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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 January 4, 2016 5 Expires: July 7, 2016 7 A Framework for SDP Attributes when Multiplexing 8 draft-ietf-mmusic-sdp-mux-attributes-11 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 July 7, 2016. 46 Copyright Notice 48 Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . 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: ICE . . . . . . . . . . . . . . . . . . . . . . 20 101 5.13. RFC5285: RTP Header Extensions . . . . . . . . . . . . . 21 102 5.14. RFC3605: RTCP attribute in SDP . . . . . . . . . . . . . 22 103 5.15. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 22 104 5.16. RFC7273: RTP Clock Source Signalling . . . . . . . . . . 23 105 5.17. RFC6236: Image Attributes in SDP . . . . . . . . . . . . 24 106 5.18. RFC7197: Duplication Delay Attribute in SDP . . . . . . . 25 107 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting . . . . 25 108 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions . . 25 109 5.21. RFC6230: Media Control Channel Framework . . . . . . . . 26 110 5.22. RFC6364: SDP Elements for FEC Framework . . . . . . . . . 26 111 5.23. RFC4796: Content Attribute . . . . . . . . . . . . . . . 27 112 5.24. RFC3407: SDP Simple Capability Declaration . . . . . . . 27 113 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP 114 Sessions . . . . . . . . . . . . . . . . . . . . . . . . 28 115 5.26. RFC6714: MSRP-CEMA . . . . . . . . . . . . . . . . . . . 28 116 5.27. RFC4583: SDP Format for BFCP Streams . . . . . . . . . . 29 117 5.28. RFC5547: SDP Offer/Answer for File Transfer . . . . . . . 30 118 5.29. RFC6849: SDP and RTP Media Loopback Extension . . . . . . 30 119 5.30. RFC5760: RTCP with Unicast Feedback . . . . . . . . . . . 31 120 5.31. RFC3611: RTCP XR . . . . . . . . . . . . . . . . . . . . 31 121 5.32. RFC5939: SDP Capability Negotiation . . . . . . . . . . . 32 122 5.33. RFC6871: SDP Media Capabilities Negotiation . . . . . . . 32 123 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP . . . 33 124 5.35. RFC4567: Key Management Extensions for SDP and RTSP . . . 34 125 5.36. RFC4572: Comedia over TLS in SDP . . . . . . . . . . . . 35 126 5.37. RFC4570: SDP Source Filters . . . . . . . . . . . . . . . 35 127 5.38. RFC6128: RTCP Port for Multicast Sessions . . . . . . . . 36 128 5.39. RFC6189: ZRTP . . . . . . . . . . . . . . . . . . . . . . 36 129 5.40. RFC4145: Connection-Oriented Media . . . . . . . . . . . 37 130 5.41. RFC6947: The SDP altc Attribute . . . . . . . . . . . . . 37 131 5.42. RFC7195: SDP Extension for Circuit Switched Bearers 132 in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 38 133 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) . . . 38 134 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP 135 Attributes . . . . . . . . . . . . . . . . . . . . . . . 39 136 5.45. RFC6193: Media Description for IKE in SDP . . . . . . . . 39 137 5.46. RFC2326: Real Time Streaming Protocol . . . . . . . . . . 40 138 5.47. RFC6064: SDP and RTSP Extensions for 3GPP . . . . . . . . 41 139 5.48. RFC3108: ATM SDP . . . . . . . . . . . . . . . . . . . . 44 140 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 46 141 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 47 142 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 47 143 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 47 144 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 48 145 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 49 146 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 51 147 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 51 148 5.57. RFC4975: The Message Session Relay Protocol . . . . . . . 52 149 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 53 150 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 53 151 6.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 54 152 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth . . . 54 153 6.3. RFC3890: Bandwidth Modifier for SDP . . . . . . . . . . . 55 154 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 55 155 7.1. RFC4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . . 55 156 7.2. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 56 157 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP 158 Sessions (RAMS) . . . . . . . . . . . . . . . . . . . . . 57 159 7.4. RFC6679: ECN for RTP over UDP/IP . . . . . . . . . . . . 57 160 7.5. RFC6642: Third-Party Loss Report . . . . . . . . . . . . 58 161 7.6. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 59 162 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 59 163 8.1. RFC5888: SDP Grouping Framework . . . . . . . . . . . . . 59 164 8.2. RFC3524: Mapping Media Streams to Resource 165 Reservation Flows . . . . . . . . . . . . . . . . . . . . 60 166 8.3. RFC4091: ANAT Semantics . . . . . . . . . . . . . . . . . 60 167 8.4. RFC5956: FEC Grouping Semantics in SDP . . . . . . . . . 60 168 8.5. RFC5583: Signaling Media Decoding Dependency in SDP . . . 61 169 8.6. RFC7104: Duplication Grouping Semantics in the SDP . . . 61 170 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 62 171 9.1. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 62 172 9.2. RFC7104: Duplication Grouping Semantics in the SDP . . . 62 173 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 63 174 10.1. RFC5432: QoS Mechanism Selection in SDP . . . . . . . . 63 175 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 63 176 11.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 64 177 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 64 178 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 64 179 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 65 180 13.1. RFC5109: RTP Payload Format for Generic FEC . . . . . . 65 181 14. Multiplexing Considerations for Encapsulating Attributes . . 65 182 14.1. RFC3407: cpar Attribute Analysis . . . . . . . . . . . . 66 183 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 66 184 14.2.1. Recommendation: Procedures for Potential 185 Configuration Pairing . . . . . . . . . . . . . . . 67 186 14.2.1.1. Example: Transport Capability Multiplexing . . . 68 187 14.2.1.2. Example: Attribute Capability Multiplexing . . . 69 188 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 70 189 14.3.1. Recommendation: Dealing with Payload Type Numbers . 70 190 14.3.1.1. Example: Attribute Capability Under Shared 191 Payload Type . . . . . . . . . . . . . . . . . . 70 192 14.3.2. Recommendation: Dealing with Latent Configurations . 71 193 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 72 194 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 72 195 15.2. 'Mux Category' column for subregistries . . . . . . . . 73 196 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 73 197 15.2.2. Table: att-field (session level) . . . . . . . . . . 73 198 15.2.3. Table: att-field (both session and media level) . . 74 199 15.2.4. Table: att-field (media level only) . . . . . . . . 76 200 15.2.5. Table: att-field (source level) . . . . . . . . . . 79 201 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 80 202 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 80 203 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 80 204 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 81 205 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 81 206 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 82 207 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 82 208 15.2.13. Table: SDP/RTSP key management protocol identifiers 82 209 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 83 210 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 83 211 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 83 212 15.2.17. Table: Timestamp Reference Clock Source Parameters . 84 213 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 84 214 16. Security Considerations . . . . . . . . . . . . . . . . . . . 84 215 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 85 216 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 85 217 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 88 218 19.1. Normative References . . . . . . . . . . . . . . . . . . 88 219 19.2. Informative References . . . . . . . . . . . . . . . . . 88 220 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 96 222 1. Introduction 224 SDP defines several attributes for capturing characteristics that 225 apply to the individual media descriptions (described by "m=" lines") 226 and the overall multimedia session. Typically different media types 227 (audio, video, etc.) described using different media descriptions 228 represent separate RTP sessions that are carried over individual 229 transport layer flows. However 230 [I-D.ietf-mmusic-sdp-bundle-negotiation] defines a way to use a 231 single address:port combination (BUNDLE address) for receiving media 232 associated with multiple SDP media descriptions. This would for e.g. 233 allow the usage of a single set of Interactive Connectivity 234 Establishment (ICE) [RFC5245] candidates for multiple media 235 descriptions. This in turn has made necessary to understand the 236 interpretation and usage of the SDP attributes defined for the 237 multiplexed media descriptions. 239 Given the number of SDP attributes registered with the [IANA] and 240 possibility of new attributes being defined in the future, there is 241 need for generic future-proof framework to analyze these attributes 242 for their applicability in the transport multiplexing use-cases. 244 The document starts with providing the motivation for requiring such 245 a framework. This is followed by introduction to the SDP attribute 246 analysis framework/procedures, following which several sections apply 247 the framework to the SDP attributes registered with the [IANA]. 249 2. Terminology 251 5-tuple: A collection of the following values: source address, source 252 port, destination address, destination port, and transport-layer 253 protocol. 255 3GPP: Third Generation Partnership Project; see http://www.3gpp.org 256 for more information about this organization. 258 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 259 "SHOULD", "SHOULD NOT", RECOMMENDED", "MAY", and "OPTIONAL" in this 260 document are to be interpreted as described in [RFC2119]. 262 3. Motivation 264 The time and complications of setting up ICE [RFC5245] and Datagram 265 Transport Layer Security (DTLS) based Secure Real-time Transport 266 Protocol (SRTP) [RFC5763] transports for use by RTP, and conservation 267 of ports (to avoid maintaining large number of Network Address 268 Translator (NAT) bindings open, reduce time/ports needed for ICE to 269 detect connectivity), forms a requirement to try and reduce the 270 number of transport level flows needed. This has resulted in the 271 definition of ways, such as, [I-D.ietf-mmusic-sdp-bundle-negotiation] 272 to multiplex RTP over a single transport flow in order to preserve 273 network resources such as port numbers. This imposes further 274 restrictions on applicability of the SDP attributes as they are 275 defined today. 277 The specific problem is that there are attribute combinations which 278 make sense when specified on independent "m=" lines -- as with 279 classical SDP -- that do not make sense when those "m=" lines are 280 then multiplexed over the same transport. To give an obvious 281 example, ICE permits each "m=" line to have an independently 282 specified ice-ufrag attribute. However, if the media from multiple 283 "m=" lines is multiplexed over the same ICE component, then the 284 meaning of media-level ice-ufrag attributes becomes muddled. 286 At the time of writing this document there are close to 250 SDP 287 attributes registered with the [IANA] and more will be added in the 288 future. There is no clearly defined procedure to establish the 289 validity/applicability of these attributes when used with transport 290 multiplexing. 292 4. SDP Attribute Analysis Framework 294 Attributes in an SDP session description can be defined at the 295 session-level and media-level. Informally, these attributes could be 296 semantically grouped as noted below. 298 o Attributes related to media content such as media type, encoding 299 schemes, payload types. 301 o Attributes specifying media transport characteristics like RTP/RTP 302 Control Protocol (RTCP) port numbers, network addresses, QOS. 304 o Metadata description attributes capturing session timing and 305 origin information. 307 o Attributes establishing relationships between media descriptions 308 such as grouping framework [RFC5888] 310 With the above semantic grouping as a reference, the proposed 311 framework classifies each attribute into one of the following 312 categories: 314 4.1. Category: NORMAL 316 Attributes that can be independently specified when multiplexing and 317 retain their original semantics. 319 In the example given below, the direction and label attributes are 320 independently specified for audio and video "m=" lines. These 321 attributes are not impacted by multiplexing these media streams over 322 a single transport layer flow. 324 v=0 325 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 326 s= 327 c=IN IP4 host.atlanta.example.com 328 t=0 0 329 m=audio 49172 RTP/AVP 99 330 a=sendonly 331 a=label:1 332 a=rtpmap:99 iLBC/8000 333 m=video 49172 RTP/AVP 31 334 a=recvonly 335 a=label:2 336 a=rtpmap:31 H261/90000 338 4.2. Category: NOT RECOMMENDED 340 Attributes that are not recommended for multiplexing since their 341 usage under multiplexing might lead to incorrect behavior. 343 Example: Multiplexing media descriptions over a single Datagram 344 Congestion Control Protocol (DCCP) transport [RFC5762] is NOT 345 RECOMMENDED since DCCP being a connection oriented protocol doesn't 346 allow multiple connections on the same 5-tuple. 348 v=0 349 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 350 s= 351 c=IN IP4 client.biloxi.example.com 352 t=0 0 353 m=video 5004 DCCP/RTP/AVP 99 354 a=rtpmap:99 h261/9000 355 a=dccp-service-code:SC=x52545056 356 a=setup:passive 357 a=connection:new 358 m=video 5004 DCCP/RTP/AVP 100 359 a=rtpmap:100 h261/9000 360 a=dccp-service-code:SC=x5254504f 361 a=setup:passive 362 a=connection:new 364 4.3. Category: IDENTICAL 366 Attributes and their associated values (if any) that MUST be 367 identical across all the media descriptions being multiplexed. 369 Attributes such as rtcp-mux fall into this category. Since RTCP 370 reporting is done per RTP session, RTCP Multiplexing MUST be enabled 371 for both the audio and video "m=" lines if they are transported over 372 a single 5-tuple. 374 v=0 375 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 376 s= 377 c=IN IP4 client.biloxi.example.com 378 t=0 0 379 m=audio 34567 RTP/AVP 97 380 a=rtcp-mux 381 m=video 34567 RTP/AVP 31 382 a=rtpmap:31 H261/90000 383 a=rtcp-mux 385 4.4. Category: SUM 387 Attributes can be set as they are normally used but software using 388 them in the multiplexing scenario, MUST apply the sum of all the 389 attributes being multiplexed instead of trying to use them 390 independently. This is typically used for bandwidth or other rate 391 limiting attributes to the underlying transport. 393 The software parsing the SDP sample below, should use the aggregate 394 Application Specific (AS) bandwidth value from the individual media 395 descriptions to determine the AS value for the multiplexed session. 396 Thus the calculated AS value would be 256+64 kilobits per second for 397 the given example. 399 v=0 400 o=test 2890844526 2890842807 IN IP4 client.biloxi.example.com 401 c=IN IP4 client.biloxi.example.com 402 t=0 0 403 m=audio 49170 RTP/AVP 0 404 b=AS:64 405 m=video 51372 RTP/AVP 31 406 b=AS:256 408 4.5. Category: TRANSPORT 410 Attributes that can be set normally for multiple items in a 411 multiplexed group but the software MUST pick the one that's 412 associated with the "m=" line whose information is used for setting 413 up the underlying transport. 415 In the example below, "a=crypto" attribute is defined for both the 416 audio and the video "m=" lines. The video media line's a=crypto 417 attribute is chosen since its mid value (bar) appears first in the 418 a=group:BUNDLE line. This is due to BUNDLE grouping semantic 420 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values 421 from "m=" line corresponding to the mid appearing first on the 422 a=group:BUNDLE line to be considered for setting up the RTP 423 Transport. 425 v=0 426 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 427 s= 428 c=IN IP4 host.atlanta.example.com 429 t=0 0 430 a=group:BUNDLE bar foo 431 m=audio 49172 RTP/AVP 99 432 a=mid:foo 433 a=crypto:1 AES_CM_128_HMAC_SHA1_80 434 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 435 a=rtpmap:99 iLBC/8000 436 m=video 51374 RTP/AVP 31 437 a=mid:bar 438 a=crypto:1 AES_CM_128_HMAC_SHA1_80 439 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 440 a=rtpmap:96 H261/90000 442 4.6. Category: INHERIT 444 Attributes that encapsulate other SDP attributes or parameters. 445 These attributes inherit their multiplexing characteristics from the 446 attributes or parameters they encapsulate. Such attributes are 447 defined in [RFC3407], [RFC5939] and [RFC6871] as part of a generic 448 framework for indicating and negotiating transport, media, and media 449 format related capabilities in the SDP. 451 The inheritance manifests itself when the encapsulated attribute or 452 parameter is being leveraged. In the case of SDP Capability 453 Negotiation [RFC5939] for example, this occurs when a capability 454 (encapsulating attribute) is used as part of a configuration; the 455 configuration inherits the multiplexing category of each of its 456 constituent (encapsulated) attributes and parameters. This in turn 457 MAY place constraints on what constitutes a valid configuration from 458 a multiplexing point of view, e.g. because some attributes MUST be 459 IDENTICAL (see Section 14 for further details). 461 v=0 462 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 463 s= 464 c=IN IP4 host.atlanta.example.com 465 t=0 0 466 m=video 3456 RTP/AVP 100 467 a=rtpmap:100 VP8/90000 468 a=fmtp:100 max-fr=30;max-fs=8040 469 a=sqn: 0 470 a=cdsc: 1 video RTP/AVP 100 471 a=cpar: a=rtcp-mux 472 m=video 3456 RTP/AVP 101 473 a=rtpmap:101 VP8/90000 474 a=fmtp:100 max-fr=15;max-fs=1200 475 a=cdsc: 2 video RTP/AVP 101 476 a=cpar: a=rtcp-mux 478 In the above example, the category IDENTICAL is inherited for the 479 cpar encapsulated rtcp-mux attribute. 481 4.7. Category: IDENTICAL-PER-PT 483 Attributes that define the RTP payload configuration on per Payload 484 Type basis and MUST have identical values across all the media 485 descriptions for a given RTP Payload Type when repeated. These 486 Payload Types identify the same codec configuration as defined in the 487 Section 10.1.2 of [I-D.ietf-mmusic-sdp-bundle-negotiation] under this 488 context. 490 In the SDP example below, Payload Types 96 and 97 are repeated across 491 all the video "m=" lines and all the payload specific parameters (ex: 492 rtpmap, fmtp) are identical (Note: some line breaks included are due 493 to formatting only). 495 v=0 496 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 497 s= 498 c=IN IP4 host.atlanta.example.com 499 t=0 0 500 a=group:BUNDLE cam1 cam2 501 m=video 96 97 502 a=mid:cam1 503 a=rtpmap:96 H264/90000 504 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 505 max-mbps=108000; max-br=1000 506 a=rtpmap:97 H264/90000 507 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 508 max-mbps=7200; max-br=200 509 m=video 96 97 510 a=mid:cam2 511 a=rtpmap:96 H264/90000 512 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 513 max-mbps=108000; max-br=1000 514 a=rtpmap:97 H264/90000 515 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 516 max-mbps=7200; max-br=200 518 4.8. Category: SPECIAL 520 Attributes where the text in the specification defining the attribute 521 MUST be consulted for further handling when multiplexed. 523 As an example, for the attribute extmap [RFC5285], the specification 524 defining the extension needs to be referred to understand the 525 multiplexing implications. 527 4.9. Category: TBD 529 Attributes that have not been analyzed under the proposed 530 multiplexing framework. For the purposes of implementations it is 531 advised to consider "NOT RECOMMENDED" as the category when 532 multiplexing these attributes. 534 5. Analysis of Existing Attributes 536 This section analyzes attributes listed in [IANA], grouped under the 537 IETF document that defines them. 539 The "Level" column indicates whether the attribute is currently 540 specified as: 542 o S -- Session level 543 o M -- Media level 545 o B -- Both 547 o SR -- Source-level (for a single SSRC) [RFC5576] 549 The "Mux Category" column identifies multiplexing category assigned 550 per attribute and the "Notes" column captures additional informative 551 details regarding the assigned category, wherever necessary. 553 5.1. RFC4566: SDP 555 [RFC4566] defines SDP that is intended for describing multimedia 556 sessions for the purposes of session announcement, session 557 invitation, and other forms of multimedia session initiation. 559 +-----------------+---------------------+-------+-------------------+ 560 | Name | Notes | Level | Mux Category | 561 +-----------------+---------------------+-------+-------------------+ 562 | sendrecv | Not impacted | B | NORMAL | 563 | | | | | 564 | sendonly | Not impacted | B | NORMAL | 565 | | | | | 566 | recvonly | Not impacted | B | NORMAL | 567 | | | | | 568 | inactive | Not impacted | B | NORMAL | 569 | | | | | 570 | cat | Not impacted | S | NORMAL | 571 | | | | | 572 | ptime | The attribute value | M | IDENTICAL-PER-PT | 573 | | MUST be same for a | | | 574 | | given codec | | | 575 | | configuration | | | 576 | | | | | 577 | maxptime | The attribute value | M | IDENTICAL-PER-PT | 578 | | MUST be same for a | | | 579 | | given codec | | | 580 | | configuration | | | 581 | | | | | 582 | orient | Not Impacted | M | NORMAL | 583 | | | | | 584 | framerate | The attribute value | M | IDENTICAL-PER-PT | 585 | | MUST be same for a | | | 586 | | given codec | | | 587 | | configuration | | | 588 | | | | | 589 | quality | Not Impacted | M | NORMAL | 590 | | | | | 591 | rtpmap | The attribute value | M | IDENTICAL-PER-PT | 592 | | MUST be same for a | | | 593 | | given codec | | | 594 | | configuration | | | 595 | | | | | 596 | fmtp | The attribute value | M | IDENTICAL-PER-PT | 597 | | MUST be same for a | | | 598 | | given codec | | | 599 | | configuration | | | 600 | | | | | 601 | keywds | Not impacted | S | NORMAL | 602 | | | | | 603 | type | Not Impacted | S | NORMAL | 604 | | | | | 605 | type:broadcast | Not Impacted | S | NORMAL | 606 | | | | | 607 | type:H332 | Not Impacted | S | NORMAL | 608 | | | | | 609 | type:meeting | Not Impacted | S | NORMAL | 610 | | | | | 611 | type:moderated | Not Impacted | S | NORMAL | 612 | | | | | 613 | type:test | Not Impacted | S | NORMAL | 614 | | | | | 615 | tool | Not Impacted | S | NORMAL | 616 | | | | | 617 | charset | Not Impacted | S | NORMAL | 618 | | | | | 619 | sdplang | Not Impacted | B | NORMAL | 620 | | | | | 621 | lang | Not Impacted | B | NORMAL | 622 | | | | | 623 +-----------------+---------------------+-------+-------------------+ 625 RFC4566 Attribute Analysis 627 5.2. RFC4585: RTP/AVPF 629 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 630 enables receivers to provide, statistically, more immediate feedback 631 to the senders and thus allows for short-term adaptation and 632 efficient feedback-based repair mechanisms to be implemented. 634 +----------+----------------------------+-------+-------------------+ 635 | Name | Notes | Level | Mux Category | 636 +----------+----------------------------+-------+-------------------+ 637 | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT | 638 | | attributes are Payload | | | 639 | | Type (PT) scoped, their | | | 640 | | values MUST be identical | | | 641 | | for a given PT across the | | | 642 | | multiplexed "m=" lines. | | | 643 | | | | | 644 +----------+----------------------------+-------+-------------------+ 646 RFC4585 Attribute Analysis 648 5.3. RFC5761: Multiplexing RTP and RTCP 650 [RFC5761] discusses issues that arise when multiplexing RTP data 651 packets and RTP Control Protocol (RTCP) packets on a single UDP port. 652 It describes when such multiplexing is and is not appropriate, and it 653 explains how the SDP can be used to signal multiplexed sessions. 655 +-----------+----------------------------------+-------+------------+ 656 | Name | Notes | Level | Mux | 657 | | | | Category | 658 +-----------+----------------------------------+-------+------------+ 659 | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL | 660 | | affects the entire RTP session | | | 661 | | | | | 662 +-----------+----------------------------------+-------+------------+ 664 RFC5761 Attribute Analysis 666 5.4. RFC3312: Integration of Resource Management and SIP 668 [RFC3312] defines a generic framework for preconditions, which are 669 extensible through IANA registration. This document also discusses 670 how network quality of service can be made a precondition for 671 establishment of sessions initiated by the Session Initiation 672 Protocol (SIP). These preconditions require that the participant 673 reserve network resources before continuing with the session. 675 +-------+-----------------------+-------+------------------+ 676 | Name | Notes | Level | Mux Category | 677 +-------+-----------------------+-------+------------------+ 678 | des | Refer to notes below | M | NOT RECOMMENDED | 679 | | | | | 680 | conf | Refer to notes below | M | NOT RECOMMENDED | 681 | | | | | 682 | curr | Refer to notes below | M | NOT RECOMMENDED | 683 | | | | | 684 +-------+-----------------------+-------+------------------+ 686 RFC3312 Attribute Analysis 688 NOTE: A mismatched set of preconditions across media descriptions 689 results in Session establishment failures due to inability in meeting 690 the right resource reservations requested. 692 5.5. RFC4574: SDP Label Attribute 694 [RFC4574] defines a new SDP media-level attribute: "label". The 695 "label" attribute carries a pointer to a media stream in the context 696 of an arbitrary network application that uses SDP. The sender of the 697 SDP document can attach the "label" attribute to a particular media 698 stream or streams. The application can then use the provided pointer 699 to refer to each particular media stream in its context. 701 +--------+---------------+-------+--------------+ 702 | Name | Notes | Level | Mux Category | 703 +--------+---------------+-------+--------------+ 704 | label | Not Impacted | M | NORMAL | 705 | | | | | 706 +--------+---------------+-------+--------------+ 708 RFC4574 Attribute Analysis 710 5.6. RFC5432: QOS Mechanism Selection in SDP 712 [RFC5432] defines procedures to negotiate QOS mechanisms using the 713 SDP offer/answer model. 715 +----------------+----------------------------+-------+-------------+ 716 | Name | Notes | Level | Mux | 717 | | | | Category | 718 +----------------+----------------------------+-------+-------------+ 719 | qos-mech-send | Refer to section Section | B | TRANSPORT | 720 | | 10 | | | 721 | | | | | 722 | qos-mech-recv | Refer to section Section | B | TRANSPORT | 723 | | 10 | | | 724 | | | | | 725 +----------------+----------------------------+-------+-------------+ 727 RFC5432 Attribute Analysis 729 5.7. RFC4568: SDP Security Descriptions 731 [RFC4568] defines a SDP cryptographic attribute for unicast media 732 streams. The attribute describes a cryptographic key and other 733 parameters that serve to configure security for a unicast media 734 stream in either a single message or a roundtrip exchange. 736 +---------+------------------------------------+-------+------------+ 737 | Name | Notes | Level | Mux | 738 | | | | Category | 739 +---------+------------------------------------+-------+------------+ 740 | crypto | crypto attribute MUST be the one | M | TRANSPORT | 741 | | that corresponds to the "m=" line | | | 742 | | chosen for setting up the | | | 743 | | underlying transport flow | | | 744 | | | | | 745 +---------+------------------------------------+-------+------------+ 747 RFC4568 Attribute Analysis 749 5.8. RFC5762: RTP over DCCP 751 RTP is a widely used transport for real-time multimedia on IP 752 networks. DCCP is a transport protocol that provides desirable 753 services for real-time applications. [RFC5762] specifies a mapping 754 of RTP onto DCCP, along with associated signaling, such that real- 755 time applications can make use of the services provided by DCCP. 757 +--------------------+---------------------+---------+--------------+ 758 | Name | Notes | Current | Mux Category | 759 +--------------------+---------------------+---------+--------------+ 760 | dccp-service-code | If RFC6773 is not | M | NOT | 761 | | being used in | | RECOMMENDED | 762 | | addition to | | | 763 | | RFC5762, the port | | | 764 | | in the "m=" line is | | | 765 | | a DCCP port. DCCP | | | 766 | | being a connection | | | 767 | | oriented protocol, | | | 768 | | it does not allow | | | 769 | | multiple | | | 770 | | connections on the | | | 771 | | same 5-tuple | | | 772 | | | | | 773 +--------------------+---------------------+---------+--------------+ 775 RFC5762 Attribute Analysis 777 If RFC6773 is being used in addition to RFC5762 and provided that 778 DCCP-in-UDP layer has additional demultiplexing, then it can be 779 possible to use different DCCP service codes for each DCCP flow, 780 given each uses a different DCCP port. Although doing so might 781 conflict with the media type of the "m=" line. None of this is 782 standardized yet and it wouldn't work as explained. Hence 783 multiplexing MUST NOT be performed even in this alternate scenario. 785 5.9. RFC6773: DCCP-UDP Encapsulation 787 [RFC6773] document specifies an alternative encapsulation of DCCP, 788 referred to as DCCP-UDP. This encapsulation allows DCCP to be 789 carried through the current generation of Network Address Translation 790 (NAT) middle boxes without modification of those middle boxes. 792 +------------+-------------------------------+-------+--------------+ 793 | Name | Notes | Level | Mux Category | 794 +------------+-------------------------------+-------+--------------+ 795 | dccp-port | Multiplexing MUST NOT be | M | NOT | 796 | | performed due to potential | | RECOMMENDED | 797 | | conflict between the port | | | 798 | | used for DCCP | | | 799 | | en/decapsulation and the RTP | | | 800 | | | | | 801 +------------+-------------------------------+-------+--------------+ 803 RFC6773 Attribute Analysis 805 NOTE: RFC6773 is about tunneling DCCP in UDP, with the UDP port being 806 the port of the DCCP en-/de-capsulation service. This encapsulation 807 allows arbitrary DCCP packets to be encapsulated and the DCCP port 808 chosen can conflict with the port chosen for the RTP traffic. For 809 multiplexing several DCCP-in-UDP encapsulations on the same UDP port, 810 with no RTP traffic on the same port implies collapsing several DCCP 811 port spaces together. This can or cannot work depending on the 812 nature of DCCP encapsulation and ports choices thus rendering it to 813 be very application dependent. 815 5.10. RFC5506: Reduced-Size RTCP in RTP Profile 817 [RFC5506] discusses benefits and issues that arise when allowing RTCP 818 packets to be transmitted with reduced size. 820 +-------------+--------------------------------+-------+------------+ 821 | Name | Notes | Level | Mux | 822 | | | | Category | 823 +-------------+--------------------------------+-------+------------+ 824 | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL | 825 | | entire RTP session | | | 826 | | | | | 827 +-------------+--------------------------------+-------+------------+ 829 RFC5506 Attribute Analysis 831 5.11. RFC6787: Media Resource Control Protocol Version 2 833 The Media Resource Control Protocol Version 2 (MRCPv2) allows client 834 hosts to control media service resources such as speech synthesizers, 835 recognizers, verifiers, and identifiers residing in servers on the 836 network. MRCPv2 is not a "stand-alone" protocol -- it relies on 837 other protocols, such as the SIP, to coordinate MRCPv2 clients and 838 servers, and manage session between them, and SDP to describe, 839 discover, and exchange capabilities. It also depends on SIP and SDP 840 to establish the media sessions and associated parameters between the 841 media source or sink and the media server. Once this is done, the 842 MRCPv2 exchange operates over the control session established above, 843 allowing the client to control the media processing resources on the 844 speech resource server. [RFC6787] defines attributes for this 845 purpose. 847 +-----------+---------------+-------+--------------+ 848 | Name | Notes | Level | Mux Category | 849 +-----------+---------------+-------+--------------+ 850 | resource | Not Impacted | M | NORMAL | 851 | | | | | 852 | channel | Not Impacted | M | NORMAL | 853 | | | | | 854 | cmid | Not Impacted | M | NORMAL | 855 | | | | | 856 +-----------+---------------+-------+--------------+ 858 RFC6787 Attribute Analysis 860 5.12. RFC5245: ICE 862 [RFC5245] describes a protocol for NAT traversal for UDP-based 863 multimedia sessions established with the offer/answer model. ICE 864 makes use of the Session Traversal Utilities for NAT (STUN) protocol 865 and its extension, Traversal Using Relay NAT (TURN). ICE can be used 866 by any protocol utilizing the offer/answer model, such as the SIP. 868 +--------------------+-------------------------+-------+------------+ 869 | Name | Notes | Level | Mux | 870 | | | | Category | 871 +--------------------+-------------------------+-------+------------+ 872 | ice-lite | Not Impacted | S | NORMAL | 873 | | | | | 874 | ice-options | Not Impacted | S | NORMAL | 875 | | | | | 876 | ice-mismatch | Not Impacted | S | NORMAL | 877 | | | | | 878 | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT | 879 | | that corresponds to the | | | 880 | | "m=" line chosen for | | | 881 | | setting up the | | | 882 | | underlying transport | | | 883 | | flow | | | 884 | | | | | 885 | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | 886 | | one that corresponds to | | | 887 | | the "m=" line chosen | | | 888 | | for setting up the | | | 889 | | underlying transport | | | 890 | | flow | | | 891 | | | | | 892 | candidate | ice candidate MUST be | M | TRANSPORT | 893 | | the one that | | | 894 | | corresponds to the "m=" | | | 895 | | line chosen for setting | | | 896 | | up the underlying | | | 897 | | transport flow | | | 898 | | | | | 899 | remote-candidates | ice remote candidate | M | TRANSPORT | 900 | | MUST be the one that | | | 901 | | corresponds to the "m=" | | | 902 | | line chosen for setting | | | 903 | | up the underlying | | | 904 | | transport flow | | | 905 | | | | | 906 +--------------------+-------------------------+-------+------------+ 908 RFC5245 Attribute Analysis 910 5.13. RFC5285: RTP Header Extensions 912 [RFC5285] provides a general mechanism to use the header extension 913 feature of RTP. It provides the option to use a small number of 914 small extensions in each RTP packet, where the universe of possible 915 extensions is large and registration is de-centralized. The actual 916 extensions in use in a session are signaled in the setup information 917 for that session. 919 +---------+-------------------------------------+-------+-----------+ 920 | Name | Notes | Level | Mux | 921 | | | | Category | 922 +---------+-------------------------------------+-------+-----------+ 923 | extmap | Specific RTP extension document | B | SPECIAL | 924 | | MUST be referred | | | 925 | | | | | 926 +---------+-------------------------------------+-------+-----------+ 928 RFC5285 Attribute Analysis 930 5.14. RFC3605: RTCP attribute in SDP 932 Originally, SDP assumed that RTP and RTCP were carried on consecutive 933 ports. However, this is not always true when NATs are involved. 934 [RFC3605] specifies an early mechanism to indicate the RTCP port. 936 +-------+--------------------------------------+-------+------------+ 937 | Name | Notes | Level | Mux | 938 | | | | Category | 939 +-------+--------------------------------------+-------+------------+ 940 | rtcp | RTCP Port MUST be the one that | M | TRANSPORT | 941 | | corresponds to the "m=" line chosen | | | 942 | | for setting up the underlying | | | 943 | | transport flow. | | | 944 | | | | | 945 +-------+--------------------------------------+-------+------------+ 947 RFC3605 Attribute Analysis 949 5.15. RFC5576: Source-Specific SDP Attributes 951 [RFC5576] defines a mechanism to describe RTP media sources, which 952 are identified by their synchronization source (SSRC) identifiers, in 953 SDP, to associate attributes with these sources, and to express 954 relationships among sources. It also defines several source-level 955 attributes that can be used to describe properties of media sources. 957 +----------------+----------------------+-------+-------------------+ 958 | Name | Notes | Level | Mux Category | 959 +----------------+----------------------+-------+-------------------+ 960 | ssrc | Refer to Notes below | M | NORMAL | 961 | | | | | 962 | ssrc-group | Refer to Section 9 | M | NORMAL | 963 | | for specific | | | 964 | | analysis of the | | | 965 | | grouping semantics | | | 966 | | | | | 967 | cname | Not Impacted | SR | NORMAL | 968 | | | | | 969 | previous-ssrc | Refer to notes below | SR | NORMAL | 970 | | | | | 971 | fmtp | The attribute value | SR | IDENTICAL-PER-PT | 972 | | MUST be same for a | | | 973 | | given codec | | | 974 | | configuration | | | 975 | | | | | 976 +----------------+----------------------+-------+-------------------+ 978 RFC5576 Attribute Analysis 980 NOTE: If SSRCs are repeated across "m=" lines being multiplexed, they 981 MUST all represent the same underlying RTP Source. 983 5.16. RFC7273: RTP Clock Source Signalling 985 [RFC7273] specifies SDP signalling that identifies timestamp 986 reference clock sources and SDP signalling that identifies the media 987 clock sources in a multimedia session. 989 +--------------------+---------------+-------+--------------+ 990 | Name | Notes | Level | Mux Category | 991 +--------------------+---------------+-------+--------------+ 992 | ts-refclk | Not Impacted | B | NORMAL | 993 | | | | | 994 | mediaclk | Not Impacted | B | NORMAL | 995 | | | | | 996 | ts-refclk:ntp | Not Impacted | B | NORMAL | 997 | | | | | 998 | ts-refclk:ptp | Not Impacted | B | NORMAL | 999 | | | | | 1000 | ts-refclk:gps | Not Impacted | B | NORMAL | 1001 | | | | | 1002 | ts-refclk:gal | Not Impacted | B | NORMAL | 1003 | | | | | 1004 | ts-refclk:glonass | Not Impacted | B | NORMAL | 1005 | | | | | 1006 | ts-refclk:local | Not Impacted | B | NORMAL | 1007 | | | | | 1008 | ts-refclk:private | Not Impacted | B | NORMAL | 1009 | | | | | 1010 | mediaclk:sender | Not Impacted | B | NORMAL | 1011 | | | | | 1012 | mediaclk:direct | Not Impacted | B | NORMAL | 1013 | | | | | 1014 | mediaclk:IEEE1722 | Not Impacted | B | NORMAL | 1015 | | | | | 1016 +--------------------+---------------+-------+--------------+ 1018 RFC7273 Attribute Analysis 1020 5.17. RFC6236: Image Attributes in SDP 1022 [RFC6236] proposes a new generic session setup attribute to make it 1023 possible to negotiate different image attributes such as image size. 1024 A possible use case is to make it possible for a low-end hand-held 1025 terminal to display video without the need to rescale the image, 1026 something that may consume large amounts of memory and processing 1027 power. The document also helps to maintain an optimal bitrate for 1028 video as only the image size that is desired by the receiver is 1029 transmitted. 1031 +------------+--------------------------+-------+-------------------+ 1032 | Name | Notes | Level | Mux Category | 1033 +------------+--------------------------+-------+-------------------+ 1034 | imageattr | The attribute value MUST | M | IDENTICAL-PER-PT | 1035 | | be same for a given | | | 1036 | | codec configuration | | | 1037 | | | | | 1038 +------------+--------------------------+-------+-------------------+ 1040 RFC6236 Attribute Analysis 1042 5.18. RFC7197: Duplication Delay Attribute in SDP 1044 [RFC7197] defines an attribute to indicate the presence of temporally 1045 redundant media streams and the duplication delay in SDP. 1047 +--------------------+---------------+-------+--------------+ 1048 | Name | Notes | Level | Mux Category | 1049 +--------------------+---------------+-------+--------------+ 1050 | duplication-delay | Not Impacted | B | NORMAL | 1051 | | | | | 1052 +--------------------+---------------+-------+--------------+ 1054 RFC7197 Attribute Analysis 1056 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting 1058 [RFC7266] defines an RTCP Extended Report (XR) Block including two 1059 new segment types and associated SDP parameters that allow the 1060 reporting of mean opinion score (MOS) Metrics for use in a range of 1061 RTP applications. 1063 +-------------+---------------+-------+--------------+ 1064 | Name | Notes | Level | Mux Category | 1065 +-------------+---------------+-------+--------------+ 1066 | calgextmap | Not Impacted | B | NORMAL | 1067 | | | | | 1068 +-------------+---------------+-------+--------------+ 1070 RFC7266 Attribute Analysis 1072 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions 1074 [RFC6285] describes a method using the existing RTP and RTCP 1075 machinery that reduces the acquisition delay. In this method, an 1076 auxiliary unicast RTP session carrying the Reference Information to 1077 the receiver precedes or accompanies the multicast stream. This 1078 unicast RTP flow can be transmitted at a faster than natural bitrate 1079 to further accelerate the acquisition. The motivating use case for 1080 this capability is multicast applications that carry real-time 1081 compressed audio and video. 1083 +---------------+-------------------+-------+------------------+ 1084 | Name | Notes | Level | Mux Category | 1085 +---------------+-------------------+-------+------------------+ 1086 | rams-updates | Not recommended | M | NOT RECOMMENDED | 1087 | | | | | 1088 +---------------+-------------------+-------+------------------+ 1090 RFC6285 Attribute Analysis 1092 5.21. RFC6230: Media Control Channel Framework 1094 [RFC6230] describes a framework and protocol for application 1095 deployment where the application programming logic and media 1096 processing are distributed. This implies that application 1097 programming logic can seamlessly gain access to appropriate resources 1098 that are not co-located on the same physical network entity. The 1099 framework uses SIP to establish an application-level control 1100 mechanism between application servers and associated external servers 1101 such as media servers. 1103 +---------+---------------+-------+--------------+ 1104 | Name | Notes | Level | Mux Category | 1105 +---------+---------------+-------+--------------+ 1106 | cfw-id | Not Impacted | M | NORMAL | 1107 | | | | | 1108 +---------+---------------+-------+--------------+ 1110 RFC6230 Attribute Analysis 1112 5.22. RFC6364: SDP Elements for FEC Framework 1114 [RFC6364] specifies the use of SDP to describe the parameters 1115 required to signal the Forward Error Correction (FEC) Framework 1116 Configuration Information between the sender(s) and receiver(s). 1117 This document also provides examples that show the semantics for 1118 grouping multiple source and repair flows together for the 1119 applications that simultaneously use multiple instances of the FEC 1120 Framework. 1122 +------------------+-----------------------------+-------+----------+ 1123 | Name | Notes | Level | Mux | 1124 | | | | Category | 1125 +------------------+-----------------------------+-------+----------+ 1126 | fec-source-flow | Specific FEC scheme | M | SPECIAL | 1127 | | document needs to be | | | 1128 | | referred | | | 1129 | | | | | 1130 | fec-repair-flow | Specific FEC scheme | M | SPECIAL | 1131 | | document needs to be | | | 1132 | | referred | | | 1133 | | | | | 1134 | repair-window | Specific FEC scheme | M | SPECIAL | 1135 | | document needs to be | | | 1136 | | referred | | | 1137 | | | | | 1138 +------------------+-----------------------------+-------+----------+ 1140 RFC6364 Attribute Analysis 1142 5.23. RFC4796: Content Attribute 1144 [RFC4796] defines a new SDP media-level attribute, 'content'. The 1145 'content' attribute defines the content of the media stream to a more 1146 detailed level than the media description line. The sender of an SDP 1147 session description can attach the 'content' attribute to one or more 1148 media streams. The receiving application can then treat each media 1149 stream differently (e.g., show it on a big or small screen) based on 1150 its content. 1152 +----------+---------------+-------+--------------+ 1153 | Name | Notes | Level | Mux Category | 1154 +----------+---------------+-------+--------------+ 1155 | content | Not Impacted | M | NORMAL | 1156 | | | | | 1157 +----------+---------------+-------+--------------+ 1159 RFC4796 Attribute Analysis 1161 5.24. RFC3407: SDP Simple Capability Declaration 1163 [RFC3407] defines a set of SDP attributes that enables SDP to provide 1164 a minimal and backwards compatible capability declaration mechanism. 1166 +----------+------------------------+-------+--------------+ 1167 | Name | Notes | Level | Mux Category | 1168 +----------+------------------------+-------+--------------+ 1169 | sqn | Not Impacted | B | NORMAL | 1170 | | | | | 1171 | cdsc | Not Impacted. | B | NORMAL | 1172 | | | | | 1173 | cpar | Refer to Section 14 | B | INHERIT | 1174 | | | | | 1175 | cparmin | Refer to notes below | B | SPECIAL | 1176 | | | | | 1177 | cparmax | Refer to notes below | B | SPECIAL | 1178 | | | | | 1179 +----------+------------------------+-------+--------------+ 1181 RFC3407 Attribute Analysis 1183 NOTE: Since the attributes (a=cparmin and a=cparmax) define minimum 1184 and maximum numerical values associated with the attributes described 1185 in a=cpar, it is recommended to consult the document defining the 1186 attribute. 1188 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP Sessions 1190 [RFC6284] presents a port mapping solution that allows RTP receivers 1191 to choose their own ports for an auxiliary unicast session in RTP 1192 applications using both unicast and multicast services. The solution 1193 provides protection against denial-of-service or packet amplification 1194 attacks that could be used to cause one or more RTP packets to be 1195 sent to a victim client. 1197 +------------------+-------------------------+-------+--------------+ 1198 | Name | Notes | Level | Mux Category | 1199 +------------------+-------------------------+-------+--------------+ 1200 | portmapping-req | Not recommended, if | M | NOT | 1201 | | port mapping is | | RECOMMENDED | 1202 | | required by the | | | 1203 | | application | | | 1204 | | | | | 1205 +------------------+-------------------------+-------+--------------+ 1207 RFC6284 Attribute Analysis 1209 5.26. RFC6714: MSRP-CEMA 1211 [RFC6714] defines a Message Session Relay Protocol (MSRP) extension, 1212 Connection Establishment for Media Anchoring (CEMA). Support of this 1213 extension is OPTIONAL. The extension allows middle boxes to anchor 1214 the MSRP connection, without the need for middle boxes to modify the 1215 MSRP messages; thus, it also enables secure end-to-end MSRP 1216 communication in networks where such middle boxes are deployed. This 1217 document also defines a SDP attribute, 'msrp-cema', that MSRP 1218 endpoints use to indicate support of the CEMA extension. 1220 +------------+-----------------------+-------+--------------+ 1221 | Name | Notes | Level | Mux Category | 1222 +------------+-----------------------+-------+--------------+ 1223 | msrp-cema | Refer to notes below | M | TBD | 1224 | | | | | 1225 +------------+-----------------------+-------+--------------+ 1227 RFC6714 Attribute Analysis 1229 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1230 there exists no publicly available specification that defines 1231 procedures for multiplexing/demultiplexing MRSP flows over a single 1232 5-tuple. Once such a specification is available, the multiplexing 1233 categories assignments for the attributes in this section MUST be 1234 revisited. 1236 5.27. RFC4583: SDP Format for BFCP Streams 1238 [RFC4583] document specifies how to describe Binary Floor Control 1239 Protocol (BFCP) streams in SDP descriptions. User agents using the 1240 offer/answer model to establish BFCP streams use this format in their 1241 offers and answers. 1243 +------------+---------------------------------+-------+------------+ 1244 | Name | Notes | Level | Mux | 1245 | | | | Category | 1246 +------------+---------------------------------+-------+------------+ 1247 | floorctrl | The attribute MUST be repeated | M | IDENTICAL | 1248 | | across all the multiplexed "m=" | | | 1249 | | lines | | | 1250 | | | | | 1251 | confid | Not Impacted | M | NORMAL | 1252 | | | | | 1253 | userid | Not Impacted | M | NORMAL | 1254 | | | | | 1255 | floorid | The floorid MUST be globally | M | NORMAL | 1256 | | unique | | | 1257 | | | | | 1258 +------------+---------------------------------+-------+------------+ 1260 RFC4583 Attribute Analysis 1262 5.28. RFC5547: SDP Offer/Answer for File Transfer 1264 [RFC5547] provides a mechanism to negotiate the transfer of one or 1265 more files between two endpoints by using the SDP offer/answer model 1266 specified in [RFC3264]. 1268 +-------------------+-----------------------+-------+--------------+ 1269 | Name | Notes | Level | Mux Category | 1270 +-------------------+-----------------------+-------+--------------+ 1271 | file-selector | Refer to notes below | M | TBD | 1272 | | | | | 1273 | file-transfer-id | Refer to notes below | M | TBD | 1274 | | | | | 1275 | file-disposition | Refer to notes below | M | TBD | 1276 | | | | | 1277 | file-date | Refer to notes below | M | TBD | 1278 | | | | | 1279 | file-icon | Refer to notes below | M | TBD | 1280 | | | | | 1281 | file-range | Refer to notes below | M | TBD | 1282 | | | | | 1283 +-------------------+-----------------------+-------+--------------+ 1285 RFC5547 Attribute Analysis 1287 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1288 there exists no publicly available specification that defines 1289 procedures for multiplexing/demultiplexing MRSP flows over a single 1290 5-tuple. Once such a specification is available, the multiplexing 1291 categories assignments for attributes in this section MUST be 1292 revisited. 1294 5.29. RFC6849: SDP and RTP Media Loopback Extension 1296 [RFC6849] adds new SDP media types and attributes, which enable 1297 establishment of media sessions where the media is looped back to the 1298 transmitter. Such media sessions will serve as monitoring and 1299 troubleshooting tools by providing the means for measurement of more 1300 advanced Voice over IP (VoIP), Real-time Text, and Video over IP 1301 performance metrics. 1303 +---------------------+-----------------+-------+-------------------+ 1304 | Name | Notes | Level | Mux Category | 1305 +---------------------+-----------------+-------+-------------------+ 1306 | loopback rtp-pkt- | The attribute | M | IDENTICAL-PER-PT | 1307 | loopback | value MUST be | | | 1308 | | same for a | | | 1309 | | given codec | | | 1310 | | configuration | | | 1311 | | | | | 1312 | loopback rtp-media- | The attribute | M | IDENTICAL-PER-PT | 1313 | loopback | value MUST be | | | 1314 | | same for a | | | 1315 | | given codec | | | 1316 | | configuration | | | 1317 | | | | | 1318 | loopback-source | Not Impacted | M | NORMAL | 1319 | | | | | 1320 | loopback-mirror | Not Impacted | M | NORMAL | 1321 | | | | | 1322 +---------------------+-----------------+-------+-------------------+ 1324 RFC6849 Analysis 1326 5.30. RFC5760: RTCP with Unicast Feedback 1328 [RFC5760] specifies an extension to RTCP to use unicast feedback to a 1329 multicast sender. The proposed extension is useful for single-source 1330 multicast sessions such as Source-Specific Multicast (SSM) 1331 communication where the traditional model of many-to-many group 1332 communication is either not available or not desired. 1334 +---------------+------------------------------+-------+------------+ 1335 | Name | Notes | Level | Mux | 1336 | | | | Category | 1337 +---------------+------------------------------+-------+------------+ 1338 | rtcp-unicast | The attribute MUST be | M | IDENTICAL | 1339 | | reported across all "m=" | | | 1340 | | lines multiplexed | | | 1341 | | | | | 1342 +---------------+------------------------------+-------+------------+ 1344 RFC5760 Attribute Analysis 1346 5.31. RFC3611: RTCP XR 1348 [RFC3611] defines the Extended Report (XR) packet type for RTCP, and 1349 defines how the use of XR packets can be signaled by an application 1350 if it employs the Session Description Protocol (SDP). 1352 +----------+---------------+-------+--------------+ 1353 | Name | Notes | Level | Mux Category | 1354 +----------+---------------+-------+--------------+ 1355 | rtcp-xr | Not Impacted | B | NORMAL | 1356 | | | | | 1357 +----------+---------------+-------+--------------+ 1359 RFC3611 Attribute Analysis 1361 5.32. RFC5939: SDP Capability Negotiation 1363 [RFC5939] defines a general SDP Capability Negotiation framework. It 1364 also specifies how to provide attributes and transport protocols as 1365 capabilities and negotiate them using the framework. Extensions for 1366 other types of capabilities (e.g., media types and media formats) may 1367 be provided in other documents. 1369 +---------+-----------------------+-------+--------------+ 1370 | Name | Notes | Level | Mux Category | 1371 +---------+-----------------------+-------+--------------+ 1372 | pcfg | Refer to Section 14 | M | SPECIAL | 1373 | | | | | 1374 | acfg | Refer to Section 14 | M | SPECIAL | 1375 | | | | | 1376 | csup | Not Impacted | B | NORMAL | 1377 | | | | | 1378 | creq | Not Impacted | B | NORMAL | 1379 | | | | | 1380 | acap | Refer to Section 14 | B | INHERIT | 1381 | | | | | 1382 | tcap | Refer to Section 14 | B | INHERIT | 1383 | | | | | 1384 | cap-v0 | Not Impacted | B | NORMAL | 1385 | | | | | 1386 +---------+-----------------------+-------+--------------+ 1388 RFC5939 Attribute Analysis 1390 5.33. RFC6871: SDP Media Capabilities Negotiation 1392 SDP capability negotiation provides a general framework for 1393 indicating and negotiating capabilities in SDP. The base framework 1394 defines only capabilities for negotiating transport protocols and 1395 attributes. [RFC6871] extends the framework by defining media 1396 capabilities that can be used to negotiate media types and their 1397 associated parameters. 1399 +---------+-----------------------+-------+-------------------+ 1400 | Name | Notes | Level | Mux Category | 1401 +---------+-----------------------+-------+-------------------+ 1402 | rmcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1403 | | | | | 1404 | omcap | Not Impacted | B | NORMAL | 1405 | | | | | 1406 | mfcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1407 | | | | | 1408 | mscap | Refer to Section 14 | B | INHERIT | 1409 | | | | | 1410 | lcfg | Refer to Section 14 | B | SPECIAL | 1411 | | | | | 1412 | sescap | Refer to notes below | S | NOT RECOMMENDED | 1413 | | | | | 1414 | med-v0 | Not Impacted | S | NORMAL | 1415 | | | | | 1416 +---------+-----------------------+-------+-------------------+ 1418 RFC6871 - Attribute Analysis 1420 NOTE: The "sescap" attribute is NOT RECOMMENDED for use with 1421 multiplexing. The reason is that it requires the use of unique 1422 configuration numbers across the entire SDP (per [RFC6871]) as 1423 opposed to within a media description only (per [RFC5939]). As 1424 described in Section 14, the use of identical configuration numbers 1425 between multiplexed (bundled) media descriptions is the default way 1426 of indicating compatible configurations in a bundle. 1428 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP 1430 [RFC7006] extends the SDP capability negotiation framework to allow 1431 endpoints to negotiate three additional SDP capabilities. In 1432 particular, this memo provides a mechanism to negotiate bandwidth 1433 ("b=" line), connection data ("c=" line), and session or media titles 1434 ("i=" line for each session or media). 1436 +----------+-----------------------------------+-------+------------+ 1437 | Name | Notes | Level | Mux | 1438 | | | | Category | 1439 +----------+-----------------------------------+-------+------------+ 1440 | bcap | Inherit the category SUM as | B | INHERIT | 1441 | | applicable to b= attribute | | | 1442 | | | | | 1443 | bcap-v0 | Not Impacted | B | NORMAL | 1444 | | | | | 1445 | ccap | The connection address type MUST | B | IDENTICAL | 1446 | | be identical across all the | | | 1447 | | multiplexed "m=" lines | | | 1448 | | | | | 1449 | ccap-v0 | Not Impacted | B | NORMAL | 1450 | | | | | 1451 | icap | Not Impacted | B | NORMAL | 1452 | | | | | 1453 | icap-v0 | Not Impacted | B | NORMAL | 1454 | | | | | 1455 +----------+-----------------------------------+-------+------------+ 1457 RFC7006 - Attribute Analysis 1459 5.35. RFC4567: Key Management Extensions for SDP and RTSP 1461 [RFC4567] defines general extensions for SDP and Real Time Streaming 1462 Protocol (RTSP) to carry messages, as specified by a key management 1463 protocol, in order to secure the media. These extensions are 1464 presented as a framework, to be used by one or more key management 1465 protocols. As such, their use is meaningful only when complemented 1466 by an appropriate key management protocol. 1468 +-----------+----------------------------------+-------+------------+ 1469 | Name | Notes | Level | Mux | 1470 | | | | Category | 1471 +-----------+----------------------------------+-------+------------+ 1472 | key-mgmt | Key management protocol MUST be | B | IDENTICAL | 1473 | | identical across all the "m=" | | | 1474 | | lines | | | 1475 | | | | | 1476 | mikey | Key management protocol MUST be | B | IDENTICAL | 1477 | | identical across all the "m=" | | | 1478 | | lines | | | 1479 | | | | | 1480 +-----------+----------------------------------+-------+------------+ 1482 RFC4567 Attribute Analysis 1484 5.36. RFC4572: Comedia over TLS in SDP 1486 [RFC4572] specifies how to establish secure connection-oriented media 1487 transport sessions over the Transport Layer Security (TLS) protocol 1488 using SDP. It defines a new SDP protocol identifier, 'TCP/TLS'. It 1489 also defines the syntax and semantics for an SDP 'fingerprint' 1490 attribute that identifies the certificate that will be presented for 1491 the TLS session. This mechanism allows media transport over TLS 1492 connections to be established securely, so long as the integrity of 1493 session descriptions is assured. 1495 +--------------+-------------------------------+-------+------------+ 1496 | Name | Notes | Level | Mux | 1497 | | | | Category | 1498 +--------------+-------------------------------+-------+------------+ 1499 | fingerprint | fingerprint value from the | B | TRANSPORT | 1500 | | "m=" line defining the | | | 1501 | | underlying transport is | | | 1502 | | chosen | | | 1503 | | | | | 1504 +--------------+-------------------------------+-------+------------+ 1506 RFC4572 Attribute Analysis 1508 5.37. RFC4570: SDP Source Filters 1510 [RFC4570] describes how to adapt SDP to express one or more source 1511 addresses as a source filter for one or more destination "connection" 1512 addresses. It defines the syntax and semantics for an SDP "source- 1513 filter" attribute that may reference either IPv4 or IPv6 address(es) 1514 as either an inclusive or exclusive source list for either multicast 1515 or unicast destinations. In particular, an inclusive source-filter 1516 can be used to specify a Source-Specific Multicast (SSM) session. 1518 +----------------+-----------------------------+-------+------------+ 1519 | Name | Notes | Level | Mux | 1520 | | | | Category | 1521 +----------------+-----------------------------+-------+------------+ 1522 | source-filter | The attribute MUST be | B | IDENTICAL | 1523 | | repeated across all "m=" | | | 1524 | | lines multiplexed | | | 1525 | | | | | 1526 +----------------+-----------------------------+-------+------------+ 1528 RFC4570 Attribute Analysis 1530 5.38. RFC6128: RTCP Port for Multicast Sessions 1532 SDP has an attribute that allows RTP applications to specify an 1533 address and a port associated with the RTCP traffic. In RTP-based 1534 source-specific multicast (SSM) sessions, the same attribute is used 1535 to designate the address and the RTCP port of the Feedback Target in 1536 the SDP description. However, the RTCP port associated with the SSM 1537 session itself cannot be specified by the same attribute to avoid 1538 ambiguity, and thus, is required to be derived from the "m=" line of 1539 the media description. Deriving the RTCP port from the "m=" line 1540 imposes an unnecessary restriction. [RFC6128] removes this 1541 restriction by introducing a new SDP attribute. 1543 +-----------------+----------------------------+-------+------------+ 1544 | Name | Notes | Level | Mux | 1545 | | | | Category | 1546 +-----------------+----------------------------+-------+------------+ 1547 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | 1548 | | be identical across all | | | 1549 | | the "m=" lines | | | 1550 | | | | | 1551 +-----------------+----------------------------+-------+------------+ 1553 RFC6128 Attribute Analysis 1555 5.39. RFC6189: ZRTP 1557 [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman 1558 exchange to agree on a session key and parameters for establishing 1559 unicast SRTP sessions for (VoIP applications. 1561 +------------+---------------------------------+-------+------------+ 1562 | Name | Notes | Level | Mux | 1563 | | | | Category | 1564 +------------+---------------------------------+-------+------------+ 1565 | zrtp-hash | zrtp-hash attribute MUST be the | M | TRANSPORT | 1566 | | one that corresponds to the | | | 1567 | | "m=" line chosen for setting up | | | 1568 | | the underlying transport flow | | | 1569 | | | | | 1570 +------------+---------------------------------+-------+------------+ 1572 RFC6189 Attribute Analysis 1574 5.40. RFC4145: Connection-Oriented Media 1576 [RFC4145] describes how to express media transport over TCP using 1577 SDP. It defines the SDP 'TCP' protocol identifier, the SDP 'setup' 1578 attribute, which describes the connection setup procedure, and the 1579 SDP 'connection' attribute, which handles connection reestablishment. 1581 +-------------+--------------------------------+-------+------------+ 1582 | Name | Notes | Level | Mux | 1583 | | | | Category | 1584 +-------------+--------------------------------+-------+------------+ 1585 | setup | The attribute MUST be | B | IDENTICAL | 1586 | | identical across all "m=" | | | 1587 | | lines | | | 1588 | | | | | 1589 | connection | Thee attribute MUST be | B | IDENTICAL | 1590 | | identical across all "m=" | | | 1591 | | lines | | | 1592 | | | | | 1593 +-------------+--------------------------------+-------+------------+ 1595 RFC4145 Attribute Analysis 1597 5.41. RFC6947: The SDP altc Attribute 1599 [RFC6947] proposes a mechanism that allows the same SDP offer to 1600 carry multiple IP addresses of different address families (e.g., IPv4 1601 and IPv6). The proposed attribute, the "altc" attribute, solves the 1602 backward-compatibility problem that plagued Alternative Network 1603 Address Types (ANAT) due to their syntax. 1605 +-------+--------------------------------------+-------+------------+ 1606 | Name | Notes | Level | Mux | 1607 | | | | Category | 1608 +-------+--------------------------------------+-------+------------+ 1609 | altc | The IP Address and port MUST be the | M | TRANSPORT | 1610 | | one that corresponds to the "m=" | | | 1611 | | line chosen for setting up the | | | 1612 | | underlying transport flow | | | 1613 | | | | | 1614 +-------+--------------------------------------+-------+------------+ 1616 RFC6947 Attribute Analysis 1618 5.42. RFC7195: SDP Extension for Circuit Switched Bearers in PSTN 1620 [RFC7195] describes use cases, requirements, and protocol extensions 1621 for using SDP offer/answer model for establishing audio and video 1622 media streams over circuit-switched bearers in the Public Switched 1623 Telephone Network (PSTN). 1625 +--------------------------+-------------------+-------+------------+ 1626 | Name | Notes | Level | Mux | 1627 | | | | Category | 1628 +--------------------------+-------------------+-------+------------+ 1629 | cs-correlation:callerid | Refer to notes | M | TBD | 1630 | | below | | | 1631 | | | | | 1632 | cs-correlation:uuie | Refer to notes | M | TBD | 1633 | | below | | | 1634 | | | | | 1635 | cs-correlation:dtmf | Refer to notes | M | TBD | 1636 | | below | | | 1637 | | | | | 1638 | cs-correlation:external | Refer to notes | M | TBD | 1639 | | below | | | 1640 | | | | | 1641 +--------------------------+-------------------+-------+------------+ 1643 RFC7195 Attribute Analysis 1645 NOTE: [RFC7195] defines SDP attributes for establishing audio and 1646 video media streams over circuit-switched bearers by defining a new 1647 nettype value "PSTN". However, section 7.2 of 1648 [I-D.ietf-mmusic-sdp-bundle-negotiation] requires the "c=" line 1649 nettype value of "IN". If in future there exists a specification 1650 that defines procedures to multiplex media streams over nettype 1651 "PSTN", the multiplexing categories for attributes in this section 1652 MUST be revisited. 1654 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) 1656 [RFC7272] defines a new RTCP Packet Type and an RTCP Extended Report 1657 (XR) Block Type to be used for achieving Inter-Destination Media 1658 Synchronization (IDMS). 1660 +------------+---------------+-------+--------------+ 1661 | Name | Notes | Level | Mux Category | 1662 +------------+---------------+-------+--------------+ 1663 | rtcp-idms | Not Impacted | M | NORMAL | 1664 | | | | | 1665 +------------+---------------+-------+--------------+ 1667 RFC7272 Attribute Analysis 1669 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP 1670 Attributes 1672 [RFC5159] provides descriptions of SDP attributes used by the Open 1673 Mobile Alliance's Broadcast Service and Content Protection 1674 specification. 1676 +---------------------+-----------------------+-------+-------------+ 1677 | Name | Notes | Level | Mux | 1678 | | | | Category | 1679 +---------------------+-----------------------+-------+-------------+ 1680 | bcastversion | Not Impacted | S | NORMAL | 1681 | | | | | 1682 | stkmstream | Not Impacted | B | NORMAL | 1683 | | | | | 1684 | SRTPAuthentication | Needs further | M | TBD | 1685 | | analysis | | | 1686 | | | | | 1687 | SRTPROCTxRate | Needs further | M | TBD | 1688 | | analysis | | | 1689 | | | | | 1690 +---------------------+-----------------------+-------+-------------+ 1692 RFC5159 Attribute Analysis 1694 5.45. RFC6193: Media Description for IKE in SDP 1696 [RFC6193] specifies how to establish a media session that represents 1697 a virtual private network using the Session Initiation Protocol for 1698 the purpose of on-demand media/application sharing between peers. It 1699 extends the protocol identifier of SDP so that it can negotiate use 1700 of the Internet Key Exchange Protocol (IKE) for media sessions in the 1701 SDP offer/answer model. 1703 +-------------------+--------------------------+-------+------------+ 1704 | Name | Notes | Level | Mux | 1705 | | | | Category | 1706 +-------------------+--------------------------+-------+------------+ 1707 | ike-setup | Attribute MUST be | B | IDENTICAL | 1708 | | identical across all the | | | 1709 | | "m=" lines | | | 1710 | | | | | 1711 | psk-fingerprint | Attribute MUST be | B | IDENTICAL | 1712 | | identical across all the | | | 1713 | | "m=" lines | | | 1714 | | | | | 1715 | ike-esp | Attribute MUST be | B | IDENTICAL | 1716 | | identical across all the | | | 1717 | | "m=" lines | | | 1718 | | | | | 1719 | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL | 1720 | | identical across all the | | | 1721 | | "m=" lines | | | 1722 | | | | | 1723 +-------------------+--------------------------+-------+------------+ 1725 RFC6193 Attribute Analysis 1727 NOTE: With the above SDP constraints, a session multiplexed with 1728 multiple "m=" lines will use only one IPSec association for all of 1729 the "m=" lines. 1731 5.46. RFC2326: Real Time Streaming Protocol 1733 The Real Time Streaming Protocol, or RTSP, is an application-level 1734 protocol for control over the delivery of data with real-time 1735 properties. RTSP provides an extensible framework to enable 1736 controlled, on-demand delivery of real-time data, such as audio and 1737 video. 1739 +----------+---------------------------------+-------+--------------+ 1740 | Name | Notes | Level | Mux Category | 1741 +----------+---------------------------------+-------+--------------+ 1742 | etag | RTSP is not supported for RTP | B | NOT | 1743 | | Stream multiplexing | | RECOMMENDED | 1744 | | | | | 1745 | range | RTSP is not supported for RTP | B | NOT | 1746 | | Stream multiplexing | | RECOMMENDED | 1747 | | | | | 1748 | control | RTSP is not supported for RTP | B | NOT | 1749 | | Stream multiplexing | | RECOMMENDED | 1750 | | | | | 1751 | mtag | RTSP is not supported for RTP | B | NOT | 1752 | | Stream multiplexing | | RECOMMENDED | 1753 | | | | | 1754 +----------+---------------------------------+-------+--------------+ 1756 RFC2326 Attribute Analysis 1758 NOTE: [RFC2326] defines SDP attributes that are applicable in the 1759 declarative usage of SDP alone. For purposes of this document, only 1760 the Offer/Answer usage of SDP is considered as mandated by 1761 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1763 5.47. RFC6064: SDP and RTSP Extensions for 3GPP 1765 The Packet-switched Streaming Service (PSS) and the Multimedia 1766 Broadcast/Multicast Service (MBMS) defined by 3GPP use SDP and RTSP 1767 with some extensions. [RFC6064] provides information about these 1768 extensions and registers the RTSP and SDP extensions with IANA. 1770 +-------------------------------+------------+-------+--------------+ 1771 | Name | Notes | Level | Mux Category | 1772 +-------------------------------+------------+-------+--------------+ 1773 | X-predecbufsize | Refer to | M | NOT | 1774 | | notes | | RECOMMENDED | 1775 | | below | | | 1776 | | | | | 1777 | X-initpredecbufperiod | Refer to | M | NOT | 1778 | | notes | | RECOMMENDED | 1779 | | below | | | 1780 | | | | | 1781 | X-initpostdecbufperiod | Refer to | M | NOT | 1782 | | notes | | RECOMMENDED | 1783 | | below | | | 1784 | | | | | 1785 | X-decbyterate | Refer to | M | NOT | 1786 | | notes | | RECOMMENDED | 1787 | | below | | | 1788 | | | | | 1789 | 3gpp-videopostdecbufsize | Refer to | M | NOT | 1790 | | notes | | RECOMMENDED | 1791 | | below | | | 1792 | | | | | 1793 | framesize | Refer to | M | NOT | 1794 | | notes | | RECOMMENDED | 1795 | | below | | | 1796 | | | | | 1797 | 3GPP-Integrity-Key | Refer to | S | NOT | 1798 | | notes | | RECOMMENDED | 1799 | | below | | | 1800 | | | | | 1801 | 3GPP-SDP-Auth | Refer to | S | NOT | 1802 | | notes | | RECOMMENDED | 1803 | | below | | | 1804 | | | | | 1805 | 3GPP-SRTP-Config | Refer to | M | NOT | 1806 | | notes | | RECOMMENDED | 1807 | | below | | | 1808 | | | | | 1809 | alt | Refer to | M | NOT | 1810 | | notes | | RECOMMENDED | 1811 | | below | | | 1812 | | | | | 1813 | alt-default-id | Refer to | M | NOT | 1814 | | notes | | RECOMMENDED | 1815 | | below | | | 1816 | | | | | 1817 | alt-group | Refer to | S | NOT | 1818 | | notes | | RECOMMENDED | 1819 | | below | | | 1820 | | | | | 1821 | 3GPP-Adaptation-Support | Refer to | M | NOT | 1822 | | notes | | RECOMMENDED | 1823 | | below | | | 1824 | | | | | 1825 | 3GPP-Asset-Information | Refer to | B | NOT | 1826 | | notes | | RECOMMENDED | 1827 | | below | | | 1828 | | | | | 1829 | mbms-mode | Refer to | B | NOT | 1830 | | notes | | RECOMMENDED | 1831 | | below | | | 1832 | | | | | 1833 | mbms-flowid | Refer to | M | NOT | 1834 | | notes | | RECOMMENDED | 1835 | | below | | | 1836 | | | | | 1837 | mbms-repair | Refer to | B | NOT | 1838 | | notes | | RECOMMENDED | 1839 | | below | | | 1840 | | | | | 1841 | 3GPP-QoE-Metrics | Refer to | M | NOT | 1842 | | notes | | RECOMMENDED | 1843 | | below | | | 1844 | | | | | 1845 | 3GPP-QoE-Metrics:Corruption | Refer to | M | NOT | 1846 | duration | notes | | RECOMMENDED | 1847 | | below | | | 1848 | | | | | 1849 | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | NOT | 1850 | duration | notes | | RECOMMENDED | 1851 | | below | | | 1852 | | | | | 1853 | 3GPP-QoE-Metrics:Initial | Refer to | M | NOT | 1854 | buffering duration | notes | | RECOMMENDED | 1855 | | below | | | 1856 | | | | | 1857 | 3GPP-QoE-Metrics:Successive | Refer to | M | NOT | 1858 | loss of RTP packets | notes | | RECOMMENDED | 1859 | | below | | | 1860 | | | | | 1861 | 3GPP-QoE-Metrics:Frame rate | Refer to | M | NOT | 1862 | deviation | notes | | RECOMMENDED | 1863 | | below | | | 1864 | | | | | 1865 | 3GPP-QoE-Metrics:Jitter | Refer to | M | NOT | 1866 | duration | notes | | RECOMMENDED | 1867 | | below | | | 1868 | | | | | 1869 | 3GPP-QoE-Metrics:Content | Refer to | B | NOT | 1870 | Switch Time | notes | | RECOMMENDED | 1871 | | below | | | 1872 | | | | | 1873 | 3GPP-QoE-Metrics:Average | Refer to | M | NOT | 1874 | Codec Bitrate | notes | | RECOMMENDED | 1875 | | below | | | 1876 | | | | | 1877 | 3GPP-QoE-Metrics:Codec | Refer to | M | NOT | 1878 | Information | notes | | RECOMMENDED | 1879 | | below | | | 1880 | | | | | 1881 | 3GPP-QoE-Metrics:Buffer | Refer to | M | NOT | 1882 | Status | notes | | RECOMMENDED | 1883 | | below | | | 1884 | | | | | 1885 +-------------------------------+------------+-------+--------------+ 1887 RFC6064 Attribute Analysis 1889 NOTE: [RFC6064] defines SDP attributes that are applicable in the 1890 declarative usage of SDP alone. For purposes of this document, only 1891 the Offer/Answer usage of SDP is considered as mandated by 1892 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1894 5.48. RFC3108: ATM SDP 1896 [RFC3108] describes conventions for using SDP described for 1897 controlling ATM Bearer Connections, and any associated ATM Adaptation 1898 Layer (AAL). 1900 +------------------------+------------------+-------+---------------+ 1901 | Name | Notes | Level | Mux Category | 1902 +------------------------+------------------+-------+---------------+ 1903 | aalType | Refer to notes | B | NOT | 1904 | | below | | RECOMMENDED | 1905 | eecid | Refer to notes | B | NOT | 1906 | | below | | RECOMMENDED | 1907 | capability | Refer to notes | B | NOT | 1908 | | below | | RECOMMENDED | 1909 | qosClass | Refer to notes | B | NOT | 1910 | | below | | RECOMMENDED | 1911 | bcob | Refer to notes | B | NOT | 1912 | | below | | RECOMMENDED | 1913 | stc | Refer to notes | B | NOT | 1914 | | below | | RECOMMENDED | 1915 | upcc | Refer to notes | B | NOT | 1916 | | below | | RECOMMENDED | 1917 | atmQOSparms | Refer to notes | B | NOT | 1918 | | below | | RECOMMENDED | 1919 | atmTrfcDesc | Refer to notes | B | NOT | 1920 | | below | | RECOMMENDED | 1921 | abrParms | Refer to notes | B | NOT | 1922 | | below | | RECOMMENDED | 1923 | abrSetup | Refer to notes | B | NOT | 1924 | | below | | RECOMMENDED | 1925 | bearerType | Refer to notes | B | NOT | 1926 | | below | | RECOMMENDED | 1927 | lij | Refer to notes | B | NOT | 1928 | | below | | RECOMMENDED | 1929 | anycast | Refer to notes | B | NOT | 1930 | | below | | RECOMMENDED | 1931 | cache | Refer to notes | B | NOT | 1932 | | below | | RECOMMENDED | 1933 | bearerSigIE | Refer to notes | B | NOT | 1934 | | below | | RECOMMENDED | 1935 | aalApp | Refer to notes | B | NOT | 1936 | | below | | RECOMMENDED | 1937 | cbrRate | Refer to notes | B | NOT | 1938 | | below | | RECOMMENDED | 1939 | sbc | Refer to notes | B | NOT | 1940 | | below | | RECOMMENDED | 1941 | clkrec | Refer to notes | B | NOT | 1942 | | below | | RECOMMENDED | 1943 | fec | Refer to notes | B | NOT | 1944 | | below | | RECOMMENDED | 1945 | prtfl | Refer to notes | B | NOT | 1946 | | below | | RECOMMENDED | 1947 | structure | Refer to notes | B | NOT | 1948 | | below | | RECOMMENDED | 1949 | cpsSDUsize | Refer to notes | B | NOT | 1950 | | below | | RECOMMENDED | 1951 | aal2CPS | Refer to notes | B | NOT | 1952 | | below | | RECOMMENDED | 1953 | aal2CPSSDUrate | Refer to notes | B | NOT | 1954 | | below | | RECOMMENDED | 1955 | aal2sscs3661unassured | Refer to notes | B | NOT | 1956 | | below | | RECOMMENDED | 1957 | aal2sscs3661assured | Refer to notes | B | NOT | 1958 | | below | | RECOMMENDED | 1959 | aal2sscs3662 | Refer to notes | B | NOT | 1960 | | below | | RECOMMENDED | 1961 | aal5sscop | Refer to notes | B | NOT | 1962 | | below | | RECOMMENDED | 1963 | atmmap | Refer to notes | B | NOT | 1964 | | below | | RECOMMENDED | 1965 | silenceSupp | Refer to notes | B | NOT | 1966 | | below | | RECOMMENDED | 1967 | ecan | Refer to notes | B | NOT | 1968 | | below | | RECOMMENDED | 1969 | gc | Refer to notes | B | NOT | 1970 | | below | | RECOMMENDED | 1971 | profileDesc | Refer to notes | B | NOT | 1972 | | below | | RECOMMENDED | 1973 | vsel | Refer to notes | B | NOT | 1974 | | below | | RECOMMENDED | 1975 | dsel | Refer to notes | B | NOT | 1976 | | below | | RECOMMENDED | 1977 | fsel | Refer to notes | B | NOT | 1978 | | below | | RECOMMENDED | 1979 | onewaySel | Refer to notes | B | NOT | 1980 | | below | | RECOMMENDED | 1981 | codecconfig | Refer to notes | B | NOT | 1982 | | below | | RECOMMENDED | 1983 | isup_usi | Refer to notes | B | NOT | 1984 | | below | | RECOMMENDED | 1985 | uiLayer1_Prot | Refer to notes | B | NOT | 1986 | | below | | RECOMMENDED | 1987 | chain | Refer to notes | B | NOT | 1988 | | below | | RECOMMENDED | 1989 | | | | | 1990 +------------------------+------------------+-------+---------------+ 1992 RFC3108 Attribute Analysis 1994 NOTE: RFC3108 describes conventions for using SDP for characterizing 1995 ATM bearer connections using an AAL1, AAL2 or AAL5 adaptation layers. 1996 For AAL1, AAL2 and AAL5, bearer connections can be used to transport 1997 single media streams. In addition, for AAL1 and AAL2, multiple media 1998 streams can be multiplexed into a bearer connection. For all 1999 adaptation types (AAL1, AAL2 and AAL5), bearer connections can be 2000 bundled into a single media group. In all cases addressed by 2001 RFC3108, a real-time media stream (voice, video, voiceband data, 2002 pseudo-wire, and others) or a multiplex of media streams is mapped 2003 directly into an ATM connection. RFC3108 does not address cases 2004 where ATM serves as a low-level transport pipe for IP packets which 2005 in turn can carry one or more real-time (e.g. VoIP) media sessions 2006 with a life-cycle different from that of the underlying ATM 2007 transport. 2009 5.49. 3GPP TS 26.114 2011 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and 2012 interaction 2014 +----------------------+-------------------------+-------+----------+ 2015 | Name | Notes | Level | Mux | 2016 | | | | Category | 2017 +----------------------+-------------------------+-------+----------+ 2018 | 3gpp_sync_info | Usage defined for the | M | NORMAL | 2019 | | IP Multimedia Subsystem | | | 2020 | | | | | 2021 | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL | 2022 | | IP Multimedia Subsystem | | | 2023 | | | | | 2024 +----------------------+-------------------------+-------+----------+ 2026 3GPP TS 26.114 Attribute Analysis 2028 5.50. 3GPP TS 183.063 2030 [R3GPPTS183.063] Telecommunications and Internet converged Services 2031 and Protocols for Advanced Networking (TISPAN); 2033 +---------------------+---------------+-------+--------------+ 2034 | Name | Notes | Level | Mux Category | 2035 +---------------------+---------------+-------+--------------+ 2036 | PSCid | Not Impacted | S | NORMAL | 2037 | | | | | 2038 | bc_service | Not Impacted | S | NORMAL | 2039 | | | | | 2040 | bc_program | Not Impacted | S | NORMAL | 2041 | | | | | 2042 | bc_service_package | Not Impacted | S | NORMAL | 2043 | | | | | 2044 +---------------------+---------------+-------+--------------+ 2046 3GPP TS 183.063 Attribute Analysis 2048 5.51. 3GPP TS 24.182 2050 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting 2051 tones 2053 +-------------+---------------------------------+-------+-----------+ 2054 | Name | Notes | Level | Mux | 2055 | | | | Category | 2056 +-------------+---------------------------------+-------+-----------+ 2057 | g.3gpp.cat | Usage defined for the IP | M | NORMAL | 2058 | | Multimedia Subsystem | | | 2059 | | | | | 2060 +-------------+---------------------------------+-------+-----------+ 2062 3GPP TS 24.182 Attribute Analysis 2064 5.52. 3GPP TS 24.183 2066 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing 2067 Signal 2068 +-------------+---------------------------------+-------+-----------+ 2069 | Name | Notes | Level | Mux | 2070 | | | | Category | 2071 +-------------+---------------------------------+-------+-----------+ 2072 | g.3gpp.crs | Usage defined for the IP | M | NORMAL | 2073 | | Multimedia Subsystem | | | 2074 | | | | | 2075 +-------------+---------------------------------+-------+-----------+ 2077 3GPP TS 24.183 Attribute Analysis 2079 5.53. 3GPP TS 24.229 2081 [R3GPPTS24.229] specifies IP multimedia call control protocol based 2082 on Session Initial protocol and Session Description Protocol. 2084 +------------------+---------------------------+-------+------------+ 2085 | Name | Notes | Level | Mux | 2086 | | | | Category | 2087 +------------------+---------------------------+-------+------------+ 2088 | secondary-realm | secondary-realm MUST be | M | TRANSPORT | 2089 | | the one that corresponds | | | 2090 | | to the "m=" line chosen | | | 2091 | | for setting up the | | | 2092 | | underlying transport flow | | | 2093 | | | | | 2094 | visited-realm | visited-realm MUST be the | M | TRANSPORT | 2095 | | one that corresponds to | | | 2096 | | the "m=" line chosen for | | | 2097 | | setting up the underlying | | | 2098 | | transport flow | | | 2099 | | | | | 2100 | omr-m-cksum | Not Impacted | M | NORMAL | 2101 | | | | | 2102 | omr-s-cksum | Not Impacted | M | NORMAL | 2103 | | | | | 2104 | omr-m-att | Not Impacted | M | NORMAL | 2105 | | | | | 2106 | omr-s-att | Not Impacted | M | NORMAL | 2107 | | | | | 2108 | omr-m-bw | Not Impacted | M | NORMAL | 2109 | | | | | 2110 | omr-s-bw | Not Impacted | M | NORMAL | 2111 | | | | | 2112 | omr-codecs | Not Impacted | M | NORMAL | 2113 | | | | | 2114 +------------------+---------------------------+-------+------------+ 2116 3GPP TS 24.229 Attribute Analysis 2118 5.54. ITU T.38 2120 [T.38] defines procedures for real-time Group 3 facsimile 2121 communications over IP networks. 2123 +------------------------+--------------------+-------+-------------+ 2124 | Name | Notes | Level | Mux | 2125 | | | | Category | 2126 +------------------------+--------------------+-------+-------------+ 2127 | T38FaxVersion | Refer to notes | M | TBD | 2128 | | below | | | 2129 | | | | | 2130 | T38MaxBitRate | Refer to notes | M | TBD | 2131 | | below | | | 2132 | | | | | 2133 | T38FaxFillBitRemoval | Refer to notes | M | TBD | 2134 | | below | | | 2135 | | | | | 2136 | T38FaxTranscodingMMR | Refer to notes | M | TBD | 2137 | | below | | | 2138 | | | | | 2139 | T38FaxTranscodingJBIG | Refer to notes | M | TBD | 2140 | | below | | | 2141 | | | | | 2142 | T38FaxRateManagement | Refer to notes | M | TBD | 2143 | | below | | | 2144 | | | | | 2145 | T38FaxMaxBuffer | Refer to notes | M | TBD | 2146 | | below | | | 2147 | | | | | 2148 | T38FaxMaxDatagram | Refer to notes | M | TBD | 2149 | | below | | | 2150 | | | | | 2151 | T38FaxUdpEC | Refer to notes | M | TBD | 2152 | | below | | | 2153 | | | | | 2154 | T38FaxMaxIFP | Refer to notes | M | TBD | 2155 | | below | | | 2156 | | | | | 2157 | T38FaxUdpECDepth | Refer to notes | M | TBD | 2158 | | below | | | 2159 | | | | | 2160 | T38FaxUdpFECMaxSpan | Refer to notes | M | TBD | 2161 | | below | | | 2162 | | | | | 2163 | T38ModemType | Refer to notes | M | TBD | 2164 | | below | | | 2165 | | | | | 2166 | T38VendorInfo | Refer to notes | M | TBD | 2167 | | below | | | 2168 | | | | | 2169 +------------------------+--------------------+-------+-------------+ 2171 ITU T.38 Attribute Analysis 2173 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2174 there exists no publicly available specification that defines 2175 procedures for multiplexing/demultiplexing fax protocols flows over a 2176 single 5-tuple. Once such a specification is available, the 2177 multiplexing category assignments for the attributes in this section 2178 MUST be revisited. 2180 5.55. ITU-T Q.1970 2182 [Q.1970] defines Bearer Independent Call Control (BICC) IP bearer 2183 control protocol. 2185 +--------+---------------------------------------+-------+----------+ 2186 | Name | Notes | Level | Mux | 2187 | | | | Category | 2188 +--------+---------------------------------------+-------+----------+ 2189 | ipbcp | ipbcp version identifies type of IP | S | SPECIAL | 2190 | | bearer control protocol (IPBCP) | | | 2191 | | message used in BICC (ITU-T Q.1901) | | | 2192 | | environment which are limited to | | | 2193 | | single media payload. Pertinent ITU-T | | | 2194 | | specifications needs to be referred | | | 2195 | | while multiplexing | | | 2196 | | | | | 2197 +--------+---------------------------------------+-------+----------+ 2199 ITU-T Q.1970 Attribute Analysis 2201 5.56. ITU-T H.248.15 2203 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 2204 package attribute 2205 +-----------+------------------------------------+-------+----------+ 2206 | Name | Notes | Level | Mux | 2207 | | | | Category | 2208 +-----------+------------------------------------+-------+----------+ 2209 | h248item | It is only applicable for | B | SPECIAL | 2210 | | signaling the inclusion of H.248 | | | 2211 | | extension packages to a gateway | | | 2212 | | via the local and remote | | | 2213 | | descriptors. The attribute itself | | | 2214 | | is unaffected by multiplexing, but | | | 2215 | | the packaged referenced in a | | | 2216 | | specific use of the attribute can | | | 2217 | | be impacted. Further analysis of | | | 2218 | | each package is needed to | | | 2219 | | determine if there is an issue. | | | 2220 | | This is only a concern in | | | 2221 | | environments using a decomposed | | | 2222 | | server/gateway with H.248 signaled | | | 2223 | | between them. The ITU-T will need | | | 2224 | | to do further analysis of various | | | 2225 | | packages when they specify how to | | | 2226 | | signal the use of multiplexing to | | | 2227 | | a gateway | | | 2228 | | | | | 2229 +-----------+------------------------------------+-------+----------+ 2231 ITU-T H.248.15 Attribute Analysis 2233 5.57. RFC4975: The Message Session Relay Protocol 2235 [RFC4975] the Message Session Relay Protocol, a protocol for 2236 transmitting a series of related instant messages in the context of a 2237 session. Message sessions are treated like any other media stream 2238 when set up via a rendezvous or session creation protocol such as the 2239 Session Initiation Protocol. 2241 +-----------------------+---------------------+-------+-------------+ 2242 | Name | Notes | Level | Mux | 2243 | | | | Category | 2244 +-----------------------+---------------------+-------+-------------+ 2245 | accept-types | Refer to notes | M | TBD | 2246 | | below | | | 2247 | | | | | 2248 | accept-wrapped-types | Refer to notes | M | TBD | 2249 | | below | | | 2250 | | | | | 2251 | max-size | Refer to notes | M | TBD | 2252 | | below | | | 2253 | | | | | 2254 | path | Refer to notes | M | TBD | 2255 | | below | | | 2256 | | | | | 2257 +-----------------------+---------------------+-------+-------------+ 2259 RFC4975 Attribute Analysis 2261 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2262 there exists no publicly available specification that defines 2263 procedures for multiplexing/demultiplexing MRSP flows over a single 2264 5-tuple. Once such a specification is available, the multiplexing 2265 categories assignments for the attributes in this section MUST be 2266 revisited. 2268 5.58. Historical Attributes 2270 This section specifies analysis for the attributes that are included 2271 for historic usage alone by the [IANA]. 2273 +----------+----------------------+-------+------------------+ 2274 | Name | Notes | Level | Mux Category | 2275 +----------+----------------------+-------+------------------+ 2276 | rtpred1 | Historic attributes | M | NOT RECOMMENDED | 2277 | | | | | 2278 | rtpred2 | Historic attributes | M | NOT RECOMMENDED | 2279 | | | | | 2280 +----------+----------------------+-------+------------------+ 2282 Historical Attribute Analysis 2284 6. bwtype Attribute Analysis 2286 This section specifies handling of specific bandwidth attributes when 2287 used in multiplexing scenarios. 2289 6.1. RFC4566: SDP 2291 [RFC4566] defines SDP that is intended for describing multimedia 2292 sessions for the purposes of session announcement, session 2293 invitation, and other forms of multimedia session initiation. 2295 +------------+-----------------------------------+-------+----------+ 2296 | Name | Notes | Level | Mux | 2297 | | | | Category | 2298 +------------+-----------------------------------+-------+----------+ 2299 | bwtype:CT | Not Impacted | S | NORMAL | 2300 | | | | | 2301 | bwtype:AS | For the media level usage, the | B | SUM | 2302 | | aggregate of individual bandwidth | | | 2303 | | values is considered | | | 2304 | | | | | 2305 +------------+-----------------------------------+-------+----------+ 2307 RFC4566 bwtype Analysis 2309 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth 2311 [RFC3556] defines an extension to SDP to specify two additional 2312 modifiers for the bandwidth attribute. These modifiers may be used 2313 to specify the bandwidth allowed for RTCP packets in a RTP session. 2315 +------------+-----------------------------------+-------+----------+ 2316 | Name | Notes | Level | Mux | 2317 | | | | Category | 2318 +------------+-----------------------------------+-------+----------+ 2319 | bwtype:RS | Session level usage represents | B | SUM | 2320 | | session aggregate and media level | | | 2321 | | usage indicates SUM of the | | | 2322 | | individual values while | | | 2323 | | multiplexing | | | 2324 | | | | | 2325 | bwtype:RR | Session level usage represents | B | SUM | 2326 | | session aggregate and media level | | | 2327 | | usage indicates SUM of the | | | 2328 | | individual values while | | | 2329 | | multiplexing | | | 2330 | | | | | 2331 +------------+-----------------------------------+-------+----------+ 2333 RFC3556 bwtype Analysis 2335 6.3. RFC3890: Bandwidth Modifier for SDP 2337 [RFC3890] defines SDP Transport Independent Application Specific 2338 Maximum (TIAS) bandwidth modifier that does not include transport 2339 overhead; instead an additional packet rate attribute is defined. 2340 The transport independent bit-rate value together with the maximum 2341 packet rate can then be used to calculate the real bit-rate over the 2342 transport actually used. 2344 +--------------+---------------------------------+-------+----------+ 2345 | Name | Notes | Level | Mux | 2346 | | | | Category | 2347 +--------------+---------------------------------+-------+----------+ 2348 | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL | 2349 | | clearly defined Offer/Answer | | | 2350 | | usage. | | | 2351 | | | | | 2352 | maxprate | The usage of TIAS and maxprate | B | SPECIAL | 2353 | | is not well defined under | | | 2354 | | multiplexing | | | 2355 | | | | | 2356 +--------------+---------------------------------+-------+----------+ 2358 RFC3890 bwtype Analysis 2360 NOTE: The intention of TIAS is that the media level bit-rate is 2361 multiplied with the known per-packet overhead for the selected 2362 transport and the maxprate value to determine the worst case bit-rate 2363 from the transport to more accurately capture the required usage. 2364 Summing TIAS values independently across "m=" lines and multiplying 2365 the computed sum with maxprate and the per-packet overhead would 2366 inflate the value significantly. Instead performing multiplication 2367 and adding the individual values is a more appropriate usage. 2369 7. rtcp-fb Attribute Analysis 2371 This section analyzes rtcp-fb SDP attributes. 2373 7.1. RFC4585: RTP/AVPF 2375 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 2376 enables receivers to provide, statistically, more immediate feedback 2377 to the senders and thus allows for short-term adaptation and 2378 efficient feedback-based repair mechanisms to be implemented. 2380 +----------+----------------------------+-------+-------------------+ 2381 | Name | Notes | Level | Mux Category | 2382 +----------+----------------------------+-------+-------------------+ 2383 | ack rpsi | The attribute value MUST | M | IDENTICAL-PER-PT | 2384 | | be same for a given codec | | | 2385 | | configuration | | | 2386 | | | | | 2387 | ack app | Feedback parameters MUST | M | SPECIAL | 2388 | | be handled in the app | | | 2389 | | specific way when | | | 2390 | | multiplexed | | | 2391 | | | | | 2392 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2393 | | be same for a given codec | | | 2394 | | configuration | | | 2395 | | | | | 2396 | nack pli | The attribute value MUST | M | IDENTICAL-PER-PT | 2397 | | be same for a given codec | | | 2398 | | configuration | | | 2399 | | | | | 2400 | nack sli | The attribute value MUST | M | IDENTICAL-PER-PT | 2401 | | be same for a given codec | | | 2402 | | configuration | | | 2403 | | | | | 2404 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2405 | rpsi | be same for a given codec | | | 2406 | | configuration | | | 2407 | | | | | 2408 | nack app | Feedback parameters MUST | M | SPECIAL | 2409 | | be handled in the app | | | 2410 | | specific way when | | | 2411 | | multiplexed | | | 2412 | | | | | 2413 | trr-int | The attribute value MUST | M | IDENTICAL-PER-PT | 2414 | | be same for a given codec | | | 2415 | | configuration | | | 2416 | | | | | 2417 +----------+----------------------------+-------+-------------------+ 2419 RFC4585 Attribute Analysis 2421 7.2. RFC5104: Codec Control Messages in AVPF 2423 [RFC5104] specifies a few extensions to the messages defined in the 2424 Audio-Visual Profile with Feedback (AVPF). They are helpful 2425 primarily in conversational multimedia scenarios where centralized 2426 multipoint functionalities are in use. However, some are also usable 2427 in smaller multicast environments and point-to-point calls. 2429 +------+--------------------------------+-------+-------------------+ 2430 | Name | Notes | Level | Mux Category | 2431 +------+--------------------------------+-------+-------------------+ 2432 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2433 | | same for a given codec | | | 2434 | | configuration | | | 2435 | | | | | 2436 +------+--------------------------------+-------+-------------------+ 2438 RFC5104 Attribute Analysis 2440 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP Sessions 2441 (RAMS) 2443 [RFC6285] describes a method using the existing RTP and RTCP 2444 machinery that reduces the acquisition delay. In this method, an 2445 auxiliary unicast RTP session carrying the Reference Information to 2446 the receiver precedes or accompanies the multicast stream. This 2447 unicast RTP flow can be transmitted at a faster than natural bitrate 2448 to further accelerate the acquisition. The motivating use case for 2449 this capability is multicast applications that carry real-time 2450 compressed audio and video. 2452 +-------+-------------------------------+-------+-------------------+ 2453 | Name | Notes | Level | Mux Category | 2454 +-------+-------------------------------+-------+-------------------+ 2455 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2456 | rai | same for a given codec | | | 2457 | | configuration | | | 2458 | | | | | 2459 +-------+-------------------------------+-------+-------------------+ 2461 RFC6285 Attribute Analysis 2463 7.4. RFC6679: ECN for RTP over UDP/IP 2465 [RFC6679] specifies how Explicit Congestion Notification (ECN) can be 2466 used with the RTP running over UDP, using the RTCP as a feedback 2467 mechanism. It defines a new RTCP Extended Report (XR) block for 2468 periodic ECN feedback, a new RTCP transport feedback message for 2469 timely reporting of congestion events, and a STUN extension used in 2470 the optional initialization method using ICE. 2472 +------------------+---------------------------+-------+------------+ 2473 | Name | Notes | Level | Mux | 2474 | | | | Category | 2475 +------------------+---------------------------+-------+------------+ 2476 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | 2477 | | the RTP session level | | | 2478 | | | | | 2479 | nack ecn | This attribute enables | M | IDENTICAL | 2480 | | ECN at the RTP session | | | 2481 | | level | | | 2482 | | | | | 2483 +------------------+---------------------------+-------+------------+ 2485 RFC6679 Attribute Analysis 2487 7.5. RFC6642: Third-Party Loss Report 2489 In a large RTP session using the RTCP feedback mechanism defined in 2490 [RFC4585], a feedback target may experience transient overload if 2491 some event causes a large number of receivers to send feedback at 2492 once. This overload is usually avoided by ensuring that feedback 2493 reports are forwarded to all receivers, allowing them to avoid 2494 sending duplicate feedback reports. However, there are cases where 2495 it is not recommended to forward feedback reports, and this may allow 2496 feedback implosion. [RFC6642] memo discusses these cases and defines 2497 a new RTCP Third-Party Loss Report that can be used to inform 2498 receivers that the feedback target is aware of some loss event, 2499 allowing them to suppress feedback. Associated SDP signaling is also 2500 defined. 2502 +--------+------------------------------+-------+-------------------+ 2503 | Name | Notes | Level | Mux Category | 2504 +--------+------------------------------+-------+-------------------+ 2505 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2506 | tllei | same for a given codec | | | 2507 | | configuration | | | 2508 | | | | | 2509 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2510 | pslei | same for a given codec | | | 2511 | | configuration | | | 2512 | | | | | 2513 +--------+------------------------------+-------+-------------------+ 2515 RFC6642 Attribute Analysis 2517 7.6. RFC5104: Codec Control Messages in AVPF 2519 [RFC5104] specifies a few extensions to the messages defined in the 2520 Audio-Visual Profile with Feedback (AVPF). They are helpful 2521 primarily in conversational multimedia scenarios where centralized 2522 multipoint functionalities are in use. However, some are also usable 2523 in smaller multicast environments and point-to-point calls. 2525 +--------+------------------------------+-------+-------------------+ 2526 | Name | Notes | Level | Mux Category | 2527 +--------+------------------------------+-------+-------------------+ 2528 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2529 | fir | same for a given codec | | | 2530 | | configuration | | | 2531 | | | | | 2532 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2533 | tmmbr | same for a given codec | | | 2534 | | configuration | | | 2535 | | | | | 2536 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2537 | tstr | same for a given codec | | | 2538 | | configuration | | | 2539 | | | | | 2540 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2541 | vbcm | same for a given codec | | | 2542 | | configuration | | | 2543 | | | | | 2544 +--------+------------------------------+-------+-------------------+ 2546 RFC5104 Attribute Analysis 2548 8. group Attribute Analysis 2550 This section analyzes SDP "group" attribute semantics [RFC5888]. 2552 8.1. RFC5888: SDP Grouping Framework 2554 [RFC5888] defines a framework to group "m" lines in SDP for different 2555 purposes. 2557 +------------+---------------+-------+--------------+ 2558 | Name | Notes | Level | Mux Category | 2559 +------------+---------------+-------+--------------+ 2560 | group:LS | Not Impacted | S | NORMAL | 2561 | | | | | 2562 | group:FID | Not Impacted | S | NORMAL | 2563 | | | | | 2564 +------------+---------------+-------+--------------+ 2566 RFC5888 Attribute Analysis 2568 8.2. RFC3524: Mapping Media Streams to Resource Reservation Flows 2570 [RFC3524] defines an extension to the SDP grouping framework. It 2571 allows requesting a group of media streams to be mapped into a single 2572 resource reservation flow. The SDP syntax needed is defined, as well 2573 as a new "semantics" attribute called Single Reservation Flow (SRF). 2575 +------------+---------------+-------+--------------+ 2576 | Name | Notes | Level | Mux Category | 2577 +------------+---------------+-------+--------------+ 2578 | group:SRF | Not Impacted | S | NORMAL | 2579 | | | | | 2580 +------------+---------------+-------+--------------+ 2582 RFC3524 Attribute Analysis 2584 8.3. RFC4091: ANAT Semantics 2586 [RFC4091] defines ANAT semantics for the SDP grouping framework. The 2587 ANAT semantics allow alternative types of network addresses to 2588 establish a particular media stream. 2590 +-------------+---------------------------+-------+-----------------+ 2591 | Name | Notes | Level | Mux Category | 2592 +-------------+---------------------------+-------+-----------------+ 2593 | group:ANAT | ANAT semantics is | S | NOT RECOMMENDED | 2594 | | obseleted | | | 2595 | | | | | 2596 +-------------+---------------------------+-------+-----------------+ 2598 RFC4091 Attribute Analysis 2600 8.4. RFC5956: FEC Grouping Semantics in SDP 2602 [RFC5956] defines the semantics for grouping the associated source 2603 and FEC-based (Forward Error Correction) repair flows in SDP. The 2604 semantics defined in the document are to be used with the SDP 2605 Grouping Framework [RFC5888]. These semantics allow the description 2606 of grouping relationships between the source and repair flows when 2607 one or more source and/or repair flows are associated in the same 2608 group, and they provide support for additive repair flows. SSRC- 2609 level (Synchronization Source) grouping semantics are also defined in 2610 this document for RTP streams using SSRC multiplexing. 2612 +---------------+---------------+-------+--------------+ 2613 | Name | Notes | Level | Mux Category | 2614 +---------------+---------------+-------+--------------+ 2615 | group:FEC-FR | Not Impacted | S | NORMAL | 2616 | | | | | 2617 +---------------+---------------+-------+--------------+ 2619 RFC5956 Attribute Analysis 2621 8.5. RFC5583: Signaling Media Decoding Dependency in SDP 2623 [RFC5583] defines semantics that allow for signaling the decoding 2624 dependency of different media descriptions with the same media type 2625 in SDP. This is required, for example, if media data is separated 2626 and transported in different network streams as a result of the use 2627 of a layered or multiple descriptive media coding process. 2629 +------------+--------------------------+-------+-------------------+ 2630 | Name | Notes | Level | Mux Category | 2631 +------------+--------------------------+-------+-------------------+ 2632 | group:DDP | Not Impacted | S | NORMAL | 2633 | | | | | 2634 | depend lay | The attribute value MUST | M | IDENTICAL-PER-PT | 2635 | | be same for a given | | | 2636 | | codec configuration | | | 2637 | | | | | 2638 | depend mdc | The attribute value MUST | M | IDENTICAL-PER-PT | 2639 | | be same for a given | | | 2640 | | codec configuration | | | 2641 | | | | | 2642 +------------+--------------------------+-------+-------------------+ 2644 RFC5583 Attribute Analysis 2646 8.6. RFC7104: Duplication Grouping Semantics in the SDP 2648 [RFC7104] defines the semantics for grouping redundant streams in 2649 SDP, The semantics defined in this document are to be used with the 2650 SDP Grouping Framework. Grouping semantics at the SSRC)level are 2651 also defined in this document for RTP streams using SSRC 2652 multiplexing. 2654 +------------+---------------+-------+--------------+ 2655 | Name | Notes | Level | Mux Category | 2656 +------------+---------------+-------+--------------+ 2657 | group:DUP | Not Impacted | S | NORMAL | 2658 | | | | | 2659 +------------+---------------+-------+--------------+ 2661 RFC7104 Attribute Analysis 2663 9. ssrc-group Attribute Analysis 2665 This section analyzes "ssrc-group" semantics. 2667 9.1. RFC5576: Source-Specific SDP Attributes 2669 [RFC5576] defines a mechanism to describe RTP media sources, which 2670 are identified by their synchronization source (SSRC) identifiers, in 2671 SDP, to associate attributes with these sources, and to express 2672 relationships among sources. It also defines several source-level 2673 attributes that can be used to describe properties of media sources. 2675 +--------------------+---------------+-------+--------------+ 2676 | Name | Notes | Level | Mux Category | 2677 +--------------------+---------------+-------+--------------+ 2678 | ssrc-group:FID | Not Impacted | SR | NORMAL | 2679 | | | | | 2680 | ssrc-group:FEC | Not Impacted | SR | NORMAL | 2681 | | | | | 2682 | ssrc-group:FEC-FR | Not Impacted | SR | NORMAL | 2683 | | | | | 2684 +--------------------+---------------+-------+--------------+ 2686 RFC5576 Attribute Analysis 2688 9.2. RFC7104: Duplication Grouping Semantics in the SDP 2690 [RFC7104] defines the semantics for grouping redundant streams in 2691 SDP. The semantics defined in this document are to be used with the 2692 SDP Grouping Framework. Grouping semantics at the Synchronization 2693 Source (SSRC) level are also defined in this document for RTP streams 2694 using SSRC multiplexing. 2696 +-----------------+---------------+-------+--------------+ 2697 | Name | Notes | Level | Mux Category | 2698 +-----------------+---------------+-------+--------------+ 2699 | ssrc-group:DUP | Not Impacted | SR | NORMAL | 2700 | | | | | 2701 +-----------------+---------------+-------+--------------+ 2703 RFC7104 Attribute Analysis 2705 10. QoS Mechanism Token Analysis 2707 This section analyzes QoS tokes specified with SDP. 2709 10.1. RFC5432: QoS Mechanism Selection in SDP 2711 [RFC5432] defines procedures to negotiate QOS mechanisms using the 2712 SDP offer/answer model. 2714 +-------+--------------------------------------+-------+------------+ 2715 | Name | Notes | Level | Mux | 2716 | | | | Category | 2717 +-------+--------------------------------------+-------+------------+ 2718 | rsvp | rsvp attribute MUST be the one that | B | TRANSPORT | 2719 | | corresponds to the "m=" line chosen | | | 2720 | | for setting up the underlying | | | 2721 | | transport flow | | | 2722 | | | | | 2723 | nsis | rsvp attribute MUST be the one that | B | TRANSPORT | 2724 | | corresponds to the "m=" line chosen | | | 2725 | | for setting up the underlying | | | 2726 | | transport | | | 2727 | | | | | 2728 +-------+--------------------------------------+-------+------------+ 2730 RFC5432 Attribute Analysis 2732 NOTE: A single Differentiated Services Code Point (DSCP) code point 2733 per flow being multiplexed doesn't impact multiplexing since QOS 2734 mechanisms are signaled/scoped per flow. For scenarios that involve 2735 having different DSCP code points for packets being transmitted over 2736 the same 5-tuple, issues as discussed in [I-D.ietf-dart-dscp-rtp] 2737 need to be taken into consideration. 2739 11. k= Attribute Analysis 2740 11.1. RFC4566: SDP 2742 [RFC4566] defines SDP that is intended for describing multimedia 2743 sessions for the purposes of session announcement, session 2744 invitation, and other forms of multimedia session initiation. 2746 +------+------------------------------------+-------+---------------+ 2747 | Name | Notes | Level | Mux Category | 2748 +------+------------------------------------+-------+---------------+ 2749 | k= | It is NOT recommended to use this | S | NOT | 2750 | | attribute | | RECOMMENDED | 2751 | | | | | 2752 +------+------------------------------------+-------+---------------+ 2754 RFC4566 Attribute Analysis 2756 12. content Attribute Analysis 2758 12.1. RFC4796 2760 [RFC4796] defines a new SDP media-level attribute, 'content'. The 2761 'content' attribute defines the content of the media stream to a more 2762 detailed level than the media description line. The sender of an SDP 2763 session description can attach the 'content' attribute to one or more 2764 media streams. The receiving application can then treat each media 2765 stream differently (e.g., show it on a big or small screen) based on 2766 its content. 2768 +------------------+---------------+-------+--------------+ 2769 | Name | Notes | Level | Mux Category | 2770 +------------------+---------------+-------+--------------+ 2771 | content:slides | Not Impacted | M | NORMAL | 2772 | | | | | 2773 | content:speaker | Not Impacted | M | NORMAL | 2774 | | | | | 2775 | content:main | Not Impacted | M | NORMAL | 2776 | | | | | 2777 | content:sl | Not Impacted | M | NORMAL | 2778 | | | | | 2779 | content:alt | Not Impacted | M | NORMAL | 2780 | | | | | 2781 +------------------+---------------+-------+--------------+ 2783 RFC4796 Attribute Analysis 2785 13. Payload Formats 2787 13.1. RFC5109: RTP Payload Format for Generic FEC 2789 [RFC5109] describes a payload format for generic Forward Error 2790 Correction (FEC) for media data encapsulated in RTP. It is based on 2791 the exclusive-or (parity) operation. The payload format allows end 2792 systems to apply protection using various protection lengths and 2793 levels, in addition to using various protection group sizes to adapt 2794 to different media and channel characteristics. It enables complete 2795 recovery of the protected packets or partial recovery of the critical 2796 parts of the payload depending on the packet loss situation. 2798 +---------------------+----------------------+-------+--------------+ 2799 | Name | Notes | Level | Mux Category | 2800 +---------------------+----------------------+-------+--------------+ 2801 | audio/ulpfec | Not recommended for | M | NOT | 2802 | | multiplexing due to | | RECOMMENDED | 2803 | | reuse of SSRCs | | | 2804 | | | | | 2805 | video/ulpfec | Not recommended for | M | NOT | 2806 | | multiplexing due to | | RECOMMENDED | 2807 | | reuse of SSRCs | | | 2808 | | | | | 2809 | text/ulpfec | Not recommended for | M | NOT | 2810 | | multiplexing due to | | RECOMMENDED | 2811 | | reuse of SSRCs | | | 2812 | | | | | 2813 | application/ulpfec | Not recommended for | M | NOT | 2814 | | multiplexing due to | | RECOMMENDED | 2815 | | reuse of SSRCs | | | 2816 | | | | | 2817 +---------------------+----------------------+-------+--------------+ 2819 RFC5109 Payload Format Analysis 2821 14. Multiplexing Considerations for Encapsulating Attributes 2823 This sections deals with recommendations for defining the 2824 multiplexing characteristics of the SDP attributes that encapsulate 2825 other SDP attributes/parameters. Such attributes as of today, for 2826 example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of 2827 a generic framework for indicating and negotiating transport, media, 2828 and media format related capabilities in the SDP. 2830 The behavior of such attributes under multiplexing is in turn defined 2831 by the multiplexing behavior of the attributes they encapsulate which 2832 are made known once the Offer/Answer negotiation process is 2833 completed. 2835 14.1. RFC3407: cpar Attribute Analysis 2837 [RFC3407] capability parameter attribute (a=cpar) encapsulates b= 2838 (bandwidth) or an a= attribute. For bandwidth attribute 2839 encapsulation, the category SUM is inherited. For the case of a= 2840 attribute, the category corresponding to the SDP attribute being 2841 encapsulated is inherited. 2843 v=0 2844 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2845 s= 2846 c=IN IP4 host.atlanta.example.com 2847 t=0 0 2848 m=video 3456 RTP/AVP 100 2849 a=rtpmap:100 VP8/90000 2850 a=sqn: 0 2851 a=cdsc: 1 video RTP/AVP 100 2852 a=cpar: a=rtcp-mux 2853 m=video 3456 RTP/AVP 101 2854 a=rtpmap:101 VP8/90000 2855 a=fmtp:100 max-fr=15;max-fs=1200 2856 a=cdsc: 2 video RTP/AVP 101 2857 a=cpar: a=rtcp-mux 2859 In the above example,the category IDENTICAL is inherited for the cpar 2860 encapsulated rtcp-mux attribute. 2862 14.2. RFC5939 Analysis 2864 [RFC5939] defines a general SDP capability negotiation framework. It 2865 also specifies how to provide transport protocols and SDP attributes 2866 as capabilities and negotiate them using the framework. 2868 For this purpose, [RFC5939] defines the following 2870 o A set of capabilities for the session and its associated media 2871 stream components, supported by each side. The attribute 2872 ("a=acap") defines how to list an attribute name and its 2873 associated value (if any) as a capability. The attribute 2874 ("a=tcap") defines how to list transport protocols (e.g., "RTP/ 2875 AVP") as capabilities. 2877 o A set of potential configurations ("a=pcfg") provided by the 2878 offerer to indicate which combinations of those capabilities can 2879 be used for the session and its associated media stream 2880 components. Potential configurations are not ready for use until 2881 fully negotiated. They provide an alternative that MAY be used, 2882 subject to SDP capability negotiation procedures. In particular 2883 the answerer MAY choose one of the potential configurations for 2884 use as part of the current Offer/Answer exchange. 2886 o An actual configuration ("a=acfg") for the session and its 2887 associated media stream components. The actual configuration 2888 identifies the potential configuration that was negotiated for 2889 use. Use of an actual configuration does not require any further 2890 negotiation. 2892 o A negotiation process that takes the current actual and the set of 2893 potential configurations (combinations of capabilities) as input 2894 and provides the negotiated actual configurations as output. In 2895 [RFC5939] the negotiation process is done independently for each 2896 media description. 2898 14.2.1. Recommendation: Procedures for Potential Configuration Pairing 2900 This section provides recommendations for entities generating and 2901 processing SDP under the generic capability negotiation framework as 2902 defined in [RFC5939] under the context of media stream multiplexing. 2904 These recommendations are provided for the purposes of enabling the 2905 Offerer to make sure that the generated potential configurations 2906 between the multiplexed streams can (easily) be negotiated to be 2907 consistent between those streams. In particular, the procedures aim 2908 to simplify Answerer's procedure to choose potential configurations 2909 that are consistent across all the multiplexed media descriptions. 2911 A potential configuration selects a set of attributes and parameters 2912 that become part of the media description when negotiated. When 2913 multiplexing media descriptions with potential configurations 2914 specified, there MAY be a need for coordinating this selection 2915 between multiplexed media descriptions to ensure the right 2916 multiplexing behavior. 2918 Although it is possible to analyze the various potential 2919 configurations in multiplexed media descriptions to find combinations 2920 that satisfy such constraints, it can quickly become complicated to 2921 do so. 2923 The procedures defined in [RFC5939] state that each potential 2924 configuration in the SDP has a unique configuration number, however 2925 the scope of uniqueness is limited to each media description. To 2926 make it simple for the answerer to chose valid combinations of 2927 potential configurations across media descriptions in a given bundle 2928 group, we provide a simple rule for constructing potential 2929 configurations 2931 o Let m-bundle be the set of media descriptions that form a given 2932 bundle . 2934 o Let m-bundle-pcfg be the set of media descriptions in m-bundle 2935 that include one or more potential configurations. 2937 o Each media description in m-bundle-pcfg MUST have at least one 2938 potential configuration with the same configuration number (e.g. 2939 "1"). 2941 o For each potential configuration with configuration number x in m- 2942 bundle-pcfg, the offerer MUST ensure that if the answerer chooses 2943 configuration number x in each of the media descriptions in m- 2944 bundle-pcfg, then the resulting SDP will have all multiplexing 2945 constraints satisfied for those media descriptions. 2947 o Since it is nearly impossible to define a generic mechanism for 2948 various capability extensions, this document does't provide 2949 procedures for dealing with the capability extension attributes. 2950 However, Section 14.3 provide analysis of media capability 2951 extension attributes as defined in [RFC6871]. 2953 The above allows the answerer to easily find multiplexing compatible 2954 combinations of potential configurations: The answerer simply choses 2955 a potential configuration (number) that is present in all of the 2956 media descriptions with potential configurations in the bundle. 2958 Note that it is still possible for the offerer to provide additional 2959 potential configurations with independent configuration numbers. The 2960 answerer will have to perform more complicated analysis to determine 2961 valid multiplexed combinations of those. 2963 14.2.1.1. Example: Transport Capability Multiplexing 2964 v=0 2965 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2966 s= 2967 c=IN IP4 host.atlanta.example.com 2968 t=0 0 2969 a=tcap:1 RTP/SAVPF 2970 a=tcap:2 RTP/SAVP 2971 a=group:BUNDLE audio video 2972 m=audio 2973 a=mid:audio 2974 a=pcfg:1 t=1 2975 a=pcfg:2 2976 m=video 2977 a=mid:video 2978 a=pcfg:1 t=1 2979 a=pcfg:2 t=2 2981 In the example above, the potential configurations that offer 2982 transport protocol capability of RTP/SAVPF has the same configuration 2983 number "1" in both the audio and video media descriptions. 2985 14.2.1.2. Example: Attribute Capability Multiplexing 2987 v=0 2988 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2989 s= 2990 c=IN IP4 host.atlanta.example.com 2991 t=0 0 2992 a=acap:1 a=rtcp-mux 2993 a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80 2994 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 2995 a=group:BUNDLE audio video 2996 m=audio 49172 RTP/AVP 99 2997 a=mid:audio 2998 a=pcfg:1 a=1 2999 a=pcfg:2 3000 m=video 560024 RTP/AVP 100 3001 a=mid:video 3002 a=pcfg:1 a=1 3003 a=pcfg:2 a=2 3005 In the example above, the potential configuration number "1" is 3006 repeated while referring to attribute capability a=rtcp-mux, since 3007 the behavior is IDENTICAL for the attribute a=rtcp-mux under 3008 multiplexing. 3010 14.3. RFC6871 Analysis 3012 [RFC6871] extends capability negotiation framework described in 3013 [RFC5939] by defining media capabilities that can be used to indicate 3014 and negotiate media types and their associated format parameters. It 3015 also allows indication of latent configurations and session 3016 capabilities. 3018 14.3.1. Recommendation: Dealing with Payload Type Numbers 3020 [RFC6871] defines a new payload type ("pt") parameter to be used with 3021 the potential, actual, and latent configuration parameters. The 3022 parameter associates RTP payload type numbers with the referenced 3023 RTP-based media format capabilities ("a=rmcap") defined in [RFC6871] 3024 and is appropriate only when the transport protocol uses RTP. This 3025 means that the same payload type number can be assigned as part of 3026 potential or actual configurations in different media descriptions in 3027 a bundle. There are rules for the usage of identical Payload Type 3028 values across multiplexed "m=" lines as described in 3029 [I-D.ietf-mmusic-sdp-bundle-negotiation], which MUST be followed here 3030 as well. As described in Section 14.2.1, the use of identical 3031 configuration numbers for compatible configurations in different 3032 media descriptions that are part of the bundle provides a way to 3033 ensure that the answerer can easily pick compatible configurations 3034 here as well. 3036 14.3.1.1. Example: Attribute Capability Under Shared Payload Type 3038 The attributes (a=rmcap, a=mfcap) follow the above recommendations 3039 under multiplexing. 3041 v=0 3042 o=- 25678 753849 IN IP4 192.0.2.1 3043 s= 3044 c=IN IP4 192.0.2.1 3045 t=0 0 3046 a=creq:med-v0 3047 m=audio 54322 RTP/AVP 96 3048 a=rtpmap:96 AMR-WB/16000/1 3049 a=fmtp:96 mode-change-capability=1; max-red=220; 3050 mode-set=0,2,4,7 3051 a=rmcap:1,3 audio AMR-WB/16000/1 3052 a=rmcap:2 audio AMR/8000/1 3053 a=mfcap:1,2 mode-change-capability=1 3054 a=mfcap:3 mode-change-capability=2 3055 a=pcfg:1 m=1 pt=1:96 3056 a=pcfg:2 m=2 pt=2:97 3057 a=pcfg:3 m=3 pt=3:98 3058 m=audio 54322 RTP/AVP 96 3059 a=rtpmap:96 AMR-WB/16000/1 3060 a=fmtp:96 mode-change-capability=1; max-red=220; 3061 mode-set=0,2,4,7 3062 a=rmcap:4 audio AMR/8000/1 3063 a=rmcap:5 audio OPUS/48000/2 3064 a=mfcap:5 minptime=40 3065 a=mfcap:4 mode-change-capability=1 3066 a=pcfg:1 m=4 pt=4:97 3067 a=pcfg:4 m=5 pt=5:101 3069 In the example above, the potential configuration number "1" is 3070 repeated when referring to media and media format capability used for 3071 the Payload Type 96. This implies that both the media capability 2 3072 and 4 along with their media format capabilities MUST refer to the 3073 same codec configuration, as per the definition of IDENTICAL-PER-PT. 3075 14.3.2. Recommendation: Dealing with Latent Configurations 3077 [RFC6871] adds the notion of a latent configurations, which provides 3078 configuration information that MAY be used to guide a subsequent 3079 offer/exchange, e.g. by adding another media stream or use 3080 alternative codec combinations not currently offered. Latent 3081 configurations have configuration numbers which cannot overlap with 3082 the potential configuration numbers [RFC6871]. Supported 3083 combinations of potential and latent configurations are indicated by 3084 use of the "a=sescap" attribute, however use of this attribute is NOT 3085 RECOMMENDED with multiplexed media, since it requires the use of 3086 unique configuration numbers across the SDP. Taken together, this 3087 means there is no well-defined way to indicate supported combinations 3088 of latent configurations, or combinations of latent and potential 3089 configurations with multiplexed media. It is still allowed to use 3090 the latent configuration attribute, however the limitations above 3091 will apply. To determine valid combinations, actual negotiation will 3092 have to be attempted subsequently instead. 3094 15. IANA Considerations 3096 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this 3097 document.] 3099 The IANA is requested to add a new column named "Mux Category" to 3100 several of the subregistries in the "Session Description Protocol 3101 (SDP) Parameters" registry. Section 15.1 defines a new subregistry 3102 for identifying the initial registrations for various multiplexing 3103 categories applicable, as proposed in this document. 3105 The tables in Section 15.2 identify name of an entry in the existing 3106 subregistry and specify the value to put in the new "Mux Category" 3107 column of the associated IANA registry. Any entries in the existing 3108 tables that do not have a value for the "Mux Category" specified in 3109 this RFC will get a value of "TBD". Future specifications can change 3110 the "TBD" entries to the correct value. 3112 15.1. New 'Multiplexing Categories' subregistry 3114 A new sub-registry needs to be defined called the "Multiplexing 3115 Categories", with the following registrations created initially: 3116 "NORMAL", "NOT RECOMMENDED", "IDENTICAL", "TRANSPORT", "SUM", 3117 "INHERIT", "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this 3118 document. 3120 Initial value registration for "Multiplexing Categories". 3122 +-------------------------+-----------+ 3123 | Multiplexing Categories | Reference | 3124 +-------------------------+-----------+ 3125 | NORMAL | RFCXXXX | 3126 | NOT RECOMMENDED | RFCXXXX | 3127 | IDENTICAL | RFCXXXX | 3128 | TRANSPORT | RFCXXXX | 3129 | SUM | RFCXXXX | 3130 | INHERIT | RFCXXXX | 3131 | IDENTICAL-PER-PT | RFCXXXX | 3132 | SPECIAL | RFCXXXX | 3133 | TBD | RFCXXXX | 3134 +-------------------------+-----------+ 3135 Further entries can be registered on a first-come first-serve basis. 3136 Each registration needs to indicate the multiplexing category value 3137 to be added to the "Multiplexing Categories" subregistry as defined 3138 in this section. 3140 Such a registration MUST also indicate the applicability of the newly 3141 defined multiplexing category value to various subregistries defined 3142 at "Session Description Protocol (SDP) Parameters". 3144 The general registration procedures of [RFC4566] apply. 3146 15.2. 'Mux Category' column for subregistries 3148 Each sub-section identifies a subregistry in the "Session Description 3149 Protocol (SDP) Parameters" registry. The tables list the column that 3150 identifies the SDP attribute name/Token/Value from the corresponding 3151 subregistries and the values to be used for the new "Mux Category" 3152 column to be added. 3154 15.2.1. Table: SDP bwtype 3156 The following values are to be added to the 'SDP bwtype' subregistry 3157 in the "Session Description Protocol (SDP) Parameters" registry. The 3158 references should be updated to point at this RFC as well as the 3159 previous references. 3161 +----------+--------------+ 3162 | SDP Name | Mux Category | 3163 +----------+--------------+ 3164 | CT | NORMAL | 3165 | AS | SUM | 3166 | RS | SUM | 3167 | RR | SUM | 3168 | TIAS | SPECIAL | 3169 +----------+--------------+ 3171 15.2.2. Table: att-field (session level) 3173 The following values are to be added to the "att-field (session 3174 level)" subregistry in the "Session Description Protocol (SDP) 3175 Parameters" registry. The references should be updated to point at 3176 this RFC as well as the previous references. 3178 +---------------------+------------------+ 3179 | SDP Name | Mux Category | 3180 +---------------------+------------------+ 3181 | cat | NORMAL | 3182 | keywds | NORMAL | 3183 | type | NORMAL | 3184 | type:broadcast | NORMAL | 3185 | type:H332 | NORMAL | 3186 | type:meeting | NORMAL | 3187 | type:moderated | NORMAL | 3188 | type:test | NORMAL | 3189 | charset | NORMAL | 3190 | charset:iso8895-1 | NORMAL | 3191 | tool | NORMAL | 3192 | ipbcp | SPECIAL | 3193 | group | NORMAL | 3194 | ice-lite | NORMAL | 3195 | ice-options | NORMAL | 3196 | bcastversion | NORMAL | 3197 | 3GPP-Integrity-Key | NOT RECOMMENDED | 3198 | 3GPP-SDP-Auth | NOT RECOMMENDED | 3199 | alt-group | NOT RECOMMENDED | 3200 | PSCid | NORMAL | 3201 | bc_service | NORMAL | 3202 | bc_program | NORMAL | 3203 | bc_service_package | NORMAL | 3204 | sescap | NOT RECOMMENDED | 3205 | rtsp-ice-d-m | TBD | 3206 +---------------------+------------------+ 3208 15.2.3. Table: att-field (both session and media level) 3210 The following values are to be added to the "att-field (both session 3211 and media level)" subregistry in the "Session Description Protocol 3212 (SDP) Parameters" registry. The references should be updated to 3213 point at this RFC as well as the previous references. 3215 NOTE: The attributes from draft-ietf-rmt-flute-sdp ('flute-tsi', 3216 'flute-ch', 'FEC-declaration', 'FEC-OTI-extension', 'content-desc') 3217 were not analyzed for their multiplexing behavior due to the expired 3218 status of the draft. For purposes of this specification, the 3219 multiplexing category of 'TBD' is assigned. 3221 +-------------------------+-------------------+ 3222 | SDP Name | Mux Category | 3223 +-------------------------+-------------------+ 3224 | recvonly | NORMAL | 3225 | sendrecv | NORMAL | 3226 | sendonly | NORMAL | 3227 | sdplang | NORMAL | 3228 | lang | NORMAL | 3229 | h248item | SPECIAL | 3230 | sqn | NORMAL | 3231 | cdsc | NORMAL | 3232 | cpar | INHERIT | 3233 | cparmin | SPECIAL | 3234 | cparmax | SPECIAL | 3235 | rtcp-xr | NORMAL | 3236 | maxprate | SPECIAL | 3237 | setup | IDENTICAL | 3238 | connection | IDENTICAL | 3239 | key-mgmt | IDENTICAL | 3240 | source-filter | IDENTICAL | 3241 | inactive | NORMAL | 3242 | fingerprint | TRANSPORT | 3243 | flute-tsi | TBD | 3244 | flute-ch | TBD | 3245 | FEC-declaration | TBD | 3246 | FEC-OTI-extension | TBD | 3247 | content-desc | TBD | 3248 | ice-pwd | TRANSPORT | 3249 | ice-ufrag | TRANSPORT | 3250 | stkmstream | NORMAL | 3251 | extmap | SPECIAL | 3252 | qos-mech-send | TRANSOPORT | 3253 | qos-mech-recv | TRANSPORT | 3254 | csup | NORMAL | 3255 | creq | NORMAL | 3256 | acap | INHERIT | 3257 | tcap | INHERIT | 3258 | 3GPP-QoE-Metrics | NOT RECOMMENDED | 3259 | 3GPP-Asset-Information | NOT RECOMMENDED | 3260 | mbms-mode | NOT RECOMMENDED | 3261 | mbms-repair | NOT RECOMMENDED | 3262 | ike-setup | IDENTICAL | 3263 | psk-fingerprint | IDENTICAL | 3264 | multicast-rtcp | IDENTICAL | 3265 | rmcap | IDENTICAL-PER-PT | 3266 | omcap | NORMAL | 3267 | mfcap | IDENTICAL-PER-PT | 3268 | mscap | INHERIT | 3269 | 3gpp.iut.replication | TBD | 3270 | bcap | INHERIT | 3271 | ccap | IDENTICAL | 3272 | icap | NORMAL | 3273 | 3gpp_sync_info | NORMAL | 3274 | 3gpp_MaxRecvSDUSize | NORMAL | 3275 | etag | NOT RECOMMENDED | 3276 | duplication-delay | NORMAL | 3277 | range | NOT RECOMMENDED | 3278 | control | NOT RECOMMENDED | 3279 | mtag | NOT RECOMMENDED | 3280 | ts-refclk | NORMAL | 3281 | mediaclk | NORMAL | 3282 | calgextmap | NORMAL | 3283 +-------------------------+-------------------+ 3285 15.2.4. Table: att-field (media level only) 3287 The following values are to be added to the "att-field (media level 3288 only)" registry in the "Session Description Protocol (SDP) 3289 Parameters" registry. The references should be updated to point at 3290 this RFC as well as the previous references. 3292 +---------------------------+-------------------+ 3293 | SDP Name | Mux Category | 3294 +---------------------------+-------------------+ 3295 | ptime | IDENTICAL-PER-PT | 3296 | orient | NORMAL | 3297 | orient:portrait | NORMAL | 3298 | orient:landscape | NORMAL | 3299 | orient:seascape | NORMAL | 3300 | framerate | IDENTICAL-PER-PT | 3301 | quality | NORMAL | 3302 | rtpmap | IDENTICAL-PER-PT | 3303 | fmtp | IDENTICAL-PER-PT | 3304 | rtpred1 | NOT RECOMMENDED | 3305 | rtpred2 | NOT RECOMMENDED | 3306 | T38FaxVersion | TBD | 3307 | T38MaxBitRate | TBD | 3308 | T38FaxFillBitRemoval | TBD | 3309 | T38FaxTranscodingMMR | TBD | 3310 | T38FaxTranscodingJBIG | TBD | 3311 | T38FaxRateManagement | TBD | 3312 | T38FaxMaxBuffer | TBD | 3313 | T38FaxMaxDatagram | TBD | 3314 | T38FaxUdpEC | TBD | 3315 | maxptime | IDENTICAL-PER-PT | 3316 | des | NOT RECOMMENDED | 3317 | curr | NOT RECOMMENDED | 3318 | conf | NOT RECOMMENDED | 3319 | mid | NORMAL | 3320 | rtcp | TRANSPORT | 3321 | rtcp-fb | IDENTICAL-PER-PT | 3322 | label | NORMAL | 3323 | T38VendorInfo | TBD | 3324 | crypto | TRANSPORT | 3325 | eecid | NOT RECOMMENDED | 3326 | aalType | NOT RECOMMENDED | 3327 | capability | NOT RECOMMENDED | 3328 | qosClass | NOT RECOMMENDED | 3329 | bcob | NOT RECOMMENDED | 3330 | stc | NOT RECOMMENDED | 3331 | upcc | NOT RECOMMENDED | 3332 | atmQOSparms | NOT RECOMMENDED | 3333 | atmTrfcDesc | NOT RECOMMENDED | 3334 | abrParms | NOT RECOMMENDED | 3335 | abrSetup | NOT RECOMMENDED | 3336 | bearerType | NOT RECOMMENDED | 3337 | lij | NOT RECOMMENDED | 3338 | anycast | NOT RECOMMENDED | 3339 | cache | NOT RECOMMENDED | 3340 | bearerSigIE | NOT RECOMMENDED | 3341 | aalApp | NOT RECOMMENDED | 3342 | cbrRate | NOT RECOMMENDED | 3343 | sbc | NOT RECOMMENDED | 3344 | clkrec | NOT RECOMMENDED | 3345 | fec | NOT RECOMMENDED | 3346 | prtfl | NOT RECOMMENDED | 3347 | structure | NOT RECOMMENDED | 3348 | cpsSDUsize | NOT RECOMMENDED | 3349 | all2CPS | NOT RECOMMENDED | 3350 | all2CPSSDUrate | NOT RECOMMENDED | 3351 | aal2sscs3661unassured | NOT RECOMMENDED | 3352 | aal2sscs3661assured | NOT RECOMMENDED | 3353 | aal2sscs3662 | NOT RECOMMENDED | 3354 | aal5sscop | NOT RECOMMENDED | 3355 | atmmap | NOT RECOMMENDED | 3356 | silenceSupp | NOT RECOMMENDED | 3357 | ecan | NOT RECOMMENDED | 3358 | gc | NOT RECOMMENDED | 3359 | profileDesc | NOT RECOMMENDED | 3360 | vsel | NOT RECOMMENDED | 3361 | dsel | NOT RECOMMENDED | 3362 | fsel | NOT RECOMMENDED | 3363 | onewaySel | NOT RECOMMENDED | 3364 | codecconfig | NOT RECOMMENDED | 3365 | isup_usi | NOT RECOMMENDED | 3366 | uiLayer1_Prot | NOT RECOMMENDED | 3367 | chain | NOT RECOMMENDED | 3368 | floorctrl | IDENTICAL | 3369 | confid | NORMAL | 3370 | userid | NORMAL | 3371 | floorid | NORMAL | 3372 | FEC | NORMAL | 3373 | accept-types | TBD | 3374 | accept-wrapped-types | TBD | 3375 | max-size | TBD | 3376 | path | TBD | 3377 | dccp-service-code | NOT RECOMMENDED | 3378 | rtcp-mux | IDENTICAL | 3379 | candidate | TRANSPORT | 3380 | ice-mismatch | NORMAL | 3381 | remote-candidates | TRANSPORT | 3382 | SRTPAuthentication | TBD | 3383 | SRTPROCTxRate | TBD | 3384 | rtcp-rsize | IDENTICAL | 3385 | file-selector | TBD | 3386 | file-transfer-id | TBD | 3387 | file-disposition | TBD | 3388 | file-date | TBD | 3389 | file-icon | TBD | 3390 | file-range | TBD | 3391 | depend | IDENTICAL-PER-PT | 3392 | ssrc | NORMAL | 3393 | ssrc-group | NORMAL | 3394 | rtcp-unicast | IDENTICAL | 3395 | pcfg | SPECIAL | 3396 | acfg | SPECIAL | 3397 | zrtp-hash | TRANSPORT | 3398 | X-predecbufsize | NOT RECOMMENDED | 3399 | X-initpredecbufperiod | NOT RECOMMENDED | 3400 | X-initpostdecbufperiod | NOT RECOMMENDED | 3401 | X-decbyterate | NOT RECOMMENDED | 3402 | 3gpp-videopostdecbufsize | NOT RECOMMENDED | 3403 | framesize | NOT RECOMMENDED | 3404 | 3GPP-SRTP-Config | NOT RECOMMENDED | 3405 | alt | NOT RECOMMENDED | 3406 | alt-default-id | NOT RECOMMENDED | 3407 | 3GPP-Adaption-Support | NOT RECOMMENDED | 3408 | mbms-flowid | NOT RECOMMENDED | 3409 | fec-source-flow | SPECIAL | 3410 | fec-repair-flow | SPECIAL | 3411 | repair-window | SPECIAL | 3412 | rams-updates | NOT RECOMMENDED | 3413 | imageattr | IDENTICAL-PER-PT | 3414 | cfw-id | NORMAL | 3415 | portmapping-req | NOT RECOMMENDED | 3416 | g.3gpp.cat | NORMAL | 3417 | g.3gpp.crs | NORMAL | 3418 | ecn-capable-rtp | IDENTICAL | 3419 | visited-realm | TRANSPORT | 3420 | secondary-realm | TRANSPORT | 3421 | omr-s-cksum | NORMAL | 3422 | omr-m-cksum | NORMAL | 3423 | omr-codecs | NORMAL | 3424 | omr-m-att | NORMAL | 3425 | omr-s-att | NORMAL | 3426 | omr-m-bw | NORMAL | 3427 | omr-s-bw | NORMAL | 3428 | msrp-cema | TBD | 3429 | dccp-port | NOT RECOMMENDED | 3430 | resource | NORMAL | 3431 | channel | NORMAL | 3432 | cmid | NORMAL | 3433 | content | NORMAL | 3434 | lcfg | SPECIAL | 3435 | loopback | NORMAL | 3436 | loopback-source | NORMAL | 3437 | loopback-mirror | NORMAL | 3438 | chatroom | TBD | 3439 | altc | TRANSPORT | 3440 | T38FaxMaxIFP | TBD | 3441 | T38FaxUdpECDepth | TBD | 3442 | T38FaxUdpFECMaxSpan | TBD | 3443 | T38ModemType | TBD | 3444 | cs-correlation | TBD | 3445 | rtcp-idms | NORMAL | 3446 +---------------------------+-------------------+ 3448 15.2.5. Table: att-field (source level) 3450 The following values are to be added to the "att-field (source 3451 level)" registry in the "Session Description Protocol (SDP) 3452 Parameters" registry. The references should be updated to point at 3453 this RFC as well as the previous references. 3455 +----------------+-------------------+ 3456 | SDP Name | Mux Category | 3457 +----------------+-------------------+ 3458 | cname | NORMAL | 3459 | previous-ssrc | NORMAL | 3460 | fmtp | IDENTICAL-PER-PT | 3461 | ts-refclk | NORMAL | 3462 | mediaclk | NORMAL | 3463 +----------------+-------------------+ 3465 15.2.6. Table: content SDP Parameters 3467 The following values are to be added to the "content SDP Parameters" 3468 subregistry in the "Session Description Protocol (SDP) Parameters" 3469 registry. The references should be updated to point at this RFC as 3470 well as the previous references. 3472 +----------+--------------+ 3473 | SDP Name | Mux Category | 3474 +----------+--------------+ 3475 | slides | NORMAL | 3476 | speaker | NORMAL | 3477 | sl | NORMAL | 3478 | main | NORMAL | 3479 | alt | NORMAL | 3480 +----------+--------------+ 3482 15.2.7. Table: Semantics for the 'group' SDP Attribute 3484 The following values are to be added to the "Semantics for the 3485 "group" SDP Attribute" subregistry in the "Session Description 3486 Protocol (SDP) Parameters" registry. The references should be 3487 updated to point at this RFC as well as the previous references. 3489 +---------+------------------+ 3490 | Token | Mux Category | 3491 +---------+------------------+ 3492 | LS | NORMAL | 3493 | FID | NORMAL | 3494 | SRF | NORMAL | 3495 | ANAT | NOT RECOMMENDED | 3496 | FEC | NORMAL | 3497 | FEC-FR | NORMAL | 3498 | CS | NORMAL | 3499 | DDP | NORMAL | 3500 | DUP | NORMAL | 3501 +---------+------------------+ 3503 15.2.8. Table: 'rtcp-fb' Attribute Values 3505 The following values are to be added to the " 'rtcp-fb' Attribute 3506 Values" subregistry in the "Session Description Protocol (SDP) 3507 Parameters" registry. The references should be updated to point at 3508 this RFC as well as the previous references. 3510 +------------+-------------------+ 3511 | Value Name | Mux Category | 3512 +------------+-------------------+ 3513 | ack | IDENTICAL-PER-PT | 3514 | app | SPECIAL | 3515 | ccm | IDENTICAL-PER-PT | 3516 | nack | IDENTICAL-PER-PT | 3517 | trr-int | IDENTICAL-PER-PT | 3518 +------------+-------------------+ 3520 15.2.9. Table: 'ack' and 'nack' Attribute Values 3522 The following values are to be added to the " 'ack' and 'nack' 3523 Attribute Values" subregistry in the "Session Description Protocol 3524 (SDP) Parameters" registry. The references should be updated to 3525 point at this RFC as well as the previous references. 3527 +------------+-------------------+ 3528 | Value Name | Mux Category | 3529 +------------+-------------------+ 3530 | sli | IDENTICAL-PER-PT | 3531 | pli | IDENTICAL-PER-PT | 3532 | rpsi | IDENTICAL-PER-PT | 3533 | app | SPECIAL | 3534 | rai | IDENTICAL-PER-PT | 3535 | tllei | IDENTICAL-PER-PT | 3536 | pslei | IDENTICAL-PER-PT | 3537 | ecn | IDENTICAL | 3538 +------------+-------------------+ 3540 15.2.10. Table: 'depend' SDP Attribute Values 3542 The following values are to be added to the " 'depend' SDP Attribute 3543 Values" subregistry in the "Session Description Protocol (SDP) 3544 Parameters" registry. The references should be updated to point at 3545 this RFC as well as the previous references. 3547 +-------+-------------------+ 3548 | Token | Mux Category | 3549 +-------+-------------------+ 3550 | lay | IDENTICAL-PER-PT | 3551 | mdc | IDENTICAL-PER-PT | 3552 +-------+-------------------+ 3554 15.2.11. Table: 'cs-correlation' Attribute Values 3556 The following values are to be added to the " "cs-correlation" 3557 Attribute Values" subregistry in the "Session Description Protocol 3558 (SDP) Parameters" registry. The references should be updated to 3559 point at this RFC as well as the previous references. 3561 +-----------+--------------+ 3562 | Value | Mux Category | 3563 +-----------+--------------+ 3564 | callerid | TBD | 3565 | uuie | TBD | 3566 | dtmf | TBD | 3567 | external | TBD | 3568 +-----------+--------------+ 3570 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 3572 The following values are to be added to the Semantics for the 3573 "Semantics for the "ssrc-group" SDP Attribute" subregistry in the 3574 "Session Description Protocol (SDP) Parameters" registry. The 3575 references should be updated to point at this RFC as well as the 3576 previous references. 3578 +---------+--------------+ 3579 | Token | Mux Category | 3580 +---------+--------------+ 3581 | FID | NORMAL | 3582 | FEC | NORMAL | 3583 | FEC-FR | NORMAL | 3584 | DUP | NORMAL | 3585 +---------+--------------+ 3587 15.2.13. Table: SDP/RTSP key management protocol identifiers 3589 The following values are to be added to the "SDP/RTSP key management 3590 protocol identifiers" subregistry in the "Session Description 3591 Protocol (SDP) Parameters" registry. The references should be 3592 updated to point at this RFC as well as the previous references. 3594 +------------+--------------+ 3595 | Value Name | Mux Category | 3596 +------------+--------------+ 3597 | mikey | IDENTICAL | 3598 +------------+--------------+ 3600 15.2.14. Table: Codec Control Messages 3602 The following values are to be added to the "Codec Control Messages" 3603 subregistry in the "Session Description Protocol (SDP) Parameters" 3604 registry. The references should be updated to point at this RFC as 3605 well as the previous references. 3607 +------------+-------------------+ 3608 | Value Name | Mux Category | 3609 +------------+-------------------+ 3610 | fir | IDENTICAL-PER-PT | 3611 | tmmbr | IDENTICAL-PER-PT | 3612 | tstr | IDENTICAL-PER-PT | 3613 | vbcm | IDENTICAL-PER-PT | 3614 +------------+-------------------+ 3616 15.2.15. Table: QoS Mechanism Tokens 3618 The following values are to be added to the "QoS Mechanism Tokens" 3619 subregistry in the "Session Description Protocol (SDP) Parameters" 3620 registry. The references should be updated to point at this RFC as 3621 well as the previous references. 3623 +---------------+--------------+ 3624 | QoS Mechanism | Mux Category | 3625 +---------------+--------------+ 3626 | rsvp | TRANSPORT | 3627 | nsis | TRANSPORT | 3628 +---------------+--------------+ 3630 15.2.16. Table: SDP Capability Negotiation Option Tags 3632 The following values are to be added to the "SDP Capability 3633 Negotiation Option Tags" subregistry in the "Session Description 3634 Protocol (SDP) Parameters" registry. The references should be 3635 updated to point at this RFC as well as the previous references. 3637 +------------+--------------+ 3638 | Option Tag | Mux Category | 3639 +------------+--------------+ 3640 | cap-v0 | NORMAL | 3641 | med-v0 | NORMAL | 3642 | bcap-v0 | NORMAL | 3643 | ccap-v0 | NORMAL | 3644 | icap-v0 | NORMAL | 3645 +------------+--------------+ 3647 15.2.17. Table: Timestamp Reference Clock Source Parameters 3649 The following values are to be added to the "Timestamp Reference 3650 Clock Source Parameters" subregistry in the "Session Description 3651 Protocol (SDP) Parameters" registry. The references should be 3652 updated to point at this RFC as well as the previous references. 3654 +----------+--------------+ 3655 | Name | Mux Category | 3656 +----------+--------------+ 3657 | ntp | NORMAL | 3658 | ptp | NORMAL | 3659 | gps | NORMAL | 3660 | gal | NORMAL | 3661 | glonass | NORMAL | 3662 | local | NORMAL | 3663 | private | NORMAL | 3664 +----------+--------------+ 3666 15.2.18. Table: Media Clock Source Parameters 3668 The following values are to be added to the "Media Clock Source 3669 Parameters" subegistry in the "Session Description Protocol (SDP) 3670 Parameters" registry. The references should be updated to point at 3671 this RFC as well as the previous references. 3673 +-----------+--------------+ 3674 | Name | Mux Category | 3675 +-----------+--------------+ 3676 | sender | NORMAL | 3677 | direct | NORMAL | 3678 | IEEE1722 | NORMAL | 3679 +-----------+--------------+ 3681 16. Security Considerations 3683 This document does not add any new security considerations beyond the 3684 existing considerations in the RFCs for protocols that are being 3685 multiplexed together. 3687 The ways that SRTP streams are keyed is not believed to create any 3688 two-time pad vulnerability for the currently defined SRTP keying 3689 mechanism. 3691 17. Acknowledgments 3693 I would like to thank Cullen Jennings, Flemming Andreasen for 3694 suggesting the categories, contributing text and reviewing the draft. 3695 I would also link to thank Magnus Westerlund, Christer Holmberg, 3696 Jonathan Lennox, Bo Burman, Ari Keranen, and Dan Wing on suggesting 3697 structural changes helping improve the document readability. 3699 I would like also to thank following experts on their inputs and 3700 reviews as listed - Flemming Andreasen(5.24,5.32,5.33,14), Rohan 3701 Mahy(5.57), Eric Burger(5.26),Christian Huitema(5.14), Christer 3702 Holmberg(5.21,5.26,5.51,5.52), Richard Ejzak (5.44,5.53,5.54), Colin 3703 Perkins(5.7,5.8,5.9,5.58), Magnus 3704 Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Roni 3705 Evens(5.12,5.27,8.4), Subha Dhesikan(5.6,10), Dan 3706 Wing(5.7,5.12,5.35,5.39,5.45), Cullen Jennings (5.40), Ali C 3707 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 3708 (7.2,7.6), Charles Eckel(5.15,5.27,5.28,9.1,8.5), Paul Kyzivat(5.24), 3709 Ian Johansson(5.15), Saravanan Shanmugham(5.11), Paul E Jones(5.30), 3710 Rajesh Kumar(5.48), Jonathan Lennox(5.36,5,15,9.1,11.1), Mo 3711 Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Christian Huitema (5.14), Qin 3712 Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves 3713 (5.48,5.55), Thomas Stach. 3715 18. Change Log 3717 [RFC EDITOR NOTE: Please remove this section when publishing] 3719 Changes from draft-ietf-mmusic-sdp-mux-attributes-10 3721 o Incorporated Comments from Bo Burman for publication request 3723 Changes from draft-ietf-mmusic-sdp-mux-attributes-08 to draft-ietf- 3724 mmusic-sdp-mux-attributes-10 3726 o Minor nits and version update to advert expiration 3728 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 to draft-ietf- 3729 mmusic-sdp-mux-attributes-08 3731 o Assigned TBD category to all the attributes for whom there exists 3732 no specification on multiplexing behavior over the underlying 3733 transport protocol today. 3735 o Incorporated comments from Flemming and Ari (post last call) 3737 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 3738 o Incorporated last call review comments from Thomas Stach and Ari 3739 Keranen. 3741 o Fixed more nits to prep for the LastCall. 3743 Changes from draft-ietf-mmusic-sdp-mux-attributes-05 3745 o Incorporated review comments from Christian Grooves and Ari 3746 Keranen. 3748 o Fixed more nits to prep for the LastCall. 3750 Changes from draft-ietf-mmusic-sdp-mux-attributes-04 3752 o Fixed minor nits overall. 3754 o Updated Acknowledgement Sections 3756 o Last Call Version. 3758 Changes from draft-ietf-mmusic-sdp-mux-attributes-03 3760 o More re-work on the IANA section. 3762 o Clean ups preparing for the last call. 3764 Changes from draft-ietf-mmusic-sdp-mux-attributes-02 3766 o Incorporated suggestions from Flemming on Capability Negotiation. 3768 o Closed open issues from IETF90 3770 o Added IANA section to list the categories for all the SDP 3771 attributes anlayzed 3773 o Lots of cleanup 3775 o Reformatted Refernces section to use short-form notation 3777 Changes from draft-ietf-mmusic-sdp-mux-attributes-01 3779 o Updated section 15 to provide detailed recommendation on dealing 3780 with encapsulating attributes. Also updated sections 5.20, 5.28, 3781 5.29 to refer to Section 15. 3783 o Added new categories IDENTICAL-PER-PT and INHERIT 3785 o Updated Sections 16 to add the new categories. 3787 o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the 3788 category IDENTICAL-PER-PT. 3790 o Reformatted section 4 to add individual categories to their own 3791 sections. 3793 Changes from draft-ietf-mmusic-sdp-mux-attributes-00 3795 o Added Section 15 to provide recommendations on multiplexing SDP 3796 encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 3797 to refer to Section 15. 3799 o Updated Section 5.38 to incorporate PM-dir review inputs from Qin 3800 Wu 3802 o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more 3803 clarity. 3805 o Fixed few nits regarding sentence clarity and fill-in the NOTES 3806 section where information was lacking. 3808 Changes from draft-nandakumar-mmusic-mux-attributes-05 3810 o Renamed the document to be a WG document. 3812 o Added Section 14. 3814 o Updated Open Issues based on IETF88 discussions. 3816 Changes from draft-nandakumar-mmusic-mux-attributes-04 3818 o Added few OPEN ISSUES that needs to be discussed. 3820 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 3821 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 3823 o Updated Table Column name Current to Level and improved TRANSPORT 3824 category explanation on suggestions form Dan Wing. 3826 o Grouped all the rtcp-fb attribute analysis under a single section 3827 as suggested by Magnus/ 3829 Changes from draft-nandakumar-mmusic-mux-attributes-03 3831 o Maintenance change to clean up grammatical nits and wordings. 3833 Changes from draft-nandakumar-mmusic-mux-attributes-02 3834 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 3835 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 3836 the inputs from the respective RFC Authors. 3838 Changes from draft-nandakumar-mmusic-mux-attributes-01 3840 o Replaced Category BAD with NOT RECOMMENDED. 3842 o Added Category TBD. 3844 o Updated IANA Consideration Section. 3846 Changes from draft-nandakumar-mmusic-mux-attributes-00 3848 o Added new section for dealing with FEC payload types. 3850 19. References 3852 19.1. Normative References 3854 [I-D.ietf-mmusic-sdp-bundle-negotiation] 3855 Holmberg, C., Alvestrand, H., and C. Jennings, 3856 "Negotiating Media Multiplexing Using the Session 3857 Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- 3858 negotiation-23 (work in progress), July 2015. 3860 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3861 Requirement Levels", BCP 14, RFC 2119, March 1997. 3863 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 3864 Description Protocol", RFC 4566, DOI 10.17487/RFC4566, 3865 July 2006, . 3867 19.2. Informative References 3869 [H.248.15] 3870 "Gateway control protocol: SDP H.248 package attribute", 3871 . 3873 [I-D.ietf-dart-dscp-rtp] 3874 Black, D. and P. Jones, "Differentiated Services 3875 (DiffServ) and Real-time Communication", draft-ietf-dart- 3876 dscp-rtp-10 (work in progress), November 2014. 3878 [IANA] "Session Description Protocol (SDP) Parameters", 3879 . 3882 [Q.1970] "Q.1970 : BICC IP bearer control protocol", 3883 . 3885 [R3GPPTS183.063] 3886 "TISPAN - IMS based ITPV Stage 3 specification.", 3887 . 3891 [R3GPPTS24.182] 3892 "IP Multimedia Subsystem (IMS) Customized Alerting Tones 3893 (CAT); Protocol specification", 3894 . 3896 [R3GPPTS24.183] 3897 "IP Multimedia Subsystem (IMS) Customized Ringing Signal 3898 (CRS); Protocol specification", 3899 . 3901 [R3GPPTS24.229] 3902 "IP multimedia call control protocol based on Session 3903 Initiation Protocol (SIP) and Session Description Protocol 3904 (SDP);", 3905 . 3907 [R3GPPTS26.114] 3908 "IP multimedia Subsystem : Media Handling and 3909 interaction", . 3911 [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time 3912 Streaming Protocol (RTSP)", RFC 2326, DOI 10.17487/ 3913 RFC2326, April 1998, 3914 . 3916 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the 3917 Session Description Protocol (SDP) for ATM Bearer 3918 Connections", RFC 3108, DOI 10.17487/RFC3108, May 2001, 3919 . 3921 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 3922 with Session Description Protocol (SDP)", RFC 3264, DOI 3923 10.17487/RFC3264, June 2002, 3924 . 3926 [RFC3312] Camarillo, G., Ed., Marshall, W., Ed., and J. Rosenberg, 3927 "Integration of Resource Management and Session Initiation 3928 Protocol (SIP)", RFC 3312, DOI 10.17487/RFC3312, October 3929 2002, . 3931 [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple 3932 Capability Declaration", RFC 3407, DOI 10.17487/RFC3407, 3933 October 2002, . 3935 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to 3936 Resource Reservation Flows", RFC 3524, DOI 10.17487/ 3937 RFC3524, April 2003, 3938 . 3940 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth 3941 Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3942 3556, DOI 10.17487/RFC3556, July 2003, 3943 . 3945 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute 3946 in Session Description Protocol (SDP)", RFC 3605, DOI 3947 10.17487/RFC3605, October 2003, 3948 . 3950 [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., 3951 "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3952 3611, DOI 10.17487/RFC3611, November 2003, 3953 . 3955 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth 3956 Modifier for the Session Description Protocol (SDP)", RFC 3957 3890, DOI 10.17487/RFC3890, September 2004, 3958 . 3960 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network 3961 Address Types (ANAT) Semantics for the Session Description 3962 Protocol (SDP) Grouping Framework", RFC 4091, DOI 3963 10.17487/RFC4091, June 2005, 3964 . 3966 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 3967 the Session Description Protocol (SDP)", RFC 4145, DOI 3968 10.17487/RFC4145, September 2005, 3969 . 3971 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. 3972 Carrara, "Key Management Extensions for Session 3973 Description Protocol (SDP) and Real Time Streaming 3974 Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July 3975 2006, . 3977 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session 3978 Description Protocol (SDP) Security Descriptions for Media 3979 Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006, 3980 . 3982 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol 3983 (SDP) Source Filters", RFC 4570, DOI 10.17487/RFC4570, 3984 July 2006, . 3986 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the 3987 Transport Layer Security (TLS) Protocol in the Session 3988 Description Protocol (SDP)", RFC 4572, DOI 10.17487/ 3989 RFC4572, July 2006, 3990 . 3992 [RFC4574] Levin, O. and G. Camarillo, "The Session Description 3993 Protocol (SDP) Label Attribute", RFC 4574, DOI 10.17487/ 3994 RFC4574, August 2006, 3995 . 3997 [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format 3998 for Binary Floor Control Protocol (BFCP) Streams", RFC 3999 4583, DOI 10.17487/RFC4583, November 2006, 4000 . 4002 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 4003 "Extended RTP Profile for Real-time Transport Control 4004 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, DOI 4005 10.17487/RFC4585, July 2006, 4006 . 4008 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description 4009 Protocol (SDP) Content Attribute", RFC 4796, DOI 10.17487/ 4010 RFC4796, February 2007, 4011 . 4013 [RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed., 4014 "The Message Session Relay Protocol (MSRP)", RFC 4975, DOI 4015 10.17487/RFC4975, September 2007, 4016 . 4018 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 4019 "Codec Control Messages in the RTP Audio-Visual Profile 4020 with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104, 4021 February 2008, . 4023 [RFC5109] Li, A., Ed., "RTP Payload Format for Generic Forward Error 4024 Correction", RFC 5109, DOI 10.17487/RFC5109, December 4025 2007, . 4027 [RFC5159] Dondeti, L., Ed. and A. Jerichow, "Session Description 4028 Protocol (SDP) Attributes for Open Mobile Alliance (OMA) 4029 Broadcast (BCAST) Service and Content Protection", RFC 4030 5159, DOI 10.17487/RFC5159, March 2008, 4031 . 4033 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 4034 (ICE): A Protocol for Network Address Translator (NAT) 4035 Traversal for Offer/Answer Protocols", RFC 5245, DOI 4036 10.17487/RFC5245, April 2010, 4037 . 4039 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP 4040 Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July 4041 2008, . 4043 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of 4044 Service (QoS) Mechanism Selection in the Session 4045 Description Protocol (SDP)", RFC 5432, DOI 10.17487/ 4046 RFC5432, March 2009, 4047 . 4049 [RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size 4050 Real-Time Transport Control Protocol (RTCP): Opportunities 4051 and Consequences", RFC 5506, DOI 10.17487/RFC5506, April 4052 2009, . 4054 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., 4055 and P. Kyzivat, "A Session Description Protocol (SDP) 4056 Offer/Answer Mechanism to Enable File Transfer", RFC 5547, 4057 DOI 10.17487/RFC5547, May 2009, 4058 . 4060 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific 4061 Media Attributes in the Session Description Protocol 4062 (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009, 4063 . 4065 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding 4066 Dependency in the Session Description Protocol (SDP)", RFC 4067 5583, DOI 10.17487/RFC5583, July 2009, 4068 . 4070 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 4071 Protocol (RTCP) Extensions for Single-Source Multicast 4072 Sessions with Unicast Feedback", RFC 5760, DOI 10.17487/ 4073 RFC5760, February 2010, 4074 . 4076 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and 4077 Control Packets on a Single Port", RFC 5761, DOI 10.17487/ 4078 RFC5761, April 2010, 4079 . 4081 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control 4082 Protocol (DCCP)", RFC 5762, DOI 10.17487/RFC5762, April 4083 2010, . 4085 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework 4086 for Establishing a Secure Real-time Transport Protocol 4087 (SRTP) Security Context Using Datagram Transport Layer 4088 Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May 4089 2010, . 4091 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description 4092 Protocol (SDP) Grouping Framework", RFC 5888, DOI 4093 10.17487/RFC5888, June 2010, 4094 . 4096 [RFC5939] Andreasen, F., "Session Description Protocol (SDP) 4097 Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939, 4098 September 2010, . 4100 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in 4101 the Session Description Protocol", RFC 5956, DOI 10.17487/ 4102 RFC5956, September 2010, 4103 . 4105 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions 4106 Defined for 3GPP Packet-Switched Streaming Service and 4107 Multimedia Broadcast/Multicast Service", RFC 6064, DOI 4108 10.17487/RFC6064, January 2011, 4109 . 4111 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- 4112 Specific Multicast (SSM) Sessions", RFC 6128, DOI 4113 10.17487/RFC6128, February 2011, 4114 . 4116 [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: 4117 Media Path Key Agreement for Unicast Secure RTP", RFC 4118 6189, DOI 10.17487/RFC6189, April 2011, 4119 . 4121 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for 4122 the Internet Key Exchange Protocol (IKE) in the Session 4123 Description Protocol (SDP)", RFC 6193, DOI 10.17487/ 4124 RFC6193, April 2011, 4125 . 4127 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media 4128 Control Channel Framework", RFC 6230, DOI 10.17487/ 4129 RFC6230, May 2011, 4130 . 4132 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image 4133 Attributes in the Session Description Protocol (SDP)", RFC 4134 6236, DOI 10.17487/RFC6236, May 2011, 4135 . 4137 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping 4138 between Unicast and Multicast RTP Sessions", RFC 6284, DOI 4139 10.17487/RFC6284, June 2011, 4140 . 4142 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, 4143 "Unicast-Based Rapid Acquisition of Multicast RTP 4144 Sessions", RFC 6285, DOI 10.17487/RFC6285, June 2011, 4145 . 4147 [RFC6364] Begen, A., "Session Description Protocol Elements for the 4148 Forward Error Correction (FEC) Framework", RFC 6364, DOI 4149 10.17487/RFC6364, October 2011, 4150 . 4152 [RFC6642] Wu, Q., Ed., Xia, F., and R. Even, "RTP Control Protocol 4153 (RTCP) Extension for a Third-Party Loss Report", RFC 6642, 4154 DOI 10.17487/RFC6642, June 2012, 4155 . 4157 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., 4158 and K. Carlberg, "Explicit Congestion Notification (ECN) 4159 for RTP over UDP", RFC 6679, DOI 10.17487/RFC6679, August 4160 2012, . 4162 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection 4163 Establishment for Media Anchoring (CEMA) for the Message 4164 Session Relay Protocol (MSRP)", RFC 6714, DOI 10.17487/ 4165 RFC6714, August 2012, 4166 . 4168 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A 4169 Datagram Congestion Control Protocol UDP Encapsulation for 4170 NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November 4171 2012, . 4173 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control 4174 Protocol Version 2 (MRCPv2)", RFC 6787, DOI 10.17487/ 4175 RFC6787, November 2012, 4176 . 4178 [RFC6849] Kaplan, H., Ed., Hedayat, K., Venna, N., Jones, P., and N. 4179 Stratton, "An Extension to the Session Description 4180 Protocol (SDP) and Real-time Transport Protocol (RTP) for 4181 Media Loopback", RFC 6849, DOI 10.17487/RFC6849, February 4182 2013, . 4184 [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session 4185 Description Protocol (SDP) Media Capabilities 4186 Negotiation", RFC 6871, DOI 10.17487/RFC6871, February 4187 2013, . 4189 [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S. 4190 Veikkolainen, "The Session Description Protocol (SDP) 4191 Alternate Connectivity (ALTC) Attribute", RFC 6947, DOI 4192 10.17487/RFC6947, May 2013, 4193 . 4195 [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman, 4196 "Miscellaneous Capabilities Negotiation in the Session 4197 Description Protocol (SDP)", RFC 7006, DOI 10.17487/ 4198 RFC7006, September 2013, 4199 . 4201 [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping 4202 Semantics in the Session Description Protocol", RFC 7104, 4203 DOI 10.17487/RFC7104, January 2014, 4204 . 4206 [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session 4207 Description Protocol (SDP) Extension for Setting Audio and 4208 Video Media Streams over Circuit-Switched Bearers in the 4209 Public Switched Telephone Network (PSTN)", RFC 7195, DOI 4210 10.17487/RFC7195, May 2014, 4211 . 4213 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay 4214 Attribute in the Session Description Protocol", RFC 7197, 4215 DOI 10.17487/RFC7197, April 2014, 4216 . 4218 [RFC7266] Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control 4219 Protocol (RTCP) Extended Report (XR) Blocks for Mean 4220 Opinion Score (MOS) Metric Reporting", RFC 7266, DOI 4221 10.17487/RFC7266, June 2014, 4222 . 4224 [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O., 4225 Boronat, F., Montagud, M., and K. Gross, "Inter- 4226 Destination Media Synchronization (IDMS) Using the RTP 4227 Control Protocol (RTCP)", RFC 7272, DOI 10.17487/RFC7272, 4228 June 2014, . 4230 [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H. 4231 Stokking, "RTP Clock Source Signalling", RFC 7273, DOI 4232 10.17487/RFC7273, June 2014, 4233 . 4235 [T.38] "Procedures for real-time Group 3 facsimile communication 4236 over IP networks", . 4238 Author's Address 4240 Suhas Nandakumar 4241 Cisco 4242 170 West Tasman Drive 4243 San Jose, CA 95134 4244 USA 4246 Email: snandaku@cisco.com