=rtpmap:101 VP8/90000 2852 a=fmtp:100 max-fr=15;max-fs=1200 2853 a=cdsc: 2 video RTP/AVP 101 2854 a=cpar: a=rtcp-mux 2856 In the above example,the category IDENTICAL is inherited for the cpar 2857 encapsulated rtcp-mux attribute. 2859 14.2. RFC5939 Analysis 2861 [RFC5939] defines a general SDP capability negotiation framework. It 2862 also specifies how to provide transport protocols and SDP attributes 2863 as capabilities and negotiate them using the framework. 2865 For this purpose, [RFC5939] defines the following 2867 o A set of capabilities for the session and its associated media 2868 stream components, supported by each side. The attribute 2869 ("a=acap") defines how to list an attribute name and its 2870 associated value (if any) as a capability. The attribute 2871 ("a=tcap") defines how to list transport protocols (e.g., "RTP/ 2872 AVP") as capabilities. 2874 o A set of potential configurations ("a=pcfg") provided by the 2875 offerer to indicate which combinations of those capabilities can 2876 be used for the session and its associated media stream 2877 components. Potential configurations are not ready for use until 2878 fully negotiated. They provide an alternative that MAY be used, 2879 subject to SDP capability negotiation procedures. In particular 2880 the answerer MAY choose one of the potential configurations for 2881 use as part of the current Offer/Answer exchange. 2883 o An actual configuration ("a=acfg") for the session and its 2884 associated media stream components. The actual configuration 2885 identifies the potential configuration that was negotiated for 2886 use. Use of an actual configuration does not require any further 2887 negotiation. 2889 o A negotiation process that takes the current actual and the set of 2890 potential configurations (combinations of capabilities) as input 2891 and provides the negotiated actual configurations as output. In 2892 [RFC5939] the negotiation process is done independently for each 2893 media description. 2895 14.2.1. Recommendation - Procedures for Potential Configuration Pairing 2897 This section provides recommendations for entities generating and 2898 processing SDP under the generic capability negotiation framework as 2899 defined in [RFC5939] under the context of media stream multiplexing. 2901 These recommendations are provided for the purposes of enabling the 2902 Offerer to make sure that the generated potential configurations 2903 between the multiplexed streams can (easily) be negotiated to be 2904 consistent between those streams. In particular, the procedures aim 2905 to simplify Answerer's procedure to choose potential configurations 2906 that are consistent across all the multiplexed media descriptions. 2908 A potential configuration selects a set of attributes and parameters 2909 that become part of the media description when negotiated. When 2910 multiplexing media descriptions with potential configurations 2911 specified, there MAY be a need for coordinating this selection 2912 between multiplexed media descriptions to ensure the right 2913 multiplexing behavior. 2915 Although it is possible to analyze the various potential 2916 configurations in multiplexed media descriptions to find combinations 2917 that satisfy such constraints, it can quickly become complicated to 2918 do so. 2920 The procedures defined in [RFC5939] state that each potential 2921 configuration in the SDP has a unique configuration number, however 2922 the scope of uniqueness is limited to each media description. To 2923 make it simple for the answerer to chose valid combinations of 2924 potential configurations across media descriptions in a given bundle 2925 group, we provide a simple rule for constructing potential 2926 configurations 2928 o Let m-bundle be the set of media descriptions that form a given 2929 bundle . 2931 o Let m-bundle-pcfg be the set of media descriptions in m-bundle 2932 that include one or more potential configurations. 2934 o Each media description in m-bundle-pcfg MUST have at least one 2935 potential configuration with the same configuration number (e.g. 2936 "1"). 2938 o For each potential configuration with configuration number x in m- 2939 bundle-pcfg, the offerer MUST ensure that if the answerer chooses 2940 configuration number x in each of the media descriptions in m- 2941 bundle-pcfg, then the resulting SDP will have all multiplexing 2942 constraints satisfied for those media descriptions. 2944 o Since it is nearly impossible to define a generic mechanism for 2945 various capability extensions, this document does't provide 2946 procedures for dealing with the capability extension attributes. 2947 However, Section 14.3 provide analysis of media capability 2948 extension attributes as defined in [RFC6871]. 2950 The above allows the answerer to easily find multiplexing compatible 2951 combinations of potential configurations: The answerer simply choses 2952 a potential configuration (number) that is present in all of the 2953 media descriptions with potential configurations in the bundle. 2955 Note that it is still possible for the offerer to provide additional 2956 potential configurations with independent configuration numbers. The 2957 answerer will have to perform more complicated analysis to determine 2958 valid multiplexed combinations of those. 2960 14.2.1.1. Example: Transport Capability Multiplexing 2961 v=0 2962 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2963 s= 2964 c=IN IP4 host.atlanta.example.com 2965 t=0 0 2966 a=tcap:1 RTP/SAVPF 2967 a=tcap:2 RTP/SAVP 2968 a=group:BUNDLE audio video 2969 m=audio 2970 a=mid:audio 2971 a=pcfg:1 t=1 2972 a=pcfg:2 2973 m=video 2974 a=mid:video 2975 a=pcfg:1 t=1 2976 a=pcfg:2 t=2 2978 In the example above, the potential configurations that offer 2979 transport protocol capability of RTP/SAVPF has the same configuration 2980 number "1" in both the audio and video media descriptions. 2982 14.2.1.2. Example: Attribute Capability Multiplexing 2984 v=0 2985 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2986 s= 2987 c=IN IP4 host.atlanta.example.com 2988 t=0 0 2989 a=acap:1 a=rtcp-mux 2990 a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80 2991 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 2992 a=group:BUNDLE audio video 2993 m=audio 49172 RTP/AVP 99 2994 a=mid:audio 2995 a=pcfg:1 a=1 2996 a=pcfg:2 2997 m=video 560024 RTP/AVP 100 2998 a=mid:video 2999 a=pcfg:1 a=1 3000 a=pcfg:2 a=2 3002 In the example above, the potential configuration number "1" is 3003 repeated while referring to attribute capability a=rtcp-mux, since 3004 the behavior is IDENTICAL for the attribute a=rtcp-mux under 3005 multiplexing. 3007 14.3. RFC6871 Analysis 3009 [RFC6871] extends capability negotiation framework described in 3010 [RFC5939] by defining media capabilities that can be used to indicate 3011 and negotiate media types and their associated format parameters. It 3012 also allows indication of latent configurations and session 3013 capabilities. 3015 14.3.1. Recommendation: Dealing with Payload Type Numbers 3017 [RFC6871] defines a new payload type ("pt") parameter to be used with 3018 the potential, actual and latent configuration parameters. The 3019 parameter associates RTP payload type numbers with the referenced 3020 RTP-based media format capabilities ("a=rmcap") defined in [RFC6871] 3021 and is appropriate only when the transport protocol uses RTP. This 3022 means that the same payload type number can be assigned as part of 3023 potential or actual configurations in different media descriptions in 3024 a bundle. There are rules for the usage of identical Payload Type 3025 values across multiplexed "m=" lines as described in 3026 [I-D.ietf-mmusic-sdp-bundle-negotiation], which MUST be followed here 3027 as well. As described in Section 14.2.1, the use of identical 3028 configuration numbers for compatible configurations in different 3029 media descriptions that are part of the bundle provides a way to 3030 ensure that the answerer can easily pick compatible configurations 3031 here as well. 3033 14.3.1.1. Example: Attribute Capability Under Shared Payload Type 3035 The attributes (a=rmcap, a=mfcap) follow the above recommendations 3036 under multiplexing. 3038 v=0 3039 o=- 25678 753849 IN IP4 192.0.2.1 3040 s= 3041 c=IN IP4 192.0.2.1 3042 t=0 0 3043 a=creq:med-v0 3044 m=audio 54322 RTP/AVP 96 3045 a=rtpmap:96 AMR-WB/16000/1 3046 a=fmtp:96 mode-change-capability=1; max-red=220; 3047 mode-set=0,2,4,7 3048 a=rmcap:1,3 audio AMR-WB/16000/1 3049 a=rmcap:2 audio AMR/8000/1 3050 a=mfcap:1,2 mode-change-capability=1 3051 a=mfcap:3 mode-change-capability=2 3052 a=pcfg:1 m=1 pt=1:96 3053 a=pcfg:2 m=2 pt=2:97 3054 a=pcfg:3 m=3 pt=3:98 3055 m=audio 54322 RTP/AVP 96 3056 a=rtpmap:96 AMR-WB/16000/1 3057 a=fmtp:96 mode-change-capability=1; max-red=220; 3058 mode-set=0,2,4,7 3059 a=rmcap:4 audio AMR/8000/1 3060 a=rmcap:5 audio OPUS/48000/2 3061 a=mfcap:5 minptime=40 3062 a=mfcap:4 mode-change-capability=1 3063 a=pcfg:1 m=4 pt=4:97 3064 a=pcfg:4 m=5 pt=5:101 3066 In the example above, the potential configuration number "1" is 3067 repeated when referring to media and media format capability used for 3068 the Payload Type 96. This implies that both the media capability 2 3069 and 4 along with their media format capabilities MUST refer to the 3070 same codec configuration, as per the definition of IDENTICAL-PER-PT. 3072 14.3.2. Recommendation: Dealing with Latent Configurations 3074 [RFC6871] adds the notion of a latent configurations, which provides 3075 configuration information that may be used to guide a subsequent 3076 offer/exchange, e.g. by adding another media stream or use 3077 alternative codec combinations not currently offered. Latent 3078 configurations have configuration numbers which cannot overlap with 3079 the potential configuration numbers [RFC6871]. Supported 3080 combinations of potential and latent configurations are indicated by 3081 use of the "a=sescap" attribute, however use of this attribute is NOT 3082 RECOMMENDED with multiplexed media, since it requires the use of 3083 unique configuration numbers across the SDP. Taken together, this 3084 means there is no well-defined way to indicate supported combinations 3085 of latent configurations, or combinations of latent and potential 3086 configurations with multiplexed media. It is still allowed to use 3087 the latent configuration attribute, however the limitations above 3088 will apply. To determine valid combinations, actual negotiation will 3089 have to be attempted subsequently instead. 3091 15. IANA Considerations 3093 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this 3094 document.] 3096 The IANA is requested to add a new column named "Mux Category" to 3097 several of the subregistries in the "Session Description Protocol 3098 (SDP) Parameters" registry. Section 15.1 defines a new subregistry 3099 for identifying the initial registrations for various multiplexing 3100 categories applicable, as proposed in this document. 3102 The tables in Section 15.2 identify name of an entry in the existing 3103 subregistry and specify the value to put in the new "Mux Category" 3104 column of the associated IANA registry. Any entries in the existing 3105 tables that do not have a value for the "Mux Category" specified in 3106 this RFC will get a value of "TBD". Future specifications can change 3107 the "TBD" entries to the correct value. 3109 15.1. New 'Multiplexing Categories' subregistry 3111 A new sub-registry needs to be defined called the "Multiplexing 3112 Categories", with the following registrations created initially: 3113 "NORMAL", "NOT RECOMMENDED", "IDENTICAL", "TRANSPORT", "SUM", 3114 "INHERIT", "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this 3115 document. 3117 Initial value registration for "Multiplexing Categories". 3119 +-------------------------+-----------+ 3120 | Multiplexing Categories | Reference | 3121 +-------------------------+-----------+ 3122 | NORMAL | RFCXXXX | 3123 | NOT RECOMMENDED | RFCXXXX | 3124 | IDENTICAL | RFCXXXX | 3125 | TRANSPORT | RFCXXXX | 3126 | SUM | RFCXXXX | 3127 | INHERIT | RFCXXXX | 3128 | IDENTICAL-PER-PT | RFCXXXX | 3129 | SPECIAL | RFCXXXX | 3130 | TBD | RFCXXXX | 3131 +-------------------------+-----------+ 3132 Further entries may be registered on a first-come first-serve basis. 3133 Each registration needs to indicate the multiplexing category value 3134 to be added to the "Multiplexing Categories" subregistry as defined 3135 in this section. 3137 Such a registration MUST also indicate the applicability of the newly 3138 defined multiplexing category value to various subregistries defined 3139 at "Session Description Protocol (SDP) Parameters". 3141 The general registration procedures of [RFC4566] apply. 3143 15.2. 'Mux Category' column for subregistries 3145 Each sub-section identifies a subregistry in the "Session Description 3146 Protocol (SDP) Parameters" registry. The tables list the column that 3147 identifies the SDP attribute name/Token/Value from the corresponding 3148 subregistries and the values to be used for the new "Mux Category" 3149 column to be added. 3151 15.2.1. Table: SDP bwtype 3153 The following values are to be added to the 'SDP bwtype' subregistry 3154 in the "Session Description Protocol (SDP) Parameters" registry. The 3155 references should be updated to point at this RFC as well as the 3156 previous references. 3158 +----------+--------------+ 3159 | SDP Name | Mux Category | 3160 +----------+--------------+ 3161 | CT | NORMAL | 3162 | AS | SUM | 3163 | RS | SUM | 3164 | RR | SUM | 3165 | TIAS | SPECIAL | 3166 +----------+--------------+ 3168 15.2.2. Table: att-field (session level) 3170 The following values are to be added to the "att-field (session 3171 level)" subregistry in the "Session Description Protocol (SDP) 3172 Parameters" registry. The references should be updated to point at 3173 this RFC as well as the previous references. 3175 +---------------------+------------------+ 3176 | SDP Name | Mux Category | 3177 +---------------------+------------------+ 3178 | cat | NORMAL | 3179 | keywds | NORMAL | 3180 | type | NORMAL | 3181 | type:broadcast | NORMAL | 3182 | type:H332 | NORMAL | 3183 | type:meeting | NORMAL | 3184 | type:moderated | NORMAL | 3185 | type:test | NORMAL | 3186 | charset | NORMAL | 3187 | charset:iso8895-1 | NORMAL | 3188 | tool | NORMAL | 3189 | ipbcp | SPECIAL | 3190 | group | NORMAL | 3191 | ice-lite | NORMAL | 3192 | ice-options | NORMAL | 3193 | bcastversion | NORMAL | 3194 | 3GPP-Integrity-Key | NOT RECOMMENDED | 3195 | 3GPP-SDP-Auth | NOT RECOMMENDED | 3196 | alt-group | NOT RECOMMENDED | 3197 | PSCid | NORMAL | 3198 | bc_service | NORMAL | 3199 | bc_program | NORMAL | 3200 | bc_service_package | NORMAL | 3201 | sescap | NOT RECOMMENDED | 3202 | rtsp-ice-d-m | NOT RECOMMENDED | 3203 +---------------------+------------------+ 3205 15.2.3. Table: att-field (both session and media level) 3207 The following values are to be added to the "att-field (both session 3208 and media level)" subregistry in the "Session Description Protocol 3209 (SDP) Parameters" registry. The references should be updated to 3210 point at this RFC as well as the previous references. 3212 NOTE: The attributes from draft-ietf-rmt-flute-sdp ('flute-tsi', 3213 'flute-ch', 'FEC-declaration', 'FEC-OTI-extension', 'content-desc') 3214 were not analyzed for their multiplexing behavior due to the expired 3215 status of the draft. For purposes of this specification, the 3216 multiplexing category of 'TBD' is assigned. 3218 +-------------------------+-------------------+ 3219 | SDP Name | Mux Category | 3220 +-------------------------+-------------------+ 3221 | recvonly | NORMAL | 3222 | sendrecv | NORMAL | 3223 | sendonly | NORMAL | 3224 | sdplang | NORMAL | 3225 | lang | NORMAL | 3226 | h248item | SPECIAL | 3227 | sqn | NORMAL | 3228 | cdsc | NORMAL | 3229 | cpar | INHERIT | 3230 | cparmin | SPECIAL | 3231 | cparmax | SPECIAL | 3232 | rtcp-xr | NORMAL | 3233 | maxprate | SPECIAL | 3234 | setup | IDENTICAL | 3235 | connection | IDENTICAL | 3236 | key-mgmt | IDENTICAL | 3237 | source-filter | IDENTICAL | 3238 | inactive | NORMAL | 3239 | fingerprint | TRANSPORT | 3240 | flute-tsi | TBD | 3241 | flute-ch | TBD | 3242 | FEC-declaration | TBD | 3243 | FEC-OTI-extension | TBD | 3244 | content-desc | TBD | 3245 | ice-pwd | TRANSPORT | 3246 | ice-ufrag | TRANSPORT | 3247 | stkmstream | NORMAL | 3248 | extmap | SPECIAL | 3249 | qos-mech-send | NORMAL | 3250 | qos-mech-recv | NORMAL | 3251 | csup | NORMAL | 3252 | creq | NORMAL | 3253 | acap | INHERIT | 3254 | tcap | INHERIT | 3255 | 3GPP-QoE-Metrics | NOT RECOMMENDED | 3256 | 3GPP-Asset-Information | NOT RECOMMENDED | 3257 | mbms-mode | NOT RECOMMENDED | 3258 | mbms-repair | NOT RECOMMENDED | 3259 | ike-setup | IDENTICAL | 3260 | psk-fingerprint | IDENTICAL | 3261 | multicast-rtcp | IDENTICAL | 3262 | rmcap | IDENTICAL-PER-PT | 3263 | omcap | NORMAL | 3264 | mfcap | IDENTICAL-PER-PT | 3265 | mscap | INHERIT | 3266 | 3gpp.iut.replication | TBD | 3267 | bcap | INHERIT | 3268 | ccap | IDENTICAL | 3269 | icap | NORMAL | 3270 | 3gpp_sync_info | NORMAL | 3271 | 3gpp_MaxRecvSDUSize | NORMAL | 3272 | etag | NOT RECOMMENDED | 3273 | duplication-delay | NORMAL | 3274 | range | NOT RECOMMENDED | 3275 | control | NOT RECOMMENDED | 3276 | mtag | NOT RECOMMENDED | 3277 | ts-refclk | NORMAL | 3278 | mediaclk | NORMAL | 3279 | calgextmap | NORMAL | 3280 +-------------------------+-------------------+ 3282 15.2.4. Table: att-field (media level only) 3284 The following values are to be added to the "att-field (media level 3285 only)" registry in the "Session Description Protocol (SDP) 3286 Parameters" registry. The references should be updated to point at 3287 this RFC as well as the previous references. 3289 +---------------------------+-------------------+ 3290 | SDP Name | Mux Category | 3291 +---------------------------+-------------------+ 3292 | ptime | IDENTICAL-PER-PT | 3293 | orient | NORMAL | 3294 | orient:portrait | NORMAL | 3295 | orient:landscape | NORMAL | 3296 | orient:seascape | NORMAL | 3297 | framerate | IDENTICAL-PER-PT | 3298 | quality | NORMAL | 3299 | rtpmap | IDENTICAL-PER-PT | 3300 | fmtp | IDENTICAL-PER-PT | 3301 | rtpred1 | NOT RECOMMENDED | 3302 | rtpred2 | NOT RECOMMENDED | 3303 | T38FaxVersion | TBD | 3304 | T38MaxBitRate | TBD | 3305 | T38FaxFillBitRemoval | TBD | 3306 | T38FaxTranscodingMMR | TBD | 3307 | T38FaxTranscodingJBIG | TBD | 3308 | T38FaxRateManagement | TBD | 3309 | T38FaxMaxBuffer | TBD | 3310 | T38FaxMaxDatagram | TBD | 3311 | T38FaxUdpEC | TBD | 3312 | maxptime | IDENTICAL-PER-PT | 3313 | des | NOT RECOMMENDED | 3314 | curr | NOT RECOMMENDED | 3315 | conf | NOT RECOMMENDED | 3316 | mid | NORMAL | 3317 | rtcp | TRANSPORT | 3318 | rtcp-fb | IDENTICAL-PER-PT | 3319 | label | NORMAL | 3320 | T38VendorInfo | TBD | 3321 | crypto | TRANSPORT | 3322 | eecid | NOT RECOMMENDED | 3323 | aalType | NOT RECOMMENDED | 3324 | capability | NOT RECOMMENDED | 3325 | qosClass | NOT RECOMMENDED | 3326 | bcob | NOT RECOMMENDED | 3327 | stc | NOT RECOMMENDED | 3328 | upcc | NOT RECOMMENDED | 3329 | atmQOSparms | NOT RECOMMENDED | 3330 | atmTrfcDesc | NOT RECOMMENDED | 3331 | abrParms | NOT RECOMMENDED | 3332 | abrSetup | NOT RECOMMENDED | 3333 | bearerType | NOT RECOMMENDED | 3334 | lij | NOT RECOMMENDED | 3335 | anycast | NOT RECOMMENDED | 3336 | cache | NOT RECOMMENDED | 3337 | bearerSigIE | NOT RECOMMENDED | 3338 | aalApp | NOT RECOMMENDED | 3339 | cbrRate | NOT RECOMMENDED | 3340 | sbc | NOT RECOMMENDED | 3341 | clkrec | NOT RECOMMENDED | 3342 | fec | NOT RECOMMENDED | 3343 | prtfl | NOT RECOMMENDED | 3344 | structure | NOT RECOMMENDED | 3345 | cpsSDUsize | NOT RECOMMENDED | 3346 | all2CPS | NOT RECOMMENDED | 3347 | all2CPSSDUrate | NOT RECOMMENDED | 3348 | aal2sscs3661unassured | NOT RECOMMENDED | 3349 | aal2sscs3661assured | NOT RECOMMENDED | 3350 | aal2sscs3662 | NOT RECOMMENDED | 3351 | aal5sscop | NOT RECOMMENDED | 3352 | atmmap | NOT RECOMMENDED | 3353 | silenceSupp | NOT RECOMMENDED | 3354 | ecan | NOT RECOMMENDED | 3355 | gc | NOT RECOMMENDED | 3356 | profileDesc | NOT RECOMMENDED | 3357 | vsel | NOT RECOMMENDED | 3358 | dsel | NOT RECOMMENDED | 3359 | fsel | NOT RECOMMENDED | 3360 | onewaySel | NOT RECOMMENDED | 3361 | codecConfig | NOT RECOMMENDED | 3362 | isup_usi | NOT RECOMMENDED | 3363 | uiLayer1_Prot | NOT RECOMMENDED | 3364 | chain | NOT RECOMMENDED | 3365 | floorctrl | IDENTICAL | 3366 | confid | NORMAL | 3367 | userid | NORMAL | 3368 | floorid | NORMAL | 3369 | FEC | NORMAL | 3370 | accept-types | TBD | 3371 | accept-wrapped-types | TBD | 3372 | max-size | TBD | 3373 | path | TBD | 3374 | dccp-service-code | NOT RECOMMENDED | 3375 | rtcp-mux | IDENTICAL | 3376 | candidate | TRANSPORT | 3377 | ice-mismatch | NORMAL | 3378 | remote-candidates | TRANSPORT | 3379 | SRTPAuthentication | TBD | 3380 | SRTPROCTxRate | TBD | 3381 | rtcp-rsize | IDENTICAL | 3382 | file-selector | TBD | 3383 | file-transfer-id | TBD | 3384 | file-disposition | TBD | 3385 | file-date | TBD | 3386 | file-icon | TBD | 3387 | file-range | NORMAL | 3388 | depend | TBD-PER-PT | 3389 | ssrc | NORMAL | 3390 | ssrc-group | NORMAL | 3391 | rtcp-unicast | IDENTICAL | 3392 | pcfg | SPECIAL | 3393 | acfg | SPECIAL | 3394 | zrtp-hash | TRANSPORT | 3395 | X-predecbufsize | NOT RECOMMENDED | 3396 | X-initpredecbufperiod | NOT RECOMMENDED | 3397 | X-initpostdecbufperiod | NOT RECOMMENDED | 3398 | X-decbyterate | NOT RECOMMENDED | 3399 | 3gpp-videopostdecbufsize | NOT RECOMMENDED | 3400 | framesize | NOT RECOMMENDED | 3401 | 3GPP-SRTP-Config | NOT RECOMMENDED | 3402 | alt | NOT RECOMMENDED | 3403 | alt-default-id | NOT RECOMMENDED | 3404 | 3GPP-Adaption-Support | NOT RECOMMENDED | 3405 | mbms-flowid | NOT RECOMMENDED | 3406 | fec-source-flow | SPECIAL | 3407 | fec-repair-flow | SPECIAL | 3408 | repair-window | SPECIAL | 3409 | rams-updates | NOT RECOMMENDED | 3410 | imageattr | IDENTICAL-PER-PT | 3411 | cfw-id | NORMAL | 3412 | portmapping-req | NOT RECOMMENDED | 3413 | g.3gpp.cat | NORMAL | 3414 | g.3gpp.crs | NORMAL | 3415 | ecn-capable-rtp | IDENTICAL | 3416 | visited-realm | TRANSPORT | 3417 | secondary-realm | TRANSPORT | 3418 | omr-s-cksum | NORMAL | 3419 | omr-m-cksum | NORMAL | 3420 | omr-codecs | NORMAL | 3421 | omr-m-att | NORMAL | 3422 | omr-s-att | NORMAL | 3423 | omr-m-bw | NORMAL | 3424 | omr-s-bw | NORMAL | 3425 | msrp-cema | TBD | 3426 | dccp-port | NOT RECOMMENDED | 3427 | resource | NORMAL | 3428 | channel | NORMAL | 3429 | cmid | NORMAL | 3430 | content | NORMAL | 3431 | lcfg | SPECIAL | 3432 | loopback | NORMAL | 3433 | loopback-source | NORMAL | 3434 | loopback-mirror | NORMAL | 3435 | chatroom | TBD | 3436 | altc | TRANSPORT | 3437 | T38FaxMaxIFP | TBD | 3438 | T38FaxUdpECDepth | TBD | 3439 | T38FaxUdpFECMaxSpan | TBD | 3440 | T38ModemType | TBD | 3441 | cs-correlation | TBD | 3442 | rtcp-idms | NORMAL | 3443 +---------------------------+-------------------+ 3445 15.2.5. Table: att-field (source level) 3447 The following values are to be added to the "att-field (source 3448 level)" registry in the "Session Description Protocol (SDP) 3449 Parameters" registry. The references should be updated to point at 3450 this RFC as well as the previous references. 3452 +----------------+-------------------+ 3453 | SDP Name | Mux Category | 3454 +----------------+-------------------+ 3455 | cname | NORMAL | 3456 | previous-ssrc | NORMAL | 3457 | fmtp | IDENTICAL-PER-PT | 3458 | ts-refclk | NORMAL | 3459 | mediaclk | NORMAL | 3460 +----------------+-------------------+ 3462 15.2.6. Table: content SDP Parameters 3464 The following values are to be added to the "content SDP Parameters" 3465 subregistry in the "Session Description Protocol (SDP) Parameters" 3466 registry. The references should be updated to point at this RFC as 3467 well as the previous references. 3469 +----------+--------------+ 3470 | SDP Name | Mux Category | 3471 +----------+--------------+ 3472 | slides | NORMAL | 3473 | speaker | NORMAL | 3474 | sl | NORMAL | 3475 | main | NORMAL | 3476 | alt | NORMAL | 3477 +----------+--------------+ 3479 15.2.7. Table: Semantics for the 'group' SDP Attribute 3481 The following values are to be added to the "Semantics for the 3482 "group" SDP Attribute" subregistry in the "Session Description 3483 Protocol (SDP) Parameters" registry. The references should be 3484 updated to point at this RFC as well as the previous references. 3486 +---------+------------------+ 3487 | Token | Mux Category | 3488 +---------+------------------+ 3489 | LS | NORMAL | 3490 | FID | NORMAL | 3491 | SRF | NORMAL | 3492 | ANAT | NOT RECOMMENDED | 3493 | FEC | NORMAL | 3494 | FEC-FR | NORMAL | 3495 | CS | NORMAL | 3496 | DDP | NORMAL | 3497 | DUP | NORMAL | 3498 +---------+------------------+ 3500 15.2.8. Table: 'rtcp-fb' Attribute Values 3502 The following values are to be added to the " 'rtcp-fb' Attribute 3503 Values" subregistry in the "Session Description Protocol (SDP) 3504 Parameters" registry. The references should be updated to point at 3505 this RFC as well as the previous references. 3507 +------------+-------------------+ 3508 | Value Name | Mux Category | 3509 +------------+-------------------+ 3510 | ack | IDENTICAL-PER-PT | 3511 | app | SPECIAL | 3512 | ccm | IDENTICAL-PER-PT | 3513 | nack | IDENTICAL-PER-PT | 3514 | trr-int | IDENTICAL-PER-PT | 3515 +------------+-------------------+ 3517 15.2.9. Table: 'ack' and 'nack' Attribute Values 3519 The following values are to be added to the " 'ack' and 'nack' 3520 Attribute Values" subregistry in the "Session Description Protocol 3521 (SDP) Parameters" registry. The references should be updated to 3522 point at this RFC as well as the previous references. 3524 +------------+-------------------+ 3525 | Value Name | Mux Category | 3526 +------------+-------------------+ 3527 | sli | IDENTICAL-PER-PT | 3528 | pli | IDENTICAL-PER-PT | 3529 | rpsi | IDENTICAL-PER-PT | 3530 | app | SPECIAL | 3531 | rai | IDENTICAL-PER-PT | 3532 | tllei | IDENTICAL-PER-PT | 3533 | pslei | IDENTICAL-PER-PT | 3534 | ecn | IDENTICAL | 3535 +------------+-------------------+ 3537 15.2.10. Table: 'depend' SDP Attribute Values 3539 The following values are to be added to the " 'depend' SDP Attribute 3540 Values" subregistry in the "Session Description Protocol (SDP) 3541 Parameters" registry. The references should be updated to point at 3542 this RFC as well as the previous references. 3544 +-------+-------------------+ 3545 | Token | Mux Category | 3546 +-------+-------------------+ 3547 | lay | IDENTICAL-PER-PT | 3548 | mdc | IDENTICAL-PER-PT | 3549 +-------+-------------------+ 3551 15.2.11. Table: 'cs-correlation' Attribute Values 3553 The following values are to be added to the " "cs-correlation" 3554 Attribute Values" subregistry in the "Session Description Protocol 3555 (SDP) Parameters" registry. The references should be updated to 3556 point at this RFC as well as the previous references. 3558 +-----------+--------------+ 3559 | Value | Mux Category | 3560 +-----------+--------------+ 3561 | callerid | TBD | 3562 | uuie | TBD | 3563 | dtmf | TBD | 3564 | external | TBD | 3565 +-----------+--------------+ 3567 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 3569 The following values are to be added to the Semantics for the 3570 "Semantics for the "ssrc-group" SDP Attribute" subregistry in the 3571 "Session Description Protocol (SDP) Parameters" registry. The 3572 references should be updated to point at this RFC as well as the 3573 previous references. 3575 +---------+--------------+ 3576 | Token | Mux Category | 3577 +---------+--------------+ 3578 | FID | NORMAL | 3579 | FEC | NORMAL | 3580 | FEC-FR | NORMAL | 3581 | DUP | NORMAL | 3582 +---------+--------------+ 3584 15.2.13. Table: SDP/RTSP key management protocol identifiers 3586 The following values are to be added to the "SDP/RTSP key management 3587 protocol identifiers" subregistry in the "Session Description 3588 Protocol (SDP) Parameters" registry. The references should be 3589 updated to point at this RFC as well as the previous references. 3591 +------------+--------------+ 3592 | Value Name | Mux Category | 3593 +------------+--------------+ 3594 | mikey | IDENTICAL | 3595 +------------+--------------+ 3597 15.2.14. Table: Codec Control Messages 3599 The following values are to be added to the "Codec Control Messages" 3600 subregistry in the "Session Description Protocol (SDP) Parameters" 3601 registry. The references should be updated to point at this RFC as 3602 well as the previous references. 3604 +------------+-------------------+ 3605 | Value Name | Mux Category | 3606 +------------+-------------------+ 3607 | fir | IDENTICAL-PER-PT | 3608 | tmmbr | IDENTICAL-PER-PT | 3609 | tstr | IDENTICAL-PER-PT | 3610 | vbcm | IDENTICAL-PER-PT | 3611 +------------+-------------------+ 3613 15.2.15. Table: QoS Mechanism Tokens 3615 The following values are to be added to the "QoS Mechanism Tokens" 3616 subregistry in the "Session Description Protocol (SDP) Parameters" 3617 registry. The references should be updated to point at this RFC as 3618 well as the previous references. 3620 +---------------+--------------+ 3621 | QoS Mechanism | Mux Category | 3622 +---------------+--------------+ 3623 | rsvp | TRANSPORT | 3624 | nsis | TRANSPORT | 3625 +---------------+--------------+ 3627 15.2.16. Table: SDP Capability Negotiation Option Tags 3629 The following values are to be added to the "SDP Capability 3630 Negotiation Option Tags" subregistry in the "Session Description 3631 Protocol (SDP) Parameters" registry. The references should be 3632 updated to point at this RFC as well as the previous references. 3634 +---------------+--------------+ 3635 | QoS Mechanism | Mux Category | 3636 +---------------+--------------+ 3637 | cap-v0 | NORMAL | 3638 | med-v0 | NORMAL | 3639 | bcap-v0 | NORMAL | 3640 | ccap-v0 | NORMAL | 3641 | icap-v0 | NORMAL | 3642 +---------------+--------------+ 3644 15.2.17. Table: Timestamp Reference Clock Source Parameters 3646 The following values are to be added to the "Timestamp Reference 3647 Clock Source Parameters" subregistry in the "Session Description 3648 Protocol (SDP) Parameters" registry. The references should be 3649 updated to point at this RFC as well as the previous references. 3651 +----------+--------------+ 3652 | Name | Mux Category | 3653 +----------+--------------+ 3654 | ntp | NORMAL | 3655 | ptp | NORMAL | 3656 | gps | NORMAL | 3657 | gal | NORMAL | 3658 | glonass | NORMAL | 3659 | local | NORMAL | 3660 | private | NORMAL | 3661 +----------+--------------+ 3663 15.2.18. Table: Media Clock Source Parameters 3665 The following values are to be added to the "Media Clock Source 3666 Parameters" subegistry in the "Session Description Protocol (SDP) 3667 Parameters" registry. The references should be updated to point at 3668 this RFC as well as the previous references. 3670 +-----------+--------------+ 3671 | Name | Mux Category | 3672 +-----------+--------------+ 3673 | sender | NORMAL | 3674 | direct | NORMAL | 3675 | IEEE1722 | NORMAL | 3676 +-----------+--------------+ 3678 16. Security Considerations 3680 This document does not add any new security considerations beyond the 3681 existing considerations in the RFCs for protocols that are being 3682 multiplexed together. 3684 The ways that SRTP streams are keyed is not believed to create any 3685 two-time pad vulnerability for the currently defined SRTP keying 3686 mechanism. 3688 17. Acknowledgments 3690 I would like to thank Cullen Jennings, Flemming Andreasen for 3691 suggesting the categories, contributing text and reviewing the draft. 3692 I would also link to thank Magnus Westerlund, Christer Holmberg, 3693 Jonathan Lennox, Bo Burman, Ari Keranen, and Dan Wing on suggesting 3694 structural changes helping improve the document readability. 3696 I would like also to thank following experts on their inputs and 3697 reviews as listed - Flemming Andreasen(5.24,5.32,5.33,14), Rohan 3698 Mahy(5.57), Eric Burger(5.26),Christian Huitema(5.14), Christer 3699 Holmberg(5.21,5.26,5.51,5.52), Richard Ejzak (5.44,5.53,5.54), Colin 3700 Perkins(5.7,5.8,5.9,5.58), Magnus 3701 Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Roni 3702 Evens(5.12,5.27,8.4), Subha Dhesikan(5.6,10), Dan 3703 Wing(5.7,5.12,5.35,5.39,5.45), Cullen Jennings (5.40), Ali C 3704 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 3705 (7.2,7.6), Charles Eckel(5.15,5.27,5.28,9.1,8.5), Paul Kyzivat(5.24), 3706 Ian Johansson(5.15), Saravanan Shanmugham(5.11), Paul E Jones(5.30), 3707 Rajesh Kumar(5.48), Jonathan Lennox(5.36,5,15,9.1,11.1), Mo 3708 Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Christian Huitema (5.14), Qin 3709 Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves 3710 (5.48,5.55), Thomas Stach. 3712 18. Change Log 3714 [RFC EDITOR NOTE: Please remove this section when publishing] 3716 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 - 08 3718 o Assigned TBD category to all the attributes for whom there exists 3719 no specification on multiplexing behavior over the underlying 3720 transport protocol today. 3722 o Incorporated comments from Flemming and Ari (post last call) 3724 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 3726 o Incorporated last call review comments from Thomas Stach and Ari 3727 Keranen. 3729 o Fixed more nits to prep for the LastCall. 3731 Changes from draft-ietf-mmusic-sdp-mux-attributes-05 3733 o Incorporated review comments from Christian Grooves and Ari 3734 Keranen. 3736 o Fixed more nits to prep for the LastCall. 3738 Changes from draft-ietf-mmusic-sdp-mux-attributes-04 3740 o Fixed minor nits overall. 3742 o Updated Acknowledgement Sections 3744 o Last Call Version. 3746 Changes from draft-ietf-mmusic-sdp-mux-attributes-03 3748 o More re-work on the IANA section. 3750 o Clean ups preparing for the last call. 3752 Changes from draft-ietf-mmusic-sdp-mux-attributes-02 3754 o Incorporated suggestions from Flemming on Capability Negotiation. 3756 o Closed open issues from IETF90 3758 o Added IANA section to list the categories for all the SDP 3759 attributes anlayzed 3761 o Lots of cleanup 3763 o Reformatted Refernces section to use short-form notation 3765 Changes from draft-ietf-mmusic-sdp-mux-attributes-01 3767 o Updated section 15 to provide detailed recommendation on dealing 3768 with encapsulating attributes. Also updated sections 5.20, 5.28, 3769 5.29 to refer to Section 15. 3771 o Added new categories IDENTICAL-PER-PT and INHERIT 3773 o Updated Sections 16 to add the new categories. 3775 o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the 3776 category IDENTICAL-PER-PT. 3778 o Reformatted section 4 to add individual categories to their own 3779 sections. 3781 Changes from draft-ietf-mmusic-sdp-mux-attributes-00 3782 o Added Section 15 to provide recommendations on multiplexing SDP 3783 encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 3784 to refer to Section 15. 3786 o Updated Section 5.38 to incorporate PM-dir review inputs from Qin 3787 Wu 3789 o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more 3790 clarity. 3792 o Fixed few nits regarding sentence clarity and fill-in the NOTES 3793 section where information was lacking. 3795 Changes from draft-nandakumar-mmusic-mux-attributes-05 3797 o Renamed the document to be a WG document. 3799 o Added Section 14. 3801 o Updated Open Issues based on IETF88 discussions. 3803 Changes from draft-nandakumar-mmusic-mux-attributes-04 3805 o Added few OPEN ISSUES that needs to be discussed. 3807 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 3808 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 3810 o Updated Table Column name Current to Level and improved TRANSPORT 3811 category explanation on suggestions form Dan Wing. 3813 o Grouped all the rtcp-fb attribute analysis under a single section 3814 as suggested by Magnus/ 3816 Changes from draft-nandakumar-mmusic-mux-attributes-03 3818 o Maintenance change to clean up grammatical nits and wordings. 3820 Changes from draft-nandakumar-mmusic-mux-attributes-02 3822 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 3823 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 3824 the inputs from the respective RFC Authors. 3826 Changes from draft-nandakumar-mmusic-mux-attributes-01 3828 o Replaced Category BAD with NOT RECOMMENDED. 3830 o Added Category TBD. 3832 o Updated IANA Consideration Section. 3834 Changes from draft-nandakumar-mmusic-mux-attributes-00 3836 o Added new section for dealing with FEC payload types. 3838 19. References 3840 19.1. Normative References 3842 [I-D.ietf-mmusic-sdp-bundle-negotiation] 3843 Holmberg, C., Alvestrand, H., and C. Jennings, 3844 "Negotiating Media Multiplexing Using the Session 3845 Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- 3846 negotiation-12 (work in progress), October 2014. 3848 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3849 Requirement Levels", BCP 14, RFC 2119, March 1997. 3851 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 3852 Description Protocol", RFC 4566, July 2006. 3854 19.2. Informative References 3856 [H.248.15] 3857 "Gateway control protocol: SDP H.248 package attribute", 3858 . 3860 [I.D-draft-ietf-dart-dscp-rtp] 3861 Black, D. and P. Jones, "Differentiated Services 3862 (DiffServ) and Real-time Communication", draft-ietf-dart- 3863 dscp-rtp-10 (work in progress), September 2014. 3865 [IANA] "Session Description Protocol (SDP) Parameters", 3866 . 3869 [Q.1970] "Q.1970 : BICC IP bearer control protocol", 3870 . 3872 [R3GPPTS183.063] 3873 "TISPAN - IMS based ITPV Stage 3 specification.", 3874 . 3877 [R3GPPTS24.182] 3878 "IP Multimedia Subsystem (IMS) Customized Alerting Tones 3879 (CAT); Protocol specification", 3880 . 3882 [R3GPPTS24.183] 3883 "IP Multimedia Subsystem (IMS) Customized Ringing Signal 3884 (CRS); Protocol specification", 3885 . 3887 [R3GPPTS24.229] 3888 "IP multimedia call control protocol based on Session 3889 Initiation Protocol (SIP) and Session Description Protocol 3890 (SDP);", 3891 . 3893 [R3GPPTS26.114] 3894 "IP multimedia Subsystem : Media Handling and 3895 interaction", 3896 . 3898 [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time 3899 Streaming Protocol (RTSP)", RFC 2326, April 1998. 3901 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the 3902 Session Description Protocol (SDP) for ATM Bearer 3903 Connections", RFC 3108, May 2001. 3905 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 3906 with Session Description Protocol (SDP)", RFC 3264, June 3907 2002. 3909 [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, 3910 "Integration of Resource Management and Session Initiation 3911 Protocol (SIP)", RFC 3312, October 2002. 3913 [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple 3914 Capability Declaration", RFC 3407, October 2002. 3916 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to 3917 Resource Reservation Flows", RFC 3524, April 2003. 3919 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth 3920 Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3921 3556, July 2003. 3923 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute 3924 in Session Description Protocol (SDP)", RFC 3605, October 3925 2003. 3927 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 3928 Protocol Extended Reports (RTCP XR)", RFC 3611, November 3929 2003. 3931 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth 3932 Modifier for the Session Description Protocol (SDP)", RFC 3933 3890, September 2004. 3935 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network 3936 Address Types (ANAT) Semantics for the Session Description 3937 Protocol (SDP) Grouping Framework", RFC 4091, June 2005. 3939 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 3940 the Session Description Protocol (SDP)", RFC 4145, 3941 September 2005. 3943 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. 3944 Carrara, "Key Management Extensions for Session 3945 Description Protocol (SDP) and Real Time Streaming 3946 Protocol (RTSP)", RFC 4567, July 2006. 3948 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session 3949 Description Protocol (SDP) Security Descriptions for Media 3950 Streams", RFC 4568, July 2006. 3952 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol 3953 (SDP) Source Filters", RFC 4570, July 2006. 3955 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the 3956 Transport Layer Security (TLS) Protocol in the Session 3957 Description Protocol (SDP)", RFC 4572, July 2006. 3959 [RFC4574] Levin, O. and G. Camarillo, "The Session Description 3960 Protocol (SDP) Label Attribute", RFC 4574, August 2006. 3962 [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format 3963 for Binary Floor Control Protocol (BFCP) Streams", RFC 3964 4583, November 2006. 3966 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 3967 "Extended RTP Profile for Real-time Transport Control 3968 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 3969 2006. 3971 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description 3972 Protocol (SDP) Content Attribute", RFC 4796, February 3973 2007. 3975 [RFC4975] Campbell, B., Mahy, R., and C. Jennings, "The Message 3976 Session Relay Protocol (MSRP)", RFC 4975, September 2007. 3978 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 3979 "Codec Control Messages in the RTP Audio-Visual Profile 3980 with Feedback (AVPF)", RFC 5104, February 2008. 3982 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 3983 Correction", RFC 5109, December 2007. 3985 [RFC5159] Dondeti, L. and A. Jerichow, "Session Description Protocol 3986 (SDP) Attributes for Open Mobile Alliance (OMA) Broadcast 3987 (BCAST) Service and Content Protection", RFC 5159, March 3988 2008. 3990 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 3991 (ICE): A Protocol for Network Address Translator (NAT) 3992 Traversal for Offer/Answer Protocols", RFC 5245, April 3993 2010. 3995 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP 3996 Header Extensions", RFC 5285, July 2008. 3998 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of 3999 Service (QoS) Mechanism Selection in the Session 4000 Description Protocol (SDP)", RFC 5432, March 2009. 4002 [RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size 4003 Real-Time Transport Control Protocol (RTCP): Opportunities 4004 and Consequences", RFC 5506, April 2009. 4006 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., 4007 and P. Kyzivat, "A Session Description Protocol (SDP) 4008 Offer/Answer Mechanism to Enable File Transfer", RFC 5547, 4009 May 2009. 4011 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific 4012 Media Attributes in the Session Description Protocol 4013 (SDP)", RFC 5576, June 2009. 4015 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding 4016 Dependency in the Session Description Protocol (SDP)", RFC 4017 5583, July 2009. 4019 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 4020 Protocol (RTCP) Extensions for Single-Source Multicast 4021 Sessions with Unicast Feedback", RFC 5760, February 2010. 4023 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and 4024 Control Packets on a Single Port", RFC 5761, April 2010. 4026 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control 4027 Protocol (DCCP)", RFC 5762, April 2010. 4029 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework 4030 for Establishing a Secure Real-time Transport Protocol 4031 (SRTP) Security Context Using Datagram Transport Layer 4032 Security (DTLS)", RFC 5763, May 2010. 4034 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description 4035 Protocol (SDP) Grouping Framework", RFC 5888, June 2010. 4037 [RFC5939] Andreasen, F., "Session Description Protocol (SDP) 4038 Capability Negotiation", RFC 5939, September 2010. 4040 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in 4041 the Session Description Protocol", RFC 5956, September 4042 2010. 4044 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions 4045 Defined for 3GPP Packet-Switched Streaming Service and 4046 Multimedia Broadcast/Multicast Service", RFC 6064, January 4047 2011. 4049 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- 4050 Specific Multicast (SSM) Sessions", RFC 6128, February 4051 2011. 4053 [RFC6189] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media 4054 Path Key Agreement for Unicast Secure RTP", RFC 6189, 4055 April 2011. 4057 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for 4058 the Internet Key Exchange Protocol (IKE) in the Session 4059 Description Protocol (SDP)", RFC 6193, April 2011. 4061 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media 4062 Control Channel Framework", RFC 6230, May 2011. 4064 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image 4065 Attributes in the Session Description Protocol (SDP)", RFC 4066 6236, May 2011. 4068 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping 4069 between Unicast and Multicast RTP Sessions", RFC 6284, 4070 June 2011. 4072 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, 4073 "Unicast-Based Rapid Acquisition of Multicast RTP 4074 Sessions", RFC 6285, June 2011. 4076 [RFC6364] Begen, A., "Session Description Protocol Elements for the 4077 Forward Error Correction (FEC) Framework", RFC 6364, 4078 October 2011. 4080 [RFC6642] Wu, Q., Xia, F., and R. Even, "RTP Control Protocol (RTCP) 4081 Extension for a Third-Party Loss Report", RFC 6642, June 4082 2012. 4084 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., 4085 and K. Carlberg, "Explicit Congestion Notification (ECN) 4086 for RTP over UDP", RFC 6679, August 2012. 4088 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection 4089 Establishment for Media Anchoring (CEMA) for the Message 4090 Session Relay Protocol (MSRP)", RFC 6714, August 2012. 4092 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A 4093 Datagram Congestion Control Protocol UDP Encapsulation for 4094 NAT Traversal", RFC 6773, November 2012. 4096 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control 4097 Protocol Version 2 (MRCPv2)", RFC 6787, November 2012. 4099 [RFC6849] Kaplan, H., Hedayat, K., Venna, N., Jones, P., and N. 4100 Stratton, "An Extension to the Session Description 4101 Protocol (SDP) and Real-time Transport Protocol (RTP) for 4102 Media Loopback", RFC 6849, February 2013. 4104 [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session 4105 Description Protocol (SDP) Media Capabilities 4106 Negotiation", RFC 6871, February 2013. 4108 [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S. 4109 Veikkolainen, "The Session Description Protocol (SDP) 4110 Alternate Connectivity (ALTC) Attribute", RFC 6947, May 4111 2013. 4113 [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman, 4114 "Miscellaneous Capabilities Negotiation in the Session 4115 Description Protocol (SDP)", RFC 7006, September 2013. 4117 [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping 4118 Semantics in the Session Description Protocol", RFC 7104, 4119 January 2014. 4121 [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session 4122 Description Protocol (SDP) Extension for Setting Audio and 4123 Video Media Streams over Circuit-Switched Bearers in the 4124 Public Switched Telephone Network (PSTN)", RFC 7195, May 4125 2014. 4127 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay 4128 Attribute in the Session Description Protocol", RFC 7197, 4129 April 2014. 4131 [RFC7266] Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control 4132 Protocol (RTCP) Extended Report (XR) Blocks for Mean 4133 Opinion Score (MOS) Metric Reporting", RFC 7266, June 4134 2014. 4136 [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O., 4137 Boronat, F., Montagud, M., and K. Gross, "Inter- 4138 Destination Media Synchronization (IDMS) Using the RTP 4139 Control Protocol (RTCP)", RFC 7272, June 2014. 4141 [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H. 4142 Stokking, "RTP Clock Source Signalling", RFC 7273, June 4143 2014. 4145 [T.38] "Procedures for real-time Group 3 facsimile communication 4146 over IP networks", . 4148 Author's Address 4150 Suhas Nandakumar 4151 Cisco 4152 170 West Tasman Drive 4153 San Jose, CA 95134 4154 USA 4156 Email: snandaku@cisco.com