idnits 2.17.1 draft-ietf-mmusic-sdp-mux-attributes-13.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 5 instances of lines with non-RFC2606-compliant FQDNs in the document. -- The document has examples using IPv4 documentation addresses according to RFC6890, but does not use any IPv6 documentation addresses. Maybe there should be IPv6 examples, too? Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (June 27, 2016) is 2832 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-54) exists of draft-ietf-mmusic-sdp-bundle-negotiation-24 ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) -- Obsolete informational reference (is this intentional?): RFC 2326 (Obsoleted by RFC 7826) -- Obsolete informational reference (is this intentional?): RFC 4091 (Obsoleted by RFC 5245) -- Obsolete informational reference (is this intentional?): RFC 4572 (Obsoleted by RFC 8122) -- Obsolete informational reference (is this intentional?): RFC 4583 (Obsoleted by RFC 8856) -- Obsolete informational reference (is this intentional?): RFC 5245 (Obsoleted by RFC 8445, RFC 8839) -- Obsolete informational reference (is this intentional?): RFC 5285 (Obsoleted by RFC 8285) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Nandakumar 3 Internet-Draft Cisco 4 Intended status: Standards Track June 27, 2016 5 Expires: December 29, 2016 7 A Framework for SDP Attributes when Multiplexing 8 draft-ietf-mmusic-sdp-mux-attributes-13 10 Abstract 12 The purpose of this specification is to provide a framework for 13 analyzing the multiplexing characteristics of Session Description 14 Protocol (SDP) attributes when SDP is used to negotiate the usage of 15 single 5-tuple for sending and receiving media associated with 16 multiple media descriptions. 18 This specification also categorizes the existing SDP attributes based 19 on the framework described herein. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on December 29, 2016. 38 Copyright Notice 40 Copyright (c) 2016 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 56 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 57 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 6 58 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 6 59 4.1. Category: NORMAL . . . . . . . . . . . . . . . . . . . . 7 60 4.2. Category: CAUTION . . . . . . . . . . . . . . . . . . . . 7 61 4.3. Category: IDENTICAL . . . . . . . . . . . . . . . . . . . 8 62 4.4. Category: SUM . . . . . . . . . . . . . . . . . . . . . . 8 63 4.5. Category: TRANSPORT . . . . . . . . . . . . . . . . . . . 9 64 4.6. Category: INHERIT . . . . . . . . . . . . . . . . . . . . 10 65 4.7. Category: IDENTICAL-PER-PT . . . . . . . . . . . . . . . 10 66 4.8. Category: SPECIAL . . . . . . . . . . . . . . . . . . . . 11 67 4.9. Category: TBD . . . . . . . . . . . . . . . . . . . . . . 11 68 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 12 69 5.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 12 70 5.2. RFC4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . . 14 71 5.3. RFC5761: Multiplexing RTP and RTCP . . . . . . . . . . . 14 72 5.4. RFC3312: Integration of Resource Management and SIP . . . 14 73 5.5. RFC4574: SDP Label Attribute . . . . . . . . . . . . . . 15 74 5.6. RFC5432: QOS Mechanism Selection in SDP . . . . . . . . . 15 75 5.7. RFC4568: SDP Security Descriptions . . . . . . . . . . . 16 76 5.8. RFC5762: RTP over DCCP . . . . . . . . . . . . . . . . . 16 77 5.9. RFC6773: DCCP-UDP Encapsulation . . . . . . . . . . . . . 17 78 5.10. RFC5506: Reduced-Size RTCP in RTP Profile . . . . . . . . 18 79 5.11. RFC6787: Media Resource Control Protocol Version 2 . . . 18 80 5.12. RFC5245: ICE . . . . . . . . . . . . . . . . . . . . . . 19 81 5.13. RFC5285: RTP Header Extensions . . . . . . . . . . . . . 20 82 5.14. RFC3605: RTCP attribute in SDP . . . . . . . . . . . . . 21 83 5.15. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 21 84 5.16. RFC7273: RTP Clock Source Signalling . . . . . . . . . . 22 85 5.17. RFC6236: Image Attributes in SDP . . . . . . . . . . . . 23 86 5.18. RFC7197: Duplication Delay Attribute in SDP . . . . . . . 24 87 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting . . . . 24 88 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions . . 24 89 5.21. RFC6230: Media Control Channel Framework . . . . . . . . 25 90 5.22. RFC6364: SDP Elements for FEC Framework . . . . . . . . . 25 91 5.23. RFC4796: Content Attribute . . . . . . . . . . . . . . . 26 92 5.24. RFC3407: SDP Simple Capability Declaration . . . . . . . 26 93 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP 94 Sessions . . . . . . . . . . . . . . . . . . . . . . . . 27 95 5.26. RFC6714: MSRP-CEMA . . . . . . . . . . . . . . . . . . . 28 96 5.27. RFC4583: SDP Format for BFCP Streams . . . . . . . . . . 28 97 5.28. RFC5547: SDP Offer/Answer for File Transfer . . . . . . . 29 98 5.29. RFC6849: SDP and RTP Media Loopback Extension . . . . . . 30 99 5.30. RFC5760: RTCP with Unicast Feedback . . . . . . . . . . . 30 100 5.31. RFC3611: RTCP XR . . . . . . . . . . . . . . . . . . . . 31 101 5.32. RFC5939: SDP Capability Negotiation . . . . . . . . . . . 31 102 5.33. RFC6871: SDP Media Capabilities Negotiation . . . . . . . 32 103 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP . . . 33 104 5.35. RFC4567: Key Management Extensions for SDP and RTSP . . . 34 105 5.36. RFC4572: Comedia over TLS in SDP . . . . . . . . . . . . 35 106 5.37. RFC4570: SDP Source Filters . . . . . . . . . . . . . . . 35 107 5.38. RFC6128: RTCP Port for Multicast Sessions . . . . . . . . 36 108 5.39. RFC6189: ZRTP . . . . . . . . . . . . . . . . . . . . . . 36 109 5.40. RFC4145: Connection-Oriented Media . . . . . . . . . . . 37 110 5.41. RFC6947: The SDP altc Attribute . . . . . . . . . . . . . 37 111 5.42. RFC7195: SDP Extension for Circuit Switched Bearers 112 in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 38 113 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) . . . 38 114 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP 115 Attributes . . . . . . . . . . . . . . . . . . . . . . . 39 116 5.45. RFC6193: Media Description for IKE in SDP . . . . . . . . 39 117 5.46. RFC2326: Real Time Streaming Protocol . . . . . . . . . . 40 118 5.47. RFC6064: SDP and RTSP Extensions for 3GPP . . . . . . . . 41 119 5.48. RFC3108: ATM SDP . . . . . . . . . . . . . . . . . . . . 43 120 5.49. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 45 121 5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . . 46 122 5.51. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 46 123 5.52. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 47 124 5.53. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 47 125 5.54. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 48 126 5.55. ITU-T Q.1970 . . . . . . . . . . . . . . . . . . . . . . 50 127 5.56. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 50 128 5.57. RFC4975: The Message Session Relay Protocol . . . . . . . 51 129 5.58. Historical Attributes . . . . . . . . . . . . . . . . . . 52 130 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 52 131 6.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 53 132 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth . . . 53 133 6.3. RFC3890: Bandwidth Modifier for SDP . . . . . . . . . . . 54 134 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 54 135 7.1. RFC4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . . 54 136 7.2. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 55 137 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP 138 Sessions (RAMS) . . . . . . . . . . . . . . . . . . . . . 56 139 7.4. RFC6679: ECN for RTP over UDP/IP . . . . . . . . . . . . 56 140 7.5. RFC6642: Third-Party Loss Report . . . . . . . . . . . . 57 141 7.6. RFC5104: Codec Control Messages in AVPF . . . . . . . . . 58 142 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 58 143 8.1. RFC5888: SDP Grouping Framework . . . . . . . . . . . . . 58 144 8.2. RFC3524: Mapping Media Streams to Resource 145 Reservation Flows . . . . . . . . . . . . . . . . . . . . 59 146 8.3. RFC4091: ANAT Semantics . . . . . . . . . . . . . . . . . 59 147 8.4. RFC5956: FEC Grouping Semantics in SDP . . . . . . . . . 59 148 8.5. RFC5583: Signaling Media Decoding Dependency in SDP . . . 60 149 8.6. RFC7104: Duplication Grouping Semantics in the SDP . . . 60 150 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 61 151 9.1. RFC5576: Source-Specific SDP Attributes . . . . . . . . . 61 152 9.2. RFC7104: Duplication Grouping Semantics in the SDP . . . 61 153 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 62 154 10.1. RFC5432: QoS Mechanism Selection in SDP . . . . . . . . 62 155 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 62 156 11.1. RFC4566: SDP . . . . . . . . . . . . . . . . . . . . . . 63 157 12. content Attribute Analysis . . . . . . . . . . . . . . . . . 63 158 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 63 159 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 64 160 13.1. RFC5109: RTP Payload Format for Generic FEC . . . . . . 64 161 14. Multiplexing Considerations for Encapsulating Attributes . . 64 162 14.1. RFC3407: cpar Attribute Analysis . . . . . . . . . . . . 65 163 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 65 164 14.2.1. Recommendation: Procedures for Potential 165 Configuration Pairing . . . . . . . . . . . . . . . 66 166 14.2.1.1. Example: Transport Capability Multiplexing . . . 67 167 14.2.1.2. Example: Attribute Capability Multiplexing . . . 68 168 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 69 169 14.3.1. Recommendation: Dealing with Payload Type Numbers . 69 170 14.3.1.1. Example: Attribute Capability Under Shared 171 Payload Type . . . . . . . . . . . . . . . . . . 69 172 14.3.2. Recommendation: Dealing with Latent Configurations . 70 173 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 71 174 15.1. New 'Multiplexing Categories' subregistry . . . . . . . 71 175 15.2. 'Mux Category' column for subregistries . . . . . . . . 72 176 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 72 177 15.2.2. Table: att-field (session level) . . . . . . . . . . 72 178 15.2.3. Table: att-field (both session and media level) . . 73 179 15.2.4. Table: att-field (media level only) . . . . . . . . 75 180 15.2.5. Table: att-field (source level) . . . . . . . . . . 78 181 15.2.6. Table: content SDP Parameters . . . . . . . . . . . 79 182 15.2.7. Table: Semantics for the 'group' SDP Attribute . . . 79 183 15.2.8. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 79 184 15.2.9. Table: 'ack' and 'nack' Attribute Values . . . . . . 80 185 15.2.10. Table: 'depend' SDP Attribute Values . . . . . . . . 80 186 15.2.11. Table: 'cs-correlation' Attribute Values . . . . . . 81 187 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 81 188 15.2.13. Table: SDP/RTSP key management protocol identifiers 81 189 15.2.14. Table: Codec Control Messages . . . . . . . . . . . 82 190 15.2.15. Table: QoS Mechanism Tokens . . . . . . . . . . . . 82 191 15.2.16. Table: SDP Capability Negotiation Option Tags . . . 82 192 15.2.17. Table: Timestamp Reference Clock Source Parameters . 83 193 15.2.18. Table: Media Clock Source Parameters . . . . . . . . 83 194 16. Security Considerations . . . . . . . . . . . . . . . . . . . 83 195 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 84 196 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 84 197 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 87 198 19.1. Normative References . . . . . . . . . . . . . . . . . . 87 199 19.2. Informative References . . . . . . . . . . . . . . . . . 87 200 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 95 202 1. Introduction 204 SDP defines several attributes for capturing characteristics that 205 apply to the individual media descriptions (described by "m=" lines") 206 and the overall multimedia session. Typically different media types 207 (audio, video, etc.) described using different media descriptions 208 represent separate RTP sessions that are carried over individual 209 transport layer flows. However 210 [I-D.ietf-mmusic-sdp-bundle-negotiation] defines a way to use a 211 single address:port combination (BUNDLE address) for receiving media 212 associated with multiple SDP media descriptions. This would, for 213 example allow the usage of a single set of Interactive Connectivity 214 Establishment (ICE) [RFC5245] candidates for multiple media 215 descriptions. This in turn has made it necessary to understand the 216 interpretation and usage of the SDP attributes defined for the 217 multiplexed media descriptions. 219 Given the number of SDP attributes registered with the [IANA] and 220 possibility of new attributes being defined in the future, there is 221 need for a framework to analyze these attributes for their 222 applicability in the transport multiplexing use-cases. 224 The document starts with providing the motivation for requiring such 225 a framework. This is followed by introduction to the SDP attribute 226 analysis framework/procedures, following which several sections apply 227 the framework to the SDP attributes registered with the [IANA]. 229 2. Terminology 231 5-tuple: A collection of the following values: source address, source 232 port, destination address, destination port, and transport-layer 233 protocol. 235 3GPP: Third Generation Partnership Project; see http://www.3gpp.org 236 for more information about this organization. 238 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 239 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 240 document are to be interpreted as described in [RFC2119]. 242 3. Motivation 244 The time and complications of setting up ICE [RFC5245] and Datagram 245 Transport Layer Security (DTLS) based Secure Real-time Transport 246 Protocol (SRTP) [RFC5763] transports for use by RTP, reasons to 247 conserve ports bindings on the Network Address Translators (NAT), 248 forms a requirement to try and reduce the number of transport level 249 flows needed. This has resulted in the definition of ways, such as 250 [I-D.ietf-mmusic-sdp-bundle-negotiation] to multiplex RTP over a 251 single transport flow in order to preserve network resources such as 252 port numbers. This imposes further restrictions on applicability of 253 the SDP attributes as they are defined today. 255 The specific problem is that there are attribute combinations which 256 make sense when specified on independent "m=" lines -- as with 257 classical SDP -- that do not make sense when those "m=" lines are 258 then multiplexed over the same transport. To give an obvious 259 example, ICE permits each "m=" line to have an independently 260 specified ice-ufrag attribute. However, if the media from multiple 261 "m=" lines is multiplexed over the same ICE component, then the 262 meaning of media-level ice-ufrag attributes becomes muddled. 264 At the time of writing this document there are close to 250 SDP 265 attributes registered with the [IANA] and more will be added in the 266 future. There is no clearly defined procedure to establish the 267 validity/applicability of these attributes when used with transport 268 multiplexing. 270 4. SDP Attribute Analysis Framework 272 Attributes in an SDP session description can be defined at the 273 session-level or media-level or source-level. Informally, there are 274 various semantic groupings for these attributes. One such grouping 275 could be notes as below: 277 o Attributes related to media content such as media type, encoding 278 schemes and payload types. 280 o Attributes specifying media transport characteristics like RTP/RTP 281 Control Protocol (RTCP) port numbers, network addresses and QOS. 283 o Metadata description attributes capturing session timing and 284 origin information. 286 o Attributes establishing relationships between media descriptions 287 such as grouping framework [RFC5888] 289 The proposed framework analyzes the SDP attributes usage under 290 multiplexing and assigns each SDP attribute to an appropriate 291 multiplexing category. Since the multiplexing categories defined in 292 this specification are independent of any informal semantic groupings 293 of the SDP attributes, the categorizations assigned are normative. 295 4.1. Category: NORMAL 297 The attributes in the NORMAL category can be independently specified 298 when multiplexed and they retain their original semantics. 300 In the example given below, the direction and label attributes are 301 independently specified for audio and video "m=" lines. These 302 attributes are not impacted by multiplexing these media streams over 303 a single transport layer flow. 305 v=0 306 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 307 s= 308 c=IN IP4 host.atlanta.example.com 309 t=0 0 310 m=audio 49172 RTP/AVP 99 311 a=sendonly 312 a=label:1 313 a=rtpmap:99 iLBC/8000 314 m=video 49172 RTP/AVP 31 315 a=recvonly 316 a=label:2 317 a=rtpmap:31 H261/90000 319 4.2. Category: CAUTION 321 The attributes in the CAUTION category are advised against 322 multiplexing since their usage under multiplexing might lead to 323 incorrect behavior. 325 Example: Multiplexing media descriptions over a single Datagram 326 Congestion Control Protocol (DCCP) transport [RFC5762] is not 327 recommended since DCCP being a connection oriented protocol doesn't 328 allow multiple connections on the same 5-tuple. 330 v=0 331 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 332 s= 333 c=IN IP4 client.biloxi.example.com 334 t=0 0 335 m=video 5004 DCCP/RTP/AVP 99 336 a=rtpmap:99 h261/9000 337 a=dccp-service-code:SC=x52545056 338 a=setup:passive 339 a=connection:new 340 m=video 5004 DCCP/RTP/AVP 100 341 a=rtpmap:100 h261/9000 342 a=dccp-service-code:SC=x5254504f 343 a=setup:passive 344 a=connection:new 346 4.3. Category: IDENTICAL 348 The attributes and their associated values (if any) in the IDENTICAL 349 category MUST be repeated across all the media descriptions under 350 multiplexing. 352 Attributes such as rtcp-mux fall into this category. Since RTCP 353 reporting is done per RTP session, RTCP Multiplexing MUST be enabled 354 for both the audio and video "m=" lines if they are transported over 355 a single 5-tuple. 357 v=0 358 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com 359 s= 360 c=IN IP4 client.biloxi.example.com 361 t=0 0 362 m=audio 34567 RTP/AVP 97 363 a=rtcp-mux 364 m=video 34567 RTP/AVP 31 365 a=rtpmap:31 H261/90000 366 a=rtcp-mux 368 4.4. Category: SUM 370 The attributes in the SUM category can be set as they are normally 371 used but software using them in the multiplexing scenario MUST apply 372 the sum of all the attributes being multiplexed instead of trying to 373 use them independently. This is typically used for bandwidth or 374 other rate limiting attributes to the underlying transport. 376 The software parsing the SDP sample below, should use the aggregate 377 Application Specific (AS) bandwidth value from the individual media 378 descriptions to determine the AS value for the multiplexed session. 379 Thus the calculated AS value would be 256+64 kilobits per second for 380 the given example. 382 v=0 383 o=test 2890844526 2890842807 IN IP4 client.biloxi.example.com 384 c=IN IP4 client.biloxi.example.com 385 t=0 0 386 m=audio 49170 RTP/AVP 0 387 b=AS:64 388 m=video 51372 RTP/AVP 31 389 b=AS:256 391 4.5. Category: TRANSPORT 393 The attributes in the TRANSPORT category can be set normally for 394 multiple items in a multiplexed group but the software MUST pick the 395 one that's associated with the "m=" line whose information is used 396 for setting up the underlying transport. 398 In the example below, "a=crypto" attribute is defined for both the 399 audio and the video "m=" lines. The video media line's a=crypto 400 attribute is chosen since its mid value (bar) appears first in the 401 a=group:BUNDLE line. This is due to BUNDLE grouping semantic 402 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values 403 from "m=" line corresponding to the mid appearing first on the 404 a=group:BUNDLE line to be considered for setting up the RTP 405 Transport. 407 v=0 408 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 409 s= 410 c=IN IP4 host.atlanta.example.com 411 t=0 0 412 a=group:BUNDLE bar foo 413 m=audio 49172 RTP/AVP 99 414 a=mid:foo 415 a=crypto:1 AES_CM_128_HMAC_SHA1_80 416 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32 417 a=rtpmap:99 iLBC/8000 418 m=video 51374 RTP/AVP 31 419 a=mid:bar 420 a=crypto:1 AES_CM_128_HMAC_SHA1_80 421 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 422 a=rtpmap:96 H261/90000 424 4.6. Category: INHERIT 426 The attributes in the INHERIT category encapsulate other SDP 427 attributes or parameters. These attributes inherit their 428 multiplexing characteristics from the attributes or parameters they 429 encapsulate. Such attributes are defined in [RFC3407], [RFC5939] and 430 [RFC6871] as part of a generic framework for indicating and 431 negotiating transport, media, and media format related capabilities 432 in the SDP. 434 The inheritance manifests itself when the encapsulated attribute or 435 parameter is being leveraged. In the case of SDP Capability 436 Negotiation [RFC5939] for example, this occurs when a capability 437 (encapsulating attribute) is used as part of a configuration; the 438 configuration inherits the multiplexing category of each of its 439 constituent (encapsulated) attributes and parameters. The inherited 440 attributes MUST be coherent in order to form a valid configuration 441 from a multiplexing point of view (see Section 14 for further 442 details). 444 v=0 445 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 446 s= 447 c=IN IP4 host.atlanta.example.com 448 t=0 0 449 m=video 3456 RTP/AVP 100 450 a=rtpmap:100 VP8/90000 451 a=fmtp:100 max-fr=30;max-fs=8040 452 a=sqn: 0 453 a=cdsc: 1 video RTP/AVP 100 454 a=cpar: a=rtcp-mux 455 m=video 3456 RTP/AVP 101 456 a=rtpmap:101 VP8/90000 457 a=fmtp:100 max-fr=15;max-fs=1200 458 a=cdsc: 2 video RTP/AVP 101 459 a=cpar: a=rtcp-mux 461 In the above example, the category IDENTICAL is inherited by the cpar 462 encapsulated rtcp-mux attribute. 464 4.7. Category: IDENTICAL-PER-PT 466 The attributes in the IDENTICAL-PER-PT category define the RTP 467 payload configuration on per Payload Type basis and MUST have 468 identical values across all the media descriptions for a given RTP 469 Payload Type when repeated. These Payload Types identify the same 470 codec configuration as defined in the Section 10.1.2 of 471 [I-D.ietf-mmusic-sdp-bundle-negotiation] under this context. 473 In the SDP example below, Payload Types 96 and 97 are repeated across 474 all the video "m=" lines and all the payload specific parameters (ex: 475 rtpmap, fmtp) are identical (Note: some line breaks included are due 476 to formatting only). 478 v=0 479 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 480 s= 481 c=IN IP4 host.atlanta.example.com 482 t=0 0 483 a=group:BUNDLE cam1 cam2 484 m=video 96 97 485 a=mid:cam1 486 a=rtpmap:96 H264/90000 487 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 488 max-mbps=108000; max-br=1000 489 a=rtpmap:97 H264/90000 490 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 491 max-mbps=7200; max-br=200 492 m=video 96 97 493 a=mid:cam2 494 a=rtpmap:96 H264/90000 495 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000; 496 max-mbps=108000; max-br=1000 497 a=rtpmap:97 H264/90000 498 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000; 499 max-mbps=7200; max-br=200 501 4.8. Category: SPECIAL 503 For the attributes in the SPECIAL category, the text in the 504 specification defining the attribute MUST be consulted for further 505 handling when multiplexed. 507 As an exampe, for the attribute extmap [RFC5285], the specification 508 defining the extension needs to be referred to understand the 509 multiplexing implications. 511 4.9. Category: TBD 513 The attributes in the TBD category have not been analyzed under the 514 proposed multiplexing framework and SHOULD NOT be multiplexed. 516 5. Analysis of Existing Attributes 518 This section analyzes attributes listed in [IANA], grouped under the 519 IETF document that defines them. 521 The "Level" column indicates whether the attribute is currently 522 specified as: 524 o S -- Session level 526 o M -- Media level 528 o B -- Both 530 o SR -- Source-level (for a single SSRC) [RFC5576] 532 The "Mux Category" column identifies multiplexing category assigned 533 per attribute and the "Notes" column captures additional informative 534 details regarding the assigned category, wherever necessary. 536 5.1. RFC4566: SDP 538 [RFC4566] defines SDP that is intended for describing multimedia 539 sessions for the purposes of session announcement, session 540 invitation, and other forms of multimedia session initiation. 542 +-----------------+---------------------+-------+-------------------+ 543 | Name | Notes | Level | Mux Category | 544 +-----------------+---------------------+-------+-------------------+ 545 | sendrecv | Not impacted | B | NORMAL | 546 | | | | | 547 | sendonly | Not impacted | B | NORMAL | 548 | | | | | 549 | recvonly | Not impacted | B | NORMAL | 550 | | | | | 551 | inactive | Not impacted | B | NORMAL | 552 | | | | | 553 | cat | Not impacted | S | NORMAL | 554 | | | | | 555 | ptime | The attribute value | M | IDENTICAL-PER-PT | 556 | | MUST be same for a | | | 557 | | given codec | | | 558 | | configuration | | | 559 | | | | | 560 | maxptime | The attribute value | M | IDENTICAL-PER-PT | 561 | | MUST be same for a | | | 562 | | given codec | | | 563 | | configuration | | | 564 | | | | | 565 | orient | Not Impacted | M | NORMAL | 566 | | | | | 567 | framerate | The attribute value | M | IDENTICAL-PER-PT | 568 | | MUST be same for a | | | 569 | | given codec | | | 570 | | configuration | | | 571 | | | | | 572 | quality | Not Impacted | M | NORMAL | 573 | | | | | 574 | rtpmap | The attribute value | M | IDENTICAL-PER-PT | 575 | | MUST be same for a | | | 576 | | given codec | | | 577 | | configuration | | | 578 | | | | | 579 | fmtp | The attribute value | M | IDENTICAL-PER-PT | 580 | | MUST be same for a | | | 581 | | given codec | | | 582 | | configuration | | | 583 | | | | | 584 | keywds | Not impacted | S | NORMAL | 585 | | | | | 586 | type | Not Impacted | S | NORMAL | 587 | | | | | 588 | type:broadcast | Not Impacted | S | NORMAL | 589 | | | | | 590 | type:H332 | Not Impacted | S | NORMAL | 591 | | | | | 592 | type:meeting | Not Impacted | S | NORMAL | 593 | | | | | 594 | type:moderated | Not Impacted | S | NORMAL | 595 | | | | | 596 | type:test | Not Impacted | S | NORMAL | 597 | | | | | 598 | tool | Not Impacted | S | NORMAL | 599 | | | | | 600 | charset | Not Impacted | S | NORMAL | 601 | | | | | 602 | sdplang | Not Impacted | B | NORMAL | 603 | | | | | 604 | lang | Not Impacted | B | NORMAL | 605 | | | | | 606 +-----------------+---------------------+-------+-------------------+ 608 5.1 RFC4566 Attribute Analysis 610 5.2. RFC4585: RTP/AVPF 612 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 613 enables receivers to provide, statistically, more immediate feedback 614 to the senders and thus allows for short-term adaptation and 615 efficient feedback-based repair mechanisms to be implemented. 617 +----------+----------------------------+-------+-------------------+ 618 | Name | Notes | Level | Mux Category | 619 +----------+----------------------------+-------+-------------------+ 620 | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT | 621 | | attributes are Payload | | | 622 | | Type (PT) scoped, their | | | 623 | | values MUST be identical | | | 624 | | for a given PT across the | | | 625 | | multiplexed "m=" lines. | | | 626 | | | | | 627 +----------+----------------------------+-------+-------------------+ 629 5.2 RFC4585 Attribute Analysis 631 5.3. RFC5761: Multiplexing RTP and RTCP 633 [RFC5761] discusses issues that arise when multiplexing RTP data 634 packets and RTP Control Protocol (RTCP) packets on a single UDP port. 635 It describes when such multiplexing is and is not appropriate, and it 636 explains how the SDP can be used to signal multiplexed sessions. 638 +-----------+----------------------------------+-------+------------+ 639 | Name | Notes | Level | Mux | 640 | | | | Category | 641 +-----------+----------------------------------+-------+------------+ 642 | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL | 643 | | affects the entire RTP session | | | 644 | | | | | 645 +-----------+----------------------------------+-------+------------+ 647 5.3 RFC5761 Attribute Analysis 649 5.4. RFC3312: Integration of Resource Management and SIP 651 [RFC3312] defines a generic framework for preconditions, which are 652 extensible through IANA registration. This document also discusses 653 how network quality of service can be made a precondition for 654 establishment of sessions initiated by the Session Initiation 655 Protocol (SIP). These preconditions require that the participant 656 reserve network resources before continuing with the session. 658 +-------+-----------------------+-------+--------------+ 659 | Name | Notes | Level | Mux Category | 660 +-------+-----------------------+-------+--------------+ 661 | des | Refer to notes below | M | CAUTION | 662 | | | | | 663 | conf | Refer to notes below | M | CAUTION | 664 | | | | | 665 | curr | Refer to notes below | M | CAUTION | 666 | | | | | 667 +-------+-----------------------+-------+--------------+ 669 5.4 RFC3312 Attribute Analysis 671 NOTE: A mismatched set of preconditions across media descriptions 672 results in Session establishment failures due to inability to meet 673 right resource reservations requested. 675 5.5. RFC4574: SDP Label Attribute 677 [RFC4574] defines a new SDP media-level attribute: "label". The 678 "label" attribute carries a pointer to a media stream in the context 679 of an arbitrary network application that uses SDP. The sender of the 680 SDP document can attach the "label" attribute to a particular media 681 stream or streams. The application can then use the provided pointer 682 to refer to each particular media stream in its context. 684 +--------+---------------+-------+--------------+ 685 | Name | Notes | Level | Mux Category | 686 +--------+---------------+-------+--------------+ 687 | label | Not Impacted | M | NORMAL | 688 | | | | | 689 +--------+---------------+-------+--------------+ 691 5.5 RFC4574 Attribute Analysis 693 5.6. RFC5432: QOS Mechanism Selection in SDP 695 [RFC5432] defines procedures to negotiate QOS mechanisms using the 696 SDP offer/answer model. 698 +----------------+----------------------------+-------+-------------+ 699 | Name | Notes | Level | Mux | 700 | | | | Category | 701 +----------------+----------------------------+-------+-------------+ 702 | qos-mech-send | Refer to section Section | B | TRANSPORT | 703 | | 10 | | | 704 | | | | | 705 | qos-mech-recv | Refer to section Section | B | TRANSPORT | 706 | | 10 | | | 707 | | | | | 708 +----------------+----------------------------+-------+-------------+ 710 5.6 RFC5432 Attribute Analysis 712 5.7. RFC4568: SDP Security Descriptions 714 [RFC4568] defines a SDP cryptographic attribute for unicast media 715 streams. The attribute describes a cryptographic key and other 716 parameters that serve to configure security for a unicast media 717 stream in either a single message or a roundtrip exchange. 719 +---------+------------------------------------+-------+------------+ 720 | Name | Notes | Level | Mux | 721 | | | | Category | 722 +---------+------------------------------------+-------+------------+ 723 | crypto | crypto attribute MUST be the one | M | TRANSPORT | 724 | | that corresponds to the "m=" line | | | 725 | | chosen for setting up the | | | 726 | | underlying transport flow | | | 727 | | | | | 728 +---------+------------------------------------+-------+------------+ 730 5.7 RFC4568 Attribute Analysis 732 5.8. RFC5762: RTP over DCCP 734 RTP is a widely used transport for real-time multimedia on IP 735 networks. DCCP is a transport protocol that provides desirable 736 services for real-time applications. [RFC5762] specifies a mapping 737 of RTP onto DCCP, along with associated signaling, such that real- 738 time applications can make use of the services provided by DCCP. 740 +--------------------+-------------------------+---------+----------+ 741 | Name | Notes | Current | Mux | 742 | | | | Category | 743 +--------------------+-------------------------+---------+----------+ 744 | dccp-service-code | If RFC6773 is not being | M | CAUTION | 745 | | used in addition to | | | 746 | | RFC5762, the port in | | | 747 | | the "m=" line is a DCCP | | | 748 | | port. DCCP being a | | | 749 | | connection oriented | | | 750 | | protocol does not allow | | | 751 | | multiple connections on | | | 752 | | the same 5-tuple | | | 753 | | | | | 754 +--------------------+-------------------------+---------+----------+ 756 5.8 RFC5762 Attribute Analysis 758 NOTE: If RFC6773 is being used in addition to RFC5762 and provided 759 that DCCP-in-UDP layer has additional demultiplexing, then it can be 760 possible to use different DCCP service codes for each DCCP flow, 761 given each uses a different DCCP port. Although doing so might 762 conflict with the media type of the "m=" line. None of this is 763 standardized yet and it wouldn't work as explained. Hence performing 764 multiplexing is not recommended even in this alternate scenario. 766 5.9. RFC6773: DCCP-UDP Encapsulation 768 [RFC6773] specifies an alternative encapsulation of DCCP, referred to 769 as DCCP-UDP. This encapsulation allows DCCP to be carried through 770 the current generation of Network Address Translation (NAT) middle 771 boxes without modification of those middle boxes. 773 +------------+-----------------------------------+-------+----------+ 774 | Name | Notes | Level | Mux | 775 | | | | Category | 776 +------------+-----------------------------------+-------+----------+ 777 | dccp-port | Multiplexing is not recommended | M | CAUTION | 778 | | due to potential conflict between | | | 779 | | the port used for DCCP | | | 780 | | en/decapsulation and the RTP | | | 781 | | | | | 782 +------------+-----------------------------------+-------+----------+ 784 5.9 RFC6773 Attribute Analysis 786 NOTE: RFC6773 is about tunneling DCCP in UDP, with the UDP port being 787 the port of the DCCP en-/de-capsulation service. This encapsulation 788 allows arbitrary DCCP packets to be encapsulated and the DCCP port 789 chosen can conflict with the port chosen for the RTP traffic. For 790 multiplexing several DCCP-in-UDP encapsulations on the same UDP port 791 with no RTP traffic on the same port implies collapsing several DCCP 792 port spaces together. This can or cannot work depending on the 793 nature of DCCP encapsulation and ports choices thus rendering it to 794 be very application dependent. 796 5.10. RFC5506: Reduced-Size RTCP in RTP Profile 798 [RFC5506] discusses benefits and issues that arise when allowing RTCP 799 packets to be transmitted with reduced size. 801 +-------------+--------------------------------+-------+------------+ 802 | Name | Notes | Level | Mux | 803 | | | | Category | 804 +-------------+--------------------------------+-------+------------+ 805 | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL | 806 | | entire RTP session | | | 807 | | | | | 808 +-------------+--------------------------------+-------+------------+ 810 5.10 RFC5506 Attribute Analysis 812 5.11. RFC6787: Media Resource Control Protocol Version 2 814 The Media Resource Control Protocol Version 2 (MRCPv2) allows client 815 hosts to control media service resources such as speech synthesizers, 816 recognizers, verifiers, and identifiers residing in servers on the 817 network. MRCPv2 is not a "stand-alone" protocol -- it relies on 818 other protocols, such as the SIP, to coordinate MRCPv2 clients and 819 servers, and manage session between them, and SDP to describe, 820 discover, and exchange capabilities. It also depends on SIP and SDP 821 to establish the media sessions and associated parameters between the 822 media source or sink and the media server. Once this is done, the 823 MRCPv2 exchange operates over the control session established above, 824 allowing the client to control the media processing resources on the 825 speech resource server. [RFC6787] defines attributes for this 826 purpose. 828 +-----------+---------------+-------+--------------+ 829 | Name | Notes | Level | Mux Category | 830 +-----------+---------------+-------+--------------+ 831 | resource | Not Impacted | M | NORMAL | 832 | | | | | 833 | channel | Not Impacted | M | NORMAL | 834 | | | | | 835 | cmid | Not Impacted | M | NORMAL | 836 | | | | | 837 +-----------+---------------+-------+--------------+ 839 5.11 RFC6787 Attribute Analysis 841 5.12. RFC5245: ICE 843 [RFC5245] describes a protocol for NAT traversal for UDP-based 844 multimedia sessions established with the offer/answer model. ICE 845 makes use of the Session Traversal Utilities for NAT (STUN) protocol 846 and its extension, Traversal Using Relay NAT (TURN). ICE can be used 847 by any protocol utilizing the offer/answer model, such as the SIP. 849 +--------------------+-------------------------+-------+------------+ 850 | Name | Notes | Level | Mux | 851 | | | | Category | 852 +--------------------+-------------------------+-------+------------+ 853 | ice-lite | Not Impacted | S | NORMAL | 854 | | | | | 855 | ice-options | Not Impacted | S | NORMAL | 856 | | | | | 857 | ice-mismatch | Not Impacted | S | NORMAL | 858 | | | | | 859 | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT | 860 | | that corresponds to the | | | 861 | | "m=" line chosen for | | | 862 | | setting up the | | | 863 | | underlying transport | | | 864 | | flow | | | 865 | | | | | 866 | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT | 867 | | one that corresponds to | | | 868 | | the "m=" line chosen | | | 869 | | for setting up the | | | 870 | | underlying transport | | | 871 | | flow | | | 872 | | | | | 873 | candidate | ice candidate MUST be | M | TRANSPORT | 874 | | the one that | | | 875 | | corresponds to the "m=" | | | 876 | | line chosen for setting | | | 877 | | up the underlying | | | 878 | | transport flow | | | 879 | | | | | 880 | remote-candidates | ice remote candidate | M | TRANSPORT | 881 | | MUST be the one that | | | 882 | | corresponds to the "m=" | | | 883 | | line chosen for setting | | | 884 | | up the underlying | | | 885 | | transport flow | | | 886 | | | | | 887 +--------------------+-------------------------+-------+------------+ 889 5.12 RFC5245 Attribute Analysis 891 5.13. RFC5285: RTP Header Extensions 893 [RFC5285] provides a general mechanism to use the header extension 894 feature of RTP. It provides the option to use a small number of 895 small extensions in each RTP packet, where the universe of possible 896 extensions is large and registration is de-centralized. The actual 897 extensions in use in a session are signaled in the setup information 898 for that session. 900 +---------+--------------------------------------+-------+----------+ 901 | Name | Notes | Level | Mux | 902 | | | | Category | 903 +---------+--------------------------------------+-------+----------+ 904 | extmap | Refer to the document defining the | B | SPECIAL | 905 | | specific RTP Extension | | | 906 | | | | | 907 +---------+--------------------------------------+-------+----------+ 909 5.13 RFC5285 Attribute Analysis 911 5.14. RFC3605: RTCP attribute in SDP 913 Originally, SDP assumed that RTP and RTCP were carried on consecutive 914 ports. However, this is not always true when NATs are involved. 915 [RFC3605] specifies an early mechanism to indicate the RTCP port. 917 +-------+--------------------------------------+-------+------------+ 918 | Name | Notes | Level | Mux | 919 | | | | Category | 920 +-------+--------------------------------------+-------+------------+ 921 | rtcp | RTCP Port MUST be the one that | M | TRANSPORT | 922 | | corresponds to the "m=" line chosen | | | 923 | | for setting up the underlying | | | 924 | | transport flow. | | | 925 | | | | | 926 +-------+--------------------------------------+-------+------------+ 928 5.14 RFC3605 Attribute Analysis 930 5.15. RFC5576: Source-Specific SDP Attributes 932 [RFC5576] defines a mechanism to describe RTP media sources, which 933 are identified by their synchronization source (SSRC) identifiers, in 934 SDP, to associate attributes with these sources, and to express 935 relationships among sources. It also defines several source-level 936 attributes that can be used to describe properties of media sources. 938 +----------------+----------------------+-------+-------------------+ 939 | Name | Notes | Level | Mux Category | 940 +----------------+----------------------+-------+-------------------+ 941 | ssrc | Refer to Notes below | M | NORMAL | 942 | | | | | 943 | ssrc-group | Refer to Section 9 | M | NORMAL | 944 | | for specific | | | 945 | | analysis of the | | | 946 | | grouping semantics | | | 947 | | | | | 948 | cname | Not Impacted | SR | NORMAL | 949 | | | | | 950 | previous-ssrc | Refer to notes below | SR | NORMAL | 951 | | | | | 952 | fmtp | The attribute value | SR | IDENTICAL-PER-PT | 953 | | MUST be same for a | | | 954 | | given codec | | | 955 | | configuration | | | 956 | | | | | 957 +----------------+----------------------+-------+-------------------+ 959 5.15 RFC5576 Attribute Analysis 961 NOTE: If SSRCs are repeated across "m=" lines being multiplexed, they 962 MUST all represent the same underlying RTP Source. 964 5.16. RFC7273: RTP Clock Source Signalling 966 [RFC7273] specifies SDP signalling that identifies timestamp 967 reference clock sources and SDP signalling that identifies the media 968 clock sources in a multimedia session. 970 +--------------------+---------------+-------+--------------+ 971 | Name | Notes | Level | Mux Category | 972 +--------------------+---------------+-------+--------------+ 973 | ts-refclk | Not Impacted | B | NORMAL | 974 | | | | | 975 | mediaclk | Not Impacted | B | NORMAL | 976 | | | | | 977 | ts-refclk:ntp | Not Impacted | B | NORMAL | 978 | | | | | 979 | ts-refclk:ptp | Not Impacted | B | NORMAL | 980 | | | | | 981 | ts-refclk:gps | Not Impacted | B | NORMAL | 982 | | | | | 983 | ts-refclk:gal | Not Impacted | B | NORMAL | 984 | | | | | 985 | ts-refclk:glonass | Not Impacted | B | NORMAL | 986 | | | | | 987 | ts-refclk:local | Not Impacted | B | NORMAL | 988 | | | | | 989 | ts-refclk:private | Not Impacted | B | NORMAL | 990 | | | | | 991 | mediaclk:sender | Not Impacted | B | NORMAL | 992 | | | | | 993 | mediaclk:direct | Not Impacted | B | NORMAL | 994 | | | | | 995 | mediaclk:IEEE1722 | Not Impacted | B | NORMAL | 996 | | | | | 997 +--------------------+---------------+-------+--------------+ 999 5.16 RFC7273 Attribute Analysis 1001 5.17. RFC6236: Image Attributes in SDP 1003 [RFC6236] proposes a new generic session setup attribute to make it 1004 possible to negotiate different image attributes such as image size. 1005 A possible use case is to make it possible for a low-end hand-held 1006 terminal to display video without the need to rescale the image, 1007 something that may consume large amounts of memory and processing 1008 power. The document also helps to maintain an optimal bitrate for 1009 video as only the image size that is desired by the receiver is 1010 transmitted. 1012 +------------+--------------------------+-------+-------------------+ 1013 | Name | Notes | Level | Mux Category | 1014 +------------+--------------------------+-------+-------------------+ 1015 | imageattr | The attribute value MUST | M | IDENTICAL-PER-PT | 1016 | | be same for a given | | | 1017 | | codec configuration | | | 1018 | | | | | 1019 +------------+--------------------------+-------+-------------------+ 1021 5.17 RFC6236 Attribute Analysis 1023 5.18. RFC7197: Duplication Delay Attribute in SDP 1025 [RFC7197] defines an attribute to indicate the presence of temporally 1026 redundant media streams and the duplication delay in SDP. 1028 +--------------------+---------------+-------+--------------+ 1029 | Name | Notes | Level | Mux Category | 1030 +--------------------+---------------+-------+--------------+ 1031 | duplication-delay | Not Impacted | B | NORMAL | 1032 | | | | | 1033 +--------------------+---------------+-------+--------------+ 1035 5.18 RFC7197 Attribute Analysis 1037 5.19. RFC7266: RTCP XR Blocks for MOS Metric Reporting 1039 [RFC7266] defines an RTCP Extended Report (XR) Block including two 1040 new segment types and associated SDP parameters that allow the 1041 reporting of mean opinion score (MOS) Metrics for use in a range of 1042 RTP applications. 1044 +-------------+---------------+-------+--------------+ 1045 | Name | Notes | Level | Mux Category | 1046 +-------------+---------------+-------+--------------+ 1047 | calgextmap | Not Impacted | B | NORMAL | 1048 | | | | | 1049 +-------------+---------------+-------+--------------+ 1051 5.19 RFC7266 Attribute Analysis 1053 5.20. RFC6285: Rapid Acquisition of Multicast RTP Sessions 1055 [RFC6285] describes a method using the existing RTP and RTCP 1056 machinery that reduces the acquisition delay. In this method, an 1057 auxiliary unicast RTP session carrying the Reference Information to 1058 the receiver precedes or accompanies the multicast stream. This 1059 unicast RTP flow can be transmitted at a faster than natural bitrate 1060 to further accelerate the acquisition. The motivating use case for 1061 this capability is multicast applications that carry real-time 1062 compressed audio and video. 1064 +---------------+-------------------+-------+--------------+ 1065 | Name | Notes | Level | Mux Category | 1066 +---------------+-------------------+-------+--------------+ 1067 | rams-updates | Not recommended | M | CAUTION | 1068 | | | | | 1069 +---------------+-------------------+-------+--------------+ 1071 5.20 RFC6285 Attribute Analysis 1073 5.21. RFC6230: Media Control Channel Framework 1075 [RFC6230] describes a framework and protocol for application 1076 deployment where the application programming logic and media 1077 processing are distributed. This implies that application 1078 programming logic can seamlessly gain access to appropriate resources 1079 that are not co-located on the same physical network entity. The 1080 framework uses SIP to establish an application-level control 1081 mechanism between application servers and associated external servers 1082 such as media servers. 1084 +---------+---------------+-------+--------------+ 1085 | Name | Notes | Level | Mux Category | 1086 +---------+---------------+-------+--------------+ 1087 | cfw-id | Not Impacted | M | NORMAL | 1088 | | | | | 1089 +---------+---------------+-------+--------------+ 1091 5.21 RFC6230 Attribute Analysis 1093 5.22. RFC6364: SDP Elements for FEC Framework 1095 [RFC6364] specifies the use of SDP to describe the parameters 1096 required to signal the Forward Error Correction (FEC) Framework 1097 Configuration Information between the sender(s) and receiver(s). 1098 This document also provides examples that show the semantics for 1099 grouping multiple source and repair flows together for the 1100 applications that simultaneously use multiple instances of the FEC 1101 Framework. 1103 +------------------+-----------------------------+-------+----------+ 1104 | Name | Notes | Level | Mux | 1105 | | | | Category | 1106 +------------------+-----------------------------+-------+----------+ 1107 | fec-source-flow | Refer to the document | M | SPECIAL | 1108 | | defining specific FEC | | | 1109 | | Scheme | | | 1110 | | | | | 1111 | fec-repair-flow | Refer to the document | M | SPECIAL | 1112 | | defining specific FEC | | | 1113 | | Scheme | | | 1114 | | | | | 1115 | repair-window | Refer to the document | M | SPECIAL | 1116 | | defining specific FEC | | | 1117 | | Scheme | | | 1118 | | | | | 1119 +------------------+-----------------------------+-------+----------+ 1121 5.22 RFC6364 Attribute Analysis 1123 5.23. RFC4796: Content Attribute 1125 [RFC4796] defines a new SDP media-level attribute, 'content'. The 1126 'content' attribute defines the content of the media stream to a more 1127 detailed level than the media description line. The sender of an SDP 1128 session description can attach the 'content' attribute to one or more 1129 media streams. The receiving application can then treat each media 1130 stream differently (e.g., show it on a big or small screen) based on 1131 its content. 1133 +----------+---------------+-------+--------------+ 1134 | Name | Notes | Level | Mux Category | 1135 +----------+---------------+-------+--------------+ 1136 | content | Not Impacted | M | NORMAL | 1137 | | | | | 1138 +----------+---------------+-------+--------------+ 1140 5.23 RFC4796 Attribute Analysis 1142 5.24. RFC3407: SDP Simple Capability Declaration 1144 [RFC3407] defines a set of SDP attributes that enables SDP to provide 1145 a minimal and backwards compatible capability declaration mechanism. 1147 +----------+------------------------+-------+--------------+ 1148 | Name | Notes | Level | Mux Category | 1149 +----------+------------------------+-------+--------------+ 1150 | sqn | Not Impacted | B | NORMAL | 1151 | | | | | 1152 | cdsc | Not Impacted. | B | NORMAL | 1153 | | | | | 1154 | cpar | Refer to Section 14 | B | INHERIT | 1155 | | | | | 1156 | cparmin | Refer to notes below | B | SPECIAL | 1157 | | | | | 1158 | cparmax | Refer to notes below | B | SPECIAL | 1159 | | | | | 1160 +----------+------------------------+-------+--------------+ 1162 5.24 RFC3407 Attribute Analysis 1164 NOTE: The attributes (a=cparmin and a=cparmax) define minimum and 1165 maximum numerical values associated with the attributes described in 1166 a=cpar. 1168 Since the cpar attribute can either define a 'b=' attribute or any 1169 'a=' attribute, the multiplexing category depends on actual attribute 1170 being encapsulated and the implications of the numerical values 1171 assigned. Hence it is recommended to consult the specification 1172 defining attributes (cparmin/cparmax) to further analyze their 1173 behavior under multiplexing. 1175 5.25. RFC6284: Port Mapping between Unicast and Multicast RTP Sessions 1177 [RFC6284] presents a port mapping solution that allows RTP receivers 1178 to choose their own ports for an auxiliary unicast session in RTP 1179 applications using both unicast and multicast services. The solution 1180 provides protection against denial-of-service or packet amplification 1181 attacks that could be used to cause one or more RTP packets to be 1182 sent to a victim client. 1184 +------------------+-----------------------------+-------+----------+ 1185 | Name | Notes | Level | Mux | 1186 | | | | Category | 1187 +------------------+-----------------------------+-------+----------+ 1188 | portmapping-req | Not recommended, if port | M | CAUTION | 1189 | | mapping is required by the | | | 1190 | | application | | | 1191 | | | | | 1192 +------------------+-----------------------------+-------+----------+ 1194 5.25 RFC6284 Attribute Analysis 1196 5.26. RFC6714: MSRP-CEMA 1198 [RFC6714] defines a Message Session Relay Protocol (MSRP) extension, 1199 Connection Establishment for Media Anchoring (CEMA). Support of this 1200 extension is optional. The extension allows middle boxes to anchor 1201 the MSRP connection, without the need for middle boxes to modify the 1202 MSRP messages; thus, it also enables secure end-to-end MSRP 1203 communication in networks where such middle boxes are deployed. This 1204 document also defines a SDP attribute, 'msrp-cema', that MSRP 1205 endpoints use to indicate support of the CEMA extension. 1207 +------------+-----------------------+-------+--------------+ 1208 | Name | Notes | Level | Mux Category | 1209 +------------+-----------------------+-------+--------------+ 1210 | msrp-cema | Refer to notes below | M | TBD | 1211 | | | | | 1212 +------------+-----------------------+-------+--------------+ 1214 5.26 RFC6714 Attribute Analysis 1216 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1217 there exists no publicly available specification that defines 1218 procedures for multiplexing/demultiplexing MRSP flows over a single 1219 5-tuple. Once such a specification is available, the multiplexing 1220 categories assignments for the attributes in this section could be 1221 revisited. 1223 5.27. RFC4583: SDP Format for BFCP Streams 1225 [RFC4583] document specifies how to describe Binary Floor Control 1226 Protocol (BFCP) streams in SDP descriptions. User agents using the 1227 offer/answer model to establish BFCP streams use this format in their 1228 offers and answers. 1230 +------------+---------------------------------+-------+------------+ 1231 | Name | Notes | Level | Mux | 1232 | | | | Category | 1233 +------------+---------------------------------+-------+------------+ 1234 | floorctrl | The attribute MUST be repeated | M | IDENTICAL | 1235 | | across all the multiplexed "m=" | | | 1236 | | lines | | | 1237 | | | | | 1238 | confid | Not Impacted | M | NORMAL | 1239 | | | | | 1240 | userid | Not Impacted | M | NORMAL | 1241 | | | | | 1242 | floorid | Not Impacted | M | NORMAL | 1243 | | | | | 1244 +------------+---------------------------------+-------+------------+ 1246 5.27 RFC4583 Attribute Analysis 1248 5.28. RFC5547: SDP Offer/Answer for File Transfer 1250 [RFC5547] provides a mechanism to negotiate the transfer of one or 1251 more files between two endpoints by using the SDP offer/answer model 1252 specified in [RFC3264]. 1254 +-------------------+-----------------------+-------+--------------+ 1255 | Name | Notes | Level | Mux Category | 1256 +-------------------+-----------------------+-------+--------------+ 1257 | file-selector | Refer to notes below | M | TBD | 1258 | | | | | 1259 | file-transfer-id | Refer to notes below | M | TBD | 1260 | | | | | 1261 | file-disposition | Refer to notes below | M | TBD | 1262 | | | | | 1263 | file-date | Refer to notes below | M | TBD | 1264 | | | | | 1265 | file-icon | Refer to notes below | M | TBD | 1266 | | | | | 1267 | file-range | Refer to notes below | M | TBD | 1268 | | | | | 1269 +-------------------+-----------------------+-------+--------------+ 1271 5.28 RFC5547 Attribute Analysis 1273 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 1274 there exists no publicly available specification that defines 1275 procedures for multiplexing/demultiplexing MRSP flows over a single 1276 5-tuple. Once such a specification is available, the multiplexing 1277 categories assignments for attributes in this section could be 1278 revisited. 1280 5.29. RFC6849: SDP and RTP Media Loopback Extension 1282 [RFC6849] adds new SDP media types and attributes, which enable 1283 establishment of media sessions where the media is looped back to the 1284 transmitter. Such media sessions will serve as monitoring and 1285 troubleshooting tools by providing the means for measurement of more 1286 advanced Voice over IP (VoIP), Real-time Text, and Video over IP 1287 performance metrics. 1289 +---------------------+-----------------+-------+-------------------+ 1290 | Name | Notes | Level | Mux Category | 1291 +---------------------+-----------------+-------+-------------------+ 1292 | loopback rtp-pkt- | The attribute | M | IDENTICAL-PER-PT | 1293 | loopback | value MUST be | | | 1294 | | same for a | | | 1295 | | given codec | | | 1296 | | configuration | | | 1297 | | | | | 1298 | loopback rtp-media- | The attribute | M | IDENTICAL-PER-PT | 1299 | loopback | value MUST be | | | 1300 | | same for a | | | 1301 | | given codec | | | 1302 | | configuration | | | 1303 | | | | | 1304 | loopback-source | Not Impacted | M | NORMAL | 1305 | | | | | 1306 | loopback-mirror | Not Impacted | M | NORMAL | 1307 | | | | | 1308 +---------------------+-----------------+-------+-------------------+ 1310 5.29 RFC6849 Analysis 1312 5.30. RFC5760: RTCP with Unicast Feedback 1314 [RFC5760] specifies an extension to RTCP to use unicast feedback to a 1315 multicast sender. The proposed extension is useful for single-source 1316 multicast sessions such as Source-Specific Multicast (SSM) 1317 communication where the traditional model of many-to-many group 1318 communication is either not available or not desired. 1320 +---------------+------------------------------+-------+------------+ 1321 | Name | Notes | Level | Mux | 1322 | | | | Category | 1323 +---------------+------------------------------+-------+------------+ 1324 | rtcp-unicast | The attribute MUST be | M | IDENTICAL | 1325 | | reported across all "m=" | | | 1326 | | lines multiplexed | | | 1327 | | | | | 1328 +---------------+------------------------------+-------+------------+ 1330 5.30 RFC5760 Attribute Analysis 1332 5.31. RFC3611: RTCP XR 1334 [RFC3611] defines the Extended Report (XR) packet type for RTCP, and 1335 defines how the use of XR packets can be signaled by an application 1336 if it employs the Session Description Protocol (SDP). 1338 +----------+---------------+-------+--------------+ 1339 | Name | Notes | Level | Mux Category | 1340 +----------+---------------+-------+--------------+ 1341 | rtcp-xr | Not Impacted | B | NORMAL | 1342 | | | | | 1343 +----------+---------------+-------+--------------+ 1345 5.31 RFC3611 Attribute Analysis 1347 5.32. RFC5939: SDP Capability Negotiation 1349 [RFC5939] defines a general SDP Capability Negotiation framework. It 1350 also specifies how to provide attributes and transport protocols as 1351 capabilities and negotiate them using the framework. Extensions for 1352 other types of capabilities (e.g., media types and media formats) may 1353 be provided in other documents. 1355 +---------+-----------------------+-------+--------------+ 1356 | Name | Notes | Level | Mux Category | 1357 +---------+-----------------------+-------+--------------+ 1358 | pcfg | Refer to Section 14 | M | SPECIAL | 1359 | | | | | 1360 | acfg | Refer to Section 14 | M | SPECIAL | 1361 | | | | | 1362 | csup | Not Impacted | B | NORMAL | 1363 | | | | | 1364 | creq | Not Impacted | B | NORMAL | 1365 | | | | | 1366 | acap | Refer to Section 14 | B | INHERIT | 1367 | | | | | 1368 | tcap | Refer to Section 14 | B | INHERIT | 1369 | | | | | 1370 | cap-v0 | Not Impacted | B | NORMAL | 1371 | | | | | 1372 +---------+-----------------------+-------+--------------+ 1374 5.32 RFC5939 Attribute Analysis 1376 5.33. RFC6871: SDP Media Capabilities Negotiation 1378 SDP capability negotiation provides a general framework for 1379 indicating and negotiating capabilities in SDP. The base framework 1380 defines only capabilities for negotiating transport protocols and 1381 attributes. [RFC6871] extends the framework by defining media 1382 capabilities that can be used to negotiate media types and their 1383 associated parameters. 1385 +---------+-----------------------+-------+-------------------+ 1386 | Name | Notes | Level | Mux Category | 1387 +---------+-----------------------+-------+-------------------+ 1388 | rmcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1389 | | | | | 1390 | omcap | Not Impacted | B | NORMAL | 1391 | | | | | 1392 | mfcap | Refer to Section 14 | B | IDENTICAL-PER-PT | 1393 | | | | | 1394 | mscap | Refer to Section 14 | B | INHERIT | 1395 | | | | | 1396 | lcfg | Refer to Section 14 | B | SPECIAL | 1397 | | | | | 1398 | sescap | Refer to notes below | S | CAUTION | 1399 | | | | | 1400 | med-v0 | Not Impacted | S | NORMAL | 1401 | | | | | 1402 +---------+-----------------------+-------+-------------------+ 1404 5.33 RFC6871 - Attribute Analysis 1406 NOTE: The "sescap" attribute is not recommended for use with 1407 multiplexing. The reason is that it requires the use of unique 1408 configuration numbers across the entire SDP (per [RFC6871]) as 1409 opposed to within a media description only (per [RFC5939]). As 1410 described in Section 14, the use of identical configuration numbers 1411 between multiplexed (bundled) media descriptions is the default way 1412 of indicating compatible configurations in a bundle. 1414 5.34. RFC7006: Miscellaneous Capabilities Negotiation SDP 1416 [RFC7006] extends the SDP capability negotiation framework to allow 1417 endpoints to negotiate three additional SDP capabilities. In 1418 particular, this memo provides a mechanism to negotiate bandwidth 1419 ("b=" line), connection data ("c=" line), and session or media titles 1420 ("i=" line for each session or media). 1422 +----------+-----------------------------------+-------+------------+ 1423 | Name | Notes | Level | Mux | 1424 | | | | Category | 1425 +----------+-----------------------------------+-------+------------+ 1426 | bcap | Inherit the category SUM as | B | INHERIT | 1427 | | applicable to b= attribute | | | 1428 | | | | | 1429 | bcap-v0 | Not Impacted | B | NORMAL | 1430 | | | | | 1431 | ccap | The connection address type MUST | B | IDENTICAL | 1432 | | be identical across all the | | | 1433 | | multiplexed "m=" lines | | | 1434 | | | | | 1435 | ccap-v0 | Not Impacted | B | NORMAL | 1436 | | | | | 1437 | icap | Not Impacted | B | NORMAL | 1438 | | | | | 1439 | icap-v0 | Not Impacted | B | NORMAL | 1440 | | | | | 1441 +----------+-----------------------------------+-------+------------+ 1443 5.34 RFC7006 - Attribute Analysis 1445 5.35. RFC4567: Key Management Extensions for SDP and RTSP 1447 [RFC4567] defines general extensions for SDP and Real Time Streaming 1448 Protocol (RTSP) to carry messages, as specified by a key management 1449 protocol, in order to secure the media. These extensions are 1450 presented as a framework, to be used by one or more key management 1451 protocols. As such, their use is meaningful only when complemented 1452 by an appropriate key management protocol. 1454 +-----------+----------------------------------+-------+------------+ 1455 | Name | Notes | Level | Mux | 1456 | | | | Category | 1457 +-----------+----------------------------------+-------+------------+ 1458 | key-mgmt | Key management protocol MUST be | B | IDENTICAL | 1459 | | identical across all the "m=" | | | 1460 | | lines | | | 1461 | | | | | 1462 | mikey | Key management protocol MUST be | B | IDENTICAL | 1463 | | identical across all the "m=" | | | 1464 | | lines | | | 1465 | | | | | 1466 +-----------+----------------------------------+-------+------------+ 1468 5.35 RFC4567 Attribute Analysis 1470 5.36. RFC4572: Comedia over TLS in SDP 1472 [RFC4572] specifies how to establish secure connection-oriented media 1473 transport sessions over the Transport Layer Security (TLS) protocol 1474 using SDP. It defines a new SDP protocol identifier, 'TCP/TLS'. It 1475 also defines the syntax and semantics for an SDP 'fingerprint' 1476 attribute that identifies the certificate that will be presented for 1477 the TLS session. This mechanism allows media transport over TLS 1478 connections to be established securely, so long as the integrity of 1479 session descriptions is assured. 1481 +--------------+-------------------------------+-------+------------+ 1482 | Name | Notes | Level | Mux | 1483 | | | | Category | 1484 +--------------+-------------------------------+-------+------------+ 1485 | fingerprint | fingerprint value from the | B | TRANSPORT | 1486 | | "m=" line defining the | | | 1487 | | underlying transport is | | | 1488 | | chosen | | | 1489 | | | | | 1490 +--------------+-------------------------------+-------+------------+ 1492 5.36 RFC4572 Attribute Analysis 1494 5.37. RFC4570: SDP Source Filters 1496 [RFC4570] describes how to adapt SDP to express one or more source 1497 addresses as a source filter for one or more destination "connection" 1498 addresses. It defines the syntax and semantics for an SDP "source- 1499 filter" attribute that may reference either IPv4 or IPv6 address(es) 1500 as either an inclusive or exclusive source list for either multicast 1501 or unicast destinations. In particular, an inclusive source-filter 1502 can be used to specify a Source-Specific Multicast (SSM) session. 1504 +----------------+-----------------------------+-------+------------+ 1505 | Name | Notes | Level | Mux | 1506 | | | | Category | 1507 +----------------+-----------------------------+-------+------------+ 1508 | source-filter | The attribute MUST be | B | IDENTICAL | 1509 | | repeated across all "m=" | | | 1510 | | lines multiplexed | | | 1511 | | | | | 1512 +----------------+-----------------------------+-------+------------+ 1514 5.37 RFC4570 Attribute Analysis 1516 5.38. RFC6128: RTCP Port for Multicast Sessions 1518 SDP has an attribute that allows RTP applications to specify an 1519 address and a port associated with the RTCP traffic. In RTP-based 1520 source-specific multicast (SSM) sessions, the same attribute is used 1521 to designate the address and the RTCP port of the Feedback Target in 1522 the SDP description. However, the RTCP port associated with the SSM 1523 session itself cannot be specified by the same attribute to avoid 1524 ambiguity, and thus, is required to be derived from the "m=" line of 1525 the media description. Deriving the RTCP port from the "m=" line 1526 imposes an unnecessary restriction. [RFC6128] removes this 1527 restriction by introducing a new SDP attribute. 1529 +-----------------+----------------------------+-------+------------+ 1530 | Name | Notes | Level | Mux | 1531 | | | | Category | 1532 +-----------------+----------------------------+-------+------------+ 1533 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL | 1534 | | be identical across all | | | 1535 | | the "m=" lines | | | 1536 | | | | | 1537 +-----------------+----------------------------+-------+------------+ 1539 5.38 RFC6128 Attribute Analysis 1541 5.39. RFC6189: ZRTP 1543 [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman 1544 exchange to agree on a session key and parameters for establishing 1545 unicast SRTP sessions for (VoIP applications. 1547 +------------+---------------------------------+-------+------------+ 1548 | Name | Notes | Level | Mux | 1549 | | | | Category | 1550 +------------+---------------------------------+-------+------------+ 1551 | zrtp-hash | zrtp-hash attribute MUST be the | M | TRANSPORT | 1552 | | one that corresponds to the | | | 1553 | | "m=" line chosen for setting up | | | 1554 | | the underlying transport flow | | | 1555 | | | | | 1556 +------------+---------------------------------+-------+------------+ 1558 5.39 RFC6189 Attribute Analysis 1560 5.40. RFC4145: Connection-Oriented Media 1562 [RFC4145] describes how to express media transport over TCP using 1563 SDP. It defines the SDP 'TCP' protocol identifier, the SDP 'setup' 1564 attribute, which describes the connection setup procedure, and the 1565 SDP 'connection' attribute, which handles connection reestablishment. 1567 +-------------+--------------------------------+-------+------------+ 1568 | Name | Notes | Level | Mux | 1569 | | | | Category | 1570 +-------------+--------------------------------+-------+------------+ 1571 | setup | The setup attribute MUST be | B | TRANSPORT | 1572 | | the one that corresponds to | | | 1573 | | the "m=" line chosen for | | | 1574 | | setting up the underlying | | | 1575 | | transport flow. | | | 1576 | | | | | 1577 | connection | The connection attribute MUST | B | TRANSPORT | 1578 | | be the one that corresponds to | | | 1579 | | the "m=" line chosen for | | | 1580 | | setting up the underlying | | | 1581 | | transport flow. | | | 1582 | | | | | 1583 +-------------+--------------------------------+-------+------------+ 1585 5.40 RFC4145 Attribute Analysis 1587 5.41. RFC6947: The SDP altc Attribute 1589 [RFC6947] proposes a mechanism that allows the same SDP offer to 1590 carry multiple IP addresses of different address families (e.g., IPv4 1591 and IPv6). The proposed attribute, the "altc" attribute, solves the 1592 backward-compatibility problem that plagued Alternative Network 1593 Address Types (ANAT) due to their syntax. 1595 +-------+--------------------------------------+-------+------------+ 1596 | Name | Notes | Level | Mux | 1597 | | | | Category | 1598 +-------+--------------------------------------+-------+------------+ 1599 | altc | The IP Address and port MUST be the | M | TRANSPORT | 1600 | | one that corresponds to the "m=" | | | 1601 | | line chosen for setting up the | | | 1602 | | underlying transport flow | | | 1603 | | | | | 1604 +-------+--------------------------------------+-------+------------+ 1606 5.41 RFC6947 Attribute Analysis 1608 5.42. RFC7195: SDP Extension for Circuit Switched Bearers in PSTN 1610 [RFC7195] describes use cases, requirements, and protocol extensions 1611 for using SDP offer/answer model for establishing audio and video 1612 media streams over circuit-switched bearers in the Public Switched 1613 Telephone Network (PSTN). 1615 +--------------------------+-------------------+-------+------------+ 1616 | Name | Notes | Level | Mux | 1617 | | | | Category | 1618 +--------------------------+-------------------+-------+------------+ 1619 | cs-correlation:callerid | Refer to notes | M | TBD | 1620 | | below | | | 1621 | | | | | 1622 | cs-correlation:uuie | Refer to notes | M | TBD | 1623 | | below | | | 1624 | | | | | 1625 | cs-correlation:dtmf | Refer to notes | M | TBD | 1626 | | below | | | 1627 | | | | | 1628 | cs-correlation:external | Refer to notes | M | TBD | 1629 | | below | | | 1630 | | | | | 1631 +--------------------------+-------------------+-------+------------+ 1633 5.42 RFC7195 Attribute Analysis 1635 NOTE: [RFC7195] defines SDP attributes for establishing audio and 1636 video media streams over circuit-switched bearers by defining a new 1637 nettype value "PSTN". However, section 7.2 of 1638 [I-D.ietf-mmusic-sdp-bundle-negotiation] requires the "c=" line 1639 nettype value of "IN". If in future there exists a specification 1640 that defines procedures to multiplex media streams over nettype 1641 "PSTN", the multiplexing categories for attributes in this section 1642 could be revisited. 1644 5.43. RFC7272: IDMS Using the RTP Control Protocol (RTCP) 1646 [RFC7272] defines a new RTCP Packet Type and an RTCP Extended Report 1647 (XR) Block Type to be used for achieving Inter-Destination Media 1648 Synchronization (IDMS). 1650 +------------+---------------+-------+--------------+ 1651 | Name | Notes | Level | Mux Category | 1652 +------------+---------------+-------+--------------+ 1653 | rtcp-idms | Not Impacted | M | NORMAL | 1654 | | | | | 1655 +------------+---------------+-------+--------------+ 1657 5.43 RFC7272 Attribute Analysis 1659 5.44. RFC5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP 1660 Attributes 1662 [RFC5159] provides descriptions of SDP attributes used by the Open 1663 Mobile Alliance's Broadcast Service and Content Protection 1664 specification. 1666 +---------------------+-----------------------+-------+-------------+ 1667 | Name | Notes | Level | Mux | 1668 | | | | Category | 1669 +---------------------+-----------------------+-------+-------------+ 1670 | bcastversion | Not Impacted | S | NORMAL | 1671 | | | | | 1672 | stkmstream | Not Impacted | B | NORMAL | 1673 | | | | | 1674 | SRTPAuthentication | Needs further | M | TBD | 1675 | | analysis | | | 1676 | | | | | 1677 | SRTPROCTxRate | Needs further | M | TBD | 1678 | | analysis | | | 1679 | | | | | 1680 +---------------------+-----------------------+-------+-------------+ 1682 5.44 RFC5159 Attribute Analysis 1684 5.45. RFC6193: Media Description for IKE in SDP 1686 [RFC6193] specifies how to establish a media session that represents 1687 a virtual private network using the Session Initiation Protocol for 1688 the purpose of on-demand media/application sharing between peers. It 1689 extends the protocol identifier of SDP so that it can negotiate use 1690 of the Internet Key Exchange Protocol (IKE) for media sessions in the 1691 SDP offer/answer model. 1693 +-------------------+----------------------------+-------+----------+ 1694 | Name | Notes | Level | Mux | 1695 | | | | Category | 1696 +-------------------+----------------------------+-------+----------+ 1697 | ike-setup | Unlikely to use IKE in the | B | CAUTION | 1698 | | context of multiplexing | | | 1699 | | | | | 1700 | psk-fingerprint | Unlikely to use IKE in the | B | CAUTION | 1701 | | context of multiplexing | | | 1702 | | | | | 1703 | ike-esp | Unlikely to use IKE in the | B | CAUTION | 1704 | | context of multiplexing | | | 1705 | | | | | 1706 | ike-esp-udpencap | Unlikely to use IKE in the | B | CAUTION | 1707 | | context of multiplexing | | | 1708 | | | | | 1709 +-------------------+----------------------------+-------+----------+ 1711 5.45 RFC6193 Attribute Analysis 1713 5.46. RFC2326: Real Time Streaming Protocol 1715 The Real Time Streaming Protocol, or RTSP, is an application-level 1716 protocol for control over the delivery of data with real-time 1717 properties. RTSP provides an extensible framework to enable 1718 controlled, on-demand delivery of real-time data, such as audio and 1719 video. 1721 +----------+------------------------------------+-------+-----------+ 1722 | Name | Notes | Level | Mux | 1723 | | | | Category | 1724 +----------+------------------------------------+-------+-----------+ 1725 | etag | RTSP is not supported for RTP | B | CAUTION | 1726 | | Stream multiplexing | | | 1727 | | | | | 1728 | range | RTSP is not supported for RTP | B | CAUTION | 1729 | | Stream multiplexing | | | 1730 | | | | | 1731 | control | RTSP is not supported for RTP | B | CAUTION | 1732 | | Stream multiplexing | | | 1733 | | | | | 1734 | mtag | RTSP is not supported for RTP | B | CAUTION | 1735 | | Stream multiplexing | | | 1736 | | | | | 1737 +----------+------------------------------------+-------+-----------+ 1739 5.46 RFC2326 Attribute Analysis 1741 NOTE: [RFC2326] defines SDP attributes that are applicable in the 1742 declarative usage of SDP alone. For purposes of this document, only 1743 the Offer/Answer usage of SDP is considered as mandated by 1744 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1746 5.47. RFC6064: SDP and RTSP Extensions for 3GPP 1748 The Packet-switched Streaming Service (PSS) and the Multimedia 1749 Broadcast/Multicast Service (MBMS) defined by 3GPP use SDP and RTSP 1750 with some extensions. [RFC6064] provides information about these 1751 extensions and registers the RTSP and SDP extensions with IANA. 1753 +--------------------------------+---------------+-------+----------+ 1754 | Name | Notes | Level | Mux | 1755 | | | | Category | 1756 +--------------------------------+---------------+-------+----------+ 1757 | X-predecbufsize | Refer to | M | CAUTION | 1758 | | notes below | | | 1759 | | | | | 1760 | X-initpredecbufperiod | Refer to | M | CAUTION | 1761 | | notes below | | | 1762 | | | | | 1763 | X-initpostdecbufperiod | Refer to | M | CAUTION | 1764 | | notes below | | | 1765 | | | | | 1766 | X-decbyterate | Refer to | M | CAUTION | 1767 | | notes below | | | 1768 | | | | | 1769 | 3gpp-videopostdecbufsize | Refer to | M | CAUTION | 1770 | | notes below | | | 1771 | | | | | 1772 | framesize | Refer to | M | CAUTION | 1773 | | notes below | | | 1774 | | | | | 1775 | 3GPP-Integrity-Key | Refer to | S | CAUTION | 1776 | | notes below | | | 1777 | | | | | 1778 | 3GPP-SDP-Auth | Refer to | S | CAUTION | 1779 | | notes below | | | 1780 | | | | | 1781 | 3GPP-SRTP-Config | Refer to | M | CAUTION | 1782 | | notes below | | | 1783 | | | | | 1784 | alt | Refer to | M | CAUTION | 1785 | | notes below | | | 1786 | | | | | 1787 | alt-default-id | Refer to | M | CAUTION | 1788 | | notes below | | | 1789 | | | | | 1790 | alt-group | Refer to | S | CAUTION | 1791 | | notes below | | | 1792 | | | | | 1793 | 3GPP-Adaptation-Support | Refer to | M | CAUTION | 1794 | | notes below | | | 1795 | | | | | 1796 | 3GPP-Asset-Information | Refer to | B | CAUTION | 1797 | | notes below | | | 1798 | | | | | 1799 | mbms-mode | Refer to | B | CAUTION | 1800 | | notes below | | | 1801 | | | | | 1802 | mbms-flowid | Refer to | M | CAUTION | 1803 | | notes below | | | 1804 | | | | | 1805 | mbms-repair | Refer to | B | CAUTION | 1806 | | notes below | | | 1807 | | | | | 1808 | 3GPP-QoE-Metrics | Refer to | M | CAUTION | 1809 | | notes below | | | 1810 | | | | | 1811 | 3GPP-QoE-Metrics:Corruption | Refer to | M | CAUTION | 1812 | duration | notes below | | | 1813 | | | | | 1814 | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | CAUTION | 1815 | duration | notes below | | | 1816 | | | | | 1817 | 3GPP-QoE-Metrics:Initial | Refer to | M | CAUTION | 1818 | buffering duration | notes below | | | 1819 | | | | | 1820 | 3GPP-QoE-Metrics:Successive | Refer to | M | CAUTION | 1821 | loss of RTP packets | notes below | | | 1822 | | | | | 1823 | 3GPP-QoE-Metrics:Frame rate | Refer to | M | CAUTION | 1824 | deviation | notes below | | | 1825 | | | | | 1826 | 3GPP-QoE-Metrics:Jitter | Refer to | M | CAUTION | 1827 | duration | notes below | | | 1828 | | | | | 1829 | 3GPP-QoE-Metrics:Content | Refer to | B | CAUTION | 1830 | Switch Time | notes below | | | 1831 | | | | | 1832 | 3GPP-QoE-Metrics:Average Codec | Refer to | M | CAUTION | 1833 | Bitrate | notes below | | | 1834 | | | | | 1835 | 3GPP-QoE-Metrics:Codec | Refer to | M | CAUTION | 1836 | Information | notes below | | | 1837 | | | | | 1838 | 3GPP-QoE-Metrics:Buffer Status | Refer to | M | CAUTION | 1839 | | notes below | | | 1840 | | | | | 1841 +--------------------------------+---------------+-------+----------+ 1843 5.47 RFC6064 Attribute Analysis 1845 NOTE: [RFC6064] defines SDP attributes that are applicable in the 1846 declarative usage of SDP alone. For purposes of this document, only 1847 the Offer/Answer usage of SDP is considered as mandated by 1848 [I-D.ietf-mmusic-sdp-bundle-negotiation]. 1850 5.48. RFC3108: ATM SDP 1852 [RFC3108] describes conventions for using SDP described for 1853 controlling ATM Bearer Connections, and any associated ATM Adaptation 1854 Layer (AAL). 1856 +------------------------+--------------------+-------+-------------+ 1857 | Name | Notes | Level | Mux | 1858 | | | | Category | 1859 +------------------------+--------------------+-------+-------------+ 1860 | aalType | Refer to notes | B | CAUTION | 1861 | | below | | | 1862 | eecid | Refer to notes | B | CAUTION | 1863 | | below | | | 1864 | capability | Refer to notes | B | CAUTION | 1865 | | below | | | 1866 | qosClass | Refer to notes | B | CAUTION | 1867 | | below | | | 1868 | bcob | Refer to notes | B | CAUTION | 1869 | | below | | | 1870 | stc | Refer to notes | B | CAUTION | 1871 | | below | | | 1872 | upcc | Refer to notes | B | CAUTION | 1873 | | below | | | 1874 | atmQOSparms | Refer to notes | B | CAUTION | 1875 | | below | | | 1876 | atmTrfcDesc | Refer to notes | B | CAUTION | 1877 | | below | | | 1878 | abrParms | Refer to notes | B | CAUTION | 1879 | | below | | | 1880 | abrSetup | Refer to notes | B | CAUTION | 1881 | | below | | | 1882 | bearerType | Refer to notes | B | CAUTION | 1883 | | below | | | 1884 | lij | Refer to notes | B | CAUTION | 1885 | | below | | | 1886 | anycast | Refer to notes | B | CAUTION | 1887 | | below | | | 1888 | cache | Refer to notes | B | CAUTION | 1889 | | below | | | 1890 | bearerSigIE | Refer to notes | B | CAUTION | 1891 | | below | | | 1892 | aalApp | Refer to notes | B | CAUTION | 1893 | | below | | | 1894 | cbrRate | Refer to notes | B | CAUTION | 1895 | | below | | | 1896 | sbc | Refer to notes | B | CAUTION | 1897 | | below | | | 1898 | clkrec | Refer to notes | B | CAUTION | 1899 | | below | | | 1900 | fec | Refer to notes | B | CAUTION | 1901 | | below | | | 1902 | prtfl | Refer to notes | B | CAUTION | 1903 | | below | | | 1904 | structure | Refer to notes | B | CAUTION | 1905 | | below | | | 1906 | cpsSDUsize | Refer to notes | B | CAUTION | 1907 | | below | | | 1908 | aal2CPS | Refer to notes | B | CAUTION | 1909 | | below | | | 1910 | aal2CPSSDUrate | Refer to notes | B | CAUTION | 1911 | | below | | | 1912 | aal2sscs3661unassured | Refer to notes | B | CAUTION | 1913 | | below | | | 1914 | aal2sscs3661assured | Refer to notes | B | CAUTION | 1915 | | below | | | 1916 | aal2sscs3662 | Refer to notes | B | CAUTION | 1917 | | below | | | 1918 | aal5sscop | Refer to notes | B | CAUTION | 1919 | | below | | | 1920 | atmmap | Refer to notes | B | CAUTION | 1921 | | below | | | 1922 | silenceSupp | Refer to notes | B | CAUTION | 1923 | | below | | | 1924 | ecan | Refer to notes | B | CAUTION | 1925 | | below | | | 1926 | gc | Refer to notes | B | CAUTION | 1927 | | below | | | 1928 | profileDesc | Refer to notes | B | CAUTION | 1929 | | below | | | 1930 | vsel | Refer to notes | B | CAUTION | 1931 | | below | | | 1932 | dsel | Refer to notes | B | CAUTION | 1933 | | below | | | 1934 | fsel | Refer to notes | B | CAUTION | 1935 | | below | | | 1936 | onewaySel | Refer to notes | B | CAUTION | 1937 | | below | | | 1938 | codecconfig | Refer to notes | B | CAUTION | 1939 | | below | | | 1940 | isup_usi | Refer to notes | B | CAUTION | 1941 | | below | | | 1942 | uiLayer1_Prot | Refer to notes | B | CAUTION | 1943 | | below | | | 1944 | chain | Refer to notes | B | CAUTION | 1945 | | below | | | 1946 | | | | | 1947 +------------------------+--------------------+-------+-------------+ 1949 5.48 RFC3108 Attribute Analysis 1951 NOTE: RFC3108 describes conventions for using SDP for characterizing 1952 ATM bearer connections using an AAL1, AAL2 or AAL5 adaptation layers. 1953 For AAL1, AAL2 and AAL5, bearer connections can be used to transport 1954 single media streams. In addition, for AAL1 and AAL2, multiple media 1955 streams can be multiplexed into a bearer connection. For all 1956 adaptation types (AAL1, AAL2 and AAL5), bearer connections can be 1957 bundled into a single media group. In all cases addressed by 1958 RFC3108, a real-time media stream (voice, video, voiceband data, 1959 pseudo-wire, and others) or a multiplex of media streams is mapped 1960 directly into an ATM connection. RFC3108 does not address cases 1961 where ATM serves as a low-level transport pipe for IP packets which 1962 in turn can carry one or more real-time (e.g. VoIP) media sessions 1963 with a life-cycle different from that of the underlying ATM 1964 transport. 1966 5.49. 3GPP TS 26.114 1968 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and 1969 interaction 1970 +----------------------+-------------------------+-------+----------+ 1971 | Name | Notes | Level | Mux | 1972 | | | | Category | 1973 +----------------------+-------------------------+-------+----------+ 1974 | 3gpp_sync_info | Usage defined for the | M | NORMAL | 1975 | | IP Multimedia Subsystem | | | 1976 | | | | | 1977 | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL | 1978 | | IP Multimedia Subsystem | | | 1979 | | | | | 1980 +----------------------+-------------------------+-------+----------+ 1982 5.49 3GPP TS 26.114 Attribute Analysis 1984 5.50. 3GPP TS 183.063 1986 [R3GPPTS183.063] Telecommunications and Internet converged Services 1987 and Protocols for Advanced Networking (TISPAN); 1989 +---------------------+---------------+-------+--------------+ 1990 | Name | Notes | Level | Mux Category | 1991 +---------------------+---------------+-------+--------------+ 1992 | PSCid | Not Impacted | S | NORMAL | 1993 | | | | | 1994 | bc_service | Not Impacted | S | NORMAL | 1995 | | | | | 1996 | bc_program | Not Impacted | S | NORMAL | 1997 | | | | | 1998 | bc_service_package | Not Impacted | S | NORMAL | 1999 | | | | | 2000 +---------------------+---------------+-------+--------------+ 2002 5.50 3GPP TS 183.063 Attribute Analysis 2004 5.51. 3GPP TS 24.182 2006 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting 2007 tones 2008 +-------------+---------------------------------+-------+-----------+ 2009 | Name | Notes | Level | Mux | 2010 | | | | Category | 2011 +-------------+---------------------------------+-------+-----------+ 2012 | g.3gpp.cat | Usage defined for the IP | M | NORMAL | 2013 | | Multimedia Subsystem | | | 2014 | | | | | 2015 +-------------+---------------------------------+-------+-----------+ 2017 5.51 3GPP TS 24.182 Attribute Analysis 2019 5.52. 3GPP TS 24.183 2021 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing 2022 Signal 2024 +-------------+---------------------------------+-------+-----------+ 2025 | Name | Notes | Level | Mux | 2026 | | | | Category | 2027 +-------------+---------------------------------+-------+-----------+ 2028 | g.3gpp.crs | Usage defined for the IP | M | NORMAL | 2029 | | Multimedia Subsystem | | | 2030 | | | | | 2031 +-------------+---------------------------------+-------+-----------+ 2033 5.52 3GPP TS 24.183 Attribute Analysis 2035 5.53. 3GPP TS 24.229 2037 [R3GPPTS24.229] specifies IP multimedia call control protocol based 2038 on Session Initial protocol and Session Description Protocol. 2040 +------------------+---------------------------+-------+------------+ 2041 | Name | Notes | Level | Mux | 2042 | | | | Category | 2043 +------------------+---------------------------+-------+------------+ 2044 | secondary-realm | secondary-realm MUST be | M | TRANSPORT | 2045 | | the one that corresponds | | | 2046 | | to the "m=" line chosen | | | 2047 | | for setting up the | | | 2048 | | underlying transport flow | | | 2049 | | | | | 2050 | visited-realm | visited-realm MUST be the | M | TRANSPORT | 2051 | | one that corresponds to | | | 2052 | | the "m=" line chosen for | | | 2053 | | setting up the underlying | | | 2054 | | transport flow | | | 2055 | | | | | 2056 | omr-m-cksum | Not Impacted | M | NORMAL | 2057 | | | | | 2058 | omr-s-cksum | Not Impacted | M | NORMAL | 2059 | | | | | 2060 | omr-m-att | Not Impacted | M | NORMAL | 2061 | | | | | 2062 | omr-s-att | Not Impacted | M | NORMAL | 2063 | | | | | 2064 | omr-m-bw | Not Impacted | M | NORMAL | 2065 | | | | | 2066 | omr-s-bw | Not Impacted | M | NORMAL | 2067 | | | | | 2068 | omr-codecs | Not Impacted | M | NORMAL | 2069 | | | | | 2070 +------------------+---------------------------+-------+------------+ 2072 5.53 3GPP TS 24.229 Attribute Analysis 2074 5.54. ITU T.38 2076 [T.38] defines procedures for real-time Group 3 facsimile 2077 communications over IP networks. 2079 +------------------------+--------------------+-------+-------------+ 2080 | Name | Notes | Level | Mux | 2081 | | | | Category | 2082 +------------------------+--------------------+-------+-------------+ 2083 | T38FaxVersion | Refer to notes | M | TBD | 2084 | | below | | | 2085 | | | | | 2086 | T38MaxBitRate | Refer to notes | M | TBD | 2087 | | below | | | 2088 | | | | | 2089 | T38FaxFillBitRemoval | Refer to notes | M | TBD | 2090 | | below | | | 2091 | | | | | 2092 | T38FaxTranscodingMMR | Refer to notes | M | TBD | 2093 | | below | | | 2094 | | | | | 2095 | T38FaxTranscodingJBIG | Refer to notes | M | TBD | 2096 | | below | | | 2097 | | | | | 2098 | T38FaxRateManagement | Refer to notes | M | TBD | 2099 | | below | | | 2100 | | | | | 2101 | T38FaxMaxBuffer | Refer to notes | M | TBD | 2102 | | below | | | 2103 | | | | | 2104 | T38FaxMaxDatagram | Refer to notes | M | TBD | 2105 | | below | | | 2106 | | | | | 2107 | T38FaxUdpEC | Refer to notes | M | TBD | 2108 | | below | | | 2109 | | | | | 2110 | T38FaxMaxIFP | Refer to notes | M | TBD | 2111 | | below | | | 2112 | | | | | 2113 | T38FaxUdpECDepth | Refer to notes | M | TBD | 2114 | | below | | | 2115 | | | | | 2116 | T38FaxUdpFECMaxSpan | Refer to notes | M | TBD | 2117 | | below | | | 2118 | | | | | 2119 | T38ModemType | Refer to notes | M | TBD | 2120 | | below | | | 2121 | | | | | 2122 | T38VendorInfo | Refer to notes | M | TBD | 2123 | | below | | | 2124 | | | | | 2125 +------------------------+--------------------+-------+-------------+ 2127 5.54 ITU T.38 Attribute Analysis 2129 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2130 there exists no publicly available specification that defines 2131 procedures for multiplexing/demultiplexing fax protocols flows over a 2132 single 5-tuple. Once such a specification is available, the 2133 multiplexing category assignments for the attributes in this section 2134 could be revisited. 2136 5.55. ITU-T Q.1970 2138 [Q.1970] defines Bearer Independent Call Control (BICC) IP bearer 2139 control protocol. 2141 +--------+---------------------------------------+-------+----------+ 2142 | Name | Notes | Level | Mux | 2143 | | | | Category | 2144 +--------+---------------------------------------+-------+----------+ 2145 | ipbcp | ipbcp version identifies type of IP | S | SPECIAL | 2146 | | bearer control protocol (IPBCP) | | | 2147 | | message used in BICC (ITU-T Q.1901) | | | 2148 | | environment which are limited to | | | 2149 | | single media payload. Refer to the | | | 2150 | | pertinent ITU-T specifications while | | | 2151 | | multiplexing | | | 2152 | | | | | 2153 +--------+---------------------------------------+-------+----------+ 2155 5.55 ITU-T Q.1970 Attribute Analysis 2157 5.56. ITU-T H.248.15 2159 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248 2160 package attribute 2161 +-----------+------------------------------------+-------+----------+ 2162 | Name | Notes | Level | Mux | 2163 | | | | Category | 2164 +-----------+------------------------------------+-------+----------+ 2165 | h248item | It is only applicable for | B | SPECIAL | 2166 | | signaling the inclusion of H.248 | | | 2167 | | extension packages to a gateway | | | 2168 | | via the local and remote | | | 2169 | | descriptors. The attribute itself | | | 2170 | | is unaffected by multiplexing, but | | | 2171 | | the packaged referenced in a | | | 2172 | | specific use of the attribute can | | | 2173 | | be impacted. Further analysis of | | | 2174 | | each package is needed to | | | 2175 | | determine if there is an issue. | | | 2176 | | This is only a concern in | | | 2177 | | environments using a decomposed | | | 2178 | | server/gateway with H.248 signaled | | | 2179 | | between them. The ITU-T will need | | | 2180 | | to do further analysis of various | | | 2181 | | packages when they specify how to | | | 2182 | | signal the use of multiplexing to | | | 2183 | | a gateway | | | 2184 | | | | | 2185 +-----------+------------------------------------+-------+----------+ 2187 5.56 ITU-T H.248.15 Attribute Analysis 2189 5.57. RFC4975: The Message Session Relay Protocol 2191 [RFC4975] the Message Session Relay Protocol, a protocol for 2192 transmitting a series of related instant messages in the context of a 2193 session. Message sessions are treated like any other media stream 2194 when set up via a rendezvous or session creation protocol such as the 2195 Session Initiation Protocol. 2197 +-----------------------+---------------------+-------+-------------+ 2198 | Name | Notes | Level | Mux | 2199 | | | | Category | 2200 +-----------------------+---------------------+-------+-------------+ 2201 | accept-types | Refer to notes | M | TBD | 2202 | | below | | | 2203 | | | | | 2204 | accept-wrapped-types | Refer to notes | M | TBD | 2205 | | below | | | 2206 | | | | | 2207 | max-size | Refer to notes | M | TBD | 2208 | | below | | | 2209 | | | | | 2210 | path | Refer to notes | M | TBD | 2211 | | below | | | 2212 | | | | | 2213 +-----------------------+---------------------+-------+-------------+ 2215 5.57 RFC4975 Attribute Analysis 2217 NOTE: As per section 9.1 of [I-D.ietf-mmusic-sdp-bundle-negotiation], 2218 there exists no publicly available specification that defines 2219 procedures for multiplexing/demultiplexing MRSP flows over a single 2220 5-tuple. Once such a specification is available, the multiplexing 2221 categories assignments for the attributes in this section could be 2222 revisited. 2224 5.58. Historical Attributes 2226 This section specifies analysis for the attributes that are included 2227 for historic usage alone by the [IANA]. 2229 +----------+----------------------+-------+--------------+ 2230 | Name | Notes | Level | Mux Category | 2231 +----------+----------------------+-------+--------------+ 2232 | rtpred1 | Historic attributes | M | CAUTION | 2233 | | | | | 2234 | rtpred2 | Historic attributes | M | CAUTION | 2235 | | | | | 2236 +----------+----------------------+-------+--------------+ 2238 5.58 Historical Attribute Analysis 2240 6. bwtype Attribute Analysis 2242 This section specifies handling of specific bandwidth attributes when 2243 used in multiplexing scenarios. 2245 6.1. RFC4566: SDP 2247 [RFC4566] defines SDP that is intended for describing multimedia 2248 sessions for the purposes of session announcement, session 2249 invitation, and other forms of multimedia session initiation. 2251 +------------+-----------------------------------+-------+----------+ 2252 | Name | Notes | Level | Mux | 2253 | | | | Category | 2254 +------------+-----------------------------------+-------+----------+ 2255 | bwtype:CT | Not Impacted | S | NORMAL | 2256 | | | | | 2257 | bwtype:AS | For the media level usage, the | B | SUM | 2258 | | aggregate of individual bandwidth | | | 2259 | | values is considered | | | 2260 | | | | | 2261 +------------+-----------------------------------+-------+----------+ 2263 6.1 RFC4566 bwtype Analysis 2265 6.2. RFC3556: SDP Bandwidth Modifiers for RTCP Bandwidth 2267 [RFC3556] defines an extension to SDP to specify two additional 2268 modifiers for the bandwidth attribute. These modifiers may be used 2269 to specify the bandwidth allowed for RTCP packets in a RTP session. 2271 +------------+-----------------------------------+-------+----------+ 2272 | Name | Notes | Level | Mux | 2273 | | | | Category | 2274 +------------+-----------------------------------+-------+----------+ 2275 | bwtype:RS | Session level usage represents | B | SUM | 2276 | | session aggregate and media level | | | 2277 | | usage indicates SUM of the | | | 2278 | | individual values while | | | 2279 | | multiplexing | | | 2280 | | | | | 2281 | bwtype:RR | Session level usage represents | B | SUM | 2282 | | session aggregate and media level | | | 2283 | | usage indicates SUM of the | | | 2284 | | individual values while | | | 2285 | | multiplexing | | | 2286 | | | | | 2287 +------------+-----------------------------------+-------+----------+ 2289 6.2 RFC3556 bwtype Analysis 2291 6.3. RFC3890: Bandwidth Modifier for SDP 2293 [RFC3890] defines SDP Transport Independent Application Specific 2294 Maximum (TIAS) bandwidth modifier that does not include transport 2295 overhead; instead an additional packet rate attribute is defined. 2296 The transport independent bit-rate value together with the maximum 2297 packet rate can then be used to calculate the real bit-rate over the 2298 transport actually used. 2300 +--------------+---------------------------------+-------+----------+ 2301 | Name | Notes | Level | Mux | 2302 | | | | Category | 2303 +--------------+---------------------------------+-------+----------+ 2304 | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL | 2305 | | defined under Offer/Answer | | | 2306 | | usage. | | | 2307 | | | | | 2308 | maxprate | The usage of TIAS and maxprate | B | SPECIAL | 2309 | | is not well defined under | | | 2310 | | multiplexing | | | 2311 | | | | | 2312 +--------------+---------------------------------+-------+----------+ 2314 6.3 RFC3890 bwtype Analysis 2316 NOTE: The intention of TIAS is that the media level bit-rate is 2317 multiplied with the known per-packet overhead for the selected 2318 transport and the maxprate value to determine the worst case bit-rate 2319 from the transport to more accurately capture the required usage. 2320 Summing TIAS values independently across "m=" lines and multiplying 2321 the computed sum with maxprate and the per-packet overhead would 2322 inflate the value significantly. Instead performing multiplication 2323 and adding the individual values is a more appropriate usage. 2325 7. rtcp-fb Attribute Analysis 2327 This section analyzes rtcp-fb SDP attributes. 2329 7.1. RFC4585: RTP/AVPF 2331 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that 2332 enables receivers to provide, statistically, more immediate feedback 2333 to the senders and thus allows for short-term adaptation and 2334 efficient feedback-based repair mechanisms to be implemented. 2336 +----------+----------------------------+-------+-------------------+ 2337 | Name | Notes | Level | Mux Category | 2338 +----------+----------------------------+-------+-------------------+ 2339 | ack rpsi | The attribute value MUST | M | IDENTICAL-PER-PT | 2340 | | be same for a given codec | | | 2341 | | configuration | | | 2342 | | | | | 2343 | ack app | Feedback parameters MUST | M | SPECIAL | 2344 | | be handled in the app | | | 2345 | | specific way when | | | 2346 | | multiplexed | | | 2347 | | | | | 2348 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2349 | | be same for a given codec | | | 2350 | | configuration | | | 2351 | | | | | 2352 | nack pli | The attribute value MUST | M | IDENTICAL-PER-PT | 2353 | | be same for a given codec | | | 2354 | | configuration | | | 2355 | | | | | 2356 | nack sli | The attribute value MUST | M | IDENTICAL-PER-PT | 2357 | | be same for a given codec | | | 2358 | | configuration | | | 2359 | | | | | 2360 | nack | The attribute value MUST | M | IDENTICAL-PER-PT | 2361 | rpsi | be same for a given codec | | | 2362 | | configuration | | | 2363 | | | | | 2364 | nack app | Feedback parameters MUST | M | SPECIAL | 2365 | | be handled in the app | | | 2366 | | specific way when | | | 2367 | | multiplexed | | | 2368 | | | | | 2369 | trr-int | The attribute value MUST | M | IDENTICAL-PER-PT | 2370 | | be same for a given codec | | | 2371 | | configuration | | | 2372 | | | | | 2373 +----------+----------------------------+-------+-------------------+ 2375 7.1 RFC4585 Attribute Analysis 2377 7.2. RFC5104: Codec Control Messages in AVPF 2379 [RFC5104] specifies a few extensions to the messages defined in the 2380 Audio-Visual Profile with Feedback (AVPF). They are helpful 2381 primarily in conversational multimedia scenarios where centralized 2382 multipoint functionalities are in use. However, some are also usable 2383 in smaller multicast environments and point-to-point calls. 2385 +------+--------------------------------+-------+-------------------+ 2386 | Name | Notes | Level | Mux Category | 2387 +------+--------------------------------+-------+-------------------+ 2388 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2389 | | same for a given codec | | | 2390 | | configuration | | | 2391 | | | | | 2392 +------+--------------------------------+-------+-------------------+ 2394 7.2 RFC5104 Attribute Analysis 2396 7.3. RFC6285: Unicast-Based Rapid Acquisition of Multicast RTP Sessions 2397 (RAMS) 2399 [RFC6285] describes a method using the existing RTP and RTCP 2400 machinery that reduces the acquisition delay. In this method, an 2401 auxiliary unicast RTP session carrying the Reference Information to 2402 the receiver precedes or accompanies the multicast stream. This 2403 unicast RTP flow can be transmitted at a faster than natural bitrate 2404 to further accelerate the acquisition. The motivating use case for 2405 this capability is multicast applications that carry real-time 2406 compressed audio and video. 2408 +-------+-------------------------------+-------+-------------------+ 2409 | Name | Notes | Level | Mux Category | 2410 +-------+-------------------------------+-------+-------------------+ 2411 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2412 | rai | same for a given codec | | | 2413 | | configuration | | | 2414 | | | | | 2415 +-------+-------------------------------+-------+-------------------+ 2417 7.3 RFC6285 Attribute Analysis 2419 7.4. RFC6679: ECN for RTP over UDP/IP 2421 [RFC6679] specifies how Explicit Congestion Notification (ECN) can be 2422 used with the RTP running over UDP, using the RTCP as a feedback 2423 mechanism. It defines a new RTCP Extended Report (XR) block for 2424 periodic ECN feedback, a new RTCP transport feedback message for 2425 timely reporting of congestion events, and a STUN extension used in 2426 the optional initialization method using ICE. 2428 +------------------+---------------------------+-------+------------+ 2429 | Name | Notes | Level | Mux | 2430 | | | | Category | 2431 +------------------+---------------------------+-------+------------+ 2432 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL | 2433 | | the RTP session level | | | 2434 | | | | | 2435 | nack ecn | This attribute enables | M | IDENTICAL | 2436 | | ECN at the RTP session | | | 2437 | | level | | | 2438 | | | | | 2439 +------------------+---------------------------+-------+------------+ 2441 7.4 RFC6679 Attribute Analysis 2443 7.5. RFC6642: Third-Party Loss Report 2445 In a large RTP session using the RTCP feedback mechanism defined in 2446 [RFC4585], a feedback target may experience transient overload if 2447 some event causes a large number of receivers to send feedback at 2448 once. This overload is usually avoided by ensuring that feedback 2449 reports are forwarded to all receivers, allowing them to avoid 2450 sending duplicate feedback reports. However, there are cases where 2451 it is not recommended to forward feedback reports, and this may allow 2452 feedback implosion. [RFC6642] memo discusses these cases and defines 2453 a new RTCP Third-Party Loss Report that can be used to inform 2454 receivers that the feedback target is aware of some loss event, 2455 allowing them to suppress feedback. Associated SDP signaling is also 2456 defined. 2458 +--------+------------------------------+-------+-------------------+ 2459 | Name | Notes | Level | Mux Category | 2460 +--------+------------------------------+-------+-------------------+ 2461 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2462 | tllei | same for a given codec | | | 2463 | | configuration | | | 2464 | | | | | 2465 | nack | The attribute value MUST be | M | IDENTICAL-PER-PT | 2466 | pslei | same for a given codec | | | 2467 | | configuration | | | 2468 | | | | | 2469 +--------+------------------------------+-------+-------------------+ 2471 7.5 RFC6642 Attribute Analysis 2473 7.6. RFC5104: Codec Control Messages in AVPF 2475 [RFC5104] specifies a few extensions to the messages defined in the 2476 Audio-Visual Profile with Feedback (AVPF). They are helpful 2477 primarily in conversational multimedia scenarios where centralized 2478 multipoint functionalities are in use. However, some are also usable 2479 in smaller multicast environments and point-to-point calls. 2481 +--------+------------------------------+-------+-------------------+ 2482 | Name | Notes | Level | Mux Category | 2483 +--------+------------------------------+-------+-------------------+ 2484 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2485 | fir | same for a given codec | | | 2486 | | configuration | | | 2487 | | | | | 2488 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2489 | tmmbr | same for a given codec | | | 2490 | | configuration | | | 2491 | | | | | 2492 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2493 | tstr | same for a given codec | | | 2494 | | configuration | | | 2495 | | | | | 2496 | ccm | The attribute value MUST be | M | IDENTICAL-PER-PT | 2497 | vbcm | same for a given codec | | | 2498 | | configuration | | | 2499 | | | | | 2500 +--------+------------------------------+-------+-------------------+ 2502 7.6 RFC5104 Attribute Analysis 2504 8. group Attribute Analysis 2506 This section analyzes SDP "group" attribute semantics [RFC5888]. 2508 8.1. RFC5888: SDP Grouping Framework 2510 [RFC5888] defines a framework to group "m" lines in SDP for different 2511 purposes. 2513 +------------+---------------+-------+--------------+ 2514 | Name | Notes | Level | Mux Category | 2515 +------------+---------------+-------+--------------+ 2516 | group:LS | Not Impacted | S | NORMAL | 2517 | | | | | 2518 | group:FID | Not Impacted | S | NORMAL | 2519 | | | | | 2520 +------------+---------------+-------+--------------+ 2522 8.1 RFC5888 Attribute Analysis 2524 8.2. RFC3524: Mapping Media Streams to Resource Reservation Flows 2526 [RFC3524] defines an extension to the SDP grouping framework. It 2527 allows requesting a group of media streams to be mapped into a single 2528 resource reservation flow. The SDP syntax needed is defined, as well 2529 as a new "semantics" attribute called Single Reservation Flow (SRF). 2531 +------------+---------------+-------+--------------+ 2532 | Name | Notes | Level | Mux Category | 2533 +------------+---------------+-------+--------------+ 2534 | group:SRF | Not Impacted | S | NORMAL | 2535 | | | | | 2536 +------------+---------------+-------+--------------+ 2538 8.2 RFC3524 Attribute Analysis 2540 8.3. RFC4091: ANAT Semantics 2542 [RFC4091] defines ANAT semantics for the SDP grouping framework. The 2543 ANAT semantics allow alternative types of network addresses to 2544 establish a particular media stream. 2546 +-------------+------------------------------+-------+--------------+ 2547 | Name | Notes | Level | Mux Category | 2548 +-------------+------------------------------+-------+--------------+ 2549 | group:ANAT | ANAT semantics is obsoleted | S | CAUTION | 2550 | | | | | 2551 +-------------+------------------------------+-------+--------------+ 2553 8.3 RFC4091 Attribute Analysis 2555 8.4. RFC5956: FEC Grouping Semantics in SDP 2557 [RFC5956] defines the semantics for grouping the associated source 2558 and FEC-based (Forward Error Correction) repair flows in SDP. The 2559 semantics defined in the document are to be used with the SDP 2560 Grouping Framework [RFC5888]. These semantics allow the description 2561 of grouping relationships between the source and repair flows when 2562 one or more source and/or repair flows are associated in the same 2563 group, and they provide support for additive repair flows. SSRC- 2564 level (Synchronization Source) grouping semantics are also defined in 2565 this document for RTP streams using SSRC multiplexing. 2567 +---------------+---------------+-------+--------------+ 2568 | Name | Notes | Level | Mux Category | 2569 +---------------+---------------+-------+--------------+ 2570 | group:FEC-FR | Not Impacted | S | NORMAL | 2571 | | | | | 2572 +---------------+---------------+-------+--------------+ 2574 8.4 RFC5956 Attribute Analysis 2576 8.5. RFC5583: Signaling Media Decoding Dependency in SDP 2578 [RFC5583] defines semantics that allow for signaling the decoding 2579 dependency of different media descriptions with the same media type 2580 in SDP. This is required, for example, if media data is separated 2581 and transported in different network streams as a result of the use 2582 of a layered or multiple descriptive media coding process. 2584 +------------+--------------------------+-------+-------------------+ 2585 | Name | Notes | Level | Mux Category | 2586 +------------+--------------------------+-------+-------------------+ 2587 | group:DDP | Not Impacted | S | NORMAL | 2588 | | | | | 2589 | depend lay | The attribute value MUST | M | IDENTICAL-PER-PT | 2590 | | be same for a given | | | 2591 | | codec configuration | | | 2592 | | | | | 2593 | depend mdc | The attribute value MUST | M | IDENTICAL-PER-PT | 2594 | | be same for a given | | | 2595 | | codec configuration | | | 2596 | | | | | 2597 +------------+--------------------------+-------+-------------------+ 2599 8.5 RFC5583 Attribute Analysis 2601 8.6. RFC7104: Duplication Grouping Semantics in the SDP 2603 [RFC7104] defines the semantics for grouping redundant streams in 2604 SDP, The semantics defined in this document are to be used with the 2605 SDP Grouping Framework. Grouping semantics at the SSRC)level are 2606 also defined in this document for RTP streams using SSRC 2607 multiplexing. 2609 +------------+---------------+-------+--------------+ 2610 | Name | Notes | Level | Mux Category | 2611 +------------+---------------+-------+--------------+ 2612 | group:DUP | Not Impacted | S | NORMAL | 2613 | | | | | 2614 +------------+---------------+-------+--------------+ 2616 8.6 RFC7104 Attribute Analysis 2618 9. ssrc-group Attribute Analysis 2620 This section analyzes "ssrc-group" semantics. 2622 9.1. RFC5576: Source-Specific SDP Attributes 2624 [RFC5576] defines a mechanism to describe RTP media sources, which 2625 are identified by their synchronization source (SSRC) identifiers, in 2626 SDP, to associate attributes with these sources, and to express 2627 relationships among sources. It also defines several source-level 2628 attributes that can be used to describe properties of media sources. 2630 +--------------------+---------------+-------+--------------+ 2631 | Name | Notes | Level | Mux Category | 2632 +--------------------+---------------+-------+--------------+ 2633 | ssrc-group:FID | Not Impacted | SR | NORMAL | 2634 | | | | | 2635 | ssrc-group:FEC | Not Impacted | SR | NORMAL | 2636 | | | | | 2637 | ssrc-group:FEC-FR | Not Impacted | SR | NORMAL | 2638 | | | | | 2639 +--------------------+---------------+-------+--------------+ 2641 9.1 RFC5576 Attribute Analysis 2643 9.2. RFC7104: Duplication Grouping Semantics in the SDP 2645 [RFC7104] defines the semantics for grouping redundant streams in 2646 SDP. The semantics defined in this document are to be used with the 2647 SDP Grouping Framework. Grouping semantics at the Synchronization 2648 Source (SSRC) level are also defined in this document for RTP streams 2649 using SSRC multiplexing. 2651 +-----------------+---------------+-------+--------------+ 2652 | Name | Notes | Level | Mux Category | 2653 +-----------------+---------------+-------+--------------+ 2654 | ssrc-group:DUP | Not Impacted | SR | NORMAL | 2655 | | | | | 2656 +-----------------+---------------+-------+--------------+ 2658 9.2 RFC7104 Attribute Analysis 2660 10. QoS Mechanism Token Analysis 2662 This section analyzes QoS tokes specified with SDP. 2664 10.1. RFC5432: QoS Mechanism Selection in SDP 2666 [RFC5432] defines procedures to negotiate QOS mechanisms using the 2667 SDP offer/answer model. 2669 +-------+--------------------------------------+-------+------------+ 2670 | Name | Notes | Level | Mux | 2671 | | | | Category | 2672 +-------+--------------------------------------+-------+------------+ 2673 | rsvp | rsvp attribute MUST be the one that | B | TRANSPORT | 2674 | | corresponds to the "m=" line chosen | | | 2675 | | for setting up the underlying | | | 2676 | | transport flow | | | 2677 | | | | | 2678 | nsis | rsvp attribute MUST be the one that | B | TRANSPORT | 2679 | | corresponds to the "m=" line chosen | | | 2680 | | for setting up the underlying | | | 2681 | | transport | | | 2682 | | | | | 2683 +-------+--------------------------------------+-------+------------+ 2685 10.1 RFC5432 Attribute Analysis 2687 NOTE: A single Differentiated Services Code Point (DSCP) code point 2688 per flow being multiplexed doesn't impact multiplexing since QOS 2689 mechanisms are signaled/scoped per flow. For scenarios that involve 2690 having different DSCP code points for packets being transmitted over 2691 the same 5-tuple, issues as discussed in [RFC7657] need to be taken 2692 into consideration. 2694 11. k= Attribute Analysis 2695 11.1. RFC4566: SDP 2697 [RFC4566] defines SDP that is intended for describing multimedia 2698 sessions for the purposes of session announcement, session 2699 invitation, and other forms of multimedia session initiation. 2701 +------+-----------------------------------------+-------+----------+ 2702 | Name | Notes | Level | Mux | 2703 | | | | Category | 2704 +------+-----------------------------------------+-------+----------+ 2705 | k= | It is not recommended to use this | S | CAUTION | 2706 | | attribute under multiplexing | | | 2707 | | | | | 2708 +------+-----------------------------------------+-------+----------+ 2710 11.1 RFC4566 Attribute Analysis 2712 12. content Attribute Analysis 2714 12.1. RFC4796 2716 [RFC4796] defines a new SDP media-level attribute, 'content'. The 2717 'content' attribute defines the content of the media stream to a more 2718 detailed level than the media description line. The sender of an SDP 2719 session description can attach the 'content' attribute to one or more 2720 media streams. The receiving application can then treat each media 2721 stream differently (e.g., show it on a big or small screen) based on 2722 its content. 2724 +------------------+---------------+-------+--------------+ 2725 | Name | Notes | Level | Mux Category | 2726 +------------------+---------------+-------+--------------+ 2727 | content:slides | Not Impacted | M | NORMAL | 2728 | | | | | 2729 | content:speaker | Not Impacted | M | NORMAL | 2730 | | | | | 2731 | content:main | Not Impacted | M | NORMAL | 2732 | | | | | 2733 | content:sl | Not Impacted | M | NORMAL | 2734 | | | | | 2735 | content:alt | Not Impacted | M | NORMAL | 2736 | | | | | 2737 +------------------+---------------+-------+--------------+ 2739 12.1 RFC4796 Attribute Analysis 2741 13. Payload Formats 2743 13.1. RFC5109: RTP Payload Format for Generic FEC 2745 [RFC5109] describes a payload format for generic Forward Error 2746 Correction (FEC) for media data encapsulated in RTP. It is based on 2747 the exclusive-or (parity) operation. The payload format allows end 2748 systems to apply protection using various protection lengths and 2749 levels, in addition to using various protection group sizes to adapt 2750 to different media and channel characteristics. It enables complete 2751 recovery of the protected packets or partial recovery of the critical 2752 parts of the payload depending on the packet loss situation. 2754 +---------------------+--------------------------+-------+----------+ 2755 | Name | Notes | Level | Mux | 2756 | | | | Category | 2757 +---------------------+--------------------------+-------+----------+ 2758 | audio/ulpfec | Not recommended for | M | CAUTION | 2759 | | multiplexing due to | | | 2760 | | reuse of SSRCs | | | 2761 | | | | | 2762 | video/ulpfec | Not recommended for | M | CAUTION | 2763 | | multiplexing due to | | | 2764 | | reuse of SSRCs | | | 2765 | | | | | 2766 | text/ulpfec | Not recommended for | M | CAUTION | 2767 | | multiplexing due to | | | 2768 | | reuse of SSRCs | | | 2769 | | | | | 2770 | application/ulpfec | Not recommended for | M | CAUTION | 2771 | | multiplexing due to | | | 2772 | | reuse of SSRCs | | | 2773 | | | | | 2774 +---------------------+--------------------------+-------+----------+ 2776 13.1 RFC5109 Payload Format Analysis 2778 14. Multiplexing Considerations for Encapsulating Attributes 2780 This sections deals with recommendations for defining the 2781 multiplexing characteristics of the SDP attributes that encapsulate 2782 other SDP attributes/parameters. Such attributes as of today, for 2783 example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of 2784 a generic framework for indicating and negotiating transport, media, 2785 and media format related capabilities in the SDP. 2787 The behavior of such attributes under multiplexing is in turn defined 2788 by the multiplexing behavior of the attributes they encapsulate which 2789 are made known once the Offer/Answer negotiation process is 2790 completed. 2792 14.1. RFC3407: cpar Attribute Analysis 2794 [RFC3407] capability parameter attribute (a=cpar) encapsulates b= 2795 (bandwidth) or an a= attribute. For bandwidth attribute 2796 encapsulation, the category SUM is inherited. For the case of a= 2797 attribute, the category corresponding to the SDP attribute being 2798 encapsulated is inherited. 2800 v=0 2801 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2802 s= 2803 c=IN IP4 host.atlanta.example.com 2804 t=0 0 2805 m=video 3456 RTP/AVP 100 2806 a=rtpmap:100 VP8/90000 2807 a=sqn: 0 2808 a=cdsc: 1 video RTP/AVP 100 2809 a=cpar: a=rtcp-mux 2810 m=video 3456 RTP/AVP 101 2811 a=rtpmap:101 VP8/90000 2812 a=fmtp:100 max-fr=15;max-fs=1200 2813 a=cdsc: 2 video RTP/AVP 101 2814 a=cpar: a=rtcp-mux 2816 In the above example,the category IDENTICAL is inherited for the cpar 2817 encapsulated rtcp-mux attribute. 2819 14.2. RFC5939 Analysis 2821 [RFC5939] defines a general SDP capability negotiation framework. It 2822 also specifies how to provide transport protocols and SDP attributes 2823 as capabilities and negotiate them using the framework. 2825 For this purpose, [RFC5939] defines the following 2827 o A set of capabilities for the session and its associated media 2828 stream components, supported by each side. The attribute 2829 ("a=acap") defines how to list an attribute name and its 2830 associated value (if any) as a capability. The attribute 2831 ("a=tcap") defines how to list transport protocols (e.g., "RTP/ 2832 AVP") as capabilities. 2834 o A set of potential configurations ("a=pcfg") provided by the 2835 offerer to indicate which combinations of those capabilities can 2836 be used for the session and its associated media stream 2837 components. Potential configurations are not ready for use until 2838 fully negotiated. They provide an alternative that MAY be used, 2839 subject to SDP capability negotiation procedures. In particular 2840 the answerer MAY choose one of the potential configurations for 2841 use as part of the current Offer/Answer exchange. 2843 o An actual configuration ("a=acfg") for the session and its 2844 associated media stream components. The actual configuration 2845 identifies the potential configuration that was negotiated for 2846 use. Use of an actual configuration does not require any further 2847 negotiation. 2849 o A negotiation process that takes the current actual and the set of 2850 potential configurations (combinations of capabilities) as input 2851 and provides the negotiated actual configurations as output. In 2852 [RFC5939] the negotiation process is done independently for each 2853 media description. 2855 14.2.1. Recommendation: Procedures for Potential Configuration Pairing 2857 This section provides recommendations for entities generating and 2858 processing SDP under the generic capability negotiation framework as 2859 defined in [RFC5939] under the context of media stream multiplexing. 2861 These recommendations are provided for the purposes of enabling the 2862 Offerer to make sure that the generated potential configurations 2863 between the multiplexed streams can (easily) be negotiated to be 2864 consistent between those streams. In particular, the procedures aim 2865 to simplify Answerer's procedure to choose potential configurations 2866 that are consistent across all the multiplexed media descriptions. 2868 A potential configuration selects a set of attributes and parameters 2869 that become part of the media description when negotiated. When 2870 multiplexing media descriptions with potential configurations 2871 specified, there MAY be a need for coordinating this selection 2872 between multiplexed media descriptions to ensure the right 2873 multiplexing behavior. 2875 Although it is possible to analyze the various potential 2876 configurations in multiplexed media descriptions to find combinations 2877 that satisfy such constraints, it can quickly become complicated to 2878 do so. 2880 The procedures defined in [RFC5939] state that each potential 2881 configuration in the SDP has a unique configuration number, however 2882 the scope of uniqueness is limited to each media description. To 2883 make it simple for the answerer to chose valid combinations of 2884 potential configurations across media descriptions in a given bundle 2885 group, we provide a simple rule for constructing potential 2886 configurations 2888 o Let m-bundle be the set of media descriptions that form a given 2889 bundle . 2891 o Let m-bundle-pcfg be the set of media descriptions in m-bundle 2892 that include one or more potential configurations. 2894 o Each media description in m-bundle-pcfg MUST have at least one 2895 potential configuration with the same configuration number (e.g. 2896 "1"). 2898 o For each potential configuration with configuration number x in m- 2899 bundle-pcfg, the offerer MUST ensure that if the answerer chooses 2900 configuration number x in each of the media descriptions in m- 2901 bundle-pcfg, then the resulting SDP will have all multiplexing 2902 constraints satisfied for those media descriptions. 2904 o Since it is nearly impossible to define a generic mechanism for 2905 various capability extensions, this document does't provide 2906 procedures for dealing with the capability extension attributes. 2907 However, Section 14.3 provide analysis of media capability 2908 extension attributes as defined in [RFC6871]. 2910 The above allows the answerer to easily find multiplexing compatible 2911 combinations of potential configurations: The answerer simply choses 2912 a potential configuration (number) that is present in all of the 2913 media descriptions with potential configurations in the bundle. 2915 Note that it is still possible for the offerer to provide additional 2916 potential configurations with independent configuration numbers. The 2917 answerer will have to perform more complicated analysis to determine 2918 valid multiplexed combinations of those. 2920 14.2.1.1. Example: Transport Capability Multiplexing 2921 v=0 2922 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2923 s= 2924 c=IN IP4 host.atlanta.example.com 2925 t=0 0 2926 a=tcap:1 RTP/SAVPF 2927 a=tcap:2 RTP/SAVP 2928 a=group:BUNDLE audio video 2929 m=audio 2930 a=mid:audio 2931 a=pcfg:1 t=1 2932 a=pcfg:2 2933 m=video 2934 a=mid:video 2935 a=pcfg:1 t=1 2936 a=pcfg:2 t=2 2938 In the example above, the potential configurations that offer 2939 transport protocol capability of RTP/SAVPF has the same configuration 2940 number "1" in both the audio and video media descriptions. 2942 14.2.1.2. Example: Attribute Capability Multiplexing 2944 v=0 2945 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com 2946 s= 2947 c=IN IP4 host.atlanta.example.com 2948 t=0 0 2949 a=acap:1 a=rtcp-mux 2950 a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80 2951 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32 2952 a=group:BUNDLE audio video 2953 m=audio 49172 RTP/AVP 99 2954 a=mid:audio 2955 a=pcfg:1 a=1 2956 a=pcfg:2 2957 m=video 560024 RTP/AVP 100 2958 a=mid:video 2959 a=pcfg:1 a=1 2960 a=pcfg:2 a=2 2962 In the example above, the potential configuration number "1" is 2963 repeated while referring to attribute capability a=rtcp-mux, since 2964 the behavior is IDENTICAL for the attribute a=rtcp-mux under 2965 multiplexing. 2967 14.3. RFC6871 Analysis 2969 [RFC6871] extends the capability negotiation framework described in 2970 [RFC5939] by defining media capabilities that can be used to indicate 2971 and negotiate media types and their associated format parameters. It 2972 also allows indication of latent configurations and session 2973 capabilities. 2975 14.3.1. Recommendation: Dealing with Payload Type Numbers 2977 [RFC6871] defines a new payload type ("pt") parameter to be used with 2978 the potential, actual, and latent configuration parameters. The 2979 parameter associates RTP payload type numbers with the referenced 2980 RTP-based media format capabilities ("a=rmcap") defined in [RFC6871] 2981 and is appropriate only when the transport protocol uses RTP. This 2982 means that the same payload type number can be assigned as part of 2983 potential or actual configurations in different media descriptions in 2984 a bundle. There are rules for the usage of identical Payload Type 2985 values across multiplexed "m=" lines as described in 2986 [I-D.ietf-mmusic-sdp-bundle-negotiation], which must be followed here 2987 as well. As described in Section 14.2.1, the use of identical 2988 configuration numbers for compatible configurations in different 2989 media descriptions that are part of the bundle provides a way to 2990 ensure that the answerer can easily pick compatible configurations 2991 here as well. 2993 14.3.1.1. Example: Attribute Capability Under Shared Payload Type 2995 The attributes (a=rmcap, a=mfcap) follow the above recommendations 2996 under multiplexing. 2998 v=0 2999 o=- 25678 753849 IN IP4 192.0.2.1 3000 s= 3001 c=IN IP4 192.0.2.1 3002 t=0 0 3003 a=creq:med-v0 3004 m=audio 54322 RTP/AVP 96 3005 a=rtpmap:96 AMR-WB/16000/1 3006 a=fmtp:96 mode-change-capability=1; max-red=220; 3007 mode-set=0,2,4,7 3008 a=rmcap:1,3 audio AMR-WB/16000/1 3009 a=rmcap:2 audio AMR/8000/1 3010 a=mfcap:1,2 mode-change-capability=1 3011 a=mfcap:3 mode-change-capability=2 3012 a=pcfg:1 m=1 pt=1:96 3013 a=pcfg:2 m=2 pt=2:97 3014 a=pcfg:3 m=3 pt=3:98 3015 m=audio 54322 RTP/AVP 96 3016 a=rtpmap:96 AMR-WB/16000/1 3017 a=fmtp:96 mode-change-capability=1; max-red=220; 3018 mode-set=0,2,4,7 3019 a=rmcap:4 audio AMR/8000/1 3020 a=rmcap:5 audio OPUS/48000/2 3021 a=mfcap:5 minptime=40 3022 a=mfcap:4 mode-change-capability=1 3023 a=pcfg:1 m=4 pt=4:97 3024 a=pcfg:4 m=5 pt=5:101 3026 In the example above, the potential configuration number "1" is 3027 repeated when referring to media and media format capability used for 3028 the Payload Type 96. This implies that both the media capability 2 3029 and 4 along with their media format capabilities MUST refer to the 3030 same codec configuration, as per the definition of IDENTICAL-PER-PT. 3032 14.3.2. Recommendation: Dealing with Latent Configurations 3034 [RFC6871] adds the notion of a latent configurations, which provides 3035 configuration information that may be used to guide a subsequent 3036 offer/exchange, e.g. by adding another media stream or use 3037 alternative codec combinations not currently offered. Latent 3038 configurations have configuration numbers which cannot overlap with 3039 the potential configuration numbers [RFC6871]. Supported 3040 combinations of potential and latent configurations are indicated by 3041 use of the "a=sescap" attribute, however use of this attribute is not 3042 recommended with multiplexed media, since it requires the use of 3043 unique configuration numbers across the SDP. Taken together, this 3044 means there is no well-defined way to indicate supported combinations 3045 of latent configurations, or combinations of latent and potential 3046 configurations with multiplexed media. It is still allowed to use 3047 the latent configuration attribute, however the limitations above 3048 will apply. To determine valid combinations, actual negotiation will 3049 have to be attempted subsequently instead. 3051 15. IANA Considerations 3053 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this 3054 document.] 3056 Section 15.1 defines a new subregistry for identifying the initial 3057 registrations for various multiplexing categories applicable, as 3058 proposed in this document. 3060 The IANA is requested to add a new column named "Mux Category" to 3061 several of the subregistries in the "Session Description Protocol 3062 (SDP) Parameters" registry. The tables in Section 15.2 identify name 3063 of an entry in the existing subregistry and specify the value to put 3064 in the new "Mux Category" column of the associated IANA registry. 3065 Any entries in the existing tables that do not have a value for the 3066 "Mux Category" specified in this RFC will get a value of "TBD". 3067 Future specifications can change the "TBD" entries to the correct 3068 value. 3070 15.1. New 'Multiplexing Categories' subregistry 3072 A new sub-registry needs to be defined called the "Multiplexing 3073 Categories", with the following registrations created initially: 3074 "NORMAL", "CAUTION", "IDENTICAL", "TRANSPORT", "SUM", "INHERIT", 3075 "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this document. 3077 Initial value registration for "Multiplexing Categories". 3079 +-------------------------+-----------+ 3080 | Multiplexing Categories | Reference | 3081 +-------------------------+-----------+ 3082 | NORMAL | RFCXXXX | 3083 | CAUTION | RFCXXXX | 3084 | IDENTICAL | RFCXXXX | 3085 | TRANSPORT | RFCXXXX | 3086 | SUM | RFCXXXX | 3087 | INHERIT | RFCXXXX | 3088 | IDENTICAL-PER-PT | RFCXXXX | 3089 | SPECIAL | RFCXXXX | 3090 | TBD | RFCXXXX | 3091 +-------------------------+-----------+ 3092 Further entries can be registered on a first-come first-serve basis. 3093 Each registration needs to indicate the multiplexing category value 3094 to be added to the "Multiplexing Categories" subregistry as defined 3095 in this section. 3097 Such a registration MUST also indicate the applicability of the newly 3098 defined multiplexing category value to various subregistries defined 3099 at "Session Description Protocol (SDP) Parameters". 3101 15.2. 'Mux Category' column for subregistries 3103 Each sub-section identifies a subregistry in the "Session Description 3104 Protocol (SDP) Parameters" registry. The tables list the column that 3105 identifies the SDP attribute name/Token/Value from the corresponding 3106 subregistries and the values to be used for the new "Mux Category" 3107 column to be added. 3109 15.2.1. Table: SDP bwtype 3111 The following values are to be added to the 'SDP bwtype' subregistry 3112 in the "Session Description Protocol (SDP) Parameters" registry. The 3113 references should be updated to point at this RFC as well as the 3114 previous references. 3116 +----------+--------------+ 3117 | SDP Name | Mux Category | 3118 +----------+--------------+ 3119 | CT | NORMAL | 3120 | AS | SUM | 3121 | RS | SUM | 3122 | RR | SUM | 3123 | TIAS | SPECIAL | 3124 +----------+--------------+ 3126 15.2.2. Table: att-field (session level) 3128 The following values are to be added to the "att-field (session 3129 level)" subregistry in the "Session Description Protocol (SDP) 3130 Parameters" registry. The references should be updated to point at 3131 this RFC as well as the previous references. 3133 +---------------------+--------------+ 3134 | SDP Name | Mux Category | 3135 +---------------------+--------------+ 3136 | cat | NORMAL | 3137 | keywds | NORMAL | 3138 | type | NORMAL | 3139 | type:broadcast | NORMAL | 3140 | type:H332 | NORMAL | 3141 | type:meeting | NORMAL | 3142 | type:moderated | NORMAL | 3143 | type:test | NORMAL | 3144 | charset | NORMAL | 3145 | charset:iso8895-1 | NORMAL | 3146 | tool | NORMAL | 3147 | ipbcp | SPECIAL | 3148 | group | NORMAL | 3149 | ice-lite | NORMAL | 3150 | ice-options | NORMAL | 3151 | bcastversion | NORMAL | 3152 | 3GPP-Integrity-Key | CAUTION | 3153 | 3GPP-SDP-Auth | CAUTION | 3154 | alt-group | CAUTION | 3155 | PSCid | NORMAL | 3156 | bc_service | NORMAL | 3157 | bc_program | NORMAL | 3158 | bc_service_package | NORMAL | 3159 | sescap | CAUTION | 3160 | rtsp-ice-d-m | TBD | 3161 +---------------------+--------------+ 3163 15.2.3. Table: att-field (both session and media level) 3165 The following values are to be added to the "att-field (both session 3166 and media level)" subregistry in the "Session Description Protocol 3167 (SDP) Parameters" registry. The references should be updated to 3168 point at this RFC as well as the previous references. 3170 NOTE: The attributes from draft-ietf-rmt-flute-sdp ('flute-tsi', 3171 'flute-ch', 'FEC-declaration', 'FEC-OTI-extension', 'content-desc') 3172 were not analyzed for their multiplexing behavior due to the expired 3173 status of the draft. For purposes of this specification, the 3174 multiplexing category of 'TBD' is assigned. 3176 +-------------------------+-------------------+ 3177 | SDP Name | Mux Category | 3178 +-------------------------+-------------------+ 3179 | recvonly | NORMAL | 3180 | sendrecv | NORMAL | 3181 | sendonly | NORMAL | 3182 | sdplang | NORMAL | 3183 | lang | NORMAL | 3184 | h248item | SPECIAL | 3185 | sqn | NORMAL | 3186 | cdsc | NORMAL | 3187 | cpar | INHERIT | 3188 | cparmin | SPECIAL | 3189 | cparmax | SPECIAL | 3190 | rtcp-xr | NORMAL | 3191 | maxprate | SPECIAL | 3192 | setup | TRANSPORT | 3193 | connection | TRANSPORT | 3194 | key-mgmt | IDENTICAL | 3195 | source-filter | IDENTICAL | 3196 | inactive | NORMAL | 3197 | fingerprint | TRANSPORT | 3198 | flute-tsi | TBD | 3199 | flute-ch | TBD | 3200 | FEC-declaration | TBD | 3201 | FEC-OTI-extension | TBD | 3202 | content-desc | TBD | 3203 | ice-pwd | TRANSPORT | 3204 | ice-ufrag | TRANSPORT | 3205 | stkmstream | NORMAL | 3206 | extmap | SPECIAL | 3207 | qos-mech-send | TRANSPORT | 3208 | qos-mech-recv | TRANSPORT | 3209 | csup | NORMAL | 3210 | creq | NORMAL | 3211 | acap | INHERIT | 3212 | tcap | INHERIT | 3213 | 3GPP-QoE-Metrics | CAUTION | 3214 | 3GPP-Asset-Information | CAUTION | 3215 | mbms-mode | CAUTION | 3216 | mbms-repair | CAUTION | 3217 | ike-setup | IDENTICAL | 3218 | psk-fingerprint | IDENTICAL | 3219 | multicast-rtcp | IDENTICAL | 3220 | rmcap | IDENTICAL-PER-PT | 3221 | omcap | NORMAL | 3222 | mfcap | IDENTICAL-PER-PT | 3223 | mscap | INHERIT | 3224 | 3gpp.iut.replication | TBD | 3225 | bcap | INHERIT | 3226 | ccap | IDENTICAL | 3227 | icap | NORMAL | 3228 | 3gpp_sync_info | NORMAL | 3229 | 3gpp_MaxRecvSDUSize | NORMAL | 3230 | etag | CAUTION | 3231 | duplication-delay | NORMAL | 3232 | range | CAUTION | 3233 | control | CAUTION | 3234 | mtag | CAUTION | 3235 | ts-refclk | NORMAL | 3236 | mediaclk | NORMAL | 3237 | calgextmap | NORMAL | 3238 +-------------------------+-------------------+ 3240 15.2.4. Table: att-field (media level only) 3242 The following values are to be added to the "att-field (media level 3243 only)" registry in the "Session Description Protocol (SDP) 3244 Parameters" registry. The references should be updated to point at 3245 this RFC as well as the previous references. 3247 +---------------------------+-------------------+ 3248 | SDP Name | Mux Category | 3249 +---------------------------+-------------------+ 3250 | ptime | IDENTICAL-PER-PT | 3251 | orient | NORMAL | 3252 | orient:portrait | NORMAL | 3253 | orient:landscape | NORMAL | 3254 | orient:seascape | NORMAL | 3255 | framerate | IDENTICAL-PER-PT | 3256 | quality | NORMAL | 3257 | rtpmap | IDENTICAL-PER-PT | 3258 | fmtp | IDENTICAL-PER-PT | 3259 | rtpred1 | CAUTION | 3260 | rtpred2 | CAUTION | 3261 | T38FaxVersion | TBD | 3262 | T38MaxBitRate | TBD | 3263 | T38FaxFillBitRemoval | TBD | 3264 | T38FaxTranscodingMMR | TBD | 3265 | T38FaxTranscodingJBIG | TBD | 3266 | T38FaxRateManagement | TBD | 3267 | T38FaxMaxBuffer | TBD | 3268 | T38FaxMaxDatagram | TBD | 3269 | T38FaxUdpEC | TBD | 3270 | maxptime | IDENTICAL-PER-PT | 3271 | des | CAUTION | 3272 | curr | CAUTION | 3273 | conf | CAUTION | 3274 | mid | NORMAL | 3275 | rtcp | TRANSPORT | 3276 | rtcp-fb | IDENTICAL-PER-PT | 3277 | label | NORMAL | 3278 | T38VendorInfo | TBD | 3279 | crypto | TRANSPORT | 3280 | eecid | CAUTION | 3281 | aalType | CAUTION | 3282 | capability | CAUTION | 3283 | qosClass | CAUTION | 3284 | bcob | CAUTION | 3285 | stc | CAUTION | 3286 | upcc | CAUTION | 3287 | atmQOSparms | CAUTION | 3288 | atmTrfcDesc | CAUTION | 3289 | abrParms | CAUTION | 3290 | abrSetup | CAUTION | 3291 | bearerType | CAUTION | 3292 | lij | CAUTION | 3293 | anycast | CAUTION | 3294 | cache | CAUTION | 3295 | bearerSigIE | CAUTION | 3296 | aalApp | CAUTION | 3297 | cbrRate | CAUTION | 3298 | sbc | CAUTION | 3299 | clkrec | CAUTION | 3300 | fec | CAUTION | 3301 | prtfl | CAUTION | 3302 | structure | CAUTION | 3303 | cpsSDUsize | CAUTION | 3304 | all2CPS | CAUTION | 3305 | all2CPSSDUrate | CAUTION | 3306 | aal2sscs3661unassured | CAUTION | 3307 | aal2sscs3661assured | CAUTION | 3308 | aal2sscs3662 | CAUTION | 3309 | aal5sscop | CAUTION | 3310 | atmmap | CAUTION | 3311 | silenceSupp | CAUTION | 3312 | ecan | CAUTION | 3313 | gc | CAUTION | 3314 | profileDesc | CAUTION | 3315 | vsel | CAUTION | 3316 | dsel | CAUTION | 3317 | fsel | CAUTION | 3318 | onewaySel | CAUTION | 3319 | codecconfig | CAUTION | 3320 | isup_usi | CAUTION | 3321 | uiLayer1_Prot | CAUTION | 3322 | chain | CAUTION | 3323 | floorctrl | IDENTICAL | 3324 | confid | NORMAL | 3325 | userid | NORMAL | 3326 | floorid | NORMAL | 3327 | FEC | NORMAL | 3328 | accept-types | TBD | 3329 | accept-wrapped-types | TBD | 3330 | max-size | TBD | 3331 | path | TBD | 3332 | dccp-service-code | CAUTION | 3333 | rtcp-mux | IDENTICAL | 3334 | candidate | TRANSPORT | 3335 | ice-mismatch | NORMAL | 3336 | remote-candidates | TRANSPORT | 3337 | SRTPAuthentication | TBD | 3338 | SRTPROCTxRate | TBD | 3339 | rtcp-rsize | IDENTICAL | 3340 | file-selector | TBD | 3341 | file-transfer-id | TBD | 3342 | file-disposition | TBD | 3343 | file-date | TBD | 3344 | file-icon | TBD | 3345 | file-range | TBD | 3346 | depend | IDENTICAL-PER-PT | 3347 | ssrc | NORMAL | 3348 | ssrc-group | NORMAL | 3349 | rtcp-unicast | IDENTICAL | 3350 | pcfg | SPECIAL | 3351 | acfg | SPECIAL | 3352 | zrtp-hash | TRANSPORT | 3353 | X-predecbufsize | CAUTION | 3354 | X-initpredecbufperiod | CAUTION | 3355 | X-initpostdecbufperiod | CAUTION | 3356 | X-decbyterate | CAUTION | 3357 | 3gpp-videopostdecbufsize | CAUTION | 3358 | framesize | CAUTION | 3359 | 3GPP-SRTP-Config | CAUTION | 3360 | alt | CAUTION | 3361 | alt-default-id | CAUTION | 3362 | 3GPP-Adaption-Support | CAUTION | 3363 | mbms-flowid | CAUTION | 3364 | fec-source-flow | SPECIAL | 3365 | fec-repair-flow | SPECIAL | 3366 | repair-window | SPECIAL | 3367 | rams-updates | CAUTION | 3368 | imageattr | IDENTICAL-PER-PT | 3369 | cfw-id | NORMAL | 3370 | portmapping-req | CAUTION | 3371 | g.3gpp.cat | NORMAL | 3372 | g.3gpp.crs | NORMAL | 3373 | ecn-capable-rtp | IDENTICAL | 3374 | visited-realm | TRANSPORT | 3375 | secondary-realm | TRANSPORT | 3376 | omr-s-cksum | NORMAL | 3377 | omr-m-cksum | NORMAL | 3378 | omr-codecs | NORMAL | 3379 | omr-m-att | NORMAL | 3380 | omr-s-att | NORMAL | 3381 | omr-m-bw | NORMAL | 3382 | omr-s-bw | NORMAL | 3383 | msrp-cema | TBD | 3384 | dccp-port | CAUTION | 3385 | resource | NORMAL | 3386 | channel | NORMAL | 3387 | cmid | NORMAL | 3388 | content | NORMAL | 3389 | lcfg | SPECIAL | 3390 | loopback | NORMAL | 3391 | loopback-source | NORMAL | 3392 | loopback-mirror | NORMAL | 3393 | chatroom | TBD | 3394 | altc | TRANSPORT | 3395 | T38FaxMaxIFP | TBD | 3396 | T38FaxUdpECDepth | TBD | 3397 | T38FaxUdpFECMaxSpan | TBD | 3398 | T38ModemType | TBD | 3399 | cs-correlation | TBD | 3400 | rtcp-idms | NORMAL | 3401 +---------------------------+-------------------+ 3403 15.2.5. Table: att-field (source level) 3405 The following values are to be added to the "att-field (source 3406 level)" registry in the "Session Description Protocol (SDP) 3407 Parameters" registry. The references should be updated to point at 3408 this RFC as well as the previous references. 3410 +----------------+-------------------+ 3411 | SDP Name | Mux Category | 3412 +----------------+-------------------+ 3413 | cname | NORMAL | 3414 | previous-ssrc | NORMAL | 3415 | fmtp | IDENTICAL-PER-PT | 3416 | ts-refclk | NORMAL | 3417 | mediaclk | NORMAL | 3418 +----------------+-------------------+ 3420 15.2.6. Table: content SDP Parameters 3422 The following values are to be added to the "content SDP Parameters" 3423 subregistry in the "Session Description Protocol (SDP) Parameters" 3424 registry. The references should be updated to point at this RFC as 3425 well as the previous references. 3427 +----------+--------------+ 3428 | SDP Name | Mux Category | 3429 +----------+--------------+ 3430 | slides | NORMAL | 3431 | speaker | NORMAL | 3432 | sl | NORMAL | 3433 | main | NORMAL | 3434 | alt | NORMAL | 3435 +----------+--------------+ 3437 15.2.7. Table: Semantics for the 'group' SDP Attribute 3439 The following values are to be added to the "Semantics for the 3440 "group" SDP Attribute" subregistry in the "Session Description 3441 Protocol (SDP) Parameters" registry. The references should be 3442 updated to point at this RFC as well as the previous references. 3444 +---------+--------------+ 3445 | Token | Mux Category | 3446 +---------+--------------+ 3447 | LS | NORMAL | 3448 | FID | NORMAL | 3449 | SRF | NORMAL | 3450 | ANAT | CAUTION | 3451 | FEC | NORMAL | 3452 | FEC-FR | NORMAL | 3453 | CS | NORMAL | 3454 | DDP | NORMAL | 3455 | DUP | NORMAL | 3456 +---------+--------------+ 3458 15.2.8. Table: 'rtcp-fb' Attribute Values 3460 The following values are to be added to the " 'rtcp-fb' Attribute 3461 Values" subregistry in the "Session Description Protocol (SDP) 3462 Parameters" registry. The references should be updated to point at 3463 this RFC as well as the previous references. 3465 +------------+-------------------+ 3466 | Value Name | Mux Category | 3467 +------------+-------------------+ 3468 | ack | IDENTICAL-PER-PT | 3469 | app | SPECIAL | 3470 | ccm | IDENTICAL-PER-PT | 3471 | nack | IDENTICAL-PER-PT | 3472 | trr-int | IDENTICAL-PER-PT | 3473 +------------+-------------------+ 3475 15.2.9. Table: 'ack' and 'nack' Attribute Values 3477 The following values are to be added to the " 'ack' and 'nack' 3478 Attribute Values" subregistry in the "Session Description Protocol 3479 (SDP) Parameters" registry. The references should be updated to 3480 point at this RFC as well as the previous references. 3482 +------------+-------------------+ 3483 | Value Name | Mux Category | 3484 +------------+-------------------+ 3485 | sli | IDENTICAL-PER-PT | 3486 | pli | IDENTICAL-PER-PT | 3487 | rpsi | IDENTICAL-PER-PT | 3488 | app | SPECIAL | 3489 | rai | IDENTICAL-PER-PT | 3490 | tllei | IDENTICAL-PER-PT | 3491 | pslei | IDENTICAL-PER-PT | 3492 | ecn | IDENTICAL | 3493 +------------+-------------------+ 3495 15.2.10. Table: 'depend' SDP Attribute Values 3497 The following values are to be added to the " 'depend' SDP Attribute 3498 Values" subregistry in the "Session Description Protocol (SDP) 3499 Parameters" registry. The references should be updated to point at 3500 this RFC as well as the previous references. 3502 +-------+-------------------+ 3503 | Token | Mux Category | 3504 +-------+-------------------+ 3505 | lay | IDENTICAL-PER-PT | 3506 | mdc | IDENTICAL-PER-PT | 3507 +-------+-------------------+ 3509 15.2.11. Table: 'cs-correlation' Attribute Values 3511 The following values are to be added to the " "cs-correlation" 3512 Attribute Values" subregistry in the "Session Description Protocol 3513 (SDP) Parameters" registry. The references should be updated to 3514 point at this RFC as well as the previous references. 3516 +-----------+--------------+ 3517 | Value | Mux Category | 3518 +-----------+--------------+ 3519 | callerid | TBD | 3520 | uuie | TBD | 3521 | dtmf | TBD | 3522 | external | TBD | 3523 +-----------+--------------+ 3525 15.2.12. Table: Semantics for the 'ssrc-group' SDP Attribute 3527 The following values are to be added to the Semantics for the 3528 "Semantics for the "ssrc-group" SDP Attribute" subregistry in the 3529 "Session Description Protocol (SDP) Parameters" registry. The 3530 references should be updated to point at this RFC as well as the 3531 previous references. 3533 +---------+--------------+ 3534 | Token | Mux Category | 3535 +---------+--------------+ 3536 | FID | NORMAL | 3537 | FEC | NORMAL | 3538 | FEC-FR | NORMAL | 3539 | DUP | NORMAL | 3540 +---------+--------------+ 3542 15.2.13. Table: SDP/RTSP key management protocol identifiers 3544 The following values are to be added to the "SDP/RTSP key management 3545 protocol identifiers" subregistry in the "Session Description 3546 Protocol (SDP) Parameters" registry. The references should be 3547 updated to point at this RFC as well as the previous references. 3549 +------------+--------------+ 3550 | Value Name | Mux Category | 3551 +------------+--------------+ 3552 | mikey | IDENTICAL | 3553 +------------+--------------+ 3555 15.2.14. Table: Codec Control Messages 3557 The following values are to be added to the "Codec Control Messages" 3558 subregistry in the "Session Description Protocol (SDP) Parameters" 3559 registry. The references should be updated to point at this RFC as 3560 well as the previous references. 3562 +------------+-------------------+ 3563 | Value Name | Mux Category | 3564 +------------+-------------------+ 3565 | fir | IDENTICAL-PER-PT | 3566 | tmmbr | IDENTICAL-PER-PT | 3567 | tstr | IDENTICAL-PER-PT | 3568 | vbcm | IDENTICAL-PER-PT | 3569 +------------+-------------------+ 3571 15.2.15. Table: QoS Mechanism Tokens 3573 The following values are to be added to the "QoS Mechanism Tokens" 3574 subregistry in the "Session Description Protocol (SDP) Parameters" 3575 registry. The references should be updated to point at this RFC as 3576 well as the previous references. 3578 +---------------+--------------+ 3579 | QoS Mechanism | Mux Category | 3580 +---------------+--------------+ 3581 | rsvp | TRANSPORT | 3582 | nsis | TRANSPORT | 3583 +---------------+--------------+ 3585 15.2.16. Table: SDP Capability Negotiation Option Tags 3587 The following values are to be added to the "SDP Capability 3588 Negotiation Option Tags" subregistry in the "Session Description 3589 Protocol (SDP) Parameters" registry. The references should be 3590 updated to point at this RFC as well as the previous references. 3592 +------------+--------------+ 3593 | Option Tag | Mux Category | 3594 +------------+--------------+ 3595 | cap-v0 | NORMAL | 3596 | med-v0 | NORMAL | 3597 | bcap-v0 | NORMAL | 3598 | ccap-v0 | NORMAL | 3599 | icap-v0 | NORMAL | 3600 +------------+--------------+ 3602 15.2.17. Table: Timestamp Reference Clock Source Parameters 3604 The following values are to be added to the "Timestamp Reference 3605 Clock Source Parameters" subregistry in the "Session Description 3606 Protocol (SDP) Parameters" registry. The references should be 3607 updated to point at this RFC as well as the previous references. 3609 +----------+--------------+ 3610 | Name | Mux Category | 3611 +----------+--------------+ 3612 | ntp | NORMAL | 3613 | ptp | NORMAL | 3614 | gps | NORMAL | 3615 | gal | NORMAL | 3616 | glonass | NORMAL | 3617 | local | NORMAL | 3618 | private | NORMAL | 3619 +----------+--------------+ 3621 15.2.18. Table: Media Clock Source Parameters 3623 The following values are to be added to the "Media Clock Source 3624 Parameters" subegistry in the "Session Description Protocol (SDP) 3625 Parameters" registry. The references should be updated to point at 3626 this RFC as well as the previous references. 3628 +-----------+--------------+ 3629 | Name | Mux Category | 3630 +-----------+--------------+ 3631 | sender | NORMAL | 3632 | direct | NORMAL | 3633 | IEEE1722 | NORMAL | 3634 +-----------+--------------+ 3636 16. Security Considerations 3638 This document does not add any new security considerations beyond the 3639 existing considerations in the RFCs for protocols that are being 3640 multiplexed together. 3642 The ways that SRTP streams are keyed is not believed to create any 3643 two-time pad vulnerability for the currently defined SRTP keying 3644 mechanism. 3646 17. Acknowledgments 3648 I would like to thank Cullen Jennings, Flemming Andreasen for 3649 suggesting the categories, contributing text and reviewing the draft. 3650 I would also link to thank Magnus Westerlund, Christer Holmberg, 3651 Jonathan Lennox, Bo Burman, Ari Keranen, and Dan Wing on suggesting 3652 structural changes helping improve the document readability. 3654 I would like also to thank following experts on their inputs and 3655 reviews as listed - Flemming Andreasen(5.24,5.32,5.33,14), Rohan 3656 Mahy(5.57), Eric Burger(5.26),Christian Huitema(5.14), Christer 3657 Holmberg(5.21,5.26,5.51,5.52), Richard Ejzak (5.44,5.53,5.54), Colin 3658 Perkins(5.7,5.8,5.9,5.58), Magnus 3659 Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Roni 3660 Evens(5.12,5.27,8.4), Subha Dhesikan(5.6,10), Dan 3661 Wing(5.7,5.12,5.35,5.39,5.45), Cullen Jennings (5.40), Ali C 3662 Begen(5.1,5.20,5.22,5.25,5.38,7.3,8.2,8.4,8.6,9.2,13.1), Bo Burman 3663 (7.2,7.6), Charles Eckel(5.15,5.27,5.28,9.1,8.5), Paul Kyzivat(5.24), 3664 Ian Johansson(5.15), Saravanan Shanmugham(5.11), Paul E Jones(5.30), 3665 Rajesh Kumar(5.48), Jonathan Lennox(5.36,5,15,9.1,11.1), Mo 3666 Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Christian Huitema (5.14), Qin 3667 Wu (5.47 PM-Dir review), Hans Stokking(5.43,5.16), Christian Groves 3668 (5.48,5.55), Thomas Stach. 3670 Thanks to Ben Campbell for AD review suggestions. 3672 18. Change Log 3674 [RFC EDITOR NOTE: Please remove this section when publishing] 3676 Changes from draft-ietf-mmusic-sdp-mux-attributes-10 - draft-ietf- 3677 mmusic-sdp-mux-attributes-13 3679 o Incorporated Comments from WGLC review and AD Evaluation 3681 Changes from draft-ietf-mmusic-sdp-mux-attributes-10 3683 o Incorporated Comments from Bo Burman for publication request 3685 Changes from draft-ietf-mmusic-sdp-mux-attributes-08 to draft-ietf- 3686 mmusic-sdp-mux-attributes-10 3688 o Minor nits and version update to advert expiration 3690 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 to draft-ietf- 3691 mmusic-sdp-mux-attributes-08 3692 o Assigned TBD category to all the attributes for whom there exists 3693 no specification on multiplexing behavior over the underlying 3694 transport protocol today. 3696 o Incorporated comments from Flemming and Ari (post last call) 3698 Changes from draft-ietf-mmusic-sdp-mux-attributes-06 3700 o Incorporated last call review comments from Thomas Stach and Ari 3701 Keranen. 3703 o Fixed more nits to prep for the LastCall. 3705 Changes from draft-ietf-mmusic-sdp-mux-attributes-05 3707 o Incorporated review comments from Christian Grooves and Ari 3708 Keranen. 3710 o Fixed more nits to prep for the LastCall. 3712 Changes from draft-ietf-mmusic-sdp-mux-attributes-04 3714 o Fixed minor nits overall. 3716 o Updated Acknowledgement Sections 3718 o Last Call Version. 3720 Changes from draft-ietf-mmusic-sdp-mux-attributes-03 3722 o More re-work on the IANA section. 3724 o Clean ups preparing for the last call. 3726 Changes from draft-ietf-mmusic-sdp-mux-attributes-02 3728 o Incorporated suggestions from Flemming on Capability Negotiation. 3730 o Closed open issues from IETF90 3732 o Added IANA section to list the categories for all the SDP 3733 attributes anlayzed 3735 o Lots of cleanup 3737 o Reformatted Refernces section to use short-form notation 3739 Changes from draft-ietf-mmusic-sdp-mux-attributes-01 3740 o Updated section 15 to provide detailed recommendation on dealing 3741 with encapsulating attributes. Also updated sections 5.20, 5.28, 3742 5.29 to refer to Section 15. 3744 o Added new categories IDENTICAL-PER-PT and INHERIT 3746 o Updated Sections 16 to add the new categories. 3748 o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the 3749 category IDENTICAL-PER-PT. 3751 o Reformatted section 4 to add individual categories to their own 3752 sections. 3754 Changes from draft-ietf-mmusic-sdp-mux-attributes-00 3756 o Added Section 15 to provide recommendations on multiplexing SDP 3757 encapsulating attributes. Also updated sections 5.20, 5.28, 5.29 3758 to refer to Section 15. 3760 o Updated Section 5.38 to incorporate PM-dir review inputs from Qin 3761 Wu 3763 o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more 3764 clarity. 3766 o Fixed few nits regarding sentence clarity and fill-in the NOTES 3767 section where information was lacking. 3769 Changes from draft-nandakumar-mmusic-mux-attributes-05 3771 o Renamed the document to be a WG document. 3773 o Added Section 14. 3775 o Updated Open Issues based on IETF88 discussions. 3777 Changes from draft-nandakumar-mmusic-mux-attributes-04 3779 o Added few OPEN ISSUES that needs to be discussed. 3781 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4, 3782 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1 3784 o Updated Table Column name Current to Level and improved TRANSPORT 3785 category explanation on suggestions form Dan Wing. 3787 o Grouped all the rtcp-fb attribute analysis under a single section 3788 as suggested by Magnus/ 3790 Changes from draft-nandakumar-mmusic-mux-attributes-03 3792 o Maintenance change to clean up grammatical nits and wordings. 3794 Changes from draft-nandakumar-mmusic-mux-attributes-02 3796 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34, 3797 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 3798 the inputs from the respective RFC Authors. 3800 Changes from draft-nandakumar-mmusic-mux-attributes-01 3802 o Replaced Category BAD with NOT-RECOMMENDED. 3804 o Added Category TBD. 3806 o Updated IANA Consideration Section. 3808 Changes from draft-nandakumar-mmusic-mux-attributes-00 3810 o Added new section for dealing with FEC payload types. 3812 19. References 3814 19.1. Normative References 3816 [I-D.ietf-mmusic-sdp-bundle-negotiation] 3817 Holmberg, C., Alvestrand, H., and C. Jennings, 3818 "Negotiating Media Multiplexing Using the Session 3819 Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- 3820 negotiation-24 (work in progress), January 2016. 3822 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3823 Requirement Levels", BCP 14, RFC 2119, March 1997. 3825 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 3826 Description Protocol", RFC 4566, DOI 10.17487/RFC4566, 3827 July 2006, . 3829 19.2. Informative References 3831 [H.248.15] 3832 "Gateway control protocol: SDP H.248 package attribute", 3833 . 3835 [IANA] "Session Description Protocol (SDP) Parameters", 3836 . 3839 [Q.1970] "Q.1970 : BICC IP bearer control protocol", 3840 . 3842 [R3GPPTS183.063] 3843 "TISPAN - IMS based ITPV Stage 3 specification.", 3844 . 3848 [R3GPPTS24.182] 3849 "IP Multimedia Subsystem (IMS) Customized Alerting Tones 3850 (CAT); Protocol specification", 3851 . 3853 [R3GPPTS24.183] 3854 "IP Multimedia Subsystem (IMS) Customized Ringing Signal 3855 (CRS); Protocol specification", 3856 . 3858 [R3GPPTS24.229] 3859 "IP multimedia call control protocol based on Session 3860 Initiation Protocol (SIP) and Session Description Protocol 3861 (SDP);", 3862 . 3864 [R3GPPTS26.114] 3865 "IP multimedia Subsystem : Media Handling and 3866 interaction", . 3868 [RFC2326] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time 3869 Streaming Protocol (RTSP)", RFC 2326, DOI 10.17487/ 3870 RFC2326, April 1998, 3871 . 3873 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the 3874 Session Description Protocol (SDP) for ATM Bearer 3875 Connections", RFC 3108, DOI 10.17487/RFC3108, May 2001, 3876 . 3878 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 3879 with Session Description Protocol (SDP)", RFC 3264, DOI 3880 10.17487/RFC3264, June 2002, 3881 . 3883 [RFC3312] Camarillo, G., Ed., Marshall, W., Ed., and J. Rosenberg, 3884 "Integration of Resource Management and Session Initiation 3885 Protocol (SIP)", RFC 3312, DOI 10.17487/RFC3312, October 3886 2002, . 3888 [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple 3889 Capability Declaration", RFC 3407, DOI 10.17487/RFC3407, 3890 October 2002, . 3892 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to 3893 Resource Reservation Flows", RFC 3524, DOI 10.17487/ 3894 RFC3524, April 2003, 3895 . 3897 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth 3898 Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3899 3556, DOI 10.17487/RFC3556, July 2003, 3900 . 3902 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute 3903 in Session Description Protocol (SDP)", RFC 3605, DOI 3904 10.17487/RFC3605, October 2003, 3905 . 3907 [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., 3908 "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3909 3611, DOI 10.17487/RFC3611, November 2003, 3910 . 3912 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth 3913 Modifier for the Session Description Protocol (SDP)", RFC 3914 3890, DOI 10.17487/RFC3890, September 2004, 3915 . 3917 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network 3918 Address Types (ANAT) Semantics for the Session Description 3919 Protocol (SDP) Grouping Framework", RFC 4091, DOI 3920 10.17487/RFC4091, June 2005, 3921 . 3923 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in 3924 the Session Description Protocol (SDP)", RFC 4145, DOI 3925 10.17487/RFC4145, September 2005, 3926 . 3928 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E. 3929 Carrara, "Key Management Extensions for Session 3930 Description Protocol (SDP) and Real Time Streaming 3931 Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July 3932 2006, . 3934 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session 3935 Description Protocol (SDP) Security Descriptions for Media 3936 Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006, 3937 . 3939 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol 3940 (SDP) Source Filters", RFC 4570, DOI 10.17487/RFC4570, 3941 July 2006, . 3943 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the 3944 Transport Layer Security (TLS) Protocol in the Session 3945 Description Protocol (SDP)", RFC 4572, DOI 10.17487/ 3946 RFC4572, July 2006, 3947 . 3949 [RFC4574] Levin, O. and G. Camarillo, "The Session Description 3950 Protocol (SDP) Label Attribute", RFC 4574, DOI 10.17487/ 3951 RFC4574, August 2006, 3952 . 3954 [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format 3955 for Binary Floor Control Protocol (BFCP) Streams", RFC 3956 4583, DOI 10.17487/RFC4583, November 2006, 3957 . 3959 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 3960 "Extended RTP Profile for Real-time Transport Control 3961 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, DOI 3962 10.17487/RFC4585, July 2006, 3963 . 3965 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description 3966 Protocol (SDP) Content Attribute", RFC 4796, DOI 10.17487/ 3967 RFC4796, February 2007, 3968 . 3970 [RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed., 3971 "The Message Session Relay Protocol (MSRP)", RFC 4975, DOI 3972 10.17487/RFC4975, September 2007, 3973 . 3975 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 3976 "Codec Control Messages in the RTP Audio-Visual Profile 3977 with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104, 3978 February 2008, . 3980 [RFC5109] Li, A., Ed., "RTP Payload Format for Generic Forward Error 3981 Correction", RFC 5109, DOI 10.17487/RFC5109, December 3982 2007, . 3984 [RFC5159] Dondeti, L., Ed. and A. Jerichow, "Session Description 3985 Protocol (SDP) Attributes for Open Mobile Alliance (OMA) 3986 Broadcast (BCAST) Service and Content Protection", RFC 3987 5159, DOI 10.17487/RFC5159, March 2008, 3988 . 3990 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 3991 (ICE): A Protocol for Network Address Translator (NAT) 3992 Traversal for Offer/Answer Protocols", RFC 5245, DOI 3993 10.17487/RFC5245, April 2010, 3994 . 3996 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP 3997 Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July 3998 2008, . 4000 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of 4001 Service (QoS) Mechanism Selection in the Session 4002 Description Protocol (SDP)", RFC 5432, DOI 10.17487/ 4003 RFC5432, March 2009, 4004 . 4006 [RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size 4007 Real-Time Transport Control Protocol (RTCP): Opportunities 4008 and Consequences", RFC 5506, DOI 10.17487/RFC5506, April 4009 2009, . 4011 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., 4012 and P. Kyzivat, "A Session Description Protocol (SDP) 4013 Offer/Answer Mechanism to Enable File Transfer", RFC 5547, 4014 DOI 10.17487/RFC5547, May 2009, 4015 . 4017 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific 4018 Media Attributes in the Session Description Protocol 4019 (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009, 4020 . 4022 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding 4023 Dependency in the Session Description Protocol (SDP)", RFC 4024 5583, DOI 10.17487/RFC5583, July 2009, 4025 . 4027 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 4028 Protocol (RTCP) Extensions for Single-Source Multicast 4029 Sessions with Unicast Feedback", RFC 5760, DOI 10.17487/ 4030 RFC5760, February 2010, 4031 . 4033 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and 4034 Control Packets on a Single Port", RFC 5761, DOI 10.17487/ 4035 RFC5761, April 2010, 4036 . 4038 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control 4039 Protocol (DCCP)", RFC 5762, DOI 10.17487/RFC5762, April 4040 2010, . 4042 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework 4043 for Establishing a Secure Real-time Transport Protocol 4044 (SRTP) Security Context Using Datagram Transport Layer 4045 Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May 4046 2010, . 4048 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description 4049 Protocol (SDP) Grouping Framework", RFC 5888, DOI 4050 10.17487/RFC5888, June 2010, 4051 . 4053 [RFC5939] Andreasen, F., "Session Description Protocol (SDP) 4054 Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939, 4055 September 2010, . 4057 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in 4058 the Session Description Protocol", RFC 5956, DOI 10.17487/ 4059 RFC5956, September 2010, 4060 . 4062 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions 4063 Defined for 3GPP Packet-Switched Streaming Service and 4064 Multimedia Broadcast/Multicast Service", RFC 6064, DOI 4065 10.17487/RFC6064, January 2011, 4066 . 4068 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source- 4069 Specific Multicast (SSM) Sessions", RFC 6128, DOI 4070 10.17487/RFC6128, February 2011, 4071 . 4073 [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: 4074 Media Path Key Agreement for Unicast Secure RTP", RFC 4075 6189, DOI 10.17487/RFC6189, April 2011, 4076 . 4078 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for 4079 the Internet Key Exchange Protocol (IKE) in the Session 4080 Description Protocol (SDP)", RFC 6193, DOI 10.17487/ 4081 RFC6193, April 2011, 4082 . 4084 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media 4085 Control Channel Framework", RFC 6230, DOI 10.17487/ 4086 RFC6230, May 2011, 4087 . 4089 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image 4090 Attributes in the Session Description Protocol (SDP)", RFC 4091 6236, DOI 10.17487/RFC6236, May 2011, 4092 . 4094 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping 4095 between Unicast and Multicast RTP Sessions", RFC 6284, DOI 4096 10.17487/RFC6284, June 2011, 4097 . 4099 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax, 4100 "Unicast-Based Rapid Acquisition of Multicast RTP 4101 Sessions", RFC 6285, DOI 10.17487/RFC6285, June 2011, 4102 . 4104 [RFC6364] Begen, A., "Session Description Protocol Elements for the 4105 Forward Error Correction (FEC) Framework", RFC 6364, DOI 4106 10.17487/RFC6364, October 2011, 4107 . 4109 [RFC6642] Wu, Q., Ed., Xia, F., and R. Even, "RTP Control Protocol 4110 (RTCP) Extension for a Third-Party Loss Report", RFC 6642, 4111 DOI 10.17487/RFC6642, June 2012, 4112 . 4114 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., 4115 and K. Carlberg, "Explicit Congestion Notification (ECN) 4116 for RTP over UDP", RFC 6679, DOI 10.17487/RFC6679, August 4117 2012, . 4119 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection 4120 Establishment for Media Anchoring (CEMA) for the Message 4121 Session Relay Protocol (MSRP)", RFC 6714, DOI 10.17487/ 4122 RFC6714, August 2012, 4123 . 4125 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A 4126 Datagram Congestion Control Protocol UDP Encapsulation for 4127 NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November 4128 2012, . 4130 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control 4131 Protocol Version 2 (MRCPv2)", RFC 6787, DOI 10.17487/ 4132 RFC6787, November 2012, 4133 . 4135 [RFC6849] Kaplan, H., Ed., Hedayat, K., Venna, N., Jones, P., and N. 4136 Stratton, "An Extension to the Session Description 4137 Protocol (SDP) and Real-time Transport Protocol (RTP) for 4138 Media Loopback", RFC 6849, DOI 10.17487/RFC6849, February 4139 2013, . 4141 [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session 4142 Description Protocol (SDP) Media Capabilities 4143 Negotiation", RFC 6871, DOI 10.17487/RFC6871, February 4144 2013, . 4146 [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S. 4147 Veikkolainen, "The Session Description Protocol (SDP) 4148 Alternate Connectivity (ALTC) Attribute", RFC 6947, DOI 4149 10.17487/RFC6947, May 2013, 4150 . 4152 [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman, 4153 "Miscellaneous Capabilities Negotiation in the Session 4154 Description Protocol (SDP)", RFC 7006, DOI 10.17487/ 4155 RFC7006, September 2013, 4156 . 4158 [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping 4159 Semantics in the Session Description Protocol", RFC 7104, 4160 DOI 10.17487/RFC7104, January 2014, 4161 . 4163 [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session 4164 Description Protocol (SDP) Extension for Setting Audio and 4165 Video Media Streams over Circuit-Switched Bearers in the 4166 Public Switched Telephone Network (PSTN)", RFC 7195, DOI 4167 10.17487/RFC7195, May 2014, 4168 . 4170 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay 4171 Attribute in the Session Description Protocol", RFC 7197, 4172 DOI 10.17487/RFC7197, April 2014, 4173 . 4175 [RFC7266] Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control 4176 Protocol (RTCP) Extended Report (XR) Blocks for Mean 4177 Opinion Score (MOS) Metric Reporting", RFC 7266, DOI 4178 10.17487/RFC7266, June 2014, 4179 . 4181 [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O., 4182 Boronat, F., Montagud, M., and K. Gross, "Inter- 4183 Destination Media Synchronization (IDMS) Using the RTP 4184 Control Protocol (RTCP)", RFC 7272, DOI 10.17487/RFC7272, 4185 June 2014, . 4187 [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H. 4188 Stokking, "RTP Clock Source Signalling", RFC 7273, DOI 4189 10.17487/RFC7273, June 2014, 4190 . 4192 [RFC7657] Black, D., Ed. and P. Jones, "Differentiated Services 4193 (Diffserv) and Real-Time Communication", RFC 7657, DOI 4194 10.17487/RFC7657, November 2015, 4195 . 4197 [T.38] "Procedures for real-time Group 3 facsimile communication 4198 over IP networks", . 4200 Author's Address 4202 Suhas Nandakumar 4203 Cisco 4204 170 West Tasman Drive 4205 San Jose, CA 95134 4206 USA 4208 Email: snandaku@cisco.com