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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 October 18, 2013 5 Expires: April 21, 2014 7 A Framework for SDP Attributes when Multiplexing 8 draft-nandakumar-mmusic-sdp-mux-attributes-05 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. In the RTCWeb WG, there is a need to use a 16 single 5-tuple for sending and receiving media associated with 17 multiple media descriptions ("m=" lines). Such a requirement has 18 raised concerns over the semantic implications of the SDP attributes 19 associated with the RTP Sessions multiplexed over a single transport 20 layer flow. 22 The scope of this specification is to provide a framework for 23 analyzing the multiplexing characteristics of SDP attributes. The 24 specification also categorizes existing attributes based on the 25 framework described herein. 27 Status of this Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on April 21, 2014. 44 Copyright Notice 46 Copyright (c) 2013 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 63 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . . 6 65 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 9 66 5.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 10 67 5.2. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . . 11 68 5.3. RFC5761 - Multiplexing RTP and RTCP . . . . . . . . . . . 12 69 5.4. RFC4574 - SDP Label Attribute . . . . . . . . . . . . . . 13 70 5.5. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . . 13 71 5.6. RFC4568 - SDP Security Descriptions . . . . . . . . . . . 14 72 5.7. RFC5762 - RTP over DCCP . . . . . . . . . . . . . . . . . 14 73 5.8. RFC6773 - DCCP-UDP Encapsulation . . . . . . . . . . . . . 15 74 5.9. RFC5506 - Reduced-Size RTCP in RTP Profile . . . . . . . . 16 75 5.10. RFC6787 - Media Resource Control Protocol Version 2 . . . 16 76 5.11. RFC5245 - Interactive Connectivity Establishment (ICE) . . 17 77 5.12. RFC5285 - RTP Header Extensions . . . . . . . . . . . . . 17 78 5.13. RFC3605 - RTCP attribute in SDP . . . . . . . . . . . . . 18 79 5.14. RFC5576 - Source-Specific SDP Attributes . . . . . . . . . 18 80 5.15. RFC6236 - Image Attributes in SDP . . . . . . . . . . . . 19 81 5.16. RFC6285 - Rapid Acquisition of Multicast RTP Sessions . . 20 82 5.17. RFC6230 - Media Control Channel Framework . . . . . . . . 20 83 5.18. RFC6364 - SDP Elements for FEC Framework . . . . . . . . . 21 84 5.19. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 21 85 5.20. RFC3407 - SDP Simple Capability Declaration . . . . . . . 22 86 5.21. RFC6284 - Port Mapping between Unicast and Multicast 87 RTP Sessions . . . . . . . . . . . . . . . . . . . . . . . 22 88 5.22. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 23 89 5.23. RFC4583 - SDP Format for BFCP Streams . . . . . . . . . . 23 90 5.24. RFC5547 - SDP Offer/Answer for File Transfer . . . . . . . 24 91 5.25. draft-ietf-mmusic-media-loopback . . . . . . . . . . . . . 24 92 5.26. RFC5760 - RTCP with Unicast Feedback . . . . . . . . . . . 25 93 5.27. RFC3611 - RTCP XR . . . . . . . . . . . . . . . . . . . . 25 94 5.28. RFC5939 - SDP Capability Negotiation . . . . . . . . . . . 25 95 5.29. draft-ietf-mmusic-sdp-media-capabilities . . . . . . . . . 26 96 5.30. RFC4567 - Key Management Extensions for SDP and RTSP . . . 27 97 5.31. RFC4572 - Comedia over TLS in SDP . . . . . . . . . . . . 27 98 5.32. RFC4570 - SDP Source Filters . . . . . . . . . . . . . . . 28 99 5.33. RFC6128 - RTCP Port for Multicast Sessions . . . . . . . . 28 100 5.34. RFC6189 - ZRTP . . . . . . . . . . . . . . . . . . . . . . 29 101 5.35. RFC4145 - Connection-Oriented Media . . . . . . . . . . . 30 102 5.36. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . . 30 103 5.37. RFC6193 - Media Description for IKE in SDP . . . . . . . . 31 104 5.38. RFC6064 - SDP and RTSP Extensions for 3GPP . . . . . . . . 32 105 5.39. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 34 106 5.40. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . . 35 107 5.41. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . . 36 108 5.42. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . . 36 109 5.43. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . . 37 110 5.44. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . . 37 111 5.45. RFC4975 - The Message Session Relay Protocol . . . . . . . 38 112 5.46. Historical . . . . . . . . . . . . . . . . . . . . . . . . 39 113 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 39 114 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 39 115 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . . 40 116 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . . 41 117 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . . 41 118 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . . 41 119 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . . 42 120 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . . 43 121 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 43 122 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 43 123 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . . 44 124 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . . 44 125 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . . 44 126 8.2. RFC3524 - Mapping Media Streams to Resource 127 Reservation Flows . . . . . . . . . . . . . . . . . . . . 45 128 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . . 45 129 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 46 130 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . . 46 131 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 47 132 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . . 47 133 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . . 47 134 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . . 47 135 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 47 136 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . . 48 137 12. content Atribute Analysis . . . . . . . . . . . . . . . . . . 48 138 12.1. RFC4796 - MSRP Relays . . . . . . . . . . . . . . . . . . 48 139 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 48 140 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . . 48 141 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 142 15. Security Considerations . . . . . . . . . . . . . . . . . . . 50 143 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50 144 17. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 50 145 18. References . . . . . . . . . . . . . . . . . . . . . . . . . . 51 146 18.1. Normative References . . . . . . . . . . . . . . . . . . . 51 147 18.2. Informative References . . . . . . . . . . . . . . . . . . 51 148 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 57 150 1. Introduction 152 Real-Time Communication Web (RTCWeb) framework requires Real-time 153 Transport Protocol as the media transport protocol and Session 154 Description Protocol (SDP) [RFC4566] for describing and negotiating 155 multi-media communication sessions. 157 SDP defines several attributes for capturing characteristics that 158 apply to the individual media descriptions (described by "m=" lines") 159 and the overall multimedia session. Typically different media types 160 (audio, video etc) described using different media descriptions 161 represent separate RTP Sessions that are carried over individual 162 transport layer flows. However, in the RTCWeb WG, a requirement has 163 arisen to multiplex several RTP Sessions over a single transport 164 layer flow. This in turn has made necessary to understand the 165 interpretation and usage of the SDP attributes defined for the 166 multiplexed media descriptions. 168 Given the number of SDP attributes registered with the IANA [IANA] 169 and possibility of new attributes being defined in the future, there 170 is need for generic future-proof framework to analyze these 171 attributes for their applicability in the transport multiplexing use- 172 cases. 174 The document starts with providing the motivation for requiring such 175 a framework. This is followed by introduction to the SDP attribute 176 analysis framework/procedures, following which several sections 177 applies the framework to the SDP attributes registered with the IANA 178 [IANA] 180 2. Terminology 182 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", 183 "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be 184 interpreted as described in [RFC2119]. 186 3. Motivation 188 The time and complications of setting up ICE [RFC5245] and DTLS-SRTP 189 [RFC5763] transports for use by RTP, and conservation of ports, forms 190 an requirement to try and reduce the number of transport level flows 191 needed. This has resulted in the definition of ways, such as, 192 [I-D.ietf-mmusic-sdp-bundle-negotiation] and 193 [I-D.ietf-avt-multiplexing-rtp] to multiplex RTP over a single 194 transport flow in order to preserve network resources such as port 195 numbers. This imposes further restrictions on applicability of these 196 SDP attributes as they are defined today. 198 The specific problem is that there are attribute combinations which 199 make sense when specified on independent m-lines -- as with classical 200 SDP -- that do not make sense when those m-lines are then multiplexed 201 over the same transport. To give an obvious example, ICE permits 202 each m-mline to have an independently specified ice-ufrag attribute. 203 However, if the media from multiple m-lines is multiplexed over the 204 same ICE component, then the meaning of media-level ice-ufrag 205 attributes becomes muddled. 207 As of today there are close to 250 SDP attributes registered with the 208 IANA [IANA] and more will be added in the future. There is no 209 clearly defined procedure to establish the validity/applicability of 210 these attribute when used with transport multiplexing. 212 4. SDP Attribute Analysis Framework 214 Attributes in an SDP session description can be defined at the 215 session-level and media-level. These attributes could be 216 semantically grouped as noted below. 218 o Attributes related to media content such as media type, encoding 219 schemes, payload types. 220 o Attributes specifying media transport characteristics like RTP/ 221 RTCP port numbers, network addresses, QOS. 222 o Metadata description attributes capturing session timing and 223 origin information. 224 o Attributes establishing relationships between media streams such 225 as grouping framework 227 With the above semantic grouping as the reference, the proposed 228 framework classifies each attribute into one of the following 229 categories: 230 NORMAL Attributes that can be independently specified when 231 multiplexing and retain their original semantics. 233 In the example given below, the direction and label attributes are 234 independently specified for audio and video m=lines. These 235 attributes are not impacted by multiplexing these media streams 236 over a single transport layer flow. 238 v=0 239 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 240 s= 241 c=IN IP4 host.atlanta.example.com 242 t=0 0 243 m=audio 49172 RTP/AVP 99 244 a=sendonly 245 a=label:1 246 a=rtpmap:99 iLBC/8000 247 m=video 49172 RTP/AVP 31 248 a=recvonly 249 a=label:2 250 a=rtpmap:31 H261/90000 252 NOT RECOMMENDED Attributes where multiplexing is not recommended if 253 these attributes are in use in the SDP since doing so MAY result 254 in incorrect behaviors 256 Example: Multiplexing media descriptions having attribute zrtp- 257 hash defined with the media descriptions lacking it, would either 258 complicate the handling of multiplexed stream or fail 259 multiplexing. 261 v=0 262 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 263 s= 264 c=IN IP4 client.biloxi.example.com 265 t=0 0 266 m=audio 3456 RTP/AVP 97 // with zrtp 267 a=rtpmap:97 iLBC/8000 268 269 a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2 270 df881ae642c371ba46df 271 272 m=video 34567 RTP/AVP 31 //without zrtp 273 a=rtpmap:31 H261/90000 275 IDENTICAL Attributes that MUST be identical across all the media 276 descriptions being multiplexed. 278 Attributes such as rtcp-mux fall into this category. Since RTCP 279 reporting is done per RTP Session, there is no way to receive RTCP 280 control data for the video m=line in the example below. Hence 281 rtcp-mux MUST be repeated for the video m=line as well, when 282 multiplexed. 284 v=0 285 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 286 s= 287 c=IN IP4 client.biloxi.example.com 288 t=0 0 289 m=audio 34567 RTP/AVP 97 290 a=rtcp-mux 291 m=video 34567 RTP/AVP 31 292 a=rtpmap:31 H261/90000 293 a=rtcp-mux 295 SUM Attributes can be set as they are normally used but software 296 using them in a multiplex case, MUST apply the sum of all the 297 attributes being multiplexed instead of trying to use each one. 298 This is typically used for bandwidth or other rate limiting 299 attributes to the underlining transport. 301 The software parsing the SDP sample below, should use the 302 aggregate Application Specific (AS) bandwidth value from the 303 individual media descriptions to determine the AS value for the 304 multiplexed session. Thus the calculated AS value would be 256+64 305 bytes for the given example. 307 v=0 308 o=mhandley 2890844526 2890842807 IN IP4 126.16.64.4 309 c=IN IP4 client.biloxi.example.com 310 t=0 0 311 m=audio 49170 RTP/AVP 0 312 b=AS:64 313 m=video 51372 RTP/AVP 31 314 b=AS:256 316 TRANSPORT Attributes that can be set normally for multiple items in 317 a multiplexed group but the software MUST pick just one of the 318 attribute of the given type for use. The one chosen is the 319 attribute associated with the "m=" line that represents the 320 information being used for the transport of the RTP. 322 In the example below, "a=crypto" attribute is defined for both the 323 audio and the video m=lines. The video media line's a=crypto 324 attribute is chosen since its mid value (bar) appears first in the 325 a=group:BUNDLE line. This is due to BUNDLE grouping semantic 326 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values 327 from m=line corresponding to the mid appearing first on the 328 a=group:BUNDLE line to be considered for setting up the RTP 329 Transport. 331 v=0 332 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 333 s= 334 c=IN IP4 host.atlanta.example.com 335 t=0 0 336 a=group:BUNDLE bar foo 337 m=audio 49172 RTP/AVP 99 338 a=mid:foo 339 a=crypto:1 AES_CM_128_HMAC_SHA1_80 340 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 341 a=rtpmap:99 iLBC/8000 342 m=video 51374 RTP/AVP 31 343 a=mid:bar 344 a=crypto:1 AES_CM_128_HMAC_SHA1_80 345 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 346 a=rtpmap:96 H261/90000 348 SPECIAL Attributes where the text in the source draft must be 349 consulted for further handling when multiplexed. 351 As an example, for the attribute extmap, the specification 352 defining the extension MUST be referred to understand the 353 multiplexing implications. 355 TBD This category defines attributes that need more information to 356 assign an appropriate category. 358 The idea behind these categories is to provide recommendations for 359 using the attributes under RTP session multiplexing scenarios. 361 Section 5 analyzes attributes listed in IANA [IANA] grouped under the 362 IETF document that defines them. The "Level" column indicates 363 whether the attribute is currently specified as: 365 o S -- Session level 366 o M -- Media level 367 o B -- Both 368 o SR -- Source-level (for a single SSRC) 370 5. Analysis of Existing Attributes 371 5.1. RFC4566 - SDP: Session Description Protocol 373 RFC4566 [RFC4566] defines the Session Description Protocol (SDP) that 374 is intended for describing multimedia sessions for the purposes of 375 session announcement, session invitation, and other forms of 376 multimedia session initiation 378 +------------+----------------+-------+----------+ 379 | Attr Name | Notes | Level | Category | 380 +------------+----------------+-------+----------+ 381 | sendrecv | Not impacted | B | NORMAL | 382 | | | | | 383 | sendonly | Not impacted | B | NORMAL | 384 | | | | | 385 | recvonly | Not impacted | B | NORMAL | 386 | | | | | 387 | inactive | Not impacted | B | NORMAL | 388 | | | | | 389 | cat | Not impacted | S | NORMAL | 390 | | | | | 391 | ptime | Not Impacted | M | NORMAL | 392 | | | | | 393 | maxptime | Not Impacted | M | NORMAL | 394 | | | | | 395 | orient | Not Impacted | M | NORMAL | 396 | | | | | 397 | framerate | Not Impacted | M | NORMAL | 398 | | | | | 399 | quality | Not Impacted | M | NORMAL | 400 | | | | | 401 | rtpmap | Not Impacted | M | NORMAL | 402 | | | | | 403 | fmtp | Not Impacted | M | NORMAL | 404 | | | | | 405 | keywds | Not impacted | S | NORMAL | 406 | | | | | 407 | type | Not Impacted | S | NORMAL | 408 | | | | | 409 | tool | Not Impacted | S | NORMAL | 410 | | | | | 411 | charset | Not Impacted | S | NORMAL | 412 | | | | | 413 | sdplang | Not Impacted | B | NORMAL | 414 | | | | | 415 | lang | Not Impacted | B | NORMAL | 416 | | | | | 417 +------------+----------------+-------+----------+ 418 RFC4566 Attribute Analysis 420 5.2. RFC4585 - RTP/AVPF 422 RFC4585 [RFC4585] defines an extension to the Audio-visual Profile 423 (AVP) that enables receivers to provide, statistically, more 424 immediate feedback to the senders and thus allows for short-term 425 adaptation and efficient feedback-based repair mechanisms to be 426 implemented. 428 +----------+-----------------------------------+-------+------------+ 429 | Attr | Notes | Level | Category | 430 | Name | | | | 431 +----------+-----------------------------------+-------+------------+ 432 | rtcp-fb | RTCP reporting happens per RTP | M | IDENTICAL | 433 | | Session. | | | 434 | | | | | 435 +----------+-----------------------------------+-------+------------+ 437 RFC4585 Attribute Analysis 439 OPEN ISSUE:Below SDP examples show 3 scenarios on implications of 440 allowing Payload Types to be repated or not repeated within the 441 BUNDLEd m= lines. 443 Scenario1: Payload Types are not shared and rtcp-fb is mandated for 444 all the multiplexed m=lines. This scenario leads into assigning 445 category "NOT IMPACTED" for rtcp-fb and its paramters since RTCP 446 reporting happens per PayloadType with in a BUNDLED RTP Session, thus 447 allowing for unique reporting. 449 a=group:BUNDLE audio video 450 m=audio 3456 RTP/AVP 97 451 a=mid:audio 452 a=rtpmap:97 iLBC/8000 453 m=video 3456 RTP/AVP 98 454 a=mid:video 455 a=rtpmap:98 VP8/90000 456 a-rtcp-fb:98 nack rpsi 458 Scenario2: Payload Types are shared and rtcp-fb is repeated across 459 all the multiplexed m= lines with same feedback type (nack). This 460 leads to assigning category "IDENTICAL" to rtcp-fb which allows NACK 461 and NACK RPSI reporting to be done for PT 98 in this example. 463 a=group:BUNDLE audio video 464 m=audio 3456 RTP/AVP 98 465 a=mid:audio 466 a=rtpmap:98 iLBC/8000 467 a=rtcp-fb:98 nack 468 m=video 3456 RTP/AVP 98 469 a=mid:video 470 a=rtpmap:98 VP8/90000 471 a-rtcp-fb:98 nack rpsi 473 In the below case, audio media line has rtcp-fb ack and video video 474 media line has rtcp-fb nack with Payload types shared. With such a 475 configuration, positive acks are reported for video stream even it 476 was not intended and negative acks are reported for audio stream 477 unintended. 479 // PTs are shared and have different feedback types 480 a=group:BUNDLE audio video 481 m=audio 3456 RTP/AVP 98 482 a=mid:audio 483 a=rtpmap:98 iLBC/8000 484 a=rtcp-fb ack // Positive ACK 485 m=video 3456 RTP/AVP 98 486 a=mid:video 487 a=rtpmap:98 VP8/90000 488 a-rtcp-fb:98 nack rpsi // Nack ACK 490 OPEN ISSUE: Should BUNDLE disallow PT to be repeated ?? What does 491 it mean if PTs are shared in the context of rtcp-fb ??. Magnus 492 pointed out that RTCP FB reporting MUST happen per (PT+Media 493 Source) when BUNDLED. If this is allowed, the category of 494 "IDENTICAL" applies with rtcp-fb for all m= lines and update 495 BUNDLE spec to mandate the behavior. Does this sound fine ? 497 5.3. RFC5761 - Multiplexing RTP and RTCP 499 RFC5761 [RFC5761] discusses issues that arise when multiplexing RTP 500 data packets and RTP Control Protocol (RTCP) packets on a single UDP 501 port. It describes when such multiplexing is and is not appropriate, 502 and it explains how the Session Description Protocol (SDP) can be 503 used to signal multiplexed sessions. 505 +-----------+----------------------------------+-------+------------+ 506 | Name | Notes | Level | Category | 507 +-----------+----------------------------------+-------+------------+ 508 | rtcp-mux | RTCP muxing should be repeated | M | IDENTICAL | 509 | | across all the m=lines | | | 510 | | | | | 511 +-----------+----------------------------------+-------+------------+ 513 RFC5761 Attribute Analysis 515 5.4. RFC4574 - SDP Label Attribute 517 RFC4574 [RFC4574] defines a new Session Description Protocol (SDP) 518 media-level attribute: "label". The "label" attribute carries a 519 pointer to a media stream in the context of an arbitrary network 520 application that uses SDP. The sender of the SDP document can attach 521 the "label" attribute to a particular media stream or streams. The 522 application can then use the provided pointer to refer to each 523 particular media stream in its context. 525 +--------+---------------+-------+----------+ 526 | Name | Notes | Level | Category | 527 +--------+---------------+-------+----------+ 528 | label | Not Impacted | M | NORMAL | 529 | | | | | 530 +--------+---------------+-------+----------+ 532 RFC4574 Attribute Analysis 534 5.5. RFC5432 - QoS Mechanism Selection in SDP 536 RFC5432 [RFC5432] defines prordures to negotiate QOS mechanisms using 537 the Session Description Protocol (SDP) offer/answer model. 539 +----------------+-------------------------------+-------+----------+ 540 | Name | Notes | Level | Category | 541 +----------------+-------------------------------+-------+----------+ 542 | qos-mech-send | Since QOS mechanism are | B | NORMAL | 543 | | signaled per flow, | | | 544 | | multiplexing multiple m=lines | | | 545 | | has no impact on per m=line | | | 546 | | QOS mechanism. | | | 547 | | | | | 548 | qos-mech-recv | Since QOS mechanism are | B | NORMAL | 549 | | signaled per flow, | | | 550 | | multiplexing multiple m=lines | | | 551 | | has no impact on per m=line | | | 552 | | QOS mechanism. | | | 553 | | | | | 554 +----------------+-------------------------------+-------+----------+ 556 RFC5432 Attribute Analysis 558 5.6. RFC4568 - SDP Security Descriptions 560 RFC4568 [RFC4568] defines a Session Description Protocol (SDP) 561 cryptographic attribute for unicast media streams. The attribute 562 describes a cryptographic key and other parameters that serve to 563 configure security for a unicast media stream in either a single 564 message or a roundtrip exchange. 566 +---------+----------------------------------+-------+--------------+ 567 | Name | Notes | Level | Category | 568 +---------+----------------------------------+-------+--------------+ 569 | crypto | The multiplexing scheme MUST | M | TRANSPORT | 570 | | ensure unique SSRCs across all | | | 571 | | the media lines multiplexed. In | | | 572 | | that case, cryptographic keys | | | 573 | | corresponding to the underlying | | | 574 | | transport is used. | | | 575 | | | | | 576 | crypto | If the multiplexing scheme | M | NOT | 577 | | cannot ensure unique SSRCs | | RECOMMENDED | 578 | | across all the media lines, | | | 579 | | multiplexing MUST NOT be | | | 580 | | performed. | | | 581 | | | | | 582 +---------+----------------------------------+-------+--------------+ 584 RFC4568 Attribute Analysis 586 5.7. RFC5762 - RTP over DCCP 588 The Real-time Transport Protocol (RTP) is a widely used transport for 589 real-time multimedia on IP networks. The Datagram Congestion Control 590 Protocol (DCCP) is a transport protocol that provides desirable 591 services for real-time applications. RFC5762 [RFC5762] specifies a 592 mapping of RTP onto DCCP, along with associated signalling, such that 593 real-time applications can make use of the services provided by DCCP 594 +--------------------+---------------------+---------+--------------+ 595 | Name | Notes | Current | Category | 596 +--------------------+---------------------+---------+--------------+ 597 | dccp-service-code | If RFC 6773 is not | M | NOT | 598 | | being used in | | RECOMMENDED | 599 | | addition to RFC | | | 600 | | 5762, the port in | | | 601 | | the m= line is a | | | 602 | | DCCP port. DCCP | | | 603 | | being a connection | | | 604 | | oriented protocol, | | | 605 | | does not allow | | | 606 | | multiple | | | 607 | | connections on the | | | 608 | | same 5-tuple. | | | 609 | | | | | 610 +--------------------+---------------------+---------+--------------+ 612 RFC5762 Attribute Analysis 614 If RFC 6773 is being used in addition to RFC 5762 and provided that 615 DCCP-in-UDP layer has additional demultiplexing, then it may be 616 possible to use different DCCP service codes for each DCCP flow, 617 given each uses a different DCCP port. Although doing so might 618 conflict with the media type of the m= line. None of this is 619 standardised yet and it wouldn't work as explained. Hence 620 multiplexing MUST NOT be performed even in this alternate scenario. 622 5.8. RFC6773 - DCCP-UDP Encapsulation 624 RFC6773 [RFC6773] document specifies an alternative encapsulation of 625 the Datagram Congestion Control Protocol (DCCP), referred to as DCCP- 626 UDP. This encapsulation allows DCCP to be carried through the 627 current generation of Network Address Translation (NAT) middleboxes 628 without modification of those middleboxes 630 +------------+-------------------------------+-------+--------------+ 631 | Name | Notes | Level | Category | 632 +------------+-------------------------------+-------+--------------+ 633 | dccp-port | Multiplexing MUST NOT be | M | NOT | 634 | | performed due to potential | | RECOMMENDED | 635 | | conflict between the port | | | 636 | | used for DCCP | | | 637 | | en/decapsulation and the | | | 638 | | RTP. | | | 639 | | | | | 640 +------------+-------------------------------+-------+--------------+ 641 RFC6773 Attribute Analysis 643 5.9. RFC5506 - Reduced-Size RTCP in RTP Profile 645 RFC5506 [RFC5506] discusses benefits and issues that arise when 646 allowing Real-time Transport Protocol (RTCP) packets to be 647 transmitted with reduced size. 649 +-------------+--------------------------------+-------+------------+ 650 | Name | Notes | Level | Category | 651 +-------------+--------------------------------+-------+------------+ 652 | rtcp-rsize | RTCP reduced size MUST be | M | IDENTICAL | 653 | | repeated across all the | | | 654 | | m=lines | | | 655 | | | | | 656 +-------------+--------------------------------+-------+------------+ 658 RFC5506 Attribute Analysis 660 5.10. RFC6787 - Media Resource Control Protocol Version 2 662 The Media Resource Control Protocol Version 2 (MRCPv2) allows client 663 hosts to control media service resources such as speech synthesizers, 664 recognizers, verifiers, and identifiers residing in servers on the 665 network. MRCPv2 is not a "stand-alone" protocol -- it relies on 666 other protocols, such as the Session Initiation Protocol (SIP), to 667 coordinate MRCPv2 clients and servers and manage sessions between 668 them, and the Session Description Protocol (SDP) to describe, 669 discover, and exchange capabilities. It also depends on SIP and SDP 670 to establish the media sessions and associated parameters between the 671 media source or sink and the media server. Once this is done, the 672 MRCPv2 exchange operates over the control session established above, 673 allowing the client to control the media processing resources on the 674 speech resource server. RFC6787 [RFC6787] defines attributes for 675 this purpose. 677 +-----------+---------------+-------+----------+ 678 | Name | Notes | Level | Category | 679 +-----------+---------------+-------+----------+ 680 | resource | Not Impacted | M | NORMAL | 681 | | | | | 682 | channel | Not Impacted | M | NORMAL | 683 | | | | | 684 | | Not Impacted | M | NORMAL | 685 | | | | | 686 +-----------+---------------+-------+----------+ 688 RFC6787 Attribute Analysis 690 5.11. RFC5245 - Interactive Connectivity Establishment (ICE) 692 RFC5245 [RFC5245] describes a protocol for Network Address 693 Translator(NAT) traversal for UDP-based multimedia sessions 694 established with the offer/answer model. This protocol is called 695 Interactive Connectivity Establishment (ICE). ICE makes use of the 696 Session Traversal Utilities for NAT (STUN) protocol and its 697 extension,Traversal Using Relay NAT (TURN). ICE can be used by any 698 protocol utilizing the offer/answer model, such as the Session 699 Initiation Protocol (SIP). 701 +--------------------+-------------------------+-------+------------+ 702 | Name | Notes | Level | Category | 703 +--------------------+-------------------------+-------+------------+ 704 | ice-lite | Not Impacted | S | NORMAL | 705 | | | | | 706 | ice-options | Not Impacted | S | NORMAL | 707 | | | | | 708 | ice-pwd | Per media-level | B | TRANSPORT | 709 | | attribute MUST be used | | | 710 | | per underlying | | | 711 | | transport flow | | | 712 | | | | | 713 | ice-ufrag | Per media-level | B | TRANSPORT | 714 | | attribute MUST be used | | | 715 | | per underlying | | | 716 | | transport flow | | | 717 | | | | | 718 | candidate | Per media-level | M | TRANSPORT | 719 | | attribute MUST be used | | | 720 | | per underlying | | | 721 | | transport flow | | | 722 | | | | | 723 | remote-candidates | Per media-level | M | TRANSPORT | 724 | | attribute MUST be used | | | 725 | | per underlying | | | 726 | | transport flow | | | 727 | | | | | 728 +--------------------+-------------------------+-------+------------+ 730 RFC5245 Attribute Analysis 732 5.12. RFC5285 - RTP Header Extensions 734 RFC5285 [RFC5285] provides a general mechanism to use the header 735 extension feature of RTP (the Real-Time Transport Protocol). It 736 provides the option to use a small number of small extensions in each 737 RTP packet, where the universe of possible extensions is large and 738 registration is de-centralized. The actual extensions in use in a 739 session are signaled in the setup information for that session. 741 +---------+--------------------------------------+-------+----------+ 742 | Name | Notes | Level | Category | 743 +---------+--------------------------------------+-------+----------+ 744 | extmap | Specific RTP extension document MUST | B | SPECIAL | 745 | | be referred | | | 746 | | | | | 747 +---------+--------------------------------------+-------+----------+ 749 RFC5285 Attribute Analysis 751 5.13. RFC3605 - RTCP attribute in SDP 753 Originally, SDP assumed that RTP and RTCP were carried on consecutive 754 ports. However, this is not always true when NATs are involved. 755 [RFC3605] specifies an early mechanism to indicate the RTCP port. 757 +-------+--------------------------------------+-------+------------+ 758 | Name | Notes | Level | Category | 759 +-------+--------------------------------------+-------+------------+ 760 | rtcp | Case1:Same RTCP port is repeated | M | TRANSPORT | 761 | | across the m=lines. Case2:Different | | | 762 | | RTCP ports renders multiplexing | | | 763 | | impossible | | | 764 | | | | | 765 +-------+--------------------------------------+-------+------------+ 767 RFC3605 Attribute Analysis 769 5.14. RFC5576 - Source-Specific SDP Attributes 771 RFC5576 [RFC5576] defines a mechanism to describe RTP media sources, 772 which are identified by their synchronization source (SSRC) 773 identifiers, in SDP, to associate attributes with these sources, and 774 to express relationships among sources. It also defines several 775 source-level attributes that can be used to describe properties of 776 media sources. 778 +----------------+---------------------------+-------+--------------+ 779 | Name | Notes | Level | Category | 780 +----------------+---------------------------+-------+--------------+ 781 | ssrc | SSRCs repeated over | M | NOT | 782 | | multiple m=lines is | | RECOMMENDED | 783 | | forbidden if the m-lines | | | 784 | | are in the same RTP | | | 785 | | session. | | | 786 | | | | | 787 | ssrc-group | Refer to section | M | SPECIAL | 788 | | Section 9 for specific | | | 789 | | analysis of the grouping | | | 790 | | semantics | | | 791 | | | | | 792 | cname | Not Impacted [Open | SR | NORMAL | 793 | | Issues: what are the | | | 794 | | rules for CNAME | | | 795 | | duplication across | | | 796 | | sessions?] | | | 797 | | | | | 798 | previous-ssrc | SSRCs repeated over | SR | NOT | 799 | | multiple m=lines | | RECOMMENDED | 800 | | complicates multiplexing | | | 801 | | | | | 802 | fmtp | Not Impacted | SR | NORMAL | 803 | | | | | 804 +----------------+---------------------------+-------+--------------+ 806 RFC5576 Attribute Analysis 808 OPEN ISSUE:LNX: There has been concern on how to deal with SSRC 809 values repeated across the multiplexed m= lines. Lennox suggested 810 to possible options to deal with it. The simpler is to say that 811 individual SSRC values in a=ssrc attributes MUST NOT be repeated 812 across bundled m-lines, but other than that the behavior is 813 normal. The more complicated is to say that SSRC attributes MAY 814 be repeated across bundled m-lines, iff the media stream satisfies 815 more than one m-line. In this case, it's up to the individual 816 source attributes to define what's allowed. 817 Should BUNDLE allow SSRCs to be repeated ? If so, should the 818 category for the source attributes be SPECIAL and update RFC5576 819 to add text to define multiplexing scenarios. 821 5.15. RFC6236 - Image Attributes in SDP 823 RFC6236 [RFC6236] proposes a new generic session setup attribute to 824 make it possible to negotiate different image attributes such as 825 image size. A possible use case is to make it possible for a low-end 826 hand-held terminal to display video without the need to rescale the 827 image,something that may consume large amounts of memory and 828 processing power. The document also helps to maintain an optimal 829 bitrate for video as only the image size that is desired by the 830 receiver is transmitted. 832 +------------+---------------+-------+----------+ 833 | Name | Notes | Level | Category | 834 +------------+---------------+-------+----------+ 835 | imageattr | Not Impacted | M | NORMAL | 836 | | | | | 837 +------------+---------------+-------+----------+ 839 RFC6236 Attribute Analysis 841 5.16. RFC6285 - Rapid Acquisition of Multicast RTP Sessions 843 RFC6285 [RFC6285] describes a method using the existing RTP and RTP 844 Control Protocol (RTCP) machinery that reduces the acquisition delay. 845 In this method, an auxiliary unicast RTP session carrying the 846 Reference Information to the receiver precedes or accompanies the 847 multicast stream. This unicast RTP flow can be transmitted at a 848 faster than natural bitrate to further accelerate the acquisition. 849 The motivating use case for this capability is multicast applications 850 that carry real-time compressed audio and video. 852 +---------------+-------------------+-------+------------------+ 853 | Name | Notes | Level | Category | 854 +---------------+-------------------+-------+------------------+ 855 | rams-updates | Not recommended | M | NOT RECOMMENDED | 856 | | | | | 857 +---------------+-------------------+-------+------------------+ 859 RFC6285 Attribute Analysis 861 5.17. RFC6230 - Media Control Channel Framework 863 RFC6230 [RFC6230] describes a framework and protocol for application 864 deployment where the application programming logic and media 865 processing are distributed. This implies that application 866 programming logic can seamlessly gain access to appropriate resources 867 that are not co-located on the same physical network entity. The 868 framework uses the Session Initiation Protocol (SIP) to establish an 869 application-level control mechanism between application servers and 870 associated external servers such as media servers. 872 +---------+-----------------+-------+----------+ 873 | Name | Notes | Level | Category | 874 +---------+-----------------+-------+----------+ 875 | cfw-id | Not Applicable | M | NORMAL | 876 | | | | | 877 +---------+-----------------+-------+----------+ 879 RFC6230 Attribute Analysis 881 5.18. RFC6364 - SDP Elements for FEC Framework 883 RFC6364 [RFC6364] specifies the use of the Session Description 884 Protocol (SDP) to describe the parameters required to signal the 885 Forward Error Correction (FEC) Framework Configuration Information 886 between the sender(s) and receiver(s). This document also provides 887 examples that show the semantics for grouping multiple source and 888 repair flows together for the applications that simultaneously use 889 multiple instances of the FEC Framework. 891 +------------------+---------------+-------+----------+ 892 | Name | Notes | Level | Category | 893 +------------------+---------------+-------+----------+ 894 | fec-source-flow | Not Impacted | M | NORMAL | 895 | | | | | 896 | fec-repair-flow | Not Impacted | M | NORMAL | 897 | | | | | 898 | repair-window | Not Impacted | M | NORMAL | 899 | | | | | 900 +------------------+---------------+-------+----------+ 902 RFC6364 Attribute Analysis 904 5.19. RFC4796 - Content Attribute 906 RFC4796 [RFC4796] defines a new Session Description Protocol (SDP) 907 media-level attribute, 'content'. The 'content' attribute defines 908 the content of the media stream to a more detailed level than the 909 media description line. The sender of an SDP session description can 910 attach the 'content' attribute to one or more media streams. The 911 receiving application can then treat each media stream differently 912 (e.g., show it on a big or small screen) based on its content. 914 +----------+---------------+-------+----------+ 915 | Name | Notes | Level | Category | 916 +----------+---------------+-------+----------+ 917 | content | Not Impacted | M | NORMAL | 918 | | | | | 919 +----------+---------------+-------+----------+ 920 RFC4796 Attribute Analysis 922 5.20. RFC3407 - SDP Simple Capability Declaration 924 RFC3407 [RFC3407] defines a set of Session Description Protocol (SDP) 925 attributes that enables SDP to provide a minimal and backwards 926 compatible capability declaration mechanism. 928 +----------+-------------------------------------+-------+----------+ 929 | Name | Notes | Level | Category | 930 +----------+-------------------------------------+-------+----------+ 931 | sqn | Not Impacted | B | NORMAL | 932 | | | | | 933 | csdc | Mismatch in the offered capability | B | TBD | 934 | | description MAY fail multiplexing. | | | 935 | | | | | 936 | cpar | Mismatch in the offered capability | B | TBD | 937 | | parameters MAY fail multiplexing. | | | 938 | | | | | 939 | cparmin | Mismatch in the offered capability | B | TBD | 940 | | parameters MAY fail multiplexing. | | | 941 | | | | | 942 | cparmax | Mismatch in the offered capability | B | TBD | 943 | | parameters MAY fail multiplexing. | | | 944 | | | | | 945 +----------+-------------------------------------+-------+----------+ 947 RFC3407 Attribute Analysis 949 5.21. RFC6284 - Port Mapping between Unicast and Multicast RTP Sessions 951 RFC6284 [RFC6284] presents a port mapping solution that allows RTP 952 receivers to choose their own ports for an auxiliary unicast session 953 in RTP applications using both unicast and multicast services. The 954 solution provides protection against denial-of-service or packet 955 amplification attacks that could be used to cause one or more RTP 956 packets to be sent to a victim client 958 +------------------+-------------------------+-------+--------------+ 959 | Name | Notes | Level | Category | 960 +------------------+-------------------------+-------+--------------+ 961 | portmapping-req | Not recommended, if | M | NOT | 962 | | port mapping is | | RECOMMENDED | 963 | | required by the | | | 964 | | application | | | 965 | | | | | 966 +------------------+-------------------------+-------+--------------+ 967 RFC6284 Attribute Analysis 969 5.22. RFC6714 - MSRP-CEMA 971 RFC6714 [RFC6714] defines a Message Session Relay Protocol (MSRP) 972 extension, Connection Establishment for Media Anchoring (CEMA). 973 Support of this extension is OPTIONAL. The extension allows 974 middleboxes to anchor the MSRP connection, without the need for 975 middleboxes to modify the MSRP messages; thus, it also enables secure 976 end-to-end MSRP communication in networks where such middleboxes are 977 deployed. This document also defines a Session Description Protocol 978 (SDP) attribute, 'msrp-cema', that MSRP endpoints use to indicate 979 support of the CEMA extension. 981 +------------+---------------+-------+----------+ 982 | Name | Notes | Level | Category | 983 +------------+---------------+-------+----------+ 984 | msrp-cema | Not Impacted | M | NORMAL | 985 | | | | | 986 +------------+---------------+-------+----------+ 988 RFC6714 Attribute Analysis 990 5.23. RFC4583 - SDP Format for BFCP Streams 992 RFC4583 [RFC4583] document specifies how to describe Binary Floor 993 Control Protocol (BFCP) streams in Session Description Protocol (SDP) 994 descriptions. User agents using the offer/answer model to establish 995 BFCP streams use this format in their offers and answers 997 +------------+-------------------------------+-------+--------------+ 998 | Name | Notes | Level | Category | 999 +------------+-------------------------------+-------+--------------+ 1000 | floorctrl | Must be repeated across all | M | IDENTICAL | 1001 | | the multiplexed m=lines | | | 1002 | | | | | 1003 | confid | Not Impacted | M | NORMAL | 1004 | | | | | 1005 | userid | Not Impacted | M | NORMAL | 1006 | | | | | 1007 | floorid | The floorid MUST be unique | M | NOT | 1008 | | across the multiplexed | | RECOMMENDED | 1009 | | m=lines | | | 1010 | | | | | 1011 +------------+-------------------------------+-------+--------------+ 1013 RFC4583 Attribute Analysis 1015 5.24. RFC5547 - SDP Offer/Answer for File Transfer 1017 RFC5547 [RFC5547] provides a mechanism to negotiate the transfer of 1018 one or more files between two endpoints by using the Session 1019 Description Protocol (SDP) offer/answer model specified in [RFC3264]. 1021 +--------------------------------+---------------+-------+----------+ 1022 | Name | Notes | Level | Category | 1023 +--------------------------------+---------------+-------+----------+ 1024 | file-selector | Not Impacted | M | NORMAL | 1025 | | | | | 1026 | file-transfer-id | Not Impacted | M | NORMAL | 1027 | | | | | 1028 | file-disposition | Not Impacted | M | NORMAL | 1029 | | | | | 1030 | file-date,file-iconfile-range | Not Impacted | M | NORMAL | 1031 | | | | | 1032 | file-iconfile-range | Not Impacted | M | NORMAL | 1033 | | | | | 1034 | file-iconfile-range | Not Impacted | M | NORMAL | 1035 | | | | | 1036 +--------------------------------+---------------+-------+----------+ 1038 RFC5547 Attribute Analysis 1040 5.25. draft-ietf-mmusic-media-loopback 1042 [MEDIA_LOOPBACK] adds new SDP media types and attributes, which 1043 enable establishment of media sessions where the media is looped back 1044 to the transmitter. Such media sessions will serve as monitoring and 1045 troubleshooting tools by providing the means for measurement of more 1046 advanced VoIP, Real-time Text and Video over IP performance metrics. 1048 +------------------------------+----------------+-------+----------+ 1049 | Name | Notes | Level | Category | 1050 +------------------------------+----------------+-------+----------+ 1051 | loopback rtp-pkt-loopback | Not Impacted | M | NORMAL | 1052 | | | | | 1053 | loopback rtp-media-loopback | Not Impacted | M | NORMAL | 1054 | | | | | 1055 | loopback-source | Not Impacted | M | NORMAL | 1056 | | | | | 1057 | loopback-mirror | Not Impacted | M | NORMAL | 1058 | | | | | 1059 +------------------------------+----------------+-------+----------+ 1061 draft-ietf-mmusic-media-loopback Attribute Analysis 1063 5.26. RFC5760 - RTCP with Unicast Feedback 1065 RFC5760 [RFC5760] specifies an extension to the Real-time Transport 1066 Control Protocol (RTCP) to use unicast feedback to a multicast 1067 sender. The proposed extension is useful for single-source multicast 1068 sessions such as Source-Specific Multicast (SSM) communication where 1069 the traditional model of many-to-many group communication is either 1070 not available or not desired. 1072 +---------------+------------------------------+-------+------------+ 1073 | Name | Notes | Level | Category | 1074 +---------------+------------------------------+-------+------------+ 1075 | rtcp-unicast | The attribute MUST be | M | IDENTICAL | 1076 | | reported across all m=lines | | | 1077 | | multiplexed | | | 1078 | | | | | 1079 +---------------+------------------------------+-------+------------+ 1081 RFC5760 Attribute Analysis 1083 5.27. RFC3611 - RTCP XR 1085 RFC3611 [RFC3611] defines the Extended Report (XR) packet type for 1086 the RTP Control Protocol (RTCP), and defines how the use of XR 1087 packets can be signaled by an application if it employs the Session 1088 Description Protocol (SDP). 1090 +----------+-----------------------------------+-------+------------+ 1091 | Name | Notes | Level | Category | 1092 +----------+-----------------------------------+-------+------------+ 1093 | rtcp-xr | The attribute MUST be reported | B | IDENTICAL | 1094 | | across all m=lines multiplexed | | | 1095 | | | | | 1096 +----------+-----------------------------------+-------+------------+ 1098 RFC3611 Attribute Analysis 1100 5.28. RFC5939 - SDP Capability Negotiation 1102 RFC5939 [RFC5939] defines a general SDP Capability Negotiation 1103 framework. It also specifies how to provide attributes and transport 1104 protocols as capabilities and negotiate them using the framework. 1105 Extensions for other types of capabilities (e.g., media types and 1106 media formats) may be provided in other documents. 1108 +-------+--------------------------------------+-------+------------+ 1109 | Name | Notes | Level | Category | 1110 +-------+--------------------------------------+-------+------------+ 1111 | pcfg | Depends on capability being | M | SPECIAL | 1112 | | negotiated | | | 1113 | | | | | 1114 | acfg | Depends on capability being | M | SPECIAL | 1115 | | negotiated | | | 1116 | | | | | 1117 | csup | Depends on capability being | B | SPECIAL | 1118 | | negotiated | | | 1119 | | | | | 1120 | creq | Depends on capability being | B | SPECIAL | 1121 | | negotiateds | | | 1122 | | | | | 1123 | acap | Depends on capability being | B | SPECIAL | 1124 | | negotiated | | | 1125 | | | | | 1126 | tcap | Repeat transport capability across | B | IDENTICAL | 1127 | | all m= lines | | | 1128 | | | | | 1129 +-------+--------------------------------------+-------+------------+ 1131 RFC5939 Attribute Analysis 1133 5.29. draft-ietf-mmusic-sdp-media-capabilities 1135 Session Description Protocol (SDP) capability negotiation provides a 1136 general framework for indicating and negotiating capabilities in SDP. 1137 The base framework defines only capabilities for negotiating 1138 transport protocols and attributes. [MEDIA_CAP] extends the 1139 framework by defining media capabilities that can be used to 1140 negotiate media types and their associated parameters. 1142 +--------+---------------+-------+----------+ 1143 | Name | Notes | Level | Category | 1144 +--------+---------------+-------+----------+ 1145 | rmcap | Not Impacted | B | NORMAL | 1146 | | | | | 1147 | omcap | Not Impacted | B | NORMAL | 1148 | | | | | 1149 | mfcap | Not Impacted | B | NORMAL | 1150 | | | | | 1151 | mscap | Not Impacted | B | NORMAL | 1152 | | | | | 1153 | lcfg | Not Impacted | B | NORMAL | 1154 | | | | | 1155 | secap | Not Impacted | S | NORMAL | 1156 | | | | | 1157 +--------+---------------+-------+----------+ 1159 draft-ietf-mmusic-sdp-media-capabilities Attribute Analysis 1161 5.30. RFC4567 - Key Management Extensions for SDP and RTSP 1163 RFC4567 [RFC4567] defines general extensions for Session Description 1164 Protocol (SDP) and Real Time Streaming Protocol (RTSP) to carry 1165 messages, as specified by a key management protocol, in order to 1166 secure the media. These extensions are presented as a framework, to 1167 be used by one or more key management protocols. As such, their use 1168 is meaningful only when complemented by an appropriate key management 1169 protocol. 1171 +-----------+----------------------------------+-------+------------+ 1172 | Name | Notes | Level | Category | 1173 +-----------+----------------------------------+-------+------------+ 1174 | key-mgmt | Key management protocol MUST be | B | IDENTICAL | 1175 | | identical across all the | | | 1176 | | m=lines | | | 1177 | | | | | 1178 +-----------+----------------------------------+-------+------------+ 1180 RFC4567 Attribute Analysis 1182 5.31. RFC4572 - Comedia over TLS in SDP 1184 RFC4572 [RFC4572] specifies how to establish secure connection- 1185 oriented media transport sessions over the Transport Layer Security 1186 (TLS) protocol using the Session Description Protocol (SDP). It 1187 defines a new SDP protocol identifier, 'TCP/TLS'. It also defines 1188 the syntax and semantics for an SDP 'fingerprint' attribute that 1189 identifies the certificate that will be presented for the TLS 1190 session. This mechanism allows media transport over TLS connections 1191 to be established securely, so long as the integrity of session 1192 descriptions is assured. 1194 +--------------+-------------------------------+-------+------------+ 1195 | Name | Notes | Level | Category | 1196 +--------------+-------------------------------+-------+------------+ 1197 | fingerprint | Fingerprint value MUST be | B | IDENTICAL | 1198 | | identical across all the | | | 1199 | | m=lines | | | 1200 | | | | | 1201 +--------------+-------------------------------+-------+------------+ 1203 RFC4572 Attribute Analysis 1205 5.32. RFC4570 - SDP Source Filters 1207 RFC4570 [RFC4570] describes how to adapt the Session Description 1208 Protocol (SDP) to express one or more source addresses as a source 1209 filter for one or more destination "connection" addresses. It 1210 defines the syntax and semantics for an SDP "source-filter" attribute 1211 that may reference either IPv4 or IPv6 address(es) as either an 1212 inclusive or exclusive source list for either multicast or unicast 1213 destinations. In particular, an inclusive source-filter can be used 1214 to specify a Source-Specific Multicast (SSM) session 1216 +----------------+-----------------------------+-------+------------+ 1217 | Name | Notes | Level | Category | 1218 +----------------+-----------------------------+-------+------------+ 1219 | source-filter | he attribute MUST be | B | IDENTICAL | 1220 | | repeated across all m=lines | | | 1221 | | multiplexed | | | 1222 | | | | | 1223 +----------------+-----------------------------+-------+------------+ 1225 RFC4570 Attribute Analysis 1227 5.33. RFC6128 - RTCP Port for Multicast Sessions 1229 The Session Description Protocol (SDP) has an attribute that allows 1230 RTP applications to specify an address and a port associated with the 1231 RTP Control Protocol (RTCP) traffic. In RTP-based source-specific 1232 multicast (SSM) sessions, the same attribute is used to designate the 1233 address and the RTCP port of the Feedback Target in the SDP 1234 description. However, the RTCP port associated with the SSM session 1235 itself cannot be specified by the same attribute to avoid ambiguity, 1236 and thus, is required to be derived from the "m=" line of the media 1237 description. Deriving the RTCP port from the "m=" line imposes an 1238 unnecessary restriction. RFC6128 [RFC6128] removes this restriction 1239 by introducing a new SDP attribute. 1241 +-----------------+----------------------------+-------+------------+ 1242 | Name | Notes | Level | Category | 1243 +-----------------+----------------------------+-------+------------+ 1244 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | 1245 | | be identical across all | | | 1246 | | the m=lines | | | 1247 | | | | | 1248 +-----------------+----------------------------+-------+------------+ 1250 RFC6128 Attribute Analysis 1252 5.34. RFC6189 - ZRTP 1254 RFC6189 [RFC6189] defines ZRTP, a protocol for media path Diffie- 1255 Hellman exchange to agree on a session key and parameters for 1256 establishing unicast Secure Real-time Transport Protocol (SRTP) 1257 sessions for Voice over IP (VoIP) applications. 1259 +------------+-------------------------------+-------+--------------+ 1260 | Name | Notes | Level | Category | 1261 +------------+-------------------------------+-------+--------------+ 1262 | zrtp-hash | Complicates if all the | M | NOT | 1263 | | m=lines are not authenticated | | RECOMMENDED | 1264 | | as given in the example | | | 1265 | | below | | | 1266 | | | | | 1267 +------------+-------------------------------+-------+--------------+ 1269 RFC6189 Attribute Analysis 1271 Example: Multiplexing media descriptions having attribute zrtp-hash 1272 defined with the media descriptions lacking it, would either 1273 complicate the handling of multiplexed stream or fail multiplexing. 1275 v=0 1276 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 1277 s= 1278 c=IN IP4 client.biloxi.example.com 1279 t=0 0 1280 m=audio 3456 RTP/AVP 97 1281 a=rtpmap:97 iLBC/8000 1282 1283 a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2 1284 df881ae642c371ba46df 1285 1286 m=video 34567 RTP/AVP 31 1287 a=rtpmap:31 H261/90000 1289 5.35. RFC4145 - Connection-Oriented Media 1291 RFC4145 [RFC4145] describes how to express media transport over TCP 1292 using the Session Description Protocol (SDP). It defines the SDP 1293 'TCP' protocol identifier, the SDP 'setup' attribute, which describes 1294 the connection setup procedure, and the SDP 'connection' attribute, 1295 which handles connection reestablishment. 1297 +-------------+--------------------------------+-------+------------+ 1298 | Name | Notes | Level | Category | 1299 +-------------+--------------------------------+-------+------------+ 1300 | setup | Should be identical across all | B | IDENTICAL | 1301 | | m=lines | | | 1302 | | | | | 1303 | connection | Should be identical across all | B | IDENTICAL | 1304 | | m=lines | | | 1305 | | | | | 1306 +-------------+--------------------------------+-------+------------+ 1308 RFC4145 Attribute Analysis 1310 5.36. RFC5159 - OMA BCAST SDP Attributes 1312 RFC5159 [RFC5159] provides descriptions of Session Description 1313 Protocol (SDP) attributes used by the Open Mobile Alliance's 1314 Broadcast Service and Content Protection specification. 1316 +---------------------+-------+-------+----------+ 1317 | Name | Notes | Level | Category | 1318 +---------------------+-------+-------+----------+ 1319 | bcastversion | | S | TBD | 1320 | | | | | 1321 | stkmstream | | B | TBD | 1322 | | | | | 1323 | SRTPAuthentication | | M | TBD | 1324 | | | | | 1325 | SRTPROCTxRate | | M | TBD | 1326 | | | | | 1327 +---------------------+-------+-------+----------+ 1329 RFC5159 Attribute Analysis 1331 5.37. RFC6193 - Media Description for IKE in SDP 1333 RFC6193 [RFC6193] specifies how to establish a media session that 1334 represents a virtual private network using the Session Initiation 1335 Protocol for the purpose of on-demand media/application sharing 1336 between peers. It extends the protocol identifier of the Session 1337 Description Protocol (SDP) so that it can negotiate use of the 1338 Internet Key Exchange Protocol (IKE) for media sessions in the SDP 1339 offer/answer model. 1341 +-------------------+--------------------------+-------+------------+ 1342 | Name | Notes | Level | Category | 1343 +-------------------+--------------------------+-------+------------+ 1344 | ike-setup | Attribute MUST be | B | IDENTICAL | 1345 | | identical across all the | | | 1346 | | m=lines | | | 1347 | | | | | 1348 | psk-fingerprint | Attribute MUST be | B | IDENTICAL | 1349 | | identical across all the | | | 1350 | | m=lines | | | 1351 | | | | | 1352 | ike-esp | Attribute MUST be | B | IDENTICAL | 1353 | | identical across all the | | | 1354 | | m=lines | | | 1355 | | | | | 1356 | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL | 1357 | | identical across all the | | | 1358 | | m=lines | | | 1359 | | | | | 1360 +-------------------+--------------------------+-------+------------+ 1362 RFC6193 Attribute Analysis 1364 With the above SDP constraints, a session multiplexed with multiple 1365 m=lines will use only one IPSec association for all of the m= lines. 1367 5.38. RFC6064 - SDP and RTSP Extensions for 3GPP 1369 The Packet-switched Streaming Service (PSS) and the Multimedia 1370 Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session 1371 Description Protocol (SDP) and Real Time Streaming Protocol (RTSP) 1372 with some extensions. RFC6064 [RFC6064] provides information about 1373 these extensions and registers the RTSP and SDP extensions with IANA. 1375 +-----------------------+----------------------+------+-------------+ 1376 | Name | Notes | Leve | Category | 1377 | | | l | | 1378 +-----------------------+----------------------+------+-------------+ 1379 | X-predecbufsize | Case1:Aggregate | M | NOT | 1380 | | total when video | | RECOMMENDED | 1381 | | m-lines are | | | 1382 | | muxed Case2:Multiple | | | 1383 | | xing with audio | | | 1384 | | m=lines is invalid | | | 1385 | | | | | 1386 | X-initpredecbufperiod | Case1:Aggregate | M | NOT | 1387 | | total when video | | RECOMMENDED | 1388 | | m-lines are | | | 1389 | | muxed Case2:Multiple | | | 1390 | | xing with audio | | | 1391 | | m=lines is invalid | | | 1392 | | | | | 1393 | X-initpostdecbufperio | Case1:Aggregate | M | NOT | 1394 | d | total when video | | RECOMMENDED | 1395 | | m-lines are | | | 1396 | | muxed Case2:Multiple | | | 1397 | | xing with audio | | | 1398 | | m=lines is invalid | | | 1399 | | | | | 1400 | X-decbyterate | Case1:Aggregate | M | NOT | 1401 | | total when video | | RECOMMENDED | 1402 | | m-lines are | | | 1403 | | muxed Case2:Multiple | | | 1404 | | xing with audio | | | 1405 | | m=lines is invalid | | | 1406 | | | | | 1407 | 3gpp-videopostdecbufs | Case1:Aggregate | M | NOT | 1408 | ize | total when video | | RECOMMENDED | 1409 | | m-lines are muxed. | | | 1410 | | Case2:Multiplexing | | | 1411 | | with audio m=lines | | | 1412 | | is invalid | | | 1413 | | | | | 1414 | framesize | Not Impacted | M | NORMAL | 1415 | | | | | 1416 | 3GPP-Integrity-Key | Not Impacted | S | NORMAL | 1417 | | | | | 1418 | 3GPP-SRTP-Config | Same config SHALL | M | NORMAL | 1419 | | apply to all the | | | 1420 | | m=lines multiplexed | | | 1421 | | | | | 1422 | alt,alt-default-id | Specifying alternate | M | TBD | 1423 | | m=lines when session | | | 1424 | | with mulitple | | | 1425 | | m=lines of different | | | 1426 | | types cannot be | | | 1427 | | clearly specified | | | 1428 | | | | | 1429 | alt-group | Complicates | M | TBD | 1430 | | selection of | | | 1431 | | alternate m=lines | | | 1432 | | grouped with | | | 1433 | | alt-group on | | | 1434 | | mulitplexing | | | 1435 | | | | | 1436 | 3GPP-Adaptation-Suppo | | M | TBD | 1437 | rt | | | | 1438 | | | | | 1439 | 3GPP-QoE-Metricsn | | B | TBD | 1440 | | | | | 1441 | 3GPP-Asset-Informatio | | B | TBD | 1442 | | | | | 1443 | | | | | 1444 | mbms-mode | | B | TBD | 1445 | | | | | 1446 | mbms-flowid | Multiplexing | M | TBD | 1447 | | multiple m=lines | | | 1448 | | complicates FEC | | | 1449 | | mappings to the | | | 1450 | | transport | | | 1451 | | addresses. | | | 1452 | | | | | 1453 | mbms-repair | | B | TBD | 1454 | | | | | 1455 +-----------------------+----------------------+------+-------------+ 1457 RFC6064 Attribute Analysis 1459 OPEN ISSUE:MW: These paramters are defined for the declarative 1460 usage in RTSP or multicast/broadcast and dont have O/A defintions. 1461 Does BUNDLE apply only to O/A usage ? 1463 5.39. RFC3108 - ATM SDP 1465 RFC3108 [RFC3108] describes conventions for using the Session 1466 Description Protocol (SDP) described for controlling ATM Bearer 1467 Connections, and any associated ATM Adaptation Layer (AAL) 1469 +------------------------+--------------+-------+----------+ 1470 | Name | Notes | Level | Category | 1471 +------------------------+--------------+-------+----------+ 1472 | aalType | NOT IMPACTED | B | NORMAL | 1473 | eecid | NOT IMPACTED | B | NORMAL | 1474 | aalType | NOT IMPACTED | B | NORMAL | 1475 | capability | NOT IMPACTED | B | NORMAL | 1476 | qosClass | NOT IMPACTED | B | NORMAL | 1477 | bcob | NOT IMPACTED | B | NORMAL | 1478 | stc | NOT IMPACTED | B | NORMAL | 1479 | upcc | NOT IMPACTED | B | NORMAL | 1480 | atmQOSparms | NOT IMPACTED | B | NORMAL | 1481 | atmTrfcDesc | NOT IMPACTED | B | NORMAL | 1482 | abrParms | NOT IMPACTED | B | NORMAL | 1483 | abrSetup | NOT IMPACTED | B | NORMAL | 1484 | bearerType | NOT IMPACTED | B | NORMAL | 1485 | lij | NOT IMPACTED | B | NORMAL | 1486 | anycast | NOT IMPACTED | B | NORMAL | 1487 | cache | NOT IMPACTED | B | NORMAL | 1488 | bearerSigIE | NOT IMPACTED | B | NORMAL | 1489 | aalApp | NOT IMPACTED | B | NORMAL | 1490 | cbrRate | NOT IMPACTED | B | NORMAL | 1491 | sbc | NOT IMPACTED | B | NORMAL | 1492 | clkrec | NOT IMPACTED | B | NORMAL | 1493 | fec | NOT IMPACTED | B | NORMAL | 1494 | prtfl | NOT IMPACTED | B | NORMAL | 1495 | structure | NOT IMPACTED | B | NORMAL | 1496 | cpsSDUsize | NOT IMPACTED | B | NORMAL | 1497 | aal2CPS | NOT IMPACTED | B | NORMAL | 1498 | aal2CPSSDUrate | NOT IMPACTED | B | NORMAL | 1499 | aal2sscs3661unassured | NOT IMPACTED | B | NORMAL | 1500 | aal2sscs3661assured | NOT IMPACTED | B | NORMAL | 1501 | aal2sscs3662 | NOT IMPACTED | B | NORMAL | 1502 | aal5sscop | NOT IMPACTED | B | NORMAL | 1503 | atmmap | NOT IMPACTED | B | NORMAL | 1504 | silenceSupp | NOT IMPACTED | B | NORMAL | 1505 | ecan | NOT IMPACTED | B | NORMAL | 1506 | gc | NOT IMPACTED | B | NORMAL | 1507 | profileDesc | NOT IMPACTED | B | NORMAL | 1508 | vsel | NOT IMPACTED | B | NORMAL | 1509 | dsel | NOT IMPACTED | B | NORMAL | 1510 | fsel | NOT IMPACTED | B | NORMAL | 1511 | onewaySel | NOT IMPACTED | B | NORMAL | 1512 | codecconfig | NOT IMPACTED | B | NORMAL | 1513 | isup_usi | NOT IMPACTED | B | NORMAL | 1514 | isup_usi | NOT IMPACTED | B | NORMAL | 1515 | chain | NOT IMPACTED | B | NORMAL | 1516 | | | | | 1517 +------------------------+--------------+-------+----------+ 1519 RFC3108 Attribute Analysis 1521 RFC3108 describes conventions for using the Session Description 1522 Protocol (SDP) for characterizing ATM bearer connections using an 1523 AAL1, AAL2 or AAL5 adaptation layers. For AAL1, AAL2 and AAL5, 1524 bearer connections can be used to transport single media streams. In 1525 addition, for AAL1 and AAL2, multiple media streams may be 1526 multiplexed into a bearer connection. For all adaptation types 1527 (AAL1, AAL2 and AAL5), bearer connections may be bundled into a 1528 single media group. In all cases addressed by RFC3108, a real-time 1529 media stream (voice, video, voiceband data, pseudo-wire and others) 1530 or a multiplex of media streams is mapped directly into an ATM 1531 connection. RFC3108 does not address cases where ATM serves as a 1532 low-level transport pipe for IP packets which in turn may carry one 1533 or more real-time (e.g. VoIP) media sessions with a life-cycle 1534 different from that of the underlying ATM transport. 1536 5.40. 3GPP TS 24.182 1538 3GPP TS 24.182 [3GPP TS 24.182] specifies IP multimedia subsystem 1539 Custom Alerting tones 1541 +-------------+----------------------------------+-------+----------+ 1542 | Name | Notes | Level | Category | 1543 +-------------+----------------------------------+-------+----------+ 1544 | g.3gpp.cat | Usage defined for the IP | M | NORMAL | 1545 | | Multimedia Subsystem | | | 1546 | | | | | 1547 +-------------+----------------------------------+-------+----------+ 1549 3GPP TS 24.182 Attribute Analysis 1551 5.41. 3GPP TS 24.183 1553 3GPP TS 24.183 [3GPP TS 24.183]specifies IP multimedia subsystem 1554 Custom Ringing Signal 1556 +-------------+----------------------------------+-------+----------+ 1557 | Name | Notes | Level | Category | 1558 +-------------+----------------------------------+-------+----------+ 1559 | g.3gpp.crs | Usage defined for the IP | M | NORMAL | 1560 | | Multimedia Subsystem | | | 1561 | | | | | 1562 +-------------+----------------------------------+-------+----------+ 1564 3GPP TS 24.183 Attribute Analysis 1566 5.42. 3GPP TS 24.229 1568 3GPP TS 24.229 [3GPP TS 24.229]IP multimedia call control protocol 1569 based on Session Initial protocol and Session Description Protocol. 1571 +------------------+---------------------------+-------+------------+ 1572 | Name | Notes | Level | Category | 1573 +------------------+---------------------------+-------+------------+ 1574 | secondary-realm | Per media-level attribute | M | TRANSPORT | 1575 | | MUST be used per | | | 1576 | | underlying transport | | | 1577 | | | | | 1578 | visited-realm | Per media-level attribute | M | TRANSPORT | 1579 | | MUST be used per | | | 1580 | | underlying transport | | | 1581 | | | | | 1582 | omr-m-cksum | Not Impacted | M | NORMAL | 1583 | | | | | 1584 | omr-s-cksum | Not Impacted | M | NORMAL | 1585 | | | | | 1586 | omr-m-att | Not Impacted | M | NORMAL | 1587 | | | | | 1588 | omr-s-bw | Not Impacted | M | NORMAL | 1589 | | | | | 1590 | omr-s-bw | Not Impacted | M | NORMAL | 1591 | | | | | 1592 | omr-m-att | Not Impacted | M | NORMAL | 1593 | | | | | 1594 | omr-codecs | Not Impacted | M | NORMAL | 1595 | | | | | 1596 +------------------+---------------------------+-------+------------+ 1598 3GPP TS 24.229 Attribute Analysis 1600 5.43. ITU T.38 1602 ITU T.38[T.38] defines procedures for real-time Group 3 fascimile 1603 communications over IP netowrks. 1605 +------------------------+---------------+-------+----------+ 1606 | Name | Notes | Level | Category | 1607 +------------------------+---------------+-------+----------+ 1608 | T38FaxVersion | Not Impacted | S | NORMAL | 1609 | | | | | 1610 | T38MaxBitRate | Not Impacted | S | NORMAL | 1611 | | | | | 1612 | T38FaxFillBitRemoval | Not Impacted | S | NORMAL | 1613 | | | | | 1614 | T38FaxTranscodingMMR | Not Impacted | S | NORMAL | 1615 | | | | | 1616 | T38FaxTranscodingJBIG | Not Impacted | S | NORMAL | 1617 | | | | | 1618 | T38FaxRateManagement | Not Impacted | S | NORMAL | 1619 | | | | | 1620 | T38FaxMaxBuffer | Not Impacted | S | NORMAL | 1621 | | | | | 1622 | T38FaxMaxDatagram | Not Impacted | S | NORMAL | 1623 | | | | | 1624 | T38FaxUdpEC | Not Impacted | S | NORMAL | 1625 | | | | | 1626 +------------------------+---------------+-------+----------+ 1628 Historic Attribute Analysis 1630 The ITU T.38 attributes are clearly unaffected by multiplexing and 1631 are specific to the working of the fax protocol itself. 1633 5.44. ITU-T H.248.15 1635 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 1636 package attribute 1637 +-----------+------------------------------------+-------+----------+ 1638 | Name | Notes | Level | Category | 1639 +-----------+------------------------------------+-------+----------+ 1640 | h248item | It is also only applicable for | B | SPECIAL | 1641 | | signaling the inclusion of H.248 | | | 1642 | | extension packages to a gateway | | | 1643 | | via the local and remote | | | 1644 | | descriptors. The attribute itself | | | 1645 | | is unaffected by multiplexing, but | | | 1646 | | the packaged referenced in a | | | 1647 | | specific use of the attribute may | | | 1648 | | be impacted. Further analysis of | | | 1649 | | each package is needed to | | | 1650 | | determine if there is an issue. | | | 1651 | | This is only a concern in | | | 1652 | | environments using a decomposed | | | 1653 | | server/gateway with H.248 signaled | | | 1654 | | between them. The ITU-T will need | | | 1655 | | to do further analysis of various | | | 1656 | | packages when they specify how to | | | 1657 | | signal the use of multiplexing to | | | 1658 | | a gateway. | | | 1659 | | | | | 1660 +-----------+------------------------------------+-------+----------+ 1662 Historic Attribute Analysis 1664 5.45. RFC4975 - The Message Session Relay Protocol 1666 RFC4975 [RFC4975] the Message Session Relay Protocol, a protocol for 1667 transmitting a series of related instant messages in the context of a 1668 session. Message sessions are treated like any other media stream 1669 when set up via a rendezvous or session creation protocol such as the 1670 Session Initiation Protocol. 1672 +-----------------------+---------------+-------+----------+ 1673 | Name | Notes | Level | Category | 1674 +-----------------------+---------------+-------+----------+ 1675 | accept-types | Not Impacted | M | NORMAL | 1676 | | | | | 1677 | accept-wrapped-types | Not Impacted | M | NORMAL | 1678 | | | | | 1679 | max-size | Not Impacted | M | NORMAL | 1680 | | | | | 1681 | path | Not Impacted | M | NORMAL | 1682 | | | | | 1683 +-----------------------+---------------+-------+----------+ 1684 RFC4975 Attribute Analysis 1686 5.46. Historical 1688 This section specifies analysis for the attributes that are included 1689 for historic usage alone by the [IANA]. 1691 +---------------------+-----------------+---------------+----------+ 1692 | Name | Notes | Level | Category | 1693 +---------------------+-----------------+---------------+----------+ 1694 | rtpred1 | Not Applicable | Not-Applcable | TBD | 1695 | | | | | 1696 | rtpred2 | Not Applicable | Not-Applcable | TBD | 1697 | | | | | 1698 | PSCid | Not Applicable | Not-Applcable | TBD | 1699 | | | | | 1700 | bc_service | Not Applicable | Not-Applcable | TBD | 1701 | | | | | 1702 | bc_program | Not Applicable | Not-Applcable | TBD | 1703 | | | | | 1704 | bc_service_package | Not Applicable | Not-Applcable | TBD | 1705 | | | | | 1706 +---------------------+-----------------+---------------+----------+ 1708 Unknowns Attribute Analysis 1710 6. bwtype Attribute Analysis 1712 This section specifies handling of specific bandwidth attributes when 1713 used in multiplexing scenarios. 1715 6.1. RFC4566 - SDP: Session Description Protocol 1717 +------------+-----------------------------------+-------+----------+ 1718 | Name | Notes | Level | Category | 1719 +------------+-----------------------------------+-------+----------+ 1720 | bwtype:CT | Aggregate bandwidth for the | S | NORMAL | 1721 | | conference | | | 1722 | | | | | 1723 | bwtype:AS | There are 2 interpretations for | B | NORMAL, | 1724 | | this attribute As a session | | SUM | 1725 | | attribute, it specifies the | | | 1726 | | session aggregate unless | | | 1727 | | media-level b=RR and/or b=RS | | | 1728 | | attributes are used. Under this | | | 1729 | | interpretation the multiplexing | | | 1730 | | scheme has no impact and belongs | | | 1731 | | to NORMAL category. For the | | | 1732 | | media level usage, the aggregate | | | 1733 | | of individual bandwidth values is | | | 1734 | | considered. | | | 1735 | | | | | 1736 +------------+-----------------------------------+-------+----------+ 1738 RFC4566 bwtype Analysis 1740 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth 1742 RFC3556 [RFC3556] defines an extension to the Session Description 1743 Protocol (SDP) to specify two additional modifiers for the bandwidth 1744 attribute. These modifiers may be used to specify the bandwidth 1745 allowed for RTP Control Protocol (RTCP) packets in a Real-time 1746 Transport Protocol (RTP) session 1748 +------------+--------------------------------+-------+-------------+ 1749 | Name | Notes | Level | Category | 1750 +------------+--------------------------------+-------+-------------+ 1751 | bwtype:RS | S level usage represents | B | NORMAL,SUM | 1752 | | session aggregate and media | | | 1753 | | level usage indicates SUM of | | | 1754 | | the individual values while | | | 1755 | | multiplexing | | | 1756 | | | | | 1757 | bwtype:RR | S level usage represents | B | NORMAL,SUM | 1758 | | session aggregate and media | | | 1759 | | level usage indicates SUM of | | | 1760 | | the individual values while | | | 1761 | | multiplexing | | | 1762 | | | | | 1763 +------------+--------------------------------+-------+-------------+ 1765 RFC3556 bwtype Analysis 1767 6.3. RFC3890 - Bandwidth Modifier for SDP 1769 RFC3890 [RFC3890] defines a Session Description Protocol (SDP) 1770 Transport Independent Application Specific Maximum (TIAS) bandwidth 1771 modifier that does not include transport overhead; instead an 1772 additional packet rate attribute is defined. The transport 1773 independent bit-rate value together with the maximum packet rate can 1774 then be used to calculate the real bit-rate over the transport 1775 actually used. 1777 +--------------+---------------------------------+-------+----------+ 1778 | Name | Notes | Level | Category | 1779 +--------------+---------------------------------+-------+----------+ 1780 | bwtype:TIAS | The usage of TIAS is not | B | TBD | 1781 | | clearly defined Offer/Answer | | | 1782 | | usage. | | | 1783 | | | | | 1784 | maxprate | The usage of TIAS and maxprate | B | TBD | 1785 | | is not well defined under | | | 1786 | | multiplexing | | | 1787 | | | | | 1788 +--------------+---------------------------------+-------+----------+ 1790 RFC3890 bwtype Analysis 1792 The intention of TIAS is that the media level bit-rate is multiplied 1793 with the known per-packet overhead for the selected transport and the 1794 maxprate value to determine the worst case bit-rate from the 1795 transport to more accurately capture the required usage. Summing 1796 TIAS values independently across m=lines and multiplying the computed 1797 sum with maxprate and the per-packet overhead would inflate the value 1798 significantly. Instead performing multiplication and adding the 1799 individual values is a more appropriate usage. This still ignores 1800 the fact that this is a send side declaration, and not intended for 1801 receiver negotiation. 1803 7. rtcp-fb Attribute Analysis 1805 This section analyzes rtcp-fb SDP attributes [RTCP-FB]. 1807 7.1. RFC4585 - RTP/AVPF 1809 RFC4585 [RFC4585] defines an extension to the Audio-visual Profile 1810 (AVP) that enables receivers to provide, statistically, more 1811 immediate feedback to the senders and thus allows for short-term 1812 adaptation and efficient feedback-based repair mechanisms to be 1813 implemented. 1815 +----------+-----------------------------------+-------+------------+ 1816 | Attr | Notes | Level | Category | 1817 | Name | | | | 1818 +----------+-----------------------------------+-------+------------+ 1819 | ack | Not Impacted | M | NORMAL | 1820 | rpsi | | | | 1821 | | | | | 1822 | ack app | Feedback parameters MUST be | M | SPECIAL | 1823 | | handled in the app specifc way | | | 1824 | | when multiplexed | | | 1825 | | | | | 1826 | nack | Not Impacted | M | NORMAL | 1827 | | | | | 1828 | nack | Not Impacted | M | NORMAL | 1829 | pli | | | | 1830 | | | | | 1831 | nack | Not Impacted | M | NORMAL | 1832 | sli | | | | 1833 | | | | | 1834 | nack | Not Impacted | M | NORMAL | 1835 | rpsi | | | | 1836 | | | | | 1837 | nack | Feedback parameters MUST be | M | SPECIAL | 1838 | app | handled in the app specifc way | | | 1839 | | when multiplexed | | | 1840 | | | | | 1841 | trr-int | This attribute applies to RTP | M | IDENTICAL | 1842 | | Session as a whole | | | 1843 | | | | | 1844 +----------+-----------------------------------+-------+------------+ 1846 RFC4585 Attribute Analysis 1848 7.2. RFC5104 - Codec Control Messages in AVPF 1850 RFC5104 [RFC5104] specifies a few extensions to the messages defined 1851 in the Audio-Visual Profile with Feedback (AVPF). They are helpful 1852 primarily in conversational multimedia scenarios where centralized 1853 multipoint functionalities are in use. However, some are also usable 1854 in smaller multicast environments and point-to-point calls. 1856 +-----------+--------------+-------+----------+ 1857 | Attr Name | Notes | Level | Category | 1858 +-----------+--------------+-------+----------+ 1859 | ccm | Not Impacted | M | Normal | 1860 | | | | | 1861 +-----------+--------------+-------+----------+ 1862 RFC5104 Attribute Analysis 1864 7.3. RFC6285 - Unicast-Based RAMS 1866 +-----------+---------------+-------+----------+ 1867 | Name | Notes | Level | Category | 1868 +-----------+---------------+-------+----------+ 1869 | nack rai | Not Impacted | M | NORMAL | 1870 | | | | | 1871 +-----------+---------------+-------+----------+ 1873 RFC6285 Attribute Analysis 1875 7.4. RFC6679 - ECN for RTP over UDP/IP 1877 RFC6679 [RFC6679] specifies how Explicit Congestion Notification 1878 (ECN) can be used with the Real-time Transport Protocol (RTP) running 1879 over UDP, using the RTP Control Protocol (RTCP) as a feedback 1880 mechanism. It defines a new RTCP Extended Report (XR) block for 1881 periodic ECN feedback, a new RTCP transport feedback message for 1882 timely reporting of congestion events, and a Session Traversal 1883 Utilities for NAT (STUN) extension used in the optional 1884 initialisation method using Interactive Connectivity Establishment 1885 (ICE) 1887 +------------------+---------------------------+-------+------------+ 1888 | Name | Notes | Level | Category | 1889 +------------------+---------------------------+-------+------------+ 1890 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | 1891 | | the RTP Session level | | | 1892 | | | | | 1893 | nack ecn | This attribute enables | M | IDENTICAL | 1894 | | ECN at the RTP session | | | 1895 | | level | | | 1896 | | | | | 1897 +------------------+---------------------------+-------+------------+ 1899 RFC6679 Attribute Analysis 1901 7.5. RFC6642 - Third-Party Loss Report 1903 In a large RTP session using the RTP Control Protocol (RTCP) feedback 1904 mechanism defined in RFC 4585 [RFC4585], a feedback target may 1905 experience transient overload if some event causes a large number of 1906 receivers to send feedback at once. This overload is usually avoided 1907 by ensuring that feedback reports are forwarded to all receivers, 1908 allowing them to avoid sending duplicate feedback reports. However, 1909 there are cases where it is not recommended to forward feedback 1910 reports, and this may allow feedback implosion. RFC6642 [RFC6642] 1911 memo discusses these cases and defines a new RTCP Third-Party Loss 1912 Report that can be used to inform receivers that the feedback target 1913 is aware of some loss event, allowing them to suppress feedback. 1914 Associated Session Description Protocol (SDP) signaling is also 1915 defined. 1917 +-------------+---------------+-------+----------+ 1918 | Name | Notes | Level | Category | 1919 +-------------+---------------+-------+----------+ 1920 | nack tllei | Not Impacted | M | NORMAL | 1921 | | | | | 1922 | nack pslei | Not Impacted | M | NORMAL | 1923 | | | | | 1924 +-------------+---------------+-------+----------+ 1926 RFC6642 Attribute Analysis 1928 7.6. RFC5104 - Codec Control Messages in AVPF 1930 +------------+--------------+-------+----------+ 1931 | Attr Name | Notes | Level | Category | 1932 +------------+--------------+-------+----------+ 1933 | ccm fir | Not Impacted | M | NORMAL | 1934 | | | | | 1935 | ccm tmmbr | Not Impacted | M | NORMAL | 1936 | | | | | 1937 | ccm tstr | Not Impacted | M | NORMAL | 1938 | | | | | 1939 | ccm vbcm | Not Impacted | M | NORMAL | 1940 | | | | | 1941 +------------+--------------+-------+----------+ 1943 RFC5104 Attribute Analysis 1945 8. group Attribute Analysis 1947 This section analyzes SDP "group" semantics [GROUP-SEM]. 1949 8.1. RFC5888 - SDP Grouping Framework 1951 RFC5888 [RFC5888] defines a framework to group "m" lines in the 1952 Session Description Protocol (SDP) for different purposes. 1954 +------------+---------------+-------+----------+ 1955 | Name | Notes | Level | Category | 1956 +------------+---------------+-------+----------+ 1957 | group:LS | Not Impacted | S | NORMAL | 1958 | | | | | 1959 | group:FID | Not Impacted | S | NORMAL | 1960 | | | | | 1961 +------------+---------------+-------+----------+ 1963 RFC5888 Attribute Analysis 1965 8.2. RFC3524 - Mapping Media Streams to Resource Reservation Flows 1967 RFC3524 [RFC3524] defines an extension to the Session Description 1968 Protocol (SDP) grouping framework. It allows requesting a group of 1969 media streams to be mapped into a single resource reservation flow. 1970 The SDP syntax needed is defined, as well as a new "semantics" 1971 attribute called Single Reservation Flow (SRF). 1973 +------------+---------------+-------+----------+ 1974 | Name | Notes | Level | Category | 1975 +------------+---------------+-------+----------+ 1976 | group:SRF | Not Impacted | S | NORMAL | 1977 | | | | | 1978 +------------+---------------+-------+----------+ 1980 RFC3524 Attribute Analysis 1982 8.3. RFC4091 - ANAT Semantics 1984 RFC4091 [RFC4091] defines the Alternative Network Address Types 1985 (ANAT) semantics for the Session Description Protocol (SDP) grouping 1986 framework. The ANAT semantics allow alternative types of network 1987 addresses to establish a particular media stream. 1989 +-------------+----------------+-------+------------------+ 1990 | Name | Notes | Level | Category | 1991 +-------------+----------------+-------+------------------+ 1992 | group:ANAT | Not Impacted | S | NOT RECOMMENDED | 1993 | | | | | 1994 +-------------+----------------+-------+------------------+ 1996 RFC4091 Attribute Analysis 1998 8.4. RFC5956 - FEC Grouping Semantics in SDP 2000 RFC5956 [RFC5956] defines the semantics for grouping the associated 2001 source and FEC-based (Forward Error Correction) repair flows in the 2002 Session Description Protocol (SDP). The semantics defined in the 2003 document are to be used with the SDP Grouping Framework (RFC 5888). 2004 These semantics allow the description of grouping relationships 2005 between the source and repair flows when one or more source and/or 2006 repair flows are associated in the same group, and they provide 2007 support for additive repair flows. SSRC-level (Synchronization 2008 Source) grouping semantics are also defined in this document for 2009 Real-time Transport Protocol (RTP) streams using SSRC multiplexing. 2011 +---------------+---------------+-------+----------+ 2012 | Name | Notes | Level | Category | 2013 +---------------+---------------+-------+----------+ 2014 | group:FEC-FR | Not Impacted | S | NORMAL | 2015 | | | | | 2016 +---------------+---------------+-------+----------+ 2018 RFC5956 Attribute Analysis 2020 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP 2022 RFC5583 [RFC5583] defines semantics that allow for signaling the 2023 decoding dependency of different media descriptions with the same 2024 media type in the Session Description Protocol (SDP). This is 2025 required, for example, if media data is separated and transported in 2026 different network streams as a result of the use of a layered or 2027 multiple descriptive media coding process. 2029 +-------------+---------------+-------+----------+ 2030 | Name | Notes | Level | Category | 2031 +-------------+---------------+-------+----------+ 2032 | depend lay | Not Impacted | M | NORMAL | 2033 | | | | | 2034 | depend mdc | Not Impacted | M | NORMAL | 2035 | | | | | 2036 +-------------+---------------+-------+----------+ 2038 RFC5583 Attribute Analysis 2040 OPEN ISSUE:Eckel: If PTs are not unique across the m=lines 2041 BUNDLED, how should this be handled ? 2043 9. ssrc-group Attribute Analysis 2045 This section analyzes "ssrc-group" semantics [SSRC-GROUP]. 2047 9.1. RFC5576 - Source-Specific SDP Attributes 2049 +---------+---------------+-------+----------+ 2050 | Name | Notes | Level | Category | 2051 +---------+---------------+-------+----------+ 2052 | FID | Not Impacted | M | NORMAL | 2053 | | | | | 2054 | FEC | Not Impacted | M | NORMAL | 2055 | | | | | 2056 | FEC-FR | Not Impacted | M | NORMAL | 2057 | | | | | 2058 +---------+---------------+-------+----------+ 2060 RFC5576 Attribute Analysis 2062 10. QoS Mechanism Token Analysis 2064 This section analyzes QoS tokes specified with SDP[QOS]. 2066 10.1. RFC5432 - QoS Mechanism Selection in SDP 2068 +-------+----------------------------------------+-------+----------+ 2069 | Name | Notes | Level | Category | 2070 +-------+----------------------------------------+-------+----------+ 2071 | rsvp | Not Impacted, since QOS mechanisms are | B | NORMAL | 2072 | | applied per flow. | | | 2073 | | | | | 2074 | nsis | Not Impacted, since QOS mechanisms are | B | NORMAL | 2075 | | applied per flow. | | | 2076 | | | | | 2077 +-------+----------------------------------------+-------+----------+ 2079 RFC5432 Attribute Analysis 2081 11. k= Attribute Analysis 2082 11.1. RFC4566 SDP: Session Description Protocol 2084 +------+------------------------------------+-------+---------------+ 2085 | Name | Notes | Level | Category | 2086 +------+------------------------------------+-------+---------------+ 2087 | k= | It is NOT recommended to use this | S | NOT | 2088 | | attribute | | RECOMMENDED | 2089 | | | | | 2090 +------+------------------------------------+-------+---------------+ 2092 RFC4566 Attribute Analysis 2094 12. content Atribute Analysis 2096 12.1. RFC4796 - MSRP Relays 2098 +------------------+---------------+-------+----------+ 2099 | Name | Notes | Level | Category | 2100 +------------------+---------------+-------+----------+ 2101 | content:slides | Not Impacted | M | NORMAL | 2102 | | | | | 2103 | content:speaker | Not Impacted | M | NORMAL | 2104 | | | | | 2105 | content:main | Not Impacted | M | NORMAL | 2106 | | | | | 2107 | content:sl | Not Impacted | M | NORMAL | 2108 | | | | | 2109 | content:alt | Not Impacted | M | NORMAL | 2110 | | | | | 2111 +------------------+---------------+-------+----------+ 2113 RFC4796 Attribute Analysis 2115 13. Payload Formats 2117 13.1. RFC5109 - RTP Payload Format for Generic FEC 2119 RFC5109 [RFC5109] describes a payload format for generic Forward 2120 Error Correction (FEC) for media data encapsulated in RTP. It is 2121 based on the exclusive-or (parity) operation. The payload format 2122 allows end systems to apply protection using various protection 2123 lengths and levels, in addition to using various protection group 2124 sizes to adapt to different media and channel characteristics. It 2125 enables complete recovery of the protected packets or partial 2126 recovery of the critical parts of the payload depending on the packet 2127 loss situation. 2129 +---------------------+----------------------+-------+--------------+ 2130 | Name | Notes | Level | Category | 2131 +---------------------+----------------------+-------+--------------+ 2132 | audio/ulpfec | Not recommended for | M | NOT | 2133 | | multiplexing due to | | RECOMMENDED | 2134 | | reuse of SSRCs | | | 2135 | | | | | 2136 | video/ulpfec | Not recommended for | M | NOT | 2137 | | multiplexing due to | | RECOMMENDED | 2138 | | reuse of SSRCs | | | 2139 | | | | | 2140 | text/ulpfec | Not recommended for | M | NOT | 2141 | | multiplexing due to | | RECOMMEDED | 2142 | | reuse of SSRCs | | | 2143 | | | | | 2144 | application/ulpfec | Not recommended for | M | NOT | 2145 | | multiplexing due to | | RECOMMENDED | 2146 | | reuse of SSRCs | | | 2147 | | | | | 2148 +---------------------+----------------------+-------+--------------+ 2150 RFC5109 Payload Format Analysis 2152 Draft draft-lennox-payload-ulp-ssrc-mux proposes a simple fix to make 2153 it possible to use ULP with multipelxing and ULP is allowed when used 2154 with that. 2156 14. IANA Considerations 2158 IANA shall register categories from this specification by expanding 2159 the Session Description Protocol (SDP) Parameters table with a column 2160 listing categories against each SDP parameter. 2162 +---------------------+ 2163 | Category | 2164 +---------------------+ 2165 | NORMAL | 2166 +---------------------+ 2167 | NOT RECOMMENDED | 2168 +---------------------+ 2169 | IDENTICAL | 2170 +---------------------+ 2171 | TRANSPORT | 2172 +---------------------+ 2173 | SPECIAL | 2174 ---------------------- 2176 15. Security Considerations 2178 All the attributes which involve security key needs a careful review 2179 to ensure two-time pad vulnerability is not created 2181 16. Acknowledgments 2183 I would like to thank Cullen Jennings for suggesting the categories, 2184 contributing text and helping review the draft. I would also link to 2185 thank Magnus, Christer and Dan on suggesting stuctural changes 2186 helping improve the document readability. 2188 I would like also to thank following experts on their inputs and 2189 reviews as listed - Rohan Mahy(5.45), Eric Burger(5.22), Christian 2190 Huitema(5.13), Christer Holmberg(5.22,5.40,5.41), Richard Ejzak 2191 (5.36,5.42,5.43,5.44,), Colin Perkins(5.7,5.8), Magnus 2192 westerlund(5.3,5.9,6.1,6.2,6.3,8.3,5.2,7,8,9), Roni 2193 Evens(5.12,5.27,8.4), Subha Dhesikan(5.5,12.1), Dan 2194 Wing(5.6,5.11,5.30,5.34,5.37), Ali C 2195 Begen(5.1,5.16,5.18,5.21,5.33,8.2,13.1,10.4,15.1), Bo Burman 2196 (7.2,7.6), Charles Eckel(5.14,5.23,5.24,10.5), Paul Kyzivat(5.24), 2197 Ian Johansson (5.11), Saravanan Shanmugham(5.10), Paul E Jones(5.25), 2198 Rajesh Kumar (5.39), Jonathan Lennox (5.31,5,14,11.1), Mo 2199 Zanaty(5.4,5.19,10.1,10.5) 2201 17. Change Log 2203 [RFC EDITOR NOTE: Please remove this section when publishing] 2205 Changes from draft-nandakumar-mmusic-mux-attributes-04 2206 o Added few OPEN ISSUES that needs to be discussed. 2207 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 2208 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 2209 o Updated Table Column name Current to Level and improved TRANSPORT 2210 category explantion on suggestions form Dan Wing. 2211 o Grouped all the rtcp-fb attribute analysis under a single section 2212 as suggested by Magnus/ 2214 Changes from draft-nandakumar-mmusic-mux-attributes-03 2215 o Maintainence change to clean up grammatical nits and wordings. 2217 Changes from draft-nandakumar-mmusic-mux-attributes-02 2218 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 2219 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 2220 the inputs from the respective RFC Authors. 2222 Changes from draft-nandakumar-mmusic-mux-attributes-01 2223 o Replaced Category BAD with NOT RECOMMENDED. 2224 o Added Category TBD. 2225 o Updated IANA Consideration Section. 2227 Changes from draft-nandakumar-mmusic-mux-attributes-00 2228 o Added new section for dealing with FEC payload types. 2230 18. References 2232 18.1. Normative References 2234 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2235 Requirement Levels", BCP 14, RFC 2119, March 1997. 2237 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 2238 Description Protocol", RFC 4566, July 2006. 2240 18.2. Informative References 2242 [3GPP TS 24.182] 2243 "IP Multimedia Subsystem (IMS) Customized Alerting Tones 2244 (CAT); Protocol specification", 2245 . 2247 [3GPP TS 24.183] 2248 "IP Multimedia Subsystem (IMS) Customized Ringing Signal 2249 (CRS); Protocol specification", 2250 . 2252 [3GPP TS 24.229] 2253 "IP multimedia call control protocol based on Session 2254 Initiation Protocol (SIP) and Session Description Protocol 2255 (SDP);", 2256 . 2258 [ACK-NACK] 2259 "S Description Protocol (SDP) RTCP ACK/NACK Feedback 2260 attributes", . 2263 [CCM] "S Description Protocol (SDP) RTCP-FB Codec Control 2264 Messages", . 2267 [GROUP-SEM] 2268 "S Description Protocol (SDP) "group" semantics", . 2272 [H.248.15] 2273 "Gateway control protocol: SDP H.248 package attribute", 2274 . 2276 [I-D.ietf-avt-multiplexing-rtp] 2277 El-Khatib, K., Luo, G., Bochmann, G., and Pinjiang. Feng, 2278 "Multiplexing Scheme for RTP Flows between Access 2279 Routers", Internet-Draft http://tools.ietf.org/html/ 2280 draft-ietf-avt-multiplexing-rtp-01, October 1999. 2282 [I-D.ietf-mmusic-sdp-bundle-negotiation] 2283 Holmberg, C., Alvestrand, H., and C. Jennings, 2284 "Multiplexing Negotiation Using Session Description 2285 Protocol (SDP) Port Numbers", 2286 draft-ietf-mmusic-sdp-bundle-negotiation-03 (work in 2287 progress), February 2013. 2289 [IANA] "S Description Protocol (SDP) Parameters", . 2293 [MEDIA_CAP] 2294 Kaplan, H., Hedayat, K., and N. Venna, "S Description 2295 Protocol (SDP) Media Capabilities Negotiation", 2296 draft-ietf-mmusic-sdp-media-capabilities-17 (work in 2297 progress), January 2013. 2299 [MEDIA_LOOPBACK] 2300 Kaplan, H., Hedayat, K., Venna, N., Jones, P., and N. 2301 Stratton, "An Extension to the Session Description 2302 Protocol (SDP) and Real-time Transport Protocol (RTP) for 2303 Media Loopback", draft-ietf-mmusic-media-loopback-27 (work 2304 in progress), January 2013. 2306 [QOS] "S Description Protocol (SDP) QoS Mechanism Tokens", . 2310 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the 2311 Session Description Protocol (SDP) for ATM Bearer 2312 Connections", RFC 3108, May 2001. 2314 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 2315 with Session Description Protocol (SDP)", RFC 3264, 2316 June 2002. 2318 [RFC3407] Andreasen, F., "S Description Protocol (SDP) Simple 2319 Capability Declaration", RFC 3407, October 2002. 2321 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to 2322 Resource Reservation Flows", RFC 3524, April 2003. 2324 [RFC3556] Casner, S., "S Description Protocol (SDP) Bandwidth 2325 Modifiers for RTP Control Protocol (RTCP) Bandwidth", 2326 RFC 3556, July 2003. 2328 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute 2329 in Session Description Protocol (SDP)", RFC 3605, 2330 October 2003. 2332 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 2333 Protocol Extended Reports (RTCP XR)", RFC 3611, 2334 November 2003. 2336 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth 2337 Modifier for the Session Description Protocol (SDP)", 2338 RFC 3890, September 2004. 2340 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network 2341 Address Types (ANAT) Semantics for the Session Description 2342 Protocol (SDP) Grouping Framework", RFC 4091, June 2005. 2344 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 2345 the Session Description Protocol (SDP)", RFC 4145, 2346 September 2005. 2348 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. 2349 Carrara, "Key Management Extensions for Session 2350 Description Protocol (SDP) and Real Time Streaming 2351 Protocol (RTSP)", RFC 4567, July 2006. 2353 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "S Description 2354 Protocol (SDP) Security Descriptions for Media Streams", 2355 RFC 4568, July 2006. 2357 [RFC4570] Quinn, B. and R. Finlayson, "S Description Protocol (SDP) 2358 Source Filters", RFC 4570, July 2006. 2360 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the 2361 Transport Layer Security (TLS) Protocol in the Session 2362 Description Protocol (SDP)", RFC 4572, July 2006. 2364 [RFC4574] Levin, O. and G. Camarillo, "The Session Description 2365 Protocol (SDP) Label Attribute", RFC 4574, August 2006. 2367 [RFC4583] Camarillo, G., "S Description Protocol (SDP) Format for 2368 Binary Floor Control Protocol (BFCP) Streams", RFC 4583, 2369 November 2006. 2371 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 2372 "Extended RTP Profile for Real-time Transport Control 2373 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, 2374 July 2006. 2376 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description 2377 Protocol (SDP) Content Attribute", RFC 4796, 2378 February 2007. 2380 [RFC4975] Campbell, B., Mahy, R., and C. Jennings, "The Message 2381 Session Relay Protocol (MSRP)", RFC 4975, September 2007. 2383 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 2384 "Codec Control Messages in the RTP Audio-Visual Profile 2385 with Feedback (AVPF)", RFC 5104, February 2008. 2387 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 2388 Correction", RFC 5109, December 2007. 2390 [RFC5159] Dondeti, L. and A. Jerichow, "S Description Protocol (SDP) 2391 Attributes for Open Mobile Alliance (OMA) Broadcast 2392 (BCAST) Service and Content Protection", RFC 5159, 2393 March 2008. 2395 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 2396 (ICE): A Protocol for Network Address Translator (NAT) 2397 Traversal for Offer/Answer Protocols", RFC 5245, 2398 July 2006. 2400 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP 2401 Header Extensions", RFC 5285, July 2008. 2403 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of 2404 Service (QoS) Mechanism Selection in the Session 2405 Description Protocol (SDP)", RFC 5432, March 2009. 2407 [RFC5506] Johansson, I., "Support for Reduced-Size Real-Time 2408 Transport Control Protocol (RTCP): Opportunities and 2409 Consequences", RFC 5506, April 2009. 2411 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., 2412 and P. Kyzivat, "A Session Description Protocol (SDP) 2413 Offer/Answer Mechanism to Enable File Transfer", RFC 5547, 2414 May 2009. 2416 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific 2417 Media Attributes in the Session Description Protocol 2418 (SDP)", RFC 5576, June 2009. 2420 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding 2421 Dependency in the Session Description Protocol (SDP)", 2422 RFC 5583, July 2009. 2424 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 2425 Protocol (RTCP) Extensions for Single-Source Multicast 2426 Sessions with Unicast Feedback", RFC 5760, February 2010. 2428 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and 2429 Control Packets on a Single Port", RFC 5761, April 2010. 2431 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control 2432 Protocol (DCCP)", RFC 5762, April 2010. 2434 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework 2435 for Establishing a Secure Real-time Transport Protocol 2436 (SRTP) Security Context Using Datagram Transport Layer 2437 Security (DTLS)", RFC 5763, May 2010. 2439 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description 2440 Protocol (SDP) Grouping Framework", RFC 5888, June 2010. 2442 [RFC5939] Andreasen, F., "S Description Protocol (SDP) Capability 2443 Negotiation", RFC 5939, September 2010. 2445 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in 2446 the Session Description Protocol", RFC 5956, 2447 September 2010. 2449 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions 2450 Defined for 3GPP Packet-Switched Streaming Service and 2451 Multimedia Broadcast/Multicast Service", RFC 6064, 2452 January 2011. 2454 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- 2455 Specific Multicast (SSM) Sessions", RFC 6128, 2456 February 2011. 2458 [RFC6189] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media 2459 Path Key Agreement for Unicast Secure RTP", RFC 6189, 2460 April 2011. 2462 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for 2463 the Internet Key Exchange Protocol (IKE) in the Session 2464 Description Protocol (SDP)", RFC 6193, April 2011. 2466 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media 2467 Control Channel Framework", RFC 6230, May 2011. 2469 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image 2470 Attributes in the Session Description Protocol (SDP)", 2471 RFC 6236, May 2011. 2473 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping 2474 between Unicast and Multicast RTP Sessions", RFC 6284, 2475 June 2011. 2477 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, 2478 "Unicast-Based Rapid Acquisition of Multicast RTP 2479 Sessions", RFC 6285, June 2011. 2481 [RFC6364] Begen, A., "S Description Protocol Elements for the 2482 Forward Error Correction (FEC) Framework", RFC 6364, 2483 October 2011. 2485 [RFC6642] Wu, Q., Xia, F., and R. Even, "RTP Control Protocol (RTCP) 2486 Extension for a Third-Party Loss Report", RFC 6642, 2487 June 2012. 2489 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., 2490 and K. Carlberg, "Explicit Congestion Notification (ECN) 2491 for RTP over UDP", RFC 6679, August 2012. 2493 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection 2494 Establishment for Media Anchoring (CEMA) for the Message 2495 Session Relay Protocol (MSRP)", RFC 6714, August 2012. 2497 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A 2498 Datagram Congestion Control Protocol UDP Encapsulation for 2499 NAT Traversal", RFC 6773, November 2012. 2501 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control 2502 Protocol Version 2 (MRCPv2)", RFC 6787, November 2012. 2504 [RTCP-FB] "S Description Protocol (SDP) RTCP Feedback attributes", < 2505 http://www.iana.org/assignments/sdp-parameters/ 2506 sdp-parameters.xml#sdp-parameters-14>. 2508 [SSRC-GROUP] 2509 "S Description Protocol (SDP) "ssrc-group" semantics", . 2513 [T.38] "Procedures for real-time Group 3 facsimile communication 2514 over IP networks", . 2516 Author's Address 2518 Suhas Nandakumar 2519 Cisco 2520 170 West Tasman Drive 2521 San Jose, CA 95134 2522 USA 2524 Email: snandaku@cisco.com