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2 Network Working Group S. Nandakumar
3 Internet-Draft Cisco
4 Intended status: Standards Track October 20, 2014
5 Expires: April 23, 2015
7 A Framework for SDP Attributes when Multiplexing
8 draft-ietf-mmusic-sdp-mux-attributes-03
10 Abstract
12 The Session Description Protocol (SDP) provides mechanisms to
13 describe attributes of multimedia sessions and of individual media
14 streams (e.g., Real-time Transport Protocol (RTP) sessions) within a
15 multimedia session. In the RTCWeb WG, there is a need to use a
16 single 5-tuple for sending and receiving media associated with
17 multiple media descriptions ("m=" lines). Such a requirement has
18 raised concerns over the semantic implications of the SDP attributes
19 associated with the RTP Media Streams multiplexed over a single
20 transport layer flow.
22 The scope of this specification is to provide a framework for
23 analyzing the multiplexing characteristics of SDP attributes. The
24 specification also categorizes existing attributes based on the
25 framework described herein.
27 Status of This Memo
29 This Internet-Draft is submitted in full conformance with the
30 provisions of BCP 78 and BCP 79.
32 Internet-Drafts are working documents of the Internet Engineering
33 Task Force (IETF). Note that other groups may also distribute
34 working documents as Internet-Drafts. The list of current Internet-
35 Drafts is at http://datatracker.ietf.org/drafts/current/.
37 Internet-Drafts are draft documents valid for a maximum of six months
38 and may be updated, replaced, or obsoleted by other documents at any
39 time. It is inappropriate to use Internet-Drafts as reference
40 material or to cite them other than as "work in progress."
42 This Internet-Draft will expire on April 23, 2015.
44 Copyright Notice
46 Copyright (c) 2014 IETF Trust and the persons identified as the
47 document authors. All rights reserved.
49 This document is subject to BCP 78 and the IETF Trust's Legal
50 Provisions Relating to IETF Documents
51 (http://trustee.ietf.org/license-info) in effect on the date of
52 publication of this document. Please review these documents
53 carefully, as they describe your rights and restrictions with respect
54 to this document. Code Components extracted from this document must
55 include Simplified BSD License text as described in Section 4.e of
56 the Trust Legal Provisions and are provided without warranty as
57 described in the Simplified BSD License.
59 This document may contain material from IETF Documents or IETF
60 Contributions published or made publicly available before November
61 10, 2008. The person(s) controlling the copyright in some of this
62 material may not have granted the IETF Trust the right to allow
63 modifications of such material outside the IETF Standards Process.
64 Without obtaining an adequate license from the person(s) controlling
65 the copyright in such materials, this document may not be modified
66 outside the IETF Standards Process, and derivative works of it may
67 not be created outside the IETF Standards Process, except to format
68 it for publication as an RFC or to translate it into languages other
69 than English.
71 Table of Contents
73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
74 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
75 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 6
76 4. SDP Attribute Analysis Framework . . . . . . . . . . . . . . 6
77 4.1. Category: NORMAL . . . . . . . . . . . . . . . . . . . . 7
78 4.2. Category: NOT RECOMMENDED . . . . . . . . . . . . . . . . 7
79 4.3. Category: IDENTICAL . . . . . . . . . . . . . . . . . . . 8
80 4.4. Category: SUM . . . . . . . . . . . . . . . . . . . . . . 8
81 4.5. Category: TRANSPORT . . . . . . . . . . . . . . . . . . . 9
82 4.6. Category: INHERIT . . . . . . . . . . . . . . . . . . . . 10
83 4.7. Category: IDENTICAL-PER-PT . . . . . . . . . . . . . . . 10
84 4.8. Category: SPECIAL . . . . . . . . . . . . . . . . . . . . 11
85 4.9. Category: TBD . . . . . . . . . . . . . . . . . . . . . . 11
86 5. Analysis of Existing Attributes . . . . . . . . . . . . . . . 11
87 5.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 12
88 5.2. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 13
89 5.3. RFC5761 - Multiplexing RTP and RTCP . . . . . . . . . . . 14
90 5.4. RFC3312 - Integration of Resource Management and (SIP) . 14
91 5.5. RFC4574 - SDP Label Attribute . . . . . . . . . . . . . . 15
92 5.6. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 15
93 5.7. RFC4568 - SDP Security Descriptions . . . . . . . . . . . 16
94 5.8. RFC5762 - RTP over DCCP . . . . . . . . . . . . . . . . . 16
95 5.9. RFC6773 - DCCP-UDP Encapsulation . . . . . . . . . . . . 17
96 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile . . . . . . . 18
97 5.11. RFC6787 - Media Resource Control Protocol Version 2 . . . 18
98 5.12. RFC5245 - Interactive Connectivity Establishment (ICE) . 19
99 5.13. RFC5285 - RTP Header Extensions . . . . . . . . . . . . . 20
100 5.14. RFC3605 - RTCP attribute in SDP . . . . . . . . . . . . . 21
101 5.15. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 21
102 5.16. RFC7273 - RTP Clock Source Signalling . . . . . . . . . . 22
103 5.17. RFC6236 - Image Attributes in SDP . . . . . . . . . . . . 23
104 5.18. RFC7197 - Duplication Delay Attribute in SDP . . . . . . 23
105 5.19. RFC7226 - RTCP XR Blocks for MOS Metric Reporting . . . 23
106 5.20. RFC6285 - Rapid Acquisition of Multicast RTP Sessions . . 24
107 5.21. RFC6230 - Media Control Channel Framework . . . . . . . . 24
108 5.22. RFC6364 - SDP Elements for FEC Framework . . . . . . . . 25
109 5.23. RFC4796 - Content Attribute . . . . . . . . . . . . . . . 25
110 5.24. RFC3407 - SDP Simple Capability Declaration . . . . . . . 25
111 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP
112 Sessions . . . . . . . . . . . . . . . . . . . . . . . . 26
113 5.26. RFC6714 - MSRP-CEMA . . . . . . . . . . . . . . . . . . . 26
114 5.27. RFC4583 - SDP Format for BFCP Streams . . . . . . . . . . 27
115 5.28. RFC5547 - SDP Offer/Answer for File Transfer . . . . . . 27
116 5.29. RFC6489 - SDP and RTP Media Loopback Extension . . . . . 28
117 5.30. RFC5760 - RTCP with Unicast Feedback . . . . . . . . . . 28
118 5.31. RFC3611 - RTCP XR . . . . . . . . . . . . . . . . . . . . 29
119 5.32. RFC5939 - SDP Capability Negotiation . . . . . . . . . . 29
120 5.33. RFC6871- SDP Media Capabilities Negotiation . . . . . . . 30
121 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP . . 31
122 5.35. RFC4567 - Key Management Extensions for SDP and RTSP . . 32
123 5.36. RFC4572 - Comedia over TLS in SDP . . . . . . . . . . . . 33
124 5.37. RFC4570 - SDP Source Filters . . . . . . . . . . . . . . 33
125 5.38. RFC6128 - RTCP Port for Multicast Sessions . . . . . . . 34
126 5.39. RFC6189 - ZRTP . . . . . . . . . . . . . . . . . . . . . 34
127 5.40. RFC4145 - Connection-Oriented Media . . . . . . . . . . . 35
128 5.41. RFC6947 - The SDP ALTC Attribute . . . . . . . . . . . . 35
129 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers
130 in PSTN . . . . . . . . . . . . . . . . . . . . . . . . . 36
131 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP) . . 36
132 5.44. RFC5159 - OMA BCAST SDP Attributes . . . . . . . . . . . 37
133 5.45. RFC6193 - Media Description for IKE in SDP . . . . . . . 37
134 5.46. RFC6064 - SDP and RTSP Extensions for 3GPP . . . . . . . 38
135 5.47. RFC3108 - ATM SDP . . . . . . . . . . . . . . . . . . . . 41
136 5.48. 3GPP TS 26.114 . . . . . . . . . . . . . . . . . . . . . 42
137 5.49. 3GPP TS 24.182 . . . . . . . . . . . . . . . . . . . . . 43
138 5.50. 3GPP TS 24.183 . . . . . . . . . . . . . . . . . . . . . 43
139 5.51. 3GPP TS 24.229 . . . . . . . . . . . . . . . . . . . . . 43
140 5.52. ITU T.38 . . . . . . . . . . . . . . . . . . . . . . . . 44
141 5.53. ITU-T-REC.Q1970 . . . . . . . . . . . . . . . . . . . . . 45
142 5.54. ITU-T H.248.15 . . . . . . . . . . . . . . . . . . . . . 46
143 5.55. RFC4975 - The Message Session Relay Protocol . . . . . . 46
144 5.56. Historical . . . . . . . . . . . . . . . . . . . . . . . 47
146 6. bwtype Attribute Analysis . . . . . . . . . . . . . . . . . . 48
147 6.1. RFC4566 - SDP: Session Description Protocol . . . . . . . 48
148 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth . . 48
149 6.3. RFC3890 - Bandwidth Modifier for SDP . . . . . . . . . . 49
150 7. rtcp-fb Attribute Analysis . . . . . . . . . . . . . . . . . 50
151 7.1. RFC4585 - RTP/AVPF . . . . . . . . . . . . . . . . . . . 50
152 7.2. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 51
153 7.3. RFC6285 - Unicast-Based RAMS . . . . . . . . . . . . . . 52
154 7.4. RFC6679 - ECN for RTP over UDP/IP . . . . . . . . . . . . 52
155 7.5. RFC6642 - Third-Party Loss Report . . . . . . . . . . . . 53
156 7.6. RFC5104 - Codec Control Messages in AVPF . . . . . . . . 54
157 8. group Attribute Analysis . . . . . . . . . . . . . . . . . . 54
158 8.1. RFC5888 - SDP Grouping Framework . . . . . . . . . . . . 54
159 8.2. RFC3524 - Mapping Media Streams to Resource
160 Reservation Flows . . . . . . . . . . . . . . . . . . . . 55
161 8.3. RFC4091 - ANAT Semantics . . . . . . . . . . . . . . . . 55
162 8.4. RFC5956 - FEC Grouping Semantics in SDP . . . . . . . . . 55
163 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP . . 56
164 8.6. RFC7104 - Duplication Grouping Semantics in the SDP . . 56
165 9. ssrc-group Attribute Analysis . . . . . . . . . . . . . . . . 57
166 9.1. RFC5576 - Source-Specific SDP Attributes . . . . . . . . 57
167 9.2. RFC7104 - Duplication Grouping Semantics in the SDP . . . 57
168 10. QoS Mechanism Token Analysis . . . . . . . . . . . . . . . . 57
169 10.1. RFC5432 - QoS Mechanism Selection in SDP . . . . . . . . 57
170 11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . . 58
171 11.1. RFC4566 SDP: Session Description Protocol . . . . . . . 58
172 12. content Atribute Analysis . . . . . . . . . . . . . . . . . . 58
173 12.1. RFC4796 . . . . . . . . . . . . . . . . . . . . . . . . 58
174 13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . . 59
175 13.1. RFC5109 - RTP Payload Format for Generic FEC . . . . . . 59
176 14. Multiplexing Considerations for Encapsulating
177 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 59
178 14.1. RFC3407 - cpar Attribute Analysis . . . . . . . . . . . 60
179 14.2. RFC5939 Analysis . . . . . . . . . . . . . . . . . . . . 60
180 14.2.1. Recommendation - Procedures for Potential
181 Configuration Pairing . . . . . . . . . . . . . . . 61
182 14.2.1.1. Example: Transport Capability Multiplexing . . . 62
183 14.2.1.2. Example: Attribute Capability Multiplexing . . . 63
184 14.3. RFC6871 Analysis . . . . . . . . . . . . . . . . . . . . 64
185 14.3.1. Recommendation: Dealing with Payload Type Numbers . 64
186 14.3.1.1. Example: Attribute Capability Under Shared
187 Payload Type . . . . . . . . . . . . . . . . . . 64
188 14.3.2. Recommendation: Dealing with Latent Configurations . 65
189 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 66
190 15.1. New Column 'Mux Category' . . . . . . . . . . . . . . . 66
191 15.2. 'Mux Category' values for SDP Registries . . . . . . . . 67
192 15.2.1. Table: SDP bwtype . . . . . . . . . . . . . . . . . 67
193 15.2.2. Table: att-field . . . . . . . . . . . . . . . . . . 68
194 15.2.3. Table: content SDP Parameters . . . . . . . . . . . 73
195 15.2.4. Table: Semantics for the 'group' SDP Attribute . . . 73
196 15.2.5. Table: 'rtcp-fb' Attribute Values . . . . . . . . . 74
197 15.2.6. Table: 'ack' and 'nack' Attribute Values . . . . . . 74
198 15.2.7. Table: 'depend' SDP Attribute Values . . . . . . . . 75
199 15.2.8. Table: 'cs-correlation' Attribute Values . . . . . . 75
200 15.2.9. Table: Semantics for the 'ssrc-group' SDP Attribute 75
201 15.2.10. Table: SDP/RTSP key management protocol identifiers 76
202 15.2.11. Table: Codec Control Messages . . . . . . . . . . . 76
203 15.2.12. Table: QoS Mechanism Tokens . . . . . . . . . . . . 76
204 15.2.13. Table: SDP Capability Negotiation Option Tags . . . 77
205 15.2.14. Table: Timestamp Reference Clock Source Parameters . 77
206 15.2.15. Table: Media Clock Source Parameters . . . . . . . . 77
207 16. Security Considerations . . . . . . . . . . . . . . . . . . . 78
208 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 78
209 18. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 78
210 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 80
211 19.1. Normative References . . . . . . . . . . . . . . . . . . 80
212 19.2. Informative References . . . . . . . . . . . . . . . . . 81
213 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 87
215 1. Introduction
217 Real-Time Communication Web (RTCWeb) framework requires Real-time
218 Transport Protocol (RTP) as the media transport protocol and Session
219 Description Protocol (SDP) [RFC4566] for describing and negotiating
220 multi-media communication sessions.
222 SDP defines several attributes for capturing characteristics that
223 apply to the individual media descriptions (described by "m=" lines")
224 and the overall multimedia session. Typically different media types
225 (audio, video etc) described using different media descriptions
226 represent separate RTP Sessions that are carried over individual
227 transport layer flows. However in the IETF RTCWEB WG, a need to use
228 a single 5-tuple for sending and receiving media associated with
229 multiple SDP media descriptions ("m=" lines) has been identified.
230 This would e.g. allow the usage of a single set of Interactive
231 Connectivity Establishment (ICE) [RFC5245] candidates for multiple
232 media descriptions. This in turn has made necessary to understand
233 the interpretation and usage of the SDP attributes defined for the
234 multiplexed media descriptions.
236 Given the number of SDP attributes registered with the IANA [IANA]
237 and possibility of new attributes being defined in the future, there
238 is need for generic future-proof framework to analyze these
239 attributes for their applicability in the transport multiplexing use-
240 cases.
242 The document starts with providing the motivation for requiring such
243 a framework. This is followed by introduction to the SDP attribute
244 analysis framework/procedures, following which several sections
245 applies the framework to the SDP attributes registered with the IANA
246 [IANA]
248 2. Terminology
250 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
251 "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
252 interpreted as described in [RFC2119].
254 3. Motivation
256 The time and complications of setting up ICE [RFC5245] and DTLS-SRTP
257 [RFC5763] transports for use by RTP, and conservation of ports, forms
258 an requirement to try and reduce the number of transport level flows
259 needed. This has resulted in the definition of ways, such as,
260 [I-D.ietf-mmusic-sdp-bundle-negotiation] to multiplex RTP over a
261 single transport flow in order to preserve network resources such as
262 port numbers. This imposes further restrictions on applicability of
263 these SDP attributes as they are defined today.
265 The specific problem is that there are attribute combinations which
266 make sense when specified on independent m-lines -- as with classical
267 SDP -- that do not make sense when those m-lines are then multiplexed
268 over the same transport. To give an obvious example, ICE permits
269 each m=line to have an independently specified ice-ufrag attribute.
270 However, if the media from multiple m-lines is multiplexed over the
271 same ICE component, then the meaning of media-level ice-ufrag
272 attributes becomes muddled.
274 As of today there are close to 250 SDP attributes registered with the
275 IANA [IANA] and more will be added in the future. There is no
276 clearly defined procedure to establish the validity/applicability of
277 these attribute when used with transport multiplexing.
279 4. SDP Attribute Analysis Framework
281 Attributes in an SDP session description can be defined at the
282 session-level and media-level. These attributes could be
283 semantically grouped as noted below.
285 o Attributes related to media content such as media type, encoding
286 schemes, payload types.
288 o Attributes specifying media transport characteristics like RTP/
289 RTCP port numbers, network addresses, QOS.
291 o Metadata description attributes capturing session timing and
292 origin information.
294 o Attributes establishing relationships between media streams such
295 as grouping framework
297 With the above semantic grouping as the reference, the proposed
298 framework classifies each attribute into one of the following
299 categories:
301 4.1. Category: NORMAL
303 Attributes that can be independently specified when multiplexing and
304 retain their original semantics.
306 In the example given below, the direction and label attributes are
307 independently specified for audio and video m=lines. These
308 attributes are not impacted by multiplexing these media streams over
309 a single transport layer flow.
311 v=0
312 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
313 s=
314 c=IN IP4 host.atlanta.example.com
315 t=0 0
316 m=audio 49172 RTP/AVP 99
317 a=sendonly
318 a=label:1
319 a=rtpmap:99 iLBC/8000
320 m=video 49172 RTP/AVP 31
321 a=recvonly
322 a=label:2
323 a=rtpmap:31 H261/90000
325 4.2. Category: NOT RECOMMENDED
327 Attributes that are recommended against multiplexing since their
328 usage under multiplexing might lead to incorrect behavior.
330 Example: Multiplexing media descriptions having attribute zrtp-hash
331 defined with the media descriptions lacking it, would either
332 complicate the handling of multiplexed streams or might fail
333 multiplexing altogether.
335 v=0
336 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
337 s=
338 c=IN IP4 client.biloxi.example.com
339 t=0 0
340 m=audio 3456 RTP/AVP 97 // with zrtp
341 a=rtpmap:97 iLBC/8000
342
343 a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2
344 df881ae642c371ba46df
345
346 m=video 34567 RTP/AVP 31 //without zrtp
347 a=rtpmap:31 H261/90000
349 4.3. Category: IDENTICAL
351 Attributes that MUST be identical across all the media descriptions
352 being multiplexed.
354 Attributes such as rtcp-mux fall into this category. Since RTCP
355 reporting is done per RTP Session, RTCP Multiplexing MUST to enabled
356 for both the audio and video m=lines in the example below if they are
357 transported over a single 5-tuple.
359 v=0
360 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
361 s=
362 c=IN IP4 client.biloxi.example.com
363 t=0 0
364 m=audio 34567 RTP/AVP 97
365 a=rtcp-mux
366 m=video 34567 RTP/AVP 31
367 a=rtpmap:31 H261/90000
368 a=rtcp-mux
370 4.4. Category: SUM
372 Attributes can be set as they are normally used but software using
373 them in a multiplex case, MUST apply the sum of all the attributes
374 being multiplexed instead of trying to use each one. This is
375 typically used for bandwidth or other rate limiting attributes to the
376 underlining transport.
378 The software parsing the SDP sample below, should use the aggregate
379 Application Specific (AS) bandwidth value from the individual media
380 descriptions to determine the AS value for the multiplexed session.
381 Thus the calculated AS value would be 256+64 bytes for the given
382 example.
384 v=0
385 o=test 2890844526 2890842807 IN IP4 126.16.64.4
386 c=IN IP4 client.biloxi.example.com
387 t=0 0
388 m=audio 49170 RTP/AVP 0
389 b=AS:64
390 m=video 51372 RTP/AVP 31
391 b=AS:256
393 4.5. Category: TRANSPORT
395 Attributes that can be set normally for multiple items in a
396 multiplexed group but the software MUST pick just one of the
397 attribute of the given type for use. The one chosen is the attribute
398 associated with the "m=" line that represents the information being
399 used for the transport of the RTP.
401 In the example below, "a=crypto" attribute is defined for both the
402 audio and the video m=lines. The video media line's a=crypto
403 attribute is chosen since its mid value (bar) appears first in the
404 a=group:BUNDLE line. This is due to BUNDLE grouping semantic
405 [I-D.ietf-mmusic-sdp-bundle-negotiation] which mandates the values
406 from m=line corresponding to the mid appearing first on the
407 a=group:BUNDLE line to be considered for setting up the RTP
408 Transport.
410 v=0
411 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
412 s=
413 c=IN IP4 host.atlanta.example.com
414 t=0 0
415 a=group:BUNDLE bar foo
416 m=audio 49172 RTP/AVP 99
417 a=mid:foo
418 a=crypto:1 AES_CM_128_HMAC_SHA1_80
419 inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32
420 a=rtpmap:99 iLBC/8000
421 m=video 51374 RTP/AVP 31
422 a=mid:bar
423 a=crypto:1 AES_CM_128_HMAC_SHA1_80
424 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32
425 a=rtpmap:96 H261/90000
427 4.6. Category: INHERIT
429 Attributes that encapsulate other SDP attributes or parameters.
430 These attributes inherit their multiplexing characteristics from the
431 attributes or parameters they encapsulate. Such attributes as of
432 today, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of a
433 generic framework for indicating and negotiating transport, media and
434 media format related capabilities in the SDP.
436 The inheritance manifests itself when the encapsulated attribute or
437 parameter is being leveraged. In the case of SDP Capability
438 Negotiation [RFC5939] for example, this occurs when a capability
439 (encapsulating attribute) is used as part of a configuration; the
440 configuration inherits the multiplexing Category of each of its
441 constituent (encapsulated) attributes and parameters. This in turn
442 may place constraints on what constitutes a valid configuartion from
443 a multiplexing point of view, e.g. because some attributes must be
444 IDENTICAL (see Section 15 for further details).
446 v=0
447 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
448 s=
449 c=IN IP4 host.atlanta.example.com
450 t=0 0
451 m=video 3456 RTP/AVP 100
452 a=rtpmap:100 VP8/90000
453 a=fmtp:100 max-fr=30;max-fs=8040
454 a=sqn: 0
455 a=cdsc: 1 video RTP/AVP 100
456 a=cpar: a=rtcp-mux
457 m=video 3456 RTP/AVP 101
458 a=rtpmap:101 VP8/90000
459 a=fmtp:100 max-fr=15;max-fs=1200
460 a=cdsc: 2 video RTP/AVP 101
461 a=cpar: a=rtcp-mux
463 In the above example , the category IDENTICAL is inherited for the
464 cpar encapsulated rtcp-mux attribute.
466 4.7. Category: IDENTICAL-PER-PT
468 Attributes that define the RTP payload configuration on per Payload
469 Type basis and MUST have identical values across all the media
470 descriptions for a given RTP Payload Type when repeated.
472 In the SDP example below, Payload Types 96 and 97 are repeated across
473 all the video m= lines and all the payload specific parameters (ex:
474 rtpmap, fmtp) are identical.
476 v=0
477 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
478 s=
479 c=IN IP4 host.atlanta.example.com
480 t=0 0
481 a=group:BUNDLE cam1, cam2
482 m = video 96 97
483 a=mid:cam1
484 a=rtpmap:96 H264/90000
485 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000;
486 max-mbps=108000; max-br=1000
487 a=rtpmap:97 H264/90000
488 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000;
489 max-mbps=7200; max-br=200
490 m = video 96 97
491 a=mid:cam2
492 a=rtpmap:96 H264/90000
493 a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000;
494 max-mbps=108000; max-br=1000
495 a=rtpmap:97 H264/90000
496 a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000;
497 max-mbps=7200; max-br=200
499 4.8. Category: SPECIAL
501 Attributes where the text in the source draft must be consulted for
502 further handling when multiplexed.
504 As an example, for the attribute extmap, the specification defining
505 the extension MUST be referred to understand the multiplexing
506 implications.
508 4.9. Category: TBD
510 Attributes that have not been analyzed under the proposed
511 multiplexing framework yet.
513 5. Analysis of Existing Attributes
515 This section analyzes attributes listed in IANA [IANA] grouped under
516 the IETF document that defines them. The "Level" column indicates
517 whether the attribute is currently specified as:
519 o S -- Session level
521 o M -- Media level
522 o B -- Both
524 o SR -- Source-level (for a single SSRC)
526 5.1. RFC4566 - SDP: Session Description Protocol
528 [RFC4566] defines the Session Description Protocol (SDP) that is
529 intended for describing multimedia sessions for the purposes of
530 session announcement, session invitation, and other forms of
531 multimedia session initiation
533 +-----------------+---------------------+-------+-------------------+
534 | Attr Name | Notes | Level | Category |
535 +-----------------+---------------------+-------+-------------------+
536 | sendrecv | Not impacted | B | NORMAL |
537 | | | | |
538 | sendonly | Not impacted | B | NORMAL |
539 | | | | |
540 | recvonly | Not impacted | B | NORMAL |
541 | | | | |
542 | inactive | Not impacted | B | NORMAL |
543 | | | | |
544 | cat | Not impacted | S | NORMAL |
545 | | | | |
546 | ptime | The attribute value | M | IDENTICAL-PER-PT |
547 | | must be same for a | | |
548 | | given codec | | |
549 | | configuration | | |
550 | | | | |
551 | maxptime | The attribute value | M | IDENTICAL-PER-PT |
552 | | must be same for a | | |
553 | | given codec | | |
554 | | configuration | | |
555 | | | | |
556 | orient | Not Impacted | M | NORMAL |
557 | | | | |
558 | framerate | The attribute value | M | IDENTICAL-PER-PT |
559 | | must be same for a | | |
560 | | given codec | | |
561 | | configuration | | |
562 | | | | |
563 | quality | Not Impacted | M | NORMAL |
564 | | | | |
565 | rtpmap | The attribute value | M | IDENTICAL-PER-PT |
566 | | must be same for a | | |
567 | | given codec | | |
568 | | configuration | | |
569 | | | | |
570 | fmtp | The attribute value | M | IDENTICAL-PER-PT |
571 | | must be same for a | | |
572 | | given codec | | |
573 | | configuration | | |
574 | | | | |
575 | keywds | Not impacted | S | NORMAL |
576 | | | | |
577 | type | Not Impacted | S | NORMAL |
578 | | | | |
579 | type:broadcast | Not Impacted | S | NORMAL |
580 | | | | |
581 | type:H332 | Not Impacted | S | NORMAL |
582 | | | | |
583 | type:meeting | Not Impacted | S | NORMAL |
584 | | | | |
585 | type:moderated | Not Impacted | S | NORMAL |
586 | | | | |
587 | type:test | Not Impacted | S | NORMAL |
588 | | | | |
589 | tool | Not Impacted | S | NORMAL |
590 | | | | |
591 | charset | Not Impacted | S | NORMAL |
592 | | | | |
593 | sdplang | Not Impacted | B | NORMAL |
594 | | | | |
595 | lang | Not Impacted | B | NORMAL |
596 | | | | |
597 +-----------------+---------------------+-------+-------------------+
599 RFC4566 Attribute Analysis
601 5.2. RFC4585 - RTP/AVPF
603 [RFC4585] defines an extension to the Audio-visual Profile (AVP) that
604 enables receivers to provide, statistically, more immediate feedback
605 to the senders and thus allows for short-term adaptation and
606 efficient feedback-based repair mechanisms to be implemented.
608 +----------+----------------------------+-------+-------------------+
609 | Attr | Notes | Level | Category |
610 | Name | | | |
611 +----------+----------------------------+-------+-------------------+
612 | rtcp-fb | Since RTCP feedback | M | IDENTICAL-PER-PT |
613 | | attributes are Payload | | |
614 | | Type (PT) scoped, their | | |
615 | | values MUST be identical | | |
616 | | for a given PT across the | | |
617 | | multiplexed m=lines. | | |
618 | | | | |
619 +----------+----------------------------+-------+-------------------+
621 RFC4585 Attribute Analysis
623 5.3. RFC5761 - Multiplexing RTP and RTCP
625 [RFC5761] discusses issues that arise when multiplexing RTP data
626 packets and RTP Control Protocol (RTCP) packets on a single UDP port.
627 It describes when such multiplexing is and is not appropriate, and it
628 explains how the Session Description Protocol (SDP) can be used to
629 signal multiplexed sessions.
631 +-----------+----------------------------------+-------+------------+
632 | Name | Notes | Level | Category |
633 +-----------+----------------------------------+-------+------------+
634 | rtcp-mux | RTP and RTCP Multiplexing | M | IDENTICAL |
635 | | affects the entire RTP Session | | |
636 | | | | |
637 +-----------+----------------------------------+-------+------------+
639 RFC5761 Attribute Analysis
641 5.4. RFC3312 - Integration of Resource Management and (SIP)
643 [RFC3312] defines a generic framework for preconditions, which are
644 extensible through IANA registration. This document also discusses
645 how network quality of service can be made a precondition for
646 establishment of sessions initiated by the Session Initiation
647 Protocol (SIP). These preconditions require that the participant
648 reserve network resources before continuing with the session.
650 +-------+-----------------------+-------+-----------------+
651 | Name | Notes | Level | Category |
652 +-------+-----------------------+-------+-----------------+
653 | des | Refer to notes below | M | NOT RECOMMEDED |
654 | | | | |
655 | conf | Refer to notes below | M | NOT RECOMMEDED |
656 | | | | |
657 | curr | Refer to notes below | M | NOT RECOMMEDED |
658 | | | | |
659 +-------+-----------------------+-------+-----------------+
661 RFC3312 Attribute Analysis
663 A mismatched set of Preconditions across media descriptions results
664 in Session establishment failures due to inability to meet the right
665 resource reservations requested.
667 5.5. RFC4574 - SDP Label Attribute
669 [RFC4574] defines a new Session Description Protocol (SDP) media-
670 level attribute: "label". The "label" attribute carries a pointer to
671 a media stream in the context of an arbitrary network application
672 that uses SDP. The sender of the SDP document can attach the "label"
673 attribute to a particular media stream or streams. The application
674 can then use the provided pointer to refer to each particular media
675 stream in its context.
677 +--------+---------------+-------+----------+
678 | Name | Notes | Level | Category |
679 +--------+---------------+-------+----------+
680 | label | Not Impacted | M | NORMAL |
681 | | | | |
682 +--------+---------------+-------+----------+
684 RFC4574 Attribute Analysis
686 5.6. RFC5432 - QoS Mechanism Selection in SDP
688 [RFC5432] defines procedures to negotiate QOS mechanisms using the
689 Session Description Protocol (SDP) offer/answer model.
691 +----------------+-------------------------------+-------+----------+
692 | Name | Notes | Level | Category |
693 +----------------+-------------------------------+-------+----------+
694 | qos-mech-send | A single DSCP code point per | B | NORMAL |
695 | | flow being multiplexed | | |
696 | | doesn't impact multiplexing | | |
697 | | since QOS mechanisms are | | |
698 | | signaled/scoped per flow. | | |
699 | | | | |
700 | qos-mech-recv | A single DSCP code point per | B | NORMAL |
701 | | flow being multiplexed | | |
702 | | doesn't impact multiplexing | | |
703 | | since QOS mechanisms are | | |
704 | | signaled/scoped per flow. | | |
705 | | | | |
706 +----------------+-------------------------------+-------+----------+
708 RFC5432 Attribute Analysis
710 For scenarios that involves having different DSCP for packets being
711 transmitted over the same 5-tuple, i.e. what is being in the same
712 bundle, has issues as discussed in [I.D-draft-ietf-dart-dscp-rtp]
714 5.7. RFC4568 - SDP Security Descriptions
716 [RFC4568] defines a Session Description Protocol (SDP) cryptographic
717 attribute for unicast media streams. The attribute describes a
718 cryptographic key and other parameters that serve to configure
719 security for a unicast media stream in either a single message or a
720 roundtrip exchange.
722 +---------+------------------------------------+-------+------------+
723 | Name | Notes | Level | Category |
724 +---------+------------------------------------+-------+------------+
725 | crypto | crypto attribute must be the one | M | TRANSPORT |
726 | | that corresponds to the m=line | | |
727 | | chosen for setting up the | | |
728 | | underlying transport flow | | |
729 | | | | |
730 +---------+------------------------------------+-------+------------+
732 RFC4568 Attribute Analysis
734 5.8. RFC5762 - RTP over DCCP
736 The Real-time Transport Protocol (RTP) is a widely used transport for
737 real-time multimedia on IP networks. The Datagram Congestion Control
738 Protocol (DCCP) is a transport protocol that provides desirable
739 services for real-time applications. [RFC5762] specifies a mapping
740 of RTP onto DCCP, along with associated signaling, such that real-
741 time applications can make use of the services provided by DCCP
743 +--------------------+---------------------+---------+--------------+
744 | Name | Notes | Current | Category |
745 +--------------------+---------------------+---------+--------------+
746 | dccp-service-code | If RFC6773 is not | M | NOT |
747 | | being used in | | RECOMMENDED |
748 | | addition to | | |
749 | | RFC5762, the port | | |
750 | | in the m= line is a | | |
751 | | DCCP port. DCCP | | |
752 | | being a connection | | |
753 | | oriented protocol, | | |
754 | | does not allow | | |
755 | | multiple | | |
756 | | connections on the | | |
757 | | same 5-tuple. | | |
758 | | | | |
759 +--------------------+---------------------+---------+--------------+
761 RFC5762 Attribute Analysis
763 If RFC6773 is being used in addition to RFC5762 and provided that
764 DCCP-in-UDP layer has additional demultiplexing, then it may be
765 possible to use different DCCP service codes for each DCCP flow,
766 given each uses a different DCCP port. Although doing so might
767 conflict with the media type of the m= line. None of this is
768 standardized yet and it wouldn't work as explained. Hence
769 multiplexing MUST NOT be performed even in this alternate scenario.
771 5.9. RFC6773 - DCCP-UDP Encapsulation
773 [RFC6773] document specifies an alternative encapsulation of the
774 Datagram Congestion Control Protocol (DCCP), referred to as DCCP-UDP.
775 This encapsulation allows DCCP to be carried through the current
776 generation of Network Address Translation (NAT) middle boxes without
777 modification of those middle boxes
778 +------------+-------------------------------+-------+--------------+
779 | Name | Notes | Level | Category |
780 +------------+-------------------------------+-------+--------------+
781 | dccp-port | Multiplexing MUST NOT be | M | NOT |
782 | | performed due to potential | | RECOMMENDED |
783 | | conflict between the port | | |
784 | | used for DCCP | | |
785 | | en/decapsulation and the RTP. | | |
786 | | | | |
787 +------------+-------------------------------+-------+--------------+
789 RFC6773 Attribute Analysis
791 Since RFC6773 is about tunnelling DCCP in UDP, with the UDP port
792 being the port of the DCCP en-/de-capsulation service. This
793 encapsulation allows arbitrary DCCP packets to be encapsulated and
794 the DCCP port choosen MAY conflict with the port chosen for the RTP
795 traffic.
797 For multiplexing several DCCP-in-UDP encapsulations on the same UDP
798 port, with no RTP traffic on the same port implies collapsing several
799 DCCP port spaces together. This MAY or MAY NOT work depending on the
800 nature of DCCP encapsulations and ports choses thus rendering it to
801 be very application dependant.
803 5.10. RFC5506 - Reduced-Size RTCP in RTP Profile
805 [RFC5506] discusses benefits and issues that arise when allowing
806 Real-time Transport Protocol (RTCP) packets to be transmitted with
807 reduced size.
809 +-------------+--------------------------------+-------+------------+
810 | Name | Notes | Level | Category |
811 +-------------+--------------------------------+-------+------------+
812 | rtcp-rsize | Reduced size RTCP affects the | M | IDENTICAL |
813 | | entire RTP Session | | |
814 | | | | |
815 +-------------+--------------------------------+-------+------------+
817 RFC5506 Attribute Analysis
819 5.11. RFC6787 - Media Resource Control Protocol Version 2
821 The Media Resource Control Protocol Version 2 (MRCPv2) allows client
822 hosts to control media service resources such as speech synthesizers,
823 recognizers, verifiers, and identifiers residing in servers on the
824 network. MRCPv2 is not a "stand-alone" protocol -- it relies on
825 other protocols, such as the Session Initiation Protocol (SIP), to
826 coordinate MRCPv2 clients and servers and manage sessions between
827 them, and the Session Description Protocol (SDP) to describe,
828 discover, and exchange capabilities. It also depends on SIP and SDP
829 to establish the media sessions and associated parameters between the
830 media source or sink and the media server. Once this is done, the
831 MRCPv2 exchange operates over the control session established above,
832 allowing the client to control the media processing resources on the
833 speech resource server. [RFC6787] defines attributes for this
834 purpose.
836 +-----------+---------------+-------+----------+
837 | Name | Notes | Level | Category |
838 +-----------+---------------+-------+----------+
839 | resource | Not Impacted | M | NORMAL |
840 | | | | |
841 | channel | Not Impacted | M | NORMAL |
842 | | | | |
843 +-----------+---------------+-------+----------+
845 RFC6787 Attribute Analysis
847 5.12. RFC5245 - Interactive Connectivity Establishment (ICE)
849 [RFC5245] describes a protocol for Network Address Translator(NAT)
850 traversal for UDP-based multimedia sessions established with the
851 offer/answer model. This protocol is called Interactive Connectivity
852 Establishment (ICE). ICE makes use of the Session Traversal
853 Utilities for NAT (STUN) protocol and its extension,Traversal Using
854 Relay NAT (TURN). ICE can be used by any protocol utilizing the
855 offer/answer model, such as the Session Initiation Protocol (SIP).
857 +--------------------+-------------------------+-------+------------+
858 | Name | Notes | Level | Category |
859 +--------------------+-------------------------+-------+------------+
860 | ice-lite | Not Impacted | S | NORMAL |
861 | | | | |
862 | ice-options | Not Impacted | S | NORMAL |
863 | | | | |
864 | ice-mismatch | Not Impacted | S | NORMAL |
865 | | | | |
866 | ice-pwd | ice-pwd MUST be the one | B | TRANSPORT |
867 | | that corresponds to the | | |
868 | | m=line chosen for | | |
869 | | setting up the | | |
870 | | underlying transport | | |
871 | | flow | | |
872 | | | | |
873 | ice-ufrag | ice-ufrag MUST be the | B | TRANSPORT |
874 | | one that corresponds to | | |
875 | | the m=line chosen for | | |
876 | | setting up the | | |
877 | | underlying transport | | |
878 | | flow | | |
879 | | | | |
880 | candidate | ice candidate MUST be | M | TRANSPORT |
881 | | the one that | | |
882 | | corresponds to the | | |
883 | | m=line chosen for | | |
884 | | setting up the | | |
885 | | underlying transport | | |
886 | | flow | | |
887 | | | | |
888 | remote-candidates | ice remote candidate | M | TRANSPORT |
889 | | MUST be the one that | | |
890 | | corresponds to the | | |
891 | | m=line chosen for | | |
892 | | setting up the | | |
893 | | underlying transport | | |
894 | | flow | | |
895 | | | | |
896 +--------------------+-------------------------+-------+------------+
898 RFC5245 Attribute Analysis
900 5.13. RFC5285 - RTP Header Extensions
902 [RFC5285] provides a general mechanism to use the header extension
903 feature of RTP (the Real-Time Transport Protocol). It provides the
904 option to use a small number of small extensions in each RTP packet,
905 where the universe of possible extensions is large and registration
906 is de-centralized. The actual extensions in use in a session are
907 signaled in the setup information for that session.
909 +---------+--------------------------------------+-------+----------+
910 | Name | Notes | Level | Category |
911 +---------+--------------------------------------+-------+----------+
912 | extmap | Specific RTP extension document MUST | B | SPECIAL |
913 | | be referred | | |
914 | | | | |
915 +---------+--------------------------------------+-------+----------+
917 RFC5285 Attribute Analysis
919 5.14. RFC3605 - RTCP attribute in SDP
921 Originally, SDP assumed that RTP and RTCP were carried on consecutive
922 ports. However, this is not always true when NATs are involved.
923 [RFC3605] specifies an early mechanism to indicate the RTCP port.
925 +-------+--------------------------------------+-------+------------+
926 | Name | Notes | Level | Category |
927 +-------+--------------------------------------+-------+------------+
928 | rtcp | Identical attribute value MUST be | M | IDENTICAL |
929 | | used since the RTCP port affects the | | |
930 | | entire RTP session. | | |
931 | | | | |
932 +-------+--------------------------------------+-------+------------+
934 RFC3605 Attribute Analysis
936 5.15. RFC5576 - Source-Specific SDP Attributes
938 [RFC5576] defines a mechanism to describe RTP media sources, which
939 are identified by their synchronization source (SSRC) identifiers, in
940 SDP, to associate attributes with these sources, and to express
941 relationships among sources. It also defines several source-level
942 attributes that can be used to describe properties of media sources.
944 +----------------+----------------------+-------+-------------------+
945 | Name | Notes | Level | Category |
946 +----------------+----------------------+-------+-------------------+
947 | ssrc | Refer to Notes below | M | NORMAL |
948 | | | | |
949 | ssrc-group | Refer to section | M | SPECIAL |
950 | | Section 9 for | | |
951 | | specific analysis of | | |
952 | | the grouping | | |
953 | | semantics | | |
954 | | | | |
955 | cname | Not Impacted [Open | SR | NORMAL |
956 | | Issues: what are the | | |
957 | | rules for CNAME | | |
958 | | duplication across | | |
959 | | sessions?] | | |
960 | | | | |
961 | previous-ssrc | Refer to notes below | SR | NORMAL |
962 | | | | |
963 | fmtp | The attribute value | SR | IDENTICAL-PER-PT |
964 | | must be same for a | | |
965 | | given codec | | |
966 | | configuration | | |
967 | | | | |
968 +----------------+----------------------+-------+-------------------+
970 RFC5576 Attribute Analysis
972 If SSRCs are repeated across m=lines being multiplexed, they MUST all
973 represent the same underlying RTP Source.
975 5.16. RFC7273 - RTP Clock Source Signalling
977 [RFC7273] specifies Session Description Protocol (SDP) signalling
978 that identifies timestamp reference clock sources and SDP signalling
979 that identifies the media clock sources in a multimedia session.
981 +------------+---------------+-----------+----------+
982 | Name | Notes | Level | Category |
983 +------------+---------------+-----------+----------+
984 | ts-refclk | Not Impacted | S, M, SR | NORMAL |
985 | | | | |
986 | mediaclk | Not Impacted | S,, M, SR | NORMAL |
987 | | | | |
988 +------------+---------------+-----------+----------+
990 RFC7273 Attribute Analysis
992 5.17. RFC6236 - Image Attributes in SDP
994 [RFC6236] proposes a new generic session setup attribute to make it
995 possible to negotiate different image attributes such as image size.
996 A possible use case is to make it possible for a low-end hand-held
997 terminal to display video without the need to rescale the
998 image,something that may consume large amounts of memory and
999 processing power. The document also helps to maintain an optimal
1000 bitrate for video as only the image size that is desired by the
1001 receiver is transmitted.
1003 +------------+--------------------------+-------+-------------------+
1004 | Name | Notes | Level | Category |
1005 +------------+--------------------------+-------+-------------------+
1006 | imageattr | The attribute value must | M | IDENTICAL-PER-PT |
1007 | | be same for a given | | |
1008 | | codec configuration | | |
1009 | | | | |
1010 +------------+--------------------------+-------+-------------------+
1012 RFC6236 Attribute Analysis
1014 5.18. RFC7197 - Duplication Delay Attribute in SDP
1016 [RFC7197] defines an attribute to indicate the presence of temporally
1017 redundant media streams and the duplication delay in the Session
1018 Description Protocol
1020 +--------------------+---------------+-------+----------+
1021 | Name | Notes | Level | Category |
1022 +--------------------+---------------+-------+----------+
1023 | duplication-delay | Not Impacted | B | NORMAL |
1024 | | | | |
1025 +--------------------+---------------+-------+----------+
1027 RFC7197 Attribute Analysis
1029 5.19. RFC7226 - RTCP XR Blocks for MOS Metric Reporting
1031 [RFC7226] defines an RTP Control Protocol (RTCP) Extended Report (XR)
1032 Block including two new segment types and associated Session
1033 Description Protocol (SDP) parameters that allow the reporting of
1034 mean opinion score (MOS) Metrics for use in a range of RTP
1035 applications.
1037 +-------------+---------------+-------+----------+
1038 | Name | Notes | Level | Category |
1039 +-------------+---------------+-------+----------+
1040 | calgextmap | Not Impacted | B | NORMAL |
1041 | | | | |
1042 +-------------+---------------+-------+----------+
1044 RFC7226 Attribute Analysis
1046 5.20. RFC6285 - Rapid Acquisition of Multicast RTP Sessions
1048 [RFC6285] describes a method using the existing RTP and RTP Control
1049 Protocol (RTCP) machinery that reduces the acquisition delay. In
1050 this method, an auxiliary unicast RTP session carrying the Reference
1051 Information to the receiver precedes or accompanies the multicast
1052 stream. This unicast RTP flow can be transmitted at a faster than
1053 natural bitrate to further accelerate the acquisition. The
1054 motivating use case for this capability is multicast applications
1055 that carry real-time compressed audio and video.
1057 +---------------+-------------------+-------+------------------+
1058 | Name | Notes | Level | Category |
1059 +---------------+-------------------+-------+------------------+
1060 | rams-updates | Not recommended | M | NOT RECOMMENDED |
1061 | | | | |
1062 +---------------+-------------------+-------+------------------+
1064 RFC6285 Attribute Analysis
1066 5.21. RFC6230 - Media Control Channel Framework
1068 [RFC6230] describes a framework and protocol for application
1069 deployment where the application programming logic and media
1070 processing are distributed. This implies that application
1071 programming logic can seamlessly gain access to appropriate resources
1072 that are not co-located on the same physical network entity. The
1073 framework uses the Session Initiation Protocol (SIP) to establish an
1074 application-level control mechanism between application servers and
1075 associated external servers such as media servers.
1077 +---------+-----------------+-------+----------+
1078 | Name | Notes | Level | Category |
1079 +---------+-----------------+-------+----------+
1080 | cfw-id | Not Applicable | M | NORMAL |
1081 | | | | |
1082 +---------+-----------------+-------+----------+
1084 RFC6230 Attribute Analysis
1086 5.22. RFC6364 - SDP Elements for FEC Framework
1088 [RFC6364] specifies the use of the Session Description Protocol (SDP)
1089 to describe the parameters required to signal the Forward Error
1090 Correction (FEC) Framework Configuration Information between the
1091 sender(s) and receiver(s). This document also provides examples that
1092 show the semantics for grouping multiple source and repair flows
1093 together for the applications that simultaneously use multiple
1094 instances of the FEC Framework.
1096 +------------------+-------+-------+----------+
1097 | Name | Notes | Level | Category |
1098 +------------------+-------+-------+----------+
1099 | fec-source-flow | | M | SPECIAL |
1100 | | | | |
1101 | fec-repair-flow | | M | SPECIAL |
1102 | | | | |
1103 | repair-window | | M | SPECIAL |
1104 | | | | |
1105 +------------------+-------+-------+----------+
1107 RFC6364 Attribute Analysis
1109 5.23. RFC4796 - Content Attribute
1111 [RFC4796] defines a new Session Description Protocol (SDP) media-
1112 level attribute, 'content'. The 'content' attribute defines the
1113 content of the media stream to a more detailed level than the media
1114 description line. The sender of an SDP session description can
1115 attach the 'content' attribute to one or more media streams. The
1116 receiving application can then treat each media stream differently
1117 (e.g., show it on a big or small screen) based on its content.
1119 +----------+---------------+-------+----------+
1120 | Name | Notes | Level | Category |
1121 +----------+---------------+-------+----------+
1122 | content | Not Impacted | M | NORMAL |
1123 | | | | |
1124 +----------+---------------+-------+----------+
1126 RFC4796 Attribute Analysis
1128 5.24. RFC3407 - SDP Simple Capability Declaration
1130 [RFC3407] defines a set of Session Description Protocol (SDP)
1131 attributes that enables SDP to provide a minimal and backwards
1132 compatible capability declaration mechanism.
1134 +----------+------------------------+-------+----------+
1135 | Name | Notes | Level | Category |
1136 +----------+------------------------+-------+----------+
1137 | sqn | Not Impacted | B | NORMAL |
1138 | | | | |
1139 | cdsc | Not Impacted. | B | NORMAL |
1140 | | | | |
1141 | cpar | Refer to Section 14 | B | INHERIT |
1142 | | | | |
1143 | cparmin | Refer to notes below | B | SPECIAL |
1144 | | | | |
1145 | cparmax | Refer to notes below | B | SPECIAL |
1146 | | | | |
1147 +----------+------------------------+-------+----------+
1149 RFC3407 Attribute Analysis
1151 Since the attributes (a=cparmin and a=cparmax) define minimum and
1152 maximum numerical values associated with the attributes described in
1153 a=cpar, it is recommended to consult the document defining the
1154 attribute for dealing under media stream multiplexing.
1156 5.25. RFC6284 - Port Mapping between Unicast and Multicast RTP Sessions
1158 [RFC6284] presents a port mapping solution that allows RTP receivers
1159 to choose their own ports for an auxiliary unicast session in RTP
1160 applications using both unicast and multicast services. The solution
1161 provides protection against denial-of-service or packet amplification
1162 attacks that could be used to cause one or more RTP packets to be
1163 sent to a victim client
1165 +------------------+-------------------------+-------+--------------+
1166 | Name | Notes | Level | Category |
1167 +------------------+-------------------------+-------+--------------+
1168 | portmapping-req | Not recommended, if | M | NOT |
1169 | | port mapping is | | RECOMMENDED |
1170 | | required by the | | |
1171 | | application | | |
1172 | | | | |
1173 +------------------+-------------------------+-------+--------------+
1175 RFC6284 Attribute Analysis
1177 5.26. RFC6714 - MSRP-CEMA
1179 [RFC6714] defines a Message Session Relay Protocol (MSRP) extension,
1180 Connection Establishment for Media Anchoring (CEMA). Support of this
1181 extension is OPTIONAL. The extension allows middle boxes to anchor
1182 the MSRP connection, without the need for middle boxes to modify the
1183 MSRP messages; thus, it also enables secure end-to-end MSRP
1184 communication in networks where such middle boxes are deployed. This
1185 document also defines a Session Description Protocol (SDP) attribute,
1186 'msrp-cema', that MSRP endpoints use to indicate support of the CEMA
1187 extension.
1189 +------------+---------------+-------+----------+
1190 | Name | Notes | Level | Category |
1191 +------------+---------------+-------+----------+
1192 | msrp-cema | Not Impacted | M | NORMAL |
1193 | | | | |
1194 +------------+---------------+-------+----------+
1196 RFC6714 Attribute Analysis
1198 5.27. RFC4583 - SDP Format for BFCP Streams
1200 [RFC4583] document specifies how to describe Binary Floor Control
1201 Protocol (BFCP) streams in Session Description Protocol (SDP)
1202 descriptions. User agents using the offer/answer model to establish
1203 BFCP streams use this format in their offers and answers
1205 +------------+---------------------------------+-------+------------+
1206 | Name | Notes | Level | Category |
1207 +------------+---------------------------------+-------+------------+
1208 | floorctrl | Must be repeated across all the | M | IDENTICAL |
1209 | | multiplexed m=lines | | |
1210 | | | | |
1211 | confid | Not Impacted | M | NORMAL |
1212 | | | | |
1213 | userid | Not Impacted | M | NORMAL |
1214 | | | | |
1215 | floorid | The floorid MUST be globally | M | NORMAL |
1216 | | unique | | |
1217 | | | | |
1218 +------------+---------------------------------+-------+------------+
1220 RFC4583 Attribute Analysis
1222 5.28. RFC5547 - SDP Offer/Answer for File Transfer
1224 [RFC5547] provides a mechanism to negotiate the transfer of one or
1225 more files between two endpoints by using the Session Description
1226 Protocol (SDP) offer/answer model specified in [RFC3264].
1228 +----------------------+---------------+-------+----------+
1229 | Name | Notes | Level | Category |
1230 +----------------------+---------------+-------+----------+
1231 | file-selector | Not Impacted | M | NORMAL |
1232 | | | | |
1233 | file-transfer-id | Not Impacted | M | NORMAL |
1234 | | | | |
1235 | file-disposition | Not Impacted | M | NORMAL |
1236 | | | | |
1237 | file-date | Not Impacted | M | NORMAL |
1238 | | | | |
1239 | file-iconfile-range | Not Impacted | M | NORMAL |
1240 | | | | |
1241 +----------------------+---------------+-------+----------+
1243 RFC5547 Attribute Analysis
1245 5.29. RFC6489 - SDP and RTP Media Loopback Extension
1247 [RFC6489] adds new SDP media types and attributes, which enable
1248 establishment of media sessions where the media is looped back to the
1249 transmitter. Such media sessions will serve as monitoring and
1250 troubleshooting tools by providing the means for measurement of more
1251 advanced VoIP, Real-time Text and Video over IP performance metrics.
1253 +------------------------------+----------------+-------+----------+
1254 | Name | Notes | Level | Category |
1255 +------------------------------+----------------+-------+----------+
1256 | loopback rtp-pkt-loopback | Not Impacted | M | NORMAL |
1257 | | | | |
1258 | loopback rtp-media-loopback | Not Impacted | M | NORMAL |
1259 | | | | |
1260 | loopback-source | Not Impacted | M | NORMAL |
1261 | | | | |
1262 | loopback-mirror | Not Impacted | M | NORMAL |
1263 | | | | |
1264 +------------------------------+----------------+-------+----------+
1266 An Extension to the Session Description Protocol (SDP) and Real-time
1267 Transport Protocol (RTP) for Media Loopback
1269 5.30. RFC5760 - RTCP with Unicast Feedback
1271 [RFC5760] specifies an extension to the Real-time Transport Control
1272 Protocol (RTCP) to use unicast feedback to a multicast sender. The
1273 proposed extension is useful for single-source multicast sessions
1274 such as Source-Specific Multicast (SSM) communication where the
1275 traditional model of many-to-many group communication is either not
1276 available or not desired.
1278 +---------------+------------------------------+-------+------------+
1279 | Name | Notes | Level | Category |
1280 +---------------+------------------------------+-------+------------+
1281 | rtcp-unicast | The attribute MUST be | M | IDENTICAL |
1282 | | reported across all m=lines | | |
1283 | | multiplexed | | |
1284 | | | | |
1285 +---------------+------------------------------+-------+------------+
1287 RFC5760 Attribute Analysis
1289 5.31. RFC3611 - RTCP XR
1291 [RFC3611] defines the Extended Report (XR) packet type for the RTP
1292 Control Protocol (RTCP), and defines how the use of XR packets can be
1293 signaled by an application if it employs the Session Description
1294 Protocol (SDP).
1296 +----------+---------------+-------+----------+
1297 | Name | Notes | Level | Category |
1298 +----------+---------------+-------+----------+
1299 | rtcp-xr | Not Impacted | B | NORMAL |
1300 | | | | |
1301 +----------+---------------+-------+----------+
1303 RFC3611 Attribute Analysis
1305 5.32. RFC5939 - SDP Capability Negotiation
1307 [RFC5939] defines a general SDP Capability Negotiation framework. It
1308 also specifies how to provide attributes and transport protocols as
1309 capabilities and negotiate them using the framework. Extensions for
1310 other types of capabilities (e.g., media types and media formats) may
1311 be provided in other documents.
1313 +---------+-------------------------------+-------+----------+
1314 | Name | Notes | Level | Category |
1315 +---------+-------------------------------+-------+----------+
1316 | pcfg | Refer to Section Section 14 | M | SPECIAL |
1317 | | | | |
1318 | acfg | Refer to Section Section 14 | M | SPECIAL |
1319 | | | | |
1320 | csup | Not Impacted | B | NORMAL |
1321 | | | | |
1322 | creq | Not Impacted | B | NORMAL |
1323 | | | | |
1324 | acap | Refer to section Section 14 | B | INHERIT |
1325 | | | | |
1326 | tcap | Refer to section Section 14 | B | INHERIT |
1327 | | | | |
1328 | cap-v0 | Not Impacted | B | NORMAL |
1329 | | | | |
1330 +---------+-------------------------------+-------+----------+
1332 RFC5939 Attribute Analysis
1334 5.33. RFC6871- SDP Media Capabilities Negotiation
1336 Session Description Protocol (SDP) capability negotiation provides a
1337 general framework for indicating and negotiating capabilities in SDP.
1338 The base framework defines only capabilities for negotiating
1339 transport protocols and attributes. [RFC6871] extends the framework
1340 by defining media capabilities that can be used to negotiate media
1341 types and their associated parameters.
1343 +---------+-----------------------------+-------+-------------------+
1344 | Name | Notes | Level | Category |
1345 +---------+-----------------------------+-------+-------------------+
1346 | rmcap | Refer to Section Section 14 | B | IDENTICAL-PER-PT |
1347 | | | | |
1348 | omcap | Not Impacted | B | NORMAL |
1349 | | | | |
1350 | mfcap | Refer to Section Section 14 | B | IDENTICAL-PER-PT |
1351 | | | | |
1352 | mscap | Refer to Section Section 14 | B | INHERIT |
1353 | | | | |
1354 | lcfg | Refer to Section Section 14 | B | SPECIAL |
1355 | | | | |
1356 | sescap | Refer to Section Section 14 | S | NOT RECOMMENDED |
1357 | | | | |
1358 | med-v0 | Not Impacted | S | NORMAL |
1359 | | | | |
1360 +---------+-----------------------------+-------+-------------------+
1362 Session Description Protocol (SDP) Media Capabilities Negotiation
1364 The "sescap" attribute is NOT RECOMMENDED for use with multiplexing.
1365 The reason is that it requires the use of unique configuration
1366 numbers across the entire SDP (per [RFC6871] as opposed to within a
1367 media description only (per [RFC5939]). As described in Section 15,
1368 the use of identical configuration numbers between multiplxed
1369 (bundled) media descriptions is the default way of indicating
1370 compatible configurations in a bundle.
1372 5.34. RFC7006 - Miscellaneous Capabilities Negotiation SDP
1374 [RFC7006] extends the SDP capability negotiation framework to allow
1375 endpoints to negotiate three additional SDP capabilities. In
1376 particular, this memo provides a mechanism to negotiate bandwidth
1377 ("b=" line), connection data ("c=" line), and session or media titles
1378 ("i=" line for each session or media).
1380 +----------+-----------------------------------+-------+------------+
1381 | Name | Notes | Level | Category |
1382 +----------+-----------------------------------+-------+------------+
1383 | bcap | Inherit the category SUM as | B | INHERIT |
1384 | | applicable to b= attribute | | |
1385 | | | | |
1386 | bcap-v0 | Not Impacted | B | NORMAL |
1387 | | | | |
1388 | ccap | The connection address type MUST | B | IDENTICAL |
1389 | | be identical across all the | | |
1390 | | multiplexed m= lines. | | |
1391 | | | | |
1392 | ccap-v0 | Not Impacted. | B | NORMAL |
1393 | | | | |
1394 | icap | Not Impacted | B | NORMAL |
1395 | | | | |
1396 | icap-v0 | Not Impacted | B | NORMAL |
1397 | | | | |
1398 +----------+-----------------------------------+-------+------------+
1400 Miscellaneous Capabilities Negotiation in the Session Description
1401 Protocol (SDP)
1403 5.35. RFC4567 - Key Management Extensions for SDP and RTSP
1405 [RFC4567] defines general extensions for Session Description Protocol
1406 (SDP) and Real Time Streaming Protocol (RTSP) to carry messages, as
1407 specified by a key management protocol, in order to secure the media.
1408 These extensions are presented as a framework, to be used by one or
1409 more key management protocols. As such, their use is meaningful only
1410 when complemented by an appropriate key management protocol.
1412 +-----------+----------------------------------+-------+------------+
1413 | Name | Notes | Level | Category |
1414 +-----------+----------------------------------+-------+------------+
1415 | key-mgmt | Key management protocol MUST be | B | IDENTICAL |
1416 | | identical across all the m=lines | | |
1417 | | | | |
1418 | mikey | Key management protocol MUST be | B | IDENTICAL |
1419 | | identical across all the m=lines | | |
1420 | | | | |
1421 +-----------+----------------------------------+-------+------------+
1423 RFC4567 Attribute Analysis
1425 5.36. RFC4572 - Comedia over TLS in SDP
1427 [RFC4572] specifies how to establish secure connection-oriented media
1428 transport sessions over the Transport Layer Security (TLS) protocol
1429 using the Session Description Protocol (SDP). It defines a new SDP
1430 protocol identifier, 'TCP/TLS'. It also defines the syntax and
1431 semantics for an SDP 'fingerprint' attribute that identifies the
1432 certificate that will be presented for the TLS session. This
1433 mechanism allows media transport over TLS connections to be
1434 established securely, so long as the integrity of session
1435 descriptions is assured.
1437 +--------------+-------------------------------+-------+------------+
1438 | Name | Notes | Level | Category |
1439 +--------------+-------------------------------+-------+------------+
1440 | fingerprint | Fingerprint value from the | B | TRANSPORT |
1441 | | m=line defining the | | |
1442 | | underlying transport is | | |
1443 | | chosen | | |
1444 | | | | |
1445 +--------------+-------------------------------+-------+------------+
1447 RFC4572 Attribute Analysis
1449 5.37. RFC4570 - SDP Source Filters
1451 [RFC4570] describes how to adapt the Session Description Protocol
1452 (SDP) to express one or more source addresses as a source filter for
1453 one or more destination "connection" addresses. It defines the
1454 syntax and semantics for an SDP "source-filter" attribute that may
1455 reference either IPv4 or IPv6 address(es) as either an inclusive or
1456 exclusive source list for either multicast or unicast destinations.
1457 In particular, an inclusive source-filter can be used to specify a
1458 Source-Specific Multicast (SSM) session
1460 +----------------+-----------------------------+-------+------------+
1461 | Name | Notes | Level | Category |
1462 +----------------+-----------------------------+-------+------------+
1463 | source-filter | The attribute MUST be | B | IDENTICAL |
1464 | | repeated across all m=lines | | |
1465 | | multiplexed | | |
1466 | | | | |
1467 +----------------+-----------------------------+-------+------------+
1469 RFC4570 Attribute Analysis
1471 5.38. RFC6128 - RTCP Port for Multicast Sessions
1473 The Session Description Protocol (SDP) has an attribute that allows
1474 RTP applications to specify an address and a port associated with the
1475 RTP Control Protocol (RTCP) traffic. In RTP-based source-specific
1476 multicast (SSM) sessions, the same attribute is used to designate the
1477 address and the RTCP port of the Feedback Target in the SDP
1478 description. However, the RTCP port associated with the SSM session
1479 itself cannot be specified by the same attribute to avoid ambiguity,
1480 and thus, is required to be derived from the "m=" line of the media
1481 description. Deriving the RTCP port from the "m=" line imposes an
1482 unnecessary restriction. [RFC6128] removes this restriction by
1483 introducing a new SDP attribute.
1485 +-----------------+----------------------------+-------+------------+
1486 | Name | Notes | Level | Category |
1487 +-----------------+----------------------------+-------+------------+
1488 | multicast-rtcp | Multicast RTCP port MUST | B | IDENTICAL |
1489 | | be identical across all | | |
1490 | | the m=lines | | |
1491 | | | | |
1492 +-----------------+----------------------------+-------+------------+
1494 RFC6128 Attribute Analysis
1496 5.39. RFC6189 - ZRTP
1498 [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman
1499 exchange to agree on a session key and parameters for establishing
1500 unicast Secure Real-time Transport Protocol (SRTP) sessions for Voice
1501 over IP (VoIP) applications.
1503 +------------+-------------------------------+-------+--------------+
1504 | Name | Notes | Level | Category |
1505 +------------+-------------------------------+-------+--------------+
1506 | zrtp-hash | Complicates if all the | M | NOT |
1507 | | m=lines are not authenticated | | RECOMMENDED |
1508 | | as given in the example below | | |
1509 | | | | |
1510 +------------+-------------------------------+-------+--------------+
1512 RFC6189 Attribute Analysis
1514 Example: Multiplexing media descriptions having attribute zrtp-hash
1515 defined with the media descriptions lacking it, would either
1516 complicate the handling of multiplexed stream or fail multiplexing.
1518 v=0
1519 o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
1520 s=
1521 c=IN IP4 client.biloxi.example.com
1522 t=0 0
1523 m=audio 3456 RTP/AVP 97
1524 a=rtpmap:97 iLBC/8000
1525
1526 a=zrtp-hash:1.10 fe30efd02423cb054e50efd0248742ac7a52c8f91bc2
1527 df881ae642c371ba46df
1528
1529 m=video 34567 RTP/AVP 31
1530 a=rtpmap:31 H261/90000
1532 5.40. RFC4145 - Connection-Oriented Media
1534 [RFC4145] describes how to express media transport over TCP using the
1535 Session Description Protocol (SDP). It defines the SDP 'TCP'
1536 protocol identifier, the SDP 'setup' attribute, which describes the
1537 connection setup procedure, and the SDP 'connection' attribute, which
1538 handles connection reestablishment.
1540 +-------------+--------------------------------+-------+------------+
1541 | Name | Notes | Level | Category |
1542 +-------------+--------------------------------+-------+------------+
1543 | setup | MUST be identical across all | B | IDENTICAL |
1544 | | m=lines | | |
1545 | | | | |
1546 | connection | MUST be identical across all | B | IDENTICAL |
1547 | | m=lines | | |
1548 | | | | |
1549 +-------------+--------------------------------+-------+------------+
1551 RFC4145 Attribute Analysis
1553 5.41. RFC6947 - The SDP ALTC Attribute
1555 [RFC6947] proposes a mechanism that allows the same SDP offer to
1556 carry multiple IP addresses of different address families (e.g., IPv4
1557 and IPv6). The proposed attribute, the "altc" attribute, solves the
1558 backward-compatibility problem that plagued Alternative Network
1559 Address Types (ANAT) due to their syntax.
1561 +-------+--------------------------------------+-------+------------+
1562 | Name | Notes | Level | Category |
1563 +-------+--------------------------------------+-------+------------+
1564 | altc | The IP Address and port must be the | M | TRANSPORT |
1565 | | one that corresponds to the m=line | | |
1566 | | chosen for setting up the underlying | | |
1567 | | transport flow. | | |
1568 | | | | |
1569 +-------+--------------------------------------+-------+------------+
1571 RFC6947 Attribute Analysis
1573 5.42. RFC7195 - SDP Extension for Circuit Switched Bearers in PSTN
1575 [RFC7195] describes use cases, requirements, and protocol extensions
1576 for using the Session Description Protocol (SDP) offer/answer model
1577 for establishing audio and video media streams over circuit-switched
1578 bearers in the Public Switched Telephone Network (PSTN).
1580 +--------------------------+----------------+-------+----------+
1581 | Name | Notes | Level | Category |
1582 +--------------------------+----------------+-------+----------+
1583 | cs-correlation:callerid | Not Impacted. | M | NORMAL |
1584 | | | | |
1585 | cs-correlation:uuie | Not Impacted. | M | NORMAL |
1586 | | | | |
1587 | cs-correlation:dtmf | Not Impacted. | M | NORMAL |
1588 | | | | |
1589 | cs-correlation:external | Not Impacted. | M | NORMAL |
1590 | | | | |
1591 +--------------------------+----------------+-------+----------+
1593 RFC7195 Attribute Analysis
1595 5.43. RFC7272 - IDMS Using the RTP Control Protocol (RTCP)
1597 [RFC7272] defines a new RTP Control Protocol (RTCP) Packet Type and
1598 an RTCP Extended Report (XR) Block Type to be used for achieving
1599 Inter-Destination Media Synchronization (IDMS).
1601 +------------+----------------+-------+----------+
1602 | Name | Notes | Level | Category |
1603 +------------+----------------+-------+----------+
1604 | rtcp-idms | Not Impacted. | M | NORMAL |
1605 | | | | |
1606 +------------+----------------+-------+----------+
1608 RFC7272 Attribute Analysis
1610 5.44. RFC5159 - OMA BCAST SDP Attributes
1612 [RFC5159] provides descriptions of Session Description Protocol (SDP)
1613 attributes used by the Open Mobile Alliance's Broadcast Service and
1614 Content Protection specification.
1616 +---------------------+---------------+-------+----------+
1617 | Name | Notes | Level | Category |
1618 +---------------------+---------------+-------+----------+
1619 | bcastversion | Not Impacted | S | NORMAL |
1620 | | | | |
1621 | stkmstream | Not Impacted | B | NORMAL |
1622 | | | | |
1623 | SRTPAuthentication | Not Impacted | M | NORMAL |
1624 | | | | |
1625 | SRTPROCTxRate | Not Impacted | M | NORMAL |
1626 | | | | |
1627 +---------------------+---------------+-------+----------+
1629 RFC5159 Attribute Analysis
1631 5.45. RFC6193 - Media Description for IKE in SDP
1633 [RFC6193] specifies how to establish a media session that represents
1634 a virtual private network using the Session Initiation Protocol for
1635 the purpose of on-demand media/application sharing between peers. It
1636 extends the protocol identifier of the Session Description Protocol
1637 (SDP) so that it can negotiate use of the Internet Key Exchange
1638 Protocol (IKE) for media sessions in the SDP offer/answer model.
1640 +-------------------+--------------------------+-------+------------+
1641 | Name | Notes | Level | Category |
1642 +-------------------+--------------------------+-------+------------+
1643 | ike-setup | Attribute MUST be | B | IDENTICAL |
1644 | | identical across all the | | |
1645 | | m=lines | | |
1646 | | | | |
1647 | psk-fingerprint | Attribute MUST be | B | IDENTICAL |
1648 | | identical across all the | | |
1649 | | m=lines | | |
1650 | | | | |
1651 | ike-esp | Attribute MUST be | B | IDENTICAL |
1652 | | identical across all the | | |
1653 | | m=lines | | |
1654 | | | | |
1655 | ike-esp-udpencap | Attribute MUST be | B | IDENTICAL |
1656 | | identical across all the | | |
1657 | | m=lines | | |
1658 | | | | |
1659 +-------------------+--------------------------+-------+------------+
1661 RFC6193 Attribute Analysis
1663 With the above SDP constraints, a session multiplexed with multiple
1664 m=lines will use only one IPSec association for all of the m= lines.
1666 5.46. RFC6064 - SDP and RTSP Extensions for 3GPP
1668 The Packet-switched Streaming Service (PSS) and the Multimedia
1669 Broadcast/Multicast Service (MBMS) defined by 3GPP use the Session
1670 Description Protocol (SDP) and Real Time Streaming Protocol (RTSP)
1671 with some extensions. [RFC6064] provides information about these
1672 extensions and registers the RTSP and SDP extensions with IANA.
1674 +-------------------------------+------------+-------+--------------+
1675 | Name | Notes | Level | Category |
1676 +-------------------------------+------------+-------+--------------+
1677 | X-predecbufsize | Refer to | M | NOT |
1678 | | notes | | RECOMMENDED |
1679 | | below | | |
1680 | | | | |
1681 | X-initpredecbufperiod | Refer to | M | NOT |
1682 | | notes | | RECOMMENDED |
1683 | | below | | |
1684 | | | | |
1685 | X-initpostdecbufperiod | Refer to | M | NOT |
1686 | | notes | | RECOMMENDED |
1687 | | below | | |
1688 | | | | |
1689 | X-decbyterate | Refer to | M | NOT |
1690 | | notes | | RECOMMENDED |
1691 | | below | | |
1692 | | | | |
1693 | 3gpp-videopostdecbufsize | Refer to | M | NOT |
1694 | | notes | | RECOMMENDED |
1695 | | below | | |
1696 | | | | |
1697 | framesize | Refer to | M | NOT |
1698 | | notes | | RECOMMENDED |
1699 | | below | | |
1700 | | | | |
1701 | 3GPP-Integrity-Key | Refer to | S | NOT |
1702 | | notes | | RECOMMENDED |
1703 | | below | | |
1704 | | | | |
1705 | 3GPP-SDP-Auth | Refer to | S | NOT |
1706 | | notes | | RECOMMENDED |
1707 | | below | | |
1708 | | | | |
1709 | 3GPP-SRTP-Config | Refer to | M | NOT |
1710 | | notes | | RECOMMENDED |
1711 | | below | | |
1712 | | | | |
1713 | alt,alt-default-id | Refer to | M | NOT |
1714 | | notes | | RECOMMENDED |
1715 | | below | | |
1716 | | | | |
1717 | alt-group | Refer to | M | NOT |
1718 | | notes | | RECOMMENDED |
1719 | | below | | |
1720 | | | | |
1721 | 3GPP-Adaptation-Support | Refer to | M | NOT |
1722 | | notes | | RECOMMENDED |
1723 | | below | | |
1724 | | | | |
1725 | 3GPP-Asset-Informatio | Refer to | B | NOT |
1726 | | notes | | RECOMMENDED |
1727 | | below | | |
1728 | | | | |
1729 | mbms-mode | Refer to | B | NOT |
1730 | | notes | | RECOMMENDED |
1731 | | below | | |
1732 | | | | |
1733 | mbms-flowid | Refer to | M | NOT |
1734 | | notes | | RECOMMENDED |
1735 | | below | | |
1736 | | | | |
1737 | mbms-repair | Refer to | B | NOT |
1738 | | notes | | RECOMMENDED |
1739 | | below | | |
1740 | | | | |
1741 | 3GPP-QoE-Metrics:Corruption | Refer to | M | NOT |
1742 | duration | notes | | RECOMMENDED |
1743 | | below | | |
1744 | | | | |
1745 | 3GPP-QoE-Metrics:Rebuffering | Refer to | M | NOT |
1746 | duration | notes | | RECOMMENDED |
1747 | | below | | |
1748 | | | | |
1749 | 3GPP-QoE-Metrics:Initial | Refer to | M | NOT |
1750 | buffering duration | notes | | RECOMMENDED |
1751 | | below | | |
1752 | | | | |
1753 | 3GPP-QoE-Metrics:Successive | Refer to | M | NOT |
1754 | loss of RTP packets | notes | | RECOMMENDED |
1755 | | below | | |
1756 | | | | |
1757 | 3GPP-QoE-Metrics:Frame rate | Refer to | M | NOT |
1758 | deviation | notes | | RECOMMENDED |
1759 | | below | | |
1760 | | | | |
1761 | 3GPP-QoE-Metrics:Jitter | Refer to | M | NOT |
1762 | duration | notes | | RECOMMENDED |
1763 | | below | | |
1764 | | | | |
1765 | 3GPP-QoE-Metrics:Content | Refer to | B | NOT |
1766 | Switch Time | notes | | RECOMMENDED |
1767 | | below | | |
1768 | | | | |
1769 | 3GPP-QoE-Metrics:Average | Refer to | M | NOT |
1770 | Codec Bitrat | notes | | RECOMMENDED |
1771 | | below | | |
1772 | | | | |
1773 | 3GPP-QoE-Metrics:Codec | Refer to | M | NOT |
1774 | Information | notes | | RECOMMENDED |
1775 | | below | | |
1776 | | | | |
1777 | 3GPP-QoE-Metrics:Buffer | Refer to | M | NOT |
1778 | Status | notes | | RECOMMENDED |
1779 | | below | | |
1780 | | | | |
1781 +-------------------------------+------------+-------+--------------+
1783 RFC6064 Attribute Analysis
1785 [RFC6064] defines SDP attributes that are applicable in the
1786 declarative usage of SDP alone. For purposes of this document, only
1787 the Offer/Answer usage of SDP is considered as mandated by
1788 [I-D.ietf-mmusic-sdp-bundle-negotiation].
1790 5.47. RFC3108 - ATM SDP
1792 RFC3108 [RFC3108] describes conventions for using the Session
1793 Description Protocol (SDP) described for controlling ATM Bearer
1794 Connections, and any associated ATM Adaptation Layer (AAL)
1796 +------------------------+--------------+-------+----------+
1797 | Name | Notes | Level | Category |
1798 +------------------------+--------------+-------+----------+
1799 | aalType | Not Impacted | B | NORMAL |
1800 | eecid | Not Impacted | B | NORMAL |
1801 | aalType | Not Impacted | B | NORMAL |
1802 | capability | Not Impacted | B | NORMAL |
1803 | qosClass | Not Impacted | B | NORMAL |
1804 | bcob | Not Impacted | B | NORMAL |
1805 | stc | Not Impacted | B | NORMAL |
1806 | upcc | Not Impacted | B | NORMAL |
1807 | atmQOSparms | Not Impacted | B | NORMAL |
1808 | atmTrfcDesc | Not Impacted | B | NORMAL |
1809 | abrParms | Not Impacted | B | NORMAL |
1810 | abrSetup | Not Impacted | B | NORMAL |
1811 | bearerType | Not Impacted | B | NORMAL |
1812 | lij | Not Impacted | B | NORMAL |
1813 | anycast | Not Impacted | B | NORMAL |
1814 | cache | Not Impacted | B | NORMAL |
1815 | bearerSigIE | Not Impacted | B | NORMAL |
1816 | aalApp | Not Impacted | B | NORMAL |
1817 | cbrRate | Not Impacted | B | NORMAL |
1818 | sbc | Not Impacted | B | NORMAL |
1819 | clkrec | Not Impacted | B | NORMAL |
1820 | fec | Not Impacted | B | NORMAL |
1821 | prtfl | Not Impacted | B | NORMAL |
1822 | structure | Not Impacted | B | NORMAL |
1823 | cpsSDUsize | Not Impacted | B | NORMAL |
1824 | aal2CPS | Not Impacted | B | NORMAL |
1825 | aal2CPSSDUrate | Not Impacted | B | NORMAL |
1826 | aal2sscs3661unassured | Not Impacted | B | NORMAL |
1827 | aal2sscs3661assured | Not Impacted | B | NORMAL |
1828 | aal2sscs3662 | Not Impacted | B | NORMAL |
1829 | aal5sscop | Not Impacted | B | NORMAL |
1830 | atmmap | Not Impacted | B | NORMAL |
1831 | silenceSupp | Not Impacted | B | NORMAL |
1832 | ecan | Not Impacted | B | NORMAL |
1833 | gc | Not Impacted | B | NORMAL |
1834 | profileDesc | Not Impacted | B | NORMAL |
1835 | vsel | Not Impacted | B | NORMAL |
1836 | dsel | Not Impacted | B | NORMAL |
1837 | fsel | Not Impacted | B | NORMAL |
1838 | onewaySel | Not Impacted | B | NORMAL |
1839 | codecconfig | Not Impacted | B | NORMAL |
1840 | isup_usi | Not Impacted | B | NORMAL |
1841 | isup_usi | Not Impacted | B | NORMAL |
1842 | chain | Not Impacted | B | NORMAL |
1843 | | | | |
1844 +------------------------+--------------+-------+----------+
1846 RFC3108 Attribute Analysis
1848 RFC3108 describes conventions for using the Session Description
1849 Protocol (SDP) for characterizing ATM bearer connections using an
1850 AAL1, AAL2 or AAL5 adaptation layers. For AAL1, AAL2 and AAL5,
1851 bearer connections can be used to transport single media streams. In
1852 addition, for AAL1 and AAL2, multiple media streams may be
1853 multiplexed into a bearer connection. For all adaptation types
1854 (AAL1, AAL2 and AAL5), bearer connections may be bundled into a
1855 single media group. In all cases addressed by RFC3108, a real-time
1856 media stream (voice, video, voiceband data, pseudo-wire and others)
1857 or a multiplex of media streams is mapped directly into an ATM
1858 connection. RFC3108 does not address cases where ATM serves as a
1859 low-level transport pipe for IP packets which in turn may carry one
1860 or more real-time (e.g. VoIP) media sessions with a life-cycle
1861 different from that of the underlying ATM transport.
1863 5.48. 3GPP TS 26.114
1865 [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and
1866 interaction
1868 +----------------------+-------------------------+-------+----------+
1869 | Name | Notes | Level | Category |
1870 +----------------------+-------------------------+-------+----------+
1871 | 3gpp_sync_info | Usage defined for the | M | NORMAL |
1872 | | IP Multimedia Subsystem | | |
1873 | | | | |
1874 | 3gpp_MaxRecvSDUSize | Usage defined for the | M | NORMAL |
1875 | | IP Multimedia Subsystem | | |
1876 | | | | |
1877 +----------------------+-------------------------+-------+----------+
1879 3GPP TS 24.182 Attribute Analysis
1881 5.49. 3GPP TS 24.182
1883 [R3GPPTS24.182] specifies IP multimedia subsystem Custom Alerting
1884 tones
1886 +-------------+----------------------------------+-------+----------+
1887 | Name | Notes | Level | Category |
1888 +-------------+----------------------------------+-------+----------+
1889 | g.3gpp.cat | Usage defined for the IP | M | NORMAL |
1890 | | Multimedia Subsystem | | |
1891 | | | | |
1892 +-------------+----------------------------------+-------+----------+
1894 3GPP TS 24.182 Attribute Analysis
1896 5.50. 3GPP TS 24.183
1898 [R3GPPTS24.183] specifies IP multimedia subsystem Custom Ringing
1899 Signal
1901 +-------------+----------------------------------+-------+----------+
1902 | Name | Notes | Level | Category |
1903 +-------------+----------------------------------+-------+----------+
1904 | g.3gpp.crs | Usage defined for the IP | M | NORMAL |
1905 | | Multimedia Subsystem | | |
1906 | | | | |
1907 +-------------+----------------------------------+-------+----------+
1909 3GPP TS 24.183 Attribute Analysis
1911 5.51. 3GPP TS 24.229
1913 [R3GPPTS24.229] specifies IP multimedia call control protocol based
1914 on Session Initial protocol and Session Description Protocol.
1916 +------------------+---------------------------+-------+------------+
1917 | Name | Notes | Level | Category |
1918 +------------------+---------------------------+-------+------------+
1919 | secondary-realm | Per media-level attribute | M | TRANSPORT |
1920 | | MUST be used per | | |
1921 | | underlying transport | | |
1922 | | | | |
1923 | visited-realm | Per media-level attribute | M | TRANSPORT |
1924 | | MUST be used per | | |
1925 | | underlying transport | | |
1926 | | | | |
1927 | omr-m-cksum | Not Impacted | M | NORMAL |
1928 | | | | |
1929 | omr-s-cksum | Not Impacted | M | NORMAL |
1930 | | | | |
1931 | omr-m-att | Not Impacted | M | NORMAL |
1932 | | | | |
1933 | omr-s-bw | Not Impacted | M | NORMAL |
1934 | | | | |
1935 | omr-s-bw | Not Impacted | M | NORMAL |
1936 | | | | |
1937 | omr-m-att | Not Impacted | M | NORMAL |
1938 | | | | |
1939 | omr-codecs | Not Impacted | M | NORMAL |
1940 | | | | |
1941 +------------------+---------------------------+-------+------------+
1943 3GPP TS 24.229 Attribute Analysis
1945 5.52. ITU T.38
1947 [T.38] defines procedures for real-time Group 3 facsimile
1948 communications over IP networks.
1950 +------------------------+---------------+-------+----------+
1951 | Name | Notes | Level | Category |
1952 +------------------------+---------------+-------+----------+
1953 | T38FaxVersion | Not Impacted | S | NORMAL |
1954 | | | | |
1955 | T38MaxBitRate | Not Impacted | S | NORMAL |
1956 | | | | |
1957 | T38FaxFillBitRemoval | Not Impacted | S | NORMAL |
1958 | | | | |
1959 | T38FaxTranscodingMMR | Not Impacted | S | NORMAL |
1960 | | | | |
1961 | T38FaxTranscodingJBIG | Not Impacted | S | NORMAL |
1962 | | | | |
1963 | T38FaxRateManagement | Not Impacted | S | NORMAL |
1964 | | | | |
1965 | T38FaxMaxBuffer | Not Impacted | S | NORMAL |
1966 | | | | |
1967 | T38FaxMaxDatagram | Not Impacted | S | NORMAL |
1968 | | | | |
1969 | T38FaxUdpEC | Not Impacted | S | NORMAL |
1970 | | | | |
1971 | T38FaxMaxIFP | Not Impacted | S | NORMAL |
1972 | | | | |
1973 | T38FaxUdpECDepth | Not Impacted | S | NORMAL |
1974 | | | | |
1975 | T38FaxUdpFECMaxSpan | Not Impacted | S | NORMAL |
1976 | | | | |
1977 | T38ModemType | Not Impacted | S | NORMAL |
1978 | | | | |
1979 +------------------------+---------------+-------+----------+
1981 Historic Attribute Analysis
1983 The ITU T.38 attributes are clearly unaffected by multiplexing and
1984 are specific to the working of the fax protocol itself.
1986 5.53. ITU-T-REC.Q1970
1988 [ITU-T-REC.Q1970] defines BICC IP bearer control protocol.
1990 +--------+---------------+-------+----------+
1991 | Name | Notes | Level | Category |
1992 +--------+---------------+-------+----------+
1993 | ipbcp | Not Impacted | S | NORMAL |
1994 | | | | |
1995 +--------+---------------+-------+----------+
1997 ITU-T-REC.Q1970 Attribute Analysis
1999 5.54. ITU-T H.248.15
2001 ITU-T H.248.15 [H.248.15] defines Gateway Control Protocol SDP H.248
2002 package attribute
2004 +-----------+------------------------------------+-------+----------+
2005 | Name | Notes | Level | Category |
2006 +-----------+------------------------------------+-------+----------+
2007 | h248item | It is also only applicable for | B | SPECIAL |
2008 | | signaling the inclusion of H.248 | | |
2009 | | extension packages to a gateway | | |
2010 | | via the local and remote | | |
2011 | | descriptors. The attribute itself | | |
2012 | | is unaffected by multiplexing, but | | |
2013 | | the packaged referenced in a | | |
2014 | | specific use of the attribute may | | |
2015 | | be impacted. Further analysis of | | |
2016 | | each package is needed to | | |
2017 | | determine if there is an issue. | | |
2018 | | This is only a concern in | | |
2019 | | environments using a decomposed | | |
2020 | | server/gateway with H.248 signaled | | |
2021 | | between them. The ITU-T will need | | |
2022 | | to do further analysis of various | | |
2023 | | packages when they specify how to | | |
2024 | | signal the use of multiplexing to | | |
2025 | | a gateway. | | |
2026 | | | | |
2027 +-----------+------------------------------------+-------+----------+
2029 Historic Attribute Analysis
2031 5.55. RFC4975 - The Message Session Relay Protocol
2033 [RFC4975] the Message Session Relay Protocol, a protocol for
2034 transmitting a series of related instant messages in the context of a
2035 session. Message sessions are treated like any other media stream
2036 when set up via a rendezvous or session creation protocol such as the
2037 Session Initiation Protocol.
2039 +-----------------------+---------------+-------+----------+
2040 | Name | Notes | Level | Category |
2041 +-----------------------+---------------+-------+----------+
2042 | accept-types | Not Impacted | M | NORMAL |
2043 | | | | |
2044 | accept-wrapped-types | Not Impacted | M | NORMAL |
2045 | | | | |
2046 | max-size | Not Impacted | M | NORMAL |
2047 | | | | |
2048 | path | Not Impacted | M | NORMAL |
2049 | | | | |
2050 +-----------------------+---------------+-------+----------+
2052 RFC4975 Attribute Analysis
2054 5.56. Historical
2056 This section specifies analysis for the attributes that are included
2057 for historic usage alone by the [IANA].
2059 +---------------------+--------------+---------------+--------------+
2060 | Name | Notes | Level | Category |
2061 +---------------------+--------------+---------------+--------------+
2062 | rtpred1 | Historic | Not-Applcable | NOT |
2063 | | attributes. | | RECOMMENDED |
2064 | | | | |
2065 | rtpred2 | Historic | Not-Applcable | NOT |
2066 | | attributes. | | RECOMMENDED |
2067 | | | | |
2068 | PSCid | Not | Not-Applcable | NORMAL |
2069 | | Applicable | | |
2070 | | | | |
2071 | bc_service | Not | Not-Applcable | NORMAL |
2072 | | Applicable | | |
2073 | | | | |
2074 | bc_program | Not | Not-Applcable | NORMAL |
2075 | | Applicable | | |
2076 | | | | |
2077 | bc_service_package | Not | Not-Applcable | NORMAL |
2078 | | Applicable | | |
2079 | | | | |
2080 +---------------------+--------------+---------------+--------------+
2082 Unknowns Attribute Analysis
2084 6. bwtype Attribute Analysis
2086 This section specifies handling of specific bandwidth attributes when
2087 used in multiplexing scenarios.
2089 6.1. RFC4566 - SDP: Session Description Protocol
2091 +------------+-----------------------------------+-------+----------+
2092 | Name | Notes | Level | Category |
2093 +------------+-----------------------------------+-------+----------+
2094 | bwtype:CT | Not Impacted | S | NORMAL |
2095 | | | | |
2096 | bwtype:AS | As a session attribute, it | B | NORMAL |
2097 | | specifies the session aggregate | | |
2098 | | unless media-level b=RR and/or | | |
2099 | | b=RS attributes are used. Under | | |
2100 | | this interpretation the | | |
2101 | | multiplexing scheme has no impact | | |
2102 | | and thus NORMAL category applies. | | |
2103 | | | | |
2104 | bwtype:AS | For the media level usage, the | B | SUM |
2105 | | aggregate of individual bandwidth | | |
2106 | | values is considered. | | |
2107 | | | | |
2108 +------------+-----------------------------------+-------+----------+
2110 RFC4566 bwtype Analysis
2112 6.2. RFC3556 - SDP Bandwidth Modifiers for RTCP Bandwidth
2114 RFC3556 [RFC3556] defines an extension to the Session Description
2115 Protocol (SDP) to specify two additional modifiers for the bandwidth
2116 attribute. These modifiers may be used to specify the bandwidth
2117 allowed for RTP Control Protocol (RTCP) packets in a Real-time
2118 Transport Protocol (RTP) session
2119 +------------+-----------------------------------+-------+----------+
2120 | Name | Notes | Level | Category |
2121 +------------+-----------------------------------+-------+----------+
2122 | bwtype:RS | Session level usage represents | B | NORMAL |
2123 | | session aggregate and media level | | |
2124 | | usage indicates SUM of the | | |
2125 | | individual values while | | |
2126 | | multiplexing | | |
2127 | | | | |
2128 | bwtype:RR | Session level usage represents | B | NORMAL |
2129 | | session aggregate and media level | | |
2130 | | usage indicates SUM of the | | |
2131 | | individual values while | | |
2132 | | multiplexing | | |
2133 | | | | |
2134 +------------+-----------------------------------+-------+----------+
2136 RFC3556 bwtype Analysis
2138 6.3. RFC3890 - Bandwidth Modifier for SDP
2140 RFC3890 [RFC3890] defines a Session Description Protocol (SDP)
2141 Transport Independent Application Specific Maximum (TIAS) bandwidth
2142 modifier that does not include transport overhead; instead an
2143 additional packet rate attribute is defined. The transport
2144 independent bit-rate value together with the maximum packet rate can
2145 then be used to calculate the real bit-rate over the transport
2146 actually used.
2148 +--------------+---------------------------------+-------+----------+
2149 | Name | Notes | Level | Category |
2150 +--------------+---------------------------------+-------+----------+
2151 | bwtype:TIAS | The usage of TIAS is not | B | SPECIAL |
2152 | | clearly defined Offer/Answer | | |
2153 | | usage. | | |
2154 | | | | |
2155 | maxprate | The usage of TIAS and maxprate | B | SPECIAL |
2156 | | is not well defined under | | |
2157 | | multiplexing | | |
2158 | | | | |
2159 +--------------+---------------------------------+-------+----------+
2161 RFC3890 bwtype Analysis
2163 The intention of TIAS is that the media level bit-rate is multiplied
2164 with the known per-packet overhead for the selected transport and the
2165 maxprate value to determine the worst case bit-rate from the
2166 transport to more accurately capture the required usage. Summing
2167 TIAS values independently across m=lines and multiplying the computed
2168 sum with maxprate and the per-packet overhead would inflate the value
2169 significantly. Instead performing multiplication and adding the
2170 individual values is a more appropriate usage. This still ignores
2171 the fact that this is a send side declaration, and not intended for
2172 receiver negotiation.
2174 7. rtcp-fb Attribute Analysis
2176 This section analyzes rtcp-fb SDP attributes.
2178 7.1. RFC4585 - RTP/AVPF
2180 RFC4585 [RFC4585] defines an extension to the Audio-visual Profile
2181 (AVP) that enables receivers to provide, statistically, more
2182 immediate feedback to the senders and thus allows for short-term
2183 adaptation and efficient feedback-based repair mechanisms to be
2184 implemented.
2186 +----------+----------------------------+-------+-------------------+
2187 | Attr | Notes | Level | Category |
2188 | Name | | | |
2189 +----------+----------------------------+-------+-------------------+
2190 | ack rpsi | The attribute value must | M | IDENTICAL-PER-PT |
2191 | | be same for a given codec | | |
2192 | | configuration | | |
2193 | | | | |
2194 | ack app | Feedback parameters MUST | M | SPECIAL |
2195 | | be handled in the app | | |
2196 | | specific way when | | |
2197 | | multiplexed | | |
2198 | | | | |
2199 | nack | The attribute value must | M | IDENTICAL-PER-PT |
2200 | | be same for a given codec | | |
2201 | | configuration | | |
2202 | | | | |
2203 | nack pli | The attribute value must | M | IDENTICAL-PER-PT |
2204 | | be same for a given codec | | |
2205 | | configuration | | |
2206 | | | | |
2207 | nack sli | The attribute value must | M | IDENTICAL-PER-PT |
2208 | | be same for a given codec | | |
2209 | | configuration | | |
2210 | | | | |
2211 | nack | The attribute value must | M | IDENTICAL-PER-PT |
2212 | rpsi | be same for a given codec | | |
2213 | | configuration | | |
2214 | | | | |
2215 | nack app | Feedback parameters MUST | M | SPECIAL |
2216 | | be handled in the app | | |
2217 | | specific way when | | |
2218 | | multiplexed | | |
2219 | | | | |
2220 | trr-int | The attribute value must | M | IDENTICAL-PER-PT |
2221 | | be same for a given codec | | |
2222 | | configuration | | |
2223 | | | | |
2224 +----------+----------------------------+-------+-------------------+
2226 RFC4585 Attribute Analysis
2228 7.2. RFC5104 - Codec Control Messages in AVPF
2230 RFC5104 [RFC5104] specifies a few extensions to the messages defined
2231 in the Audio-Visual Profile with Feedback (AVPF). They are helpful
2232 primarily in conversational multimedia scenarios where centralized
2233 multipoint functionalities are in use. However, some are also usable
2234 in smaller multicast environments and point-to-point calls.
2236 +-------+-------------------------------+-------+-------------------+
2237 | Attr | Notes | Level | Category |
2238 | Name | | | |
2239 +-------+-------------------------------+-------+-------------------+
2240 | ccm | The attribute value must be | M | IDENTICAL-PER-PT |
2241 | | same for a given codec | | |
2242 | | configuration | | |
2243 | | | | |
2244 +-------+-------------------------------+-------+-------------------+
2246 RFC5104 Attribute Analysis
2248 7.3. RFC6285 - Unicast-Based RAMS
2250 +-------+-------------------------------+-------+-------------------+
2251 | Name | Notes | Level | Category |
2252 +-------+-------------------------------+-------+-------------------+
2253 | nack | The attribute value must be | M | IDENTICAL-PER-PT |
2254 | rai | same for a given codec | | |
2255 | | configuration | | |
2256 | | | | |
2257 +-------+-------------------------------+-------+-------------------+
2259 RFC6285 Attribute Analysis
2261 7.4. RFC6679 - ECN for RTP over UDP/IP
2263 RFC6679 [RFC6679] specifies how Explicit Congestion Notification
2264 (ECN) can be used with the Real-time Transport Protocol (RTP) running
2265 over UDP, using the RTP Control Protocol (RTCP) as a feedback
2266 mechanism. It defines a new RTCP Extended Report (XR) block for
2267 periodic ECN feedback, a new RTCP transport feedback message for
2268 timely reporting of congestion events, and a Session Traversal
2269 Utilities for NAT (STUN) extension used in the optional
2270 initialization method using Interactive Connectivity Establishment
2271 (ICE)
2272 +------------------+---------------------------+-------+------------+
2273 | Name | Notes | Level | Category |
2274 +------------------+---------------------------+-------+------------+
2275 | ecn-capable-rtp | ECN markup are enabled at | M | IDENTICAL |
2276 | | the RTP Session level | | |
2277 | | | | |
2278 | nack ecn | This attribute enables | M | IDENTICAL |
2279 | | ECN at the RTP session | | |
2280 | | level | | |
2281 | | | | |
2282 +------------------+---------------------------+-------+------------+
2284 RFC6679 Attribute Analysis
2286 7.5. RFC6642 - Third-Party Loss Report
2288 In a large RTP session using the RTP Control Protocol (RTCP) feedback
2289 mechanism defined in RFC 4585 [RFC4585], a feedback target may
2290 experience transient overload if some event causes a large number of
2291 receivers to send feedback at once. This overload is usually avoided
2292 by ensuring that feedback reports are forwarded to all receivers,
2293 allowing them to avoid sending duplicate feedback reports. However,
2294 there are cases where it is not recommended to forward feedback
2295 reports, and this may allow feedback implosion. RFC6642 [RFC6642]
2296 memo discusses these cases and defines a new RTCP Third-Party Loss
2297 Report that can be used to inform receivers that the feedback target
2298 is aware of some loss event, allowing them to suppress feedback.
2299 Associated Session Description Protocol (SDP) signaling is also
2300 defined.
2302 +--------+------------------------------+-------+-------------------+
2303 | Name | Notes | Level | Category |
2304 +--------+------------------------------+-------+-------------------+
2305 | nack | The attribute value must be | M | IDENTICAL-PER-PT |
2306 | tllei | same for a given codec | | |
2307 | | configuration | | |
2308 | | | | |
2309 | nack | The attribute value must be | M | IDENTICAL-PER-PT |
2310 | pslei | same for a given codec | | |
2311 | | configuration | | |
2312 | | | | |
2313 +--------+------------------------------+-------+-------------------+
2315 RFC6642 Attribute Analysis
2317 7.6. RFC5104 - Codec Control Messages in AVPF
2319 +--------+------------------------------+-------+-------------------+
2320 | Attr | Notes | Level | Category |
2321 | Name | | | |
2322 +--------+------------------------------+-------+-------------------+
2323 | ccm | The attribute value must be | M | IDENTICAL-PER-PT |
2324 | fir | same for a given codec | | |
2325 | | configuration | | |
2326 | | | | |
2327 | ccm | The attribute value must be | M | IDENTICAL-PER-PT |
2328 | tmmbr | same for a given codec | | |
2329 | | configuration | | |
2330 | | | | |
2331 | ccm | The attribute value must be | M | IDENTICAL-PER-PT |
2332 | tstr | same for a given codec | | |
2333 | | configuration | | |
2334 | | | | |
2335 | ccm | The attribute value must be | M | IDENTICAL-PER-PT |
2336 | vbcm | same for a given codec | | |
2337 | | configuration | | |
2338 | | | | |
2339 +--------+------------------------------+-------+-------------------+
2341 RFC5104 Attribute Analysis
2343 8. group Attribute Analysis
2345 This section analyzes SDP "group" semantics.
2347 8.1. RFC5888 - SDP Grouping Framework
2349 RFC5888 [RFC5888] defines a framework to group "m" lines in the
2350 Session Description Protocol (SDP) for different purposes.
2352 +------------+---------------+-------+----------+
2353 | Name | Notes | Level | Category |
2354 +------------+---------------+-------+----------+
2355 | group:LS | Not Impacted | S | NORMAL |
2356 | | | | |
2357 | group:FID | Not Impacted | S | NORMAL |
2358 | | | | |
2359 +------------+---------------+-------+----------+
2361 RFC5888 Attribute Analysis
2363 8.2. RFC3524 - Mapping Media Streams to Resource Reservation Flows
2365 RFC3524 [RFC3524] defines an extension to the Session Description
2366 Protocol (SDP) grouping framework. It allows requesting a group of
2367 media streams to be mapped into a single resource reservation flow.
2368 The SDP syntax needed is defined, as well as a new "semantics"
2369 attribute called Single Reservation Flow (SRF).
2371 +------------+---------------+-------+----------+
2372 | Name | Notes | Level | Category |
2373 +------------+---------------+-------+----------+
2374 | group:SRF | Not Impacted | S | NORMAL |
2375 | | | | |
2376 +------------+---------------+-------+----------+
2378 RFC3524 Attribute Analysis
2380 8.3. RFC4091 - ANAT Semantics
2382 RFC4091 [RFC4091] defines the Alternative Network Address Types
2383 (ANAT) semantics for the Session Description Protocol (SDP) grouping
2384 framework. The ANAT semantics allow alternative types of network
2385 addresses to establish a particular media stream.
2387 +-------------+---------------------------+-------+-----------------+
2388 | Name | Notes | Level | Category |
2389 +-------------+---------------------------+-------+-----------------+
2390 | group:ANAT | ANAT semantics is | S | NOT RECOMMENDED |
2391 | | obseleted | | |
2392 | | | | |
2393 +-------------+---------------------------+-------+-----------------+
2395 RFC4091 Attribute Analysis
2397 8.4. RFC5956 - FEC Grouping Semantics in SDP
2399 RFC5956 [RFC5956] defines the semantics for grouping the associated
2400 source and FEC-based (Forward Error Correction) repair flows in the
2401 Session Description Protocol (SDP). The semantics defined in the
2402 document are to be used with the SDP Grouping Framework (RFC 5888).
2403 These semantics allow the description of grouping relationships
2404 between the source and repair flows when one or more source and/or
2405 repair flows are associated in the same group, and they provide
2406 support for additive repair flows. SSRC-level (Synchronization
2407 Source) grouping semantics are also defined in this document for
2408 Real-time Transport Protocol (RTP) streams using SSRC multiplexing.
2410 +---------------+---------------+-------+----------+
2411 | Name | Notes | Level | Category |
2412 +---------------+---------------+-------+----------+
2413 | group:FEC-FR | Not Impacted | S | NORMAL |
2414 | | | | |
2415 +---------------+---------------+-------+----------+
2417 RFC5956 Attribute Analysis
2419 8.5. RFC5583 - Signaling Media Decoding Dependency in SDP
2421 RFC5583 [RFC5583] defines semantics that allow for signaling the
2422 decoding dependency of different media descriptions with the same
2423 media type in the Session Description Protocol (SDP). This is
2424 required, for example, if media data is separated and transported in
2425 different network streams as a result of the use of a layered or
2426 multiple descriptive media coding process.
2428 +--------+------------------------------+-------+-------------------+
2429 | Name | Notes | Level | Category |
2430 +--------+------------------------------+-------+-------------------+
2431 | depend | The attribute value must be | M | IDENTICAL-PER-PT |
2432 | lay | same for a given codec | | |
2433 | | configuration | | |
2434 | | | | |
2435 | depend | The attribute value must be | M | IDENTICAL-PER-PT |
2436 | mdc | same for a given codec | | |
2437 | | configuration | | |
2438 | | | | |
2439 +--------+------------------------------+-------+-------------------+
2441 RFC5583 Attribute Analysis
2443 8.6. RFC7104 - Duplication Grouping Semantics in the SDP
2445 [RFC7104] defines the semantics for grouping redundant streams in the
2446 Session Description Protocol (SDP). The semantics defined in this
2447 document are to be used with the SDP Grouping Framework. Grouping
2448 semantics at the Synchronization Source (SSRC) level are also defined
2449 in this document for RTP streams using SSRC multiplexing.
2451 +------------+---------------+-------+----------+
2452 | Name | Notes | Level | Category |
2453 +------------+---------------+-------+----------+
2454 | group:DUP | Not Impacted | S | NORMAL |
2455 | | | | |
2456 +------------+---------------+-------+----------+
2458 RFC7104 Attribute Analysis
2460 9. ssrc-group Attribute Analysis
2462 This section analyzes "ssrc-group" semantics.
2464 9.1. RFC5576 - Source-Specific SDP Attributes
2466 +-------------------+---------------+-------+----------+
2467 | Name | Notes | Level | Category |
2468 +-------------------+---------------+-------+----------+
2469 | ssrc-group:FID | Not Impacted | M | NORMAL |
2470 | | | | |
2471 | ssrc-group:FEC | Not Impacted | M | NORMAL |
2472 | | | | |
2473 | ssrc-groupFEC-FR | Not Impacted | M | NORMAL |
2474 | | | | |
2475 +-------------------+---------------+-------+----------+
2477 RFC5576 Attribute Analysis
2479 9.2. RFC7104 - Duplication Grouping Semantics in the SDP
2481 +-----------------+---------------+-------+----------+
2482 | Name | Notes | Level | Category |
2483 +-----------------+---------------+-------+----------+
2484 | ssrc-group:DUP | Not Impacted | M | NORMAL |
2485 | | | | |
2486 +-----------------+---------------+-------+----------+
2488 RFC7104 Attribute Analysis
2490 10. QoS Mechanism Token Analysis
2492 This section analyzes QoS tokes specified with SDP.
2494 10.1. RFC5432 - QoS Mechanism Selection in SDP
2495 +-------+----------------------------------------+-------+----------+
2496 | Name | Notes | Level | Category |
2497 +-------+----------------------------------------+-------+----------+
2498 | rsvp | Not Impacted, since QOS mechanisms are | B | NORMAL |
2499 | | applied per flow. | | |
2500 | | | | |
2501 | nsis | Not Impacted, since QOS mechanisms are | B | NORMAL |
2502 | | applied per flow. | | |
2503 | | | | |
2504 +-------+----------------------------------------+-------+----------+
2506 RFC5432 Attribute Analysis
2508 11. k= Attribute Analysis
2510 11.1. RFC4566 SDP: Session Description Protocol
2512 +------+------------------------------------+-------+---------------+
2513 | Name | Notes | Level | Category |
2514 +------+------------------------------------+-------+---------------+
2515 | k= | It is NOT recommended to use this | S | NOT |
2516 | | attribute | | RECOMMENDED |
2517 | | | | |
2518 +------+------------------------------------+-------+---------------+
2520 RFC4566 Attribute Analysis
2522 12. content Atribute Analysis
2524 12.1. RFC4796
2526 +------------------+---------------+-------+----------+
2527 | Name | Notes | Level | Category |
2528 +------------------+---------------+-------+----------+
2529 | content:slides | Not Impacted | M | NORMAL |
2530 | | | | |
2531 | content:speaker | Not Impacted | M | NORMAL |
2532 | | | | |
2533 | content:main | Not Impacted | M | NORMAL |
2534 | | | | |
2535 | content:sl | Not Impacted | M | NORMAL |
2536 | | | | |
2537 | content:alt | Not Impacted | M | NORMAL |
2538 | | | | |
2539 +------------------+---------------+-------+----------+
2541 RFC4796 Attribute Analysis
2543 13. Payload Formats
2545 13.1. RFC5109 - RTP Payload Format for Generic FEC
2547 [RFC5109] describes a payload format for generic Forward Error
2548 Correction (FEC) for media data encapsulated in RTP. It is based on
2549 the exclusive-or (parity) operation. The payload format allows end
2550 systems to apply protection using various protection lengths and
2551 levels, in addition to using various protection group sizes to adapt
2552 to different media and channel characteristics. It enables complete
2553 recovery of the protected packets or partial recovery of the critical
2554 parts of the payload depending on the packet loss situation.
2556 +---------------------+----------------------+-------+--------------+
2557 | Name | Notes | Level | Category |
2558 +---------------------+----------------------+-------+--------------+
2559 | audio/ulpfec | Not recommended for | M | NOT |
2560 | | multiplexing due to | | RECOMMENDED |
2561 | | reuse of SSRCs | | |
2562 | | | | |
2563 | video/ulpfec | Not recommended for | M | NOT |
2564 | | multiplexing due to | | RECOMMENDED |
2565 | | reuse of SSRCs | | |
2566 | | | | |
2567 | text/ulpfec | Not recommended for | M | NOT |
2568 | | multiplexing due to | | RECOMMENDED |
2569 | | reuse of SSRCs | | |
2570 | | | | |
2571 | application/ulpfec | Not recommended for | M | NOT |
2572 | | multiplexing due to | | RECOMMENDED |
2573 | | reuse of SSRCs | | |
2574 | | | | |
2575 +---------------------+----------------------+-------+--------------+
2577 RFC5109 Payload Format Analysis
2579 Draft draft-lennox-payload-ulp-ssrc-mux proposes a simple fix to make
2580 it possible to use ULP with multiplexing and ULP is allowed when used
2581 with that.
2583 14. Multiplexing Considerations for Encapsulating Attributes
2585 This sections deals with recommendations for defining the
2586 multiplexing characteristics of the SDP attributes that encapsulate
2587 other SDP attributes/parameters. Such attributes as of today, for
2588 example, are defined in [RFC3407], [RFC5939] and [RFC6871] as part of
2589 a generic framework for indicating and negotiating transport, media
2590 and media format related capabilities in the SDP.
2592 The behavior of such attributes under multiplexing is in turn defined
2593 by the multiplexing behavior of the attributes they encapsulate which
2594 are made known once the Offer/Answer negotiation process is
2595 completed.
2597 14.1. RFC3407 - cpar Attribute Analysis
2599 RFC3407 capability parameter attribute (a=cpar) encapsulates b=
2600 (bandwidth) or an a= attribute. For bandwidth attribute
2601 encapsulation, the category SUM is inherited. For the case of a=
2602 attribute, the category corresponding to the SDP attribute being
2603 encapsulated is inherited.
2605 v=0
2606 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
2607 s=
2608 c=IN IP4 host.atlanta.example.com
2609 t=0 0
2610 m=video 3456 RTP/AVP 100
2611 a=rtpmap:100 VP8/90000
2612 a=sqn: 0
2613 a=cdsc: 1 video RTP/AVP 100
2614 a=cpar: a=rtcp-mux
2615 m=video 3456 RTP/AVP 101
2616 a=rtpmap:101 VP8/90000
2617 a=fmtp:100 max-fr=15;max-fs=1200
2618 a=cdsc: 2 video RTP/AVP 101
2619 a=cpar: a=rtcp-mux
2621 In the above example ,the category IDENTICAL is inherited for the
2622 cpar encapsulated rtcp-mux attribute.
2624 14.2. RFC5939 Analysis
2626 [RFC5939] defines a general SDP capability negotiation framework. It
2627 also specifies how to provide transport protocols and SDP attributes
2628 as capabilities and negotiate them using the framework.
2630 For this purpose, [RFC5939] defines the following
2632 o A set of capabilities for the session and its associated media
2633 stream components, supported by each side. The attribute
2634 ("a=acap") defines how to list an attribute name and its
2635 associated value (if any) as a capability. The attribute
2636 ("a=tcap") defines how to list transport protocols (e.g., "RTP/
2637 AVP") as capabilities.
2639 o A set of potential configurations ("a=pcfg") provided by the
2640 offerer to indicate whcich combination of those capabilities can
2641 be used for the session and its associated media stream
2642 components. Potential configurations are not ready for use until
2643 fully negotiated. They provide an alternative that may be used,
2644 subject to SDP capability negotiation procedures. In particular
2645 the answerer may choose one of the potential configurations for
2646 use as part of the current Offer/Answer exchange.
2648 o An actual configuration ("a=acfg") for the session and its
2649 associated media stream components. The actual configuration
2650 identifies the potential configuration that was negotiated for
2651 use. Use of an actual configuration does not require any further
2652 negotiation.
2654 o A negotiation process that takes the current actual and the set of
2655 potential configurations (combinations of capabilities) as input
2656 and provides the negotiated actual configurations as output. In
2657 [RFC5939] the negotiation process is done independently for each
2658 media description.
2660 14.2.1. Recommendation - Procedures for Potential Configuration Pairing
2662 This section provides recommendations for entities generating and
2663 processing SDP under the generic capability negotiation framework as
2664 defined in [RFC5939] under the context of media stream multiplexing.
2666 These recommendations are provided for the purposes of enabling the
2667 Offerer to make sure that the generated potential configurations
2668 between the multiplexed streams can (easily) be negotiated to be
2669 consistent between those streams. In particular, the procedures aim
2670 to simply Answerer's procedure to choose potential configurations
2671 that are consistent across all the bundled media descriptions.
2673 A potential configuration selects a set of attributes and parameters
2674 that become part of the media description when negotiated. When
2675 multiplexing media descriptions with potential configurations
2676 specified, there may be a need for coordinating this selection
2677 between multiplexed media descriptions ensuring right multiplexing
2678 behavior.
2680 Although it is possible to analyze the various potential
2681 configurations in bundled media descriptions to find combinations
2682 that satisfy such constraints, it can quickly become complicated to
2683 do so.
2685 The procedures defined in [RFC5939] state that each potential
2686 configuration in the SDP has a unique configuration number, however
2687 the scope of uniqueness is limited to each media description. To
2688 make it simple for the answerer to chose valid combinations of
2689 potential configurations across media descriptions in a given bundle
2690 group, we provide a simple rule for constructiong potential
2691 configurations:-
2693 o Let m-bundle be the set of media descriptions that form a given
2694 bundle .
2696 o Let m-bundle-pcfg be the set of media descriptions in m-bundle
2697 that include one or more potential configurations.
2699 o Each media description in m-bundle-pcfg MUST have at least one
2700 potential configuration with the same configuration number (e.g.
2701 "1").
2703 o For each potential configuration with configuration number x in m-
2704 bundle-pcfg, the offerer MUST ensure that if the answerer chooses
2705 configuration number x in each of the media descriptions in m-
2706 bundle-pcfg, then the resulting SDP will have all multiplexing
2707 constraints satisfied for those media descriptions.
2709 o Since it is nearly impossible to define a generic mechanism for
2710 various capability extensions , this document does't provide
2711 procedures for dealing with the capability extension attributes.
2712 However, Section Section 14.3 provide analysis of media capability
2713 extension attributes as defined in [RFC6871].
2715 The above allows the answerer to easily find multiplexing compatible
2716 combinations of potential configurations:- The answerer simply choses
2717 a potential configuration (number) that is present in all of the
2718 media descriptions with potential configurations in the bundle.
2720 Note that it is still possible for the offerer to provide additional
2721 potential configurations with independent configuration numbers. The
2722 answerer will have to perform more complicated analysis to determine
2723 valid multiplexed combinations of those.
2725 14.2.1.1. Example: Transport Capability Multiplexing
2726 v=0
2727 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
2728 s=
2729 c=IN IP4 host.atlanta.example.com
2730 t=0 0
2731 a=tcap:1 RTP/SAVPF
2732 a=tcap:2 RTP/SAVP
2733 a=group:BUNDLE audio video
2734 m= audio
2735 a=mid:audio
2736 a=pcfg:1 t=1
2737 a=pcfg:2
2738 m= video
2739 a=mid:video
2740 a=pcfg:1 t=1
2741 a=pcfg:2 t=2
2743 In the example above, the potential configurations that offer
2744 transport protocol capability of RTP/SAVPF has the same configuration
2745 number "1" in both the audio and video media descriptions.
2747 14.2.1.2. Example: Attribute Capability Multiplexing
2749 v=0
2750 o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
2751 s=
2752 c=IN IP4 host.atlanta.example.com
2753 t=0 0
2754 a=acap:1 a=rtcp-mux
2755 a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80
2756 inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32
2757 a=group:BUNDLE audio video
2758 m= audio 49172 RTP/AVP 99
2759 a=mid:audio
2760 a=pcfg:1 a=1
2761 a=pcfg:2
2762 m= video 560024 RTP/AVP 100
2763 a=mid:video
2764 a=pcfg:1 a=1
2765 a=pcfg:2 a=2
2767 In the example above, the potential configuration number 1 is
2768 repeated while referring to attribute capability a=rtcp-mux, since
2769 the behavior is IDENTICAL for the attribute a=rtcp-mux under
2770 multiplexing.
2772 14.3. RFC6871 Analysis
2774 [RFC6871] extends capability negotiation framework described in
2775 [RFC5939] by defining media capabilities that can be used to indicate
2776 and negotiate media types and their associated format parameters. It
2777 also allows indication of latent configurations and session
2778 capabilities (the latter of which is not recommended for use with
2779 bundled media as described in Section 5.29).
2781 14.3.1. Recommendation: Dealing with Payload Type Numbers
2783 RFC 6871 defines a new payload type ("pt") parameter to be used with
2784 the potential, actual and latent configuration parameters. The
2785 parameter associates RTP payload type numbers with the referenced
2786 RTP-based media format capabilities ("a=rmcap") defined in [RFC6871]
2787 and is appropriate only when the transport protocol uses RTP. This
2788 means that the same payload type number can be assigned as part of
2789 potential or actual configurations in different media descriptions in
2790 a bundle. There are rules for the usage of identical Payload Type
2791 values across multiplexed m=lines as described in [I-D.ietf-mmusic-
2792 sdp-bundle-negotiation], which MUST be followed here as well. As
2793 described in Section 15.2, the use of identical configuration numbers
2794 for compatible configurations in different media descriptions that
2795 are part of the bundle provides a way to ensure that the answerer can
2796 easily pick compatible configurations here as well.
2798 14.3.1.1. Example: Attribute Capability Under Shared Payload Type
2800 The attributes (a=rmcap, a=mfcap) follow the above recommendations
2801 under mutliplexing
2802 v=0
2803 o=- 25678 753849 IN IP4 192.0.2.1
2804 s=
2805 c=IN IP4 192.0.2.1
2806 t=0 0
2807 a=creq:med-v0
2808 m=audio 54322 RTP/AVP 96
2809 a=rtpmap:96 AMR-WB/16000/1
2810 a=fmtp:96 mode-change-capability=1; max-red=220;
2811 mode-set=0,2,4,7
2812 a=rmcap:1,3 audio AMR-WB/16000/1
2813 a=rmcap:2 audio AMR/8000/1
2814 a=mfcap:1,2 mode-change-capability=1
2815 a=mfcap:3 mode-change-capability=2
2816 a=pcfg:1 m=1 pt=1:96
2817 a=pcfg:2 m=2 pt=2:97
2818 a=pcfg:3 m=3 pt=3:98
2820 m=audio 54322 RTP/AVP 96
2821 a=rtpmap:96 AMR-WB/16000/1
2822 a=fmtp:96 mode-change-capability=1; max-red=220;
2823 mode-set=0,2,4,7
2824 a=rmcap:4 audio AMR/8000/1
2825 a=rmcap:5 audio OPUS/48000/2
2826 a=mfcap:5 minptime=40
2827 a=mfcap:4 mode-change-capability=1
2828 a=pcfg:1 m=4 pt=4:97
2829 a=pcfg:4 m=5 pt=5:101
2831 In the example above, the potential configuration number 1 is
2832 repeated when referring to media and media format capability used for
2833 the Payload Type 97. This implies that both the media capability 2
2834 and 4 along with their media format capabilities MUST refer to the
2835 same codec configuration , as per the definition of IDENTICAL-PER-PT
2837 14.3.2. Recommendation: Dealing with Latent Configurations
2839 RFC 6871 adds the notion of a latent configurations, which provides
2840 configuration information that may be used to guide a subsequent
2841 offer/exchange, e.g. by adding another media stream or use
2842 alternative codec combinations not currently offered. Latent
2843 configurations have configuration numbers which cannot overlap with
2844 the potential configuration numbers [RFC6871]. Supported
2845 combinations of potential and latent configurations are indicated by
2846 use of the "a=sescap" attribute, however use of this attribute is not
2847 recommended with bundled media, since it requires the use of unique
2848 configuration numbers across the SDP. Taken together, this means
2849 there is no well-defined way to indicate supported combinations of
2850 latent configurations, or combinations of latent and potential
2851 configurations with bundled media. It is still allowed to use the
2852 latent configuration attribute, however the limitations above will
2853 apply. To determine valid combinations, actual negotiation will have
2854 to be attempted subsequently instead.
2856 15. IANA Considerations
2858 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
2859 document.]
2861 The IANA is requested to add a new column named "Mux Category" to all
2862 several of the registries in the "Session Description Protocol (SDP)
2863 Parameters". Section Section 15.1 defines the new registry for
2864 identifying the initial registrations for "Mux Category" as proposed
2865 in this document. The tables in Section 15.2 identify name of an
2866 entry in the existing registry and specify the value to put in the
2867 new "Mux Category" column of the associated IANA registry. Any
2868 entries in the existing tables that do not have a value for the "Mux
2869 Category" specified in this RFC will get a value of "TBD". Future
2870 specifications can change the "TBD" entries to the correct value.
2872 15.1. New Column 'Mux Category'
2874 A new registry needs to be setup for specifying possible values for
2875 the "Mux Category" column, with the following registrations created
2876 initially: "NORMAL", "NOT RECOMMENDED", "IDENTICAL", "TRANSPORT",
2877 "IDENTICAL-PER-PT", SPECIAL" and "TBD" as defined in this document.
2879 Initial value registration for the column "Mux Category".
2881 Value name: NORMAL
2882 Reference : RFCXXXX
2884 Value name: NOT RECOMMENDED
2885 Reference : RFCXXXX
2887 Value name: IDENTICAL
2888 Reference : RFCXXXX
2890 Value name: TRANSPORT
2891 Reference : RFCXXXX
2893 Value name: IDENTICAL-PER-PT
2894 Reference : RFCXXXX
2896 Value name: SPECIAL
2897 Reference : RFCXXXX
2899 Value name: TBD
2900 Reference : RFCXXXX
2902 Further entries may be registered on a first-come first-serve basis.
2903 Each registration needs to indicate the "Mux Category" value and
2904 identify the entries in the existing registries defined at "Session
2905 Description Protocol (SDP) Parameters" to which the newly registered
2906 "Mux Category" applies. For each new registration, it is mandatory
2907 that a permanent, stable, and publicly accessible document exists
2908 that specifies the semantics of the registered parameter in the
2909 context of multiplexing and its applicability to existing registered
2910 SDP parameters as stated above. The general registration procedures
2911 of [RFC4566] apply.
2913 15.2. 'Mux Category' values for SDP Registries
2915 The various sub-sections below assigns the values to be used for the
2916 "Mux Category" column for the corresponding registries idenfied.
2918 15.2.1. Table: SDP bwtype
2920 The following values are to be added to the 'SDP bwtype' registry in
2921 the "Session Description Protocol (SDP) Parameters. The references
2922 should be updated to point at this RFC as well as the previous
2923 references.
2925 +-------+--------------+
2926 | Type | Mux Category |
2927 +-------+--------------+
2928 | CT | NORMAL |
2929 | AS | SUM |
2930 | RS | NORMAL |
2931 | RR | NORMAL |
2932 | TIAS | SPECIAL |
2933 +-------+--------------+
2935 15.2.2. Table: att-field
2937 The following values are to be added to the 'att-field' registry in
2938 the "Session Description Protocol (SDP) Parameters. The references
2939 should be updated to point at this RFC as well as the previous
2940 references.
2942 +---------------------------+-------------------+
2943 | SDP Name | Mux Category |
2944 +---------------------------+-------------------+
2945 | cat | NORMAL |
2946 | keywds | NORMAL |
2947 | type | NORMAL |
2948 | type:broadcast | NORMAL |
2949 | type:H332 | NORMAL |
2950 | type:meeting | NORMAL |
2951 | type:moderated | NORMAL |
2952 | type:test | NORMAL |
2953 | charset | NORMAL |
2954 | charset:iso8895-1 | NORMAL |
2955 | tool | NORMAL |
2956 | ipbcp | NORMAL |
2957 | group | NORMAL |
2958 | ice-lite | NORMAL |
2959 | ice-options | NORMAL |
2960 | bcastversion | NORMAL |
2961 | 3GPP-Integrity-Key | NOT RECOMMENDED |
2962 | 3GPP-SDP-Auth | NOT RECOMMENDED |
2963 | alt-group | NOT RECOMMENDED |
2964 | PSCid | NORMAL |
2965 | bc_service | NORMAL |
2966 | bc_program | NORMAL |
2967 | bc_service_package | NORMAL |
2968 | sescap | NOT RECOMMENDED |
2969 | rtsp-ice-d-m | TBD |
2970 | recvonly | NORMAL |
2971 | sendrecv | NORMAL |
2972 | sendonly | NORMAL |
2973 | sdplang | NORMAL |
2974 | lang | NORMAL |
2975 | h248item | SPECIAL |
2976 | sqn | NORMAL |
2977 | cdsc | NORMAL |
2978 | cpar | INHERIT |
2979 | cparmin | SPECIAL |
2980 | cparmax | SPECIAL |
2981 | rtcp-xr | NORMAL |
2982 | maxprate | SPECIAL |
2983 | setup | IDENTICAL |
2984 | connection | IDENTICAL |
2985 | key-mgmt | IDENTICAL |
2986 | source-filter | IDENTICAL |
2987 | inactive | NORMAL |
2988 | fingerprint | TRANSPORT |
2989 | flute-tsi | TBD |
2990 | flute-ch | TBD |
2991 | FEC-declaration | TBD |
2992 | FEC-OTI-extension | TBD |
2993 | content-desc | TBD |
2994 | ice-pwd | TRANSPORT |
2995 | ice-ufrag | TRANSPORT |
2996 | stkmstream | NORMAL |
2997 | qos-mech-send | NORMAL |
2998 | qos-mech-recv | NORMAL |
2999 | csup | NORMAL |
3000 | creq | NORMAL |
3001 | acap | INHERIT |
3002 | tcap | INHERIT |
3003 | 3GPP-QoE-Metrics | NOT RECOMMENDED |
3004 | 3GPP-Asset-Information | NOT RECOMMENDED |
3005 | mbms-mode | NORMAL |
3006 | mbms-repair | NORMAL |
3007 | ike-setup | IDENTICAL |
3008 | psk-fingerprint | IDENTICAL |
3009 | multicast-rtcp | IDENTICAL |
3010 | rmcap | IDENTICAL-PER-PT |
3011 | omcap | NORMAL |
3012 | mfcap | IDENTICAL-PER-PT |
3013 | mscap | INHERIT |
3014 | bcap | INHERIT |
3015 | ccap | IDENTICAL |
3016 | icap | NORMAL |
3017 | 3gpp_sync_info | NORMAL |
3018 | 3gpp_MaxRecvSDUSize | NORMAL |
3019 | etag | TBD |
3020 | duplication-delay | NORMAL |
3021 | range | TBD |
3022 | control | TBD |
3023 | mtag | TBD |
3024 | ts-refclk | NORMAL |
3025 | mediaclk | NORMAL |
3026 | calgextmap | NORMAL |
3027 | ptime | IDENTICAL-PER-PT |
3028 | orient | NORMAL |
3029 | orient:portrait | NORMAL |
3030 | orient:landscape | NORMAL |
3031 | orient:seascape | NORMAL |
3032 | framerate | IDENTICAL-PER-PT |
3033 | quality | NORMAL |
3034 | rtpmap | IDENTICAL-PER-PT |
3035 | fmtp | IDENTICAL-PER-PT |
3036 | rtpred1 | NOT RECOMMENDED |
3037 | rtpred2 | NOT RECOMMENDED |
3038 | T38FaxVersion | NORMAL |
3039 | T38MaxBitRate | NORMAL |
3040 | T38MaxBitRate | NORMAL |
3041 | T38FaxTranscodingMMR | NORMAL |
3042 | T38FaxTranscodingJBIG | NORMAL |
3043 | T38FaxRateManagement | NORMAL |
3044 | T38FaxMaxBuffer | NORMAL |
3045 | T38FaxMaxDatagram | NORMAL |
3046 | T38FaxUdpEC | NORMAL |
3047 | maxptime | IDENTICAL-PER-PT |
3048 | des | NORMAL |
3049 | curr | NORMAL |
3050 | conf | NORMAL |
3051 | mid | NORMAL |
3052 | rtcp | IDENTICAL |
3053 | rtcp-fb | IDENTICAL-PER-PT |
3054 | label | NORMAL |
3055 | T38VendorInfo | NORMAL |
3056 | crypto | TRANSPORT |
3057 | eecid | NORMAL |
3058 | aalType | NORMAL |
3059 | capability | NORMAL |
3060 | qosClass | NORMAL |
3061 | bcob | NORMAL |
3062 | stc | NORMAL |
3063 | upcc | NORMAL |
3064 | atmQOSparms | NORMAL |
3065 | atmQOSparms | NORMAL |
3066 | abrParms | NORMAL |
3067 | abrSetup | NORMAL |
3068 | bearerType | NORMAL |
3069 | lij | NORMAL |
3070 | anycast | NORMAL |
3071 | cache | NORMAL |
3072 | bearerSigIE | NORMAL |
3073 | aalApp | NORMAL |
3074 | cbrRate | NORMAL |
3075 | sbc | NORMAL |
3076 | clkrec | NORMAL |
3077 | fec | NORMAL |
3078 | prtfl | NORMAL |
3079 | structure | NORMAL |
3080 | cpsSDUsize | NORMAL |
3081 | all2CPS | NORMAL |
3082 | all2CPSSDUrate | NORMAL |
3083 | aal2sscs3661unassured | NORMAL |
3084 | aal2sscs3661assured | NORMAL |
3085 | aal2sscs3662 | NORMAL |
3086 | aal5sscop | NORMAL |
3087 | atmmap | NORMAL |
3088 | silenceSupp | NORMAL |
3089 | ecan | NORMAL |
3090 | gc | NORMAL |
3091 | profileDesc | NORMAL |
3092 | vsel | NORMAL |
3093 | dsel | NORMAL |
3094 | fsel | NORMAL |
3095 | onewaySel | NORMAL |
3096 | codecConfig | NORMAL |
3097 | isup_usi | NORMAL |
3098 | uiLayer1_Prot | NORMAL |
3099 | chain | NORMAL |
3100 | floorctrl | IDENTICAL |
3101 | confid | NORMAL |
3102 | userid | NORMAL |
3103 | floorid | NORMAL |
3104 | FEC | NORMAL |
3105 | profileDesc | NORMAL |
3106 | accept-types | NORMAL |
3107 | accept-wrapped-types | NORMAL |
3108 | max-size | NORMAL |
3109 | path | NORMAL |
3110 | dccp-service-code | NOT RECOMMENDED |
3111 | rtcp-mux | IDENTICAL |
3112 | candidate | TRANSPORT |
3113 | ice-mismatch | NORMAL |
3114 | remote-candidates | TRANSPORT |
3115 | SRTPAuthentication | NORMAL |
3116 | SRTPROCTxRate | NORMAL |
3117 | rtcp-rsize | IDENTICAL |
3118 | file-selector | NORMAL |
3119 | file-transfer-id | NORMAL |
3120 | file-disposition | NORMAL |
3121 | file-date | NORMAL |
3122 | file-icon | NORMAL |
3123 | file-range | NORMAL |
3124 | depend | IDENTICAL-PER-PT |
3125 | ssrc | NORMAL |
3126 | ssrc-group | NORMAL |
3127 | rtcp-unicast | IDENTICAL |
3128 | pcfg | SPECIAL |
3129 | acfg | SPECIAL |
3130 | zrtp-hash | NOT RECOMMENDED |
3131 | X-predecbufsize | NOT RECOMMENDED |
3132 | X-initpredecbufperiod | NOT RECOMMENDED |
3133 | X-initpostdecbufperiod | NOT RECOMMENDED |
3134 | X-decbyterate | NOT RECOMMENDED |
3135 | 3gpp-videopostdecbufsize | NOT RECOMMENDED |
3136 | framesize | NOT RECOMMENDED |
3137 | 3GPP-SRTP-Config | NOT RECOMMENDED |
3138 | alt | NOT RECOMMENDED |
3139 | alt-default-id | NOT RECOMMENDED |
3140 | 3GPP-Adaption-Support | NOT RECOMMENDED |
3141 | mbms-flowid | NOT RECOMMENDED |
3142 | fec-source-flow | SPECIAL |
3143 | fec-repair-flow | SPECIAL |
3144 | repair-window | SPECIAL |
3145 | rams-updates | NOT RECOMMENDED |
3146 | imageattr | IDENTICAL-PER-PT |
3147 | cfw-id | NORMAL |
3148 | portmapping-req | NOT RECOMMENDED |
3149 | g.3gpp.cat | NORMAL |
3150 | g.3gpp.crs | NORMAL |
3151 | ecm-capable-rtp | IDENTICAL-PER-PT |
3152 | visited-realm | TRANSPORT |
3153 | secondary-realm | TRANSPORT |
3154 | omr-s-cksum | NORMAL |
3155 | omr-m-Cksum | NORMAL |
3156 | omr-codecs | NORMAL |
3157 | omr-codecs | NORMAL |
3158 | omr-m-att | NORMAL |
3159 | omr-m-bw | NORMAL |
3160 | omr-s-bw | NORMAL |
3161 | msrcp-cema | NORMAL |
3162 | dccp-port | NOT RECOMMENDED |
3163 | resource | NORMAL |
3164 | channel | NORMAL |
3165 | cmid | NORMAL |
3166 | content | NORMAL |
3167 | lcfg | SPECIAL |
3168 | loopback | NORMAL |
3169 | loopback-source | NORMAL |
3170 | loopback-mirror | NORMAL |
3171 | chatroom | TBD |
3172 | altc | TRANSPORT |
3173 | T38FaxMaxIFP | NORMAL |
3174 | T38FaxUdpECDepth | NORMAL |
3175 | T38FaxUdpFECMaxSpan | NORMAL |
3176 | T38ModemType | NORMAL |
3177 | cs-correlation | NORMAL |
3178 | rtcpidms | NORMAL |
3179 | cname | NORMAL |
3180 | previous-ssrc | NORMAL |
3181 | fmtp | IDENTICAL-PER-PT |
3182 +---------------------------+-------------------+
3184 15.2.3. Table: content SDP Parameters
3186 The following values are to be added to the 'content SDP Parameters'
3187 registry in the "Session Description Protocol (SDP) Parameters. The
3188 references should be updated to point at this RFC as well as the
3189 previous references.
3191 +----------+--------------+
3192 | SDP Name | Mux Category |
3193 +----------+--------------+
3194 | slides | NORMAL |
3195 | speaker | NORMAL |
3196 | sl | NORMAL |
3197 | main | NORMAL |
3198 | alt | NORMAL |
3199 +----------+--------------+
3201 15.2.4. Table: Semantics for the 'group' SDP Attribute
3203 The following values are to be added to the Semantics for the "group"
3204 SDP Attribute registry in the "Session Description Protocol (SDP)
3205 Parameters. The references should be updated to point at this RFC as
3206 well as the previous references.
3208 +---------+------------------+
3209 | Token | Mux Category |
3210 +---------+------------------+
3211 | LS | NORMAL |
3212 | FID | NORMAL |
3213 | SRF | NORMAL |
3214 | ANAT | NOT RECOMMENDED |
3215 | FEC | NORMAL |
3216 | FEC-FR | NORMAL |
3217 | CS | NORMAL |
3218 | DDP | NORMAL |
3219 | DUP | NORMAL |
3220 +---------+------------------+
3222 15.2.5. Table: 'rtcp-fb' Attribute Values
3224 The following values are to be added to the " 'rtcp-fb' Attribute
3225 Values" registry in the "Session Description Protocol (SDP)
3226 Parameters. The references should be updated to point at this RFC as
3227 well as the previous references.
3229 +------------+-------------------+
3230 | Value Name | Mux Category |
3231 +------------+-------------------+
3232 | ack | IDENTICAL-PER-PT |
3233 | app | SPECIAL |
3234 | ccm | IDENTICAL-PER-PT |
3235 | nack | IDENTICAL-PER-PT |
3236 | trr-int | IDENTICAL-PER-PT |
3237 +------------+-------------------+
3239 15.2.6. Table: 'ack' and 'nack' Attribute Values
3241 The following values are to be added to the " 'ack' and 'nack'
3242 Attribute Values" registry in the "Session Description Protocol (SDP)
3243 Parameters. The references should be updated to point at this RFC as
3244 well as the previous references.
3246 +------------+-------------------+
3247 | Value Name | Mux Category |
3248 +------------+-------------------+
3249 | sli | IDENTICAL-PER-PT |
3250 | pli | IDENTICAL-PER-PT |
3251 | rpsi | IDENTICAL-PER-PT |
3252 | app | IDENTICAL-PER-PT |
3253 | rai | IDENTICAL-PER-PT |
3254 | tllei | IDENTICAL-PER-PT |
3255 | pslei | IDENTICAL-PER-PT |
3256 | ecn | IDENTICAL-PER-PT |
3257 +------------+-------------------+
3259 15.2.7. Table: 'depend' SDP Attribute Values
3261 The following values are to be added to the " 'depend' SDP Attribute
3262 Values" registry in the "Session Description Protocol (SDP)
3263 Parameters. The references should be updated to point at this RFC as
3264 well as the previous references.
3266 +-------+--------------+
3267 | Token | Mux Category |
3268 +-------+--------------+
3269 | lay | NORMAL |
3270 | mdc | NORMAL |
3271 +-------+--------------+
3273 15.2.8. Table: 'cs-correlation' Attribute Values
3275 The following values are to be added to the " 'cs-correlation'
3276 Attribute Values" registry in the "Session Description Protocol (SDP)
3277 Parameters. The references should be updated to point at this RFC as
3278 well as the previous references.
3280 +-----------+--------------+
3281 | Token | Mux Category |
3282 +-----------+--------------+
3283 | callerid | NORMAL |
3284 | uuie | NORMAL |
3285 | dtmf | NORMAL |
3286 | external | NORMAL |
3287 +-----------+--------------+
3289 15.2.9. Table: Semantics for the 'ssrc-group' SDP Attribute
3291 The following values are to be added to the Semantics for the "
3292 'ssrc-group' SDP Attribute" registry in the "Session Description
3293 Protocol (SDP) Parameters. The references should be updated to point
3294 at this RFC as well as the previous references.
3296 +---------+--------------+
3297 | Token | Mux Category |
3298 +---------+--------------+
3299 | FID | NORMAL |
3300 | FEC | NORMAL |
3301 | FEC-FR | NORMAL |
3302 | DUP | NORMAL |
3303 +---------+--------------+
3305 15.2.10. Table: SDP/RTSP key management protocol identifiers
3307 The following values are to be added to the "SDP/RTSP key management
3308 protocol identifiers" registry in the "Session Description Protocol
3309 (SDP) Parameters. The references should be updated to point at this
3310 RFC as well as the previous references.
3312 +------------+--------------+
3313 | Value Name | Mux Category |
3314 +------------+--------------+
3315 | mikey | IDENTICAL |
3316 +------------+--------------+
3318 15.2.11. Table: Codec Control Messages
3320 The following values are to be added to the "Codec Control Messages"
3321 registry in the "Session Description Protocol (SDP) Parameters. The
3322 references should be updated to point at this RFC as well as the
3323 previous references.
3325 +------------+-------------------+
3326 | Value Name | Mux Category |
3327 +------------+-------------------+
3328 | fir | IDENTICAL-PER-PT |
3329 | tmmbr | IDENTICAL-PER-PT |
3330 | tstr | IDENTICAL-PER-PT |
3331 | vbcm | IDENTICAL-PER-PT |
3332 +------------+-------------------+
3334 15.2.12. Table: QoS Mechanism Tokens
3336 The following values are to be added to the "QoS Mechanism Tokens"
3337 registry in the "Session Description Protocol (SDP) Parameters. The
3338 references should be updated to point at this RFC as well as the
3339 previous references.
3341 +---------------+--------------+
3342 | QoS Mechanism | Mux Category |
3343 +---------------+--------------+
3344 | rsvp | NORMAL |
3345 | nsis | NORMAL |
3346 +---------------+--------------+
3348 15.2.13. Table: SDP Capability Negotiation Option Tags
3350 The following values are to be added to the "SDP Capability
3351 Negotiation Option Tags" Registry in the "Session Description
3352 Protocol (SDP) Parameters. The references should be updated to point
3353 at this RFC as well as the previous references.
3355 +---------------+--------------+
3356 | QoS Mechanism | Mux Category |
3357 +---------------+--------------+
3358 | cap-v0 | NORMAL |
3359 | med-v0 | NORMAL |
3360 | bcap-v0 | NORMAL |
3361 | ccap-v0 | NORMAL |
3362 | icap-v0 | NORMAL |
3363 +---------------+--------------+
3365 15.2.14. Table: Timestamp Reference Clock Source Parameters
3367 The following values are to be added to the "Timestamp Reference
3368 Clock Source Parameters" Registry in the "Session Description
3369 Protocol (SDP) Parameters. The references should be updated to point
3370 at this RFC as well as the previous references.
3372 +----------+--------------+
3373 | Name | Mux Category |
3374 +----------+--------------+
3375 | ntp | NORMAL |
3376 | ptp | NORMAL |
3377 | gps | NORMAL |
3378 | gal | NORMAL |
3379 | glonass | NORMAL |
3380 | local | NORMAL |
3381 | private | NORMAL |
3382 +----------+--------------+
3384 15.2.15. Table: Media Clock Source Parameters
3386 The following values are to be added to the "Media Clock Source
3387 Parameters" Registry in the "Session Description Protocol (SDP)
3388 Parameters. The references should be updated to point at this RFC as
3389 well as the previous references.
3391 +-----------+--------------+
3392 | Name | Mux Category |
3393 +-----------+--------------+
3394 | sender | NORMAL |
3395 | direct | NORMAL |
3396 | IEEE1722 | NORMAL |
3397 +-----------+--------------+
3399 16. Security Considerations
3401 This document does not add any new security considerations beyond the
3402 existing considerations in the RFC for protocols that are being
3403 multiplexed together.
3405 The ways that SRTP streams are keyed is not believed to create any
3406 two-time pad vulnerability for the currently defined SRTP keying
3407 mechanism.
3409 17. Acknowledgments
3411 I would like to thank Cullen Jennings for suggesting the categories,
3412 contributing text and reviewing the draft. I would also link to
3413 thank Magnus, Christer, Jonathan Lennox, Bo Burman, and Dan on
3414 suggesting structural changes helping improve the document
3415 readability.
3417 I would like also to thank following experts on their inputs and
3418 reviews as listed - Flemming Andreasen(5.20,5.28,5.29,15), Rohan
3419 Mahy(5.45), Eric Burger(5.22),Christian Huitema(5.13), Christer
3420 Holmberg(5.17,5.22,5.40,5.41), Richard Ejzak (5.36,5.42,5.43,5.44),
3421 Colin Perkins(5.7,5.8), Magnus westerlund(5.2,5.3,5.9,5.26,
3422 5.27,6.1,6.2,6.3,8.3,7), Roni Evens(5.12,5.27,8.4), Subha
3423 Dhesikan(5.5,12.1,14), Dan Wing(5.6,5.11,5.30,5.34,5.37), Ali C
3424 Begen(5.1,5.16,5.18,5.21,5.33,8.2,8.4,13.1), Bo Burman (7.2,7.6),
3425 Charles Eckel(5.14,5.23,5.24,9.1,8.5), Paul Kyzivat(5.24), Ian
3426 Johansson(5.15), Saravanan Shanmugham(5.10), Paul E Jones(5.25),
3427 Rajesh Kumar(5.39), Jonathan Lennox(5.31,5,14,11.1), Mo
3428 Zanaty(5.4,5.19,8.1,8.3,8.5,12.1), Christian Huitema (5.13), Qin Wu
3429 (5.38 PM-Dir review).
3431 18. Change Log
3433 [RFC EDITOR NOTE: Please remove this section when publishing]
3435 Changes from draft-ietf-mmusic-sdp-mux-attributes-02
3436 o Incorporated suggestions from Flemming on Capability Negotiation.
3438 o Closed open issues from IETF90
3440 o Added IANA section to list the categories for all the SDP
3441 attributes anlayzed
3443 o Lots of cleanup
3445 o Reformatted Refernces section to use short-form notation
3447 Changes from draft-ietf-mmusic-sdp-mux-attributes-01
3449 o Updated section 15 to provide detailed recommendation on dealing
3450 with encapsulating attributes. Also updated sections 5.20, 5.28,
3451 5.29 to refer to Section 15.
3453 o Added new categories IDENTICAL-PER-PT and INHERIT
3455 o Updated Sections 16 to add the new categories.
3457 o Updated Sections 5.1, 5.14, 5.15, 5.38, 8.5 to reflect the
3458 category IDENTICAL-PER-PT.
3460 o Reformatted section 4 to add individual categories to their own
3461 sections.
3463 Changes from draft-ietf-mmusic-sdp-mux-attributes-00
3465 o Added Section 15 to provide recommendations on multiplexing SDP
3466 encapsulating attributes. Also updated sections 5.20, 5.28, 5.29
3467 to refer to Section 15.
3469 o Updated Section 5.38 to incorporate PM-dir review inputs from Qin
3470 Wu
3472 o Updated Sections 5.2,5.14,8.5 to refer to BUNDLE draft for more
3473 clarity.
3475 o Fixed few nits regarding sentence clarity and fill-in the NOTES
3476 section where information was lacking.
3478 Changes from draft-nandakumar-mmusic-mux-attributes-05
3480 o Renamed the document to be a WG document.
3482 o Added Section 14.
3484 o Updated Open Issues based on IETF88 discussions.
3486 Changes from draft-nandakumar-mmusic-mux-attributes-04
3488 o Added few OPEN ISSUES that needs to be discussed.
3490 o Updated sections 5.10,5.23,5,24,5,25,7.2,9.1,5.12,5.27,8.4,
3491 5.44,5.11,5.4,5.19,10.1,10.5,5.21,10.4,15.1
3493 o Updated Table Column name Current to Level and improved TRANSPORT
3494 category explanation on suggestions form Dan Wing.
3496 o Grouped all the rtcp-fb attribute analysis under a single section
3497 as suggested by Magnus/
3499 Changes from draft-nandakumar-mmusic-mux-attributes-03
3501 o Maintenance change to clean up grammatical nits and wordings.
3503 Changes from draft-nandakumar-mmusic-mux-attributes-02
3505 o Updated Sections 5.3,5.5,5.6,5.7,5.9,5.8,5.11,5.13,5.22,5.34,
3506 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
3507 the inputs from the respective RFC Authors.
3509 Changes from draft-nandakumar-mmusic-mux-attributes-01
3511 o Replaced Category BAD with NOT RECOMMENDED.
3513 o Added Category TBD.
3515 o Updated IANA Consideration Section.
3517 Changes from draft-nandakumar-mmusic-mux-attributes-00
3519 o Added new section for dealing with FEC payload types.
3521 19. References
3523 19.1. Normative References
3525 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
3526 Requirement Levels", BCP 14, RFC 2119, March 1997.
3528 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
3529 Description Protocol", RFC 4566, July 2006.
3531 19.2. Informative References
3533 [H.248.15]
3534 "Gateway control protocol: SDP H.248 package attribute",
3535 .
3537 [I-D.ietf-mmusic-sdp-bundle-negotiation]
3538 Holmberg, C., Alvestrand, H., and C. Jennings,
3539 "Negotiating Media Multiplexing Using the Session
3540 Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle-
3541 negotiation-12 (work in progress), October 2014.
3543 [I.D-draft-ietf-dart-dscp-rtp]
3544 Black, D. and P. Jones, "The Session Description Protocol
3545 (SDP) Content Attribute", draft-ietf-dart-dscp-rtp-07
3546 (work in progress), September 2014.
3548 [IANA] "S Description Protocol (SDP) Parameters",
3549 .
3552 [ITU-T-REC.Q1970]
3553 "Q.1970 : BICC IP bearer control protocol",
3554 .
3556 [R3GPPTS24.182]
3557 "IP Multimedia Subsystem (IMS) Customized Alerting Tones
3558 (CAT); Protocol specification",
3559 .
3561 [R3GPPTS24.183]
3562 "IP Multimedia Subsystem (IMS) Customized Ringing Signal
3563 (CRS); Protocol specification",
3564 .
3566 [R3GPPTS24.229]
3567 "IP multimedia call control protocol based on Session
3568 Initiation Protocol (SIP) and Session Description Protocol
3569 (SDP);",
3570 .
3572 [R3GPPTS26.114]
3573 "IP multimedia Subsystem : Media Handling and
3574 interaction",
3575 .
3577 [RFC3108] Kumar, R. and M. Mostafa, "Conventions for the use of the
3578 Session Description Protocol (SDP) for ATM Bearer
3579 Connections", RFC 3108, May 2001.
3581 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
3582 with Session Description Protocol (SDP)", RFC 3264, June
3583 2002.
3585 [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg,
3586 "Integration of Resource Management and Session Initiation
3587 Protocol (SIP)", RFC 3312, October 2002.
3589 [RFC3407] Andreasen, F., "Session Description Protocol (SDP) Simple
3590 Capability Declaration", RFC 3407, October 2002.
3592 [RFC3524] Camarillo, G. and A. Monrad, "Mapping of Media Streams to
3593 Resource Reservation Flows", RFC 3524, April 2003.
3595 [RFC3556] Casner, S., "Session Description Protocol (SDP) Bandwidth
3596 Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC
3597 3556, July 2003.
3599 [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute
3600 in Session Description Protocol (SDP)", RFC 3605, October
3601 2003.
3603 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
3604 Protocol Extended Reports (RTCP XR)", RFC 3611, November
3605 2003.
3607 [RFC3890] Westerlund, M., "A Transport Independent Bandwidth
3608 Modifier for the Session Description Protocol (SDP)", RFC
3609 3890, September 2004.
3611 [RFC4091] Camarillo, G. and J. Rosenberg, "The Alternative Network
3612 Address Types (ANAT) Semantics for the Session Description
3613 Protocol (SDP) Grouping Framework", RFC 4091, June 2005.
3615 [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in
3616 the Session Description Protocol (SDP)", RFC 4145,
3617 September 2005.
3619 [RFC4567] Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E.
3620 Carrara, "Key Management Extensions for Session
3621 Description Protocol (SDP) and Real Time Streaming
3622 Protocol (RTSP)", RFC 4567, July 2006.
3624 [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session
3625 Description Protocol (SDP) Security Descriptions for Media
3626 Streams", RFC 4568, July 2006.
3628 [RFC4570] Quinn, B. and R. Finlayson, "Session Description Protocol
3629 (SDP) Source Filters", RFC 4570, July 2006.
3631 [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the
3632 Transport Layer Security (TLS) Protocol in the Session
3633 Description Protocol (SDP)", RFC 4572, July 2006.
3635 [RFC4574] Levin, O. and G. Camarillo, "The Session Description
3636 Protocol (SDP) Label Attribute", RFC 4574, August 2006.
3638 [RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format
3639 for Binary Floor Control Protocol (BFCP) Streams", RFC
3640 4583, November 2006.
3642 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
3643 "Extended RTP Profile for Real-time Transport Control
3644 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July
3645 2006.
3647 [RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description
3648 Protocol (SDP) Content Attribute", RFC 4796, February
3649 2007.
3651 [RFC4975] Campbell, B., Mahy, R., and C. Jennings, "The Message
3652 Session Relay Protocol (MSRP)", RFC 4975, September 2007.
3654 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
3655 "Codec Control Messages in the RTP Audio-Visual Profile
3656 with Feedback (AVPF)", RFC 5104, February 2008.
3658 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error
3659 Correction", RFC 5109, December 2007.
3661 [RFC5159] Dondeti, L. and A. Jerichow, "Session Description Protocol
3662 (SDP) Attributes for Open Mobile Alliance (OMA) Broadcast
3663 (BCAST) Service and Content Protection", RFC 5159, March
3664 2008.
3666 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
3667 (ICE): A Protocol for Network Address Translator (NAT)
3668 Traversal for Offer/Answer Protocols", RFC 5245, April
3669 2010.
3671 [RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP
3672 Header Extensions", RFC 5285, July 2008.
3674 [RFC5432] Polk, J., Dhesikan, S., and G. Camarillo, "Quality of
3675 Service (QoS) Mechanism Selection in the Session
3676 Description Protocol (SDP)", RFC 5432, March 2009.
3678 [RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size
3679 Real-Time Transport Control Protocol (RTCP): Opportunities
3680 and Consequences", RFC 5506, April 2009.
3682 [RFC5547] Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S.,
3683 and P. Kyzivat, "A Session Description Protocol (SDP)
3684 Offer/Answer Mechanism to Enable File Transfer", RFC 5547,
3685 May 2009.
3687 [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific
3688 Media Attributes in the Session Description Protocol
3689 (SDP)", RFC 5576, June 2009.
3691 [RFC5583] Schierl, T. and S. Wenger, "Signaling Media Decoding
3692 Dependency in the Session Description Protocol (SDP)", RFC
3693 5583, July 2009.
3695 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control
3696 Protocol (RTCP) Extensions for Single-Source Multicast
3697 Sessions with Unicast Feedback", RFC 5760, February 2010.
3699 [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
3700 Control Packets on a Single Port", RFC 5761, April 2010.
3702 [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control
3703 Protocol (DCCP)", RFC 5762, April 2010.
3705 [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
3706 for Establishing a Secure Real-time Transport Protocol
3707 (SRTP) Security Context Using Datagram Transport Layer
3708 Security (DTLS)", RFC 5763, May 2010.
3710 [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
3711 Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
3713 [RFC5939] Andreasen, F., "Session Description Protocol (SDP)
3714 Capability Negotiation", RFC 5939, September 2010.
3716 [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in
3717 the Session Description Protocol", RFC 5956, September
3718 2010.
3720 [RFC6064] Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions
3721 Defined for 3GPP Packet-Switched Streaming Service and
3722 Multimedia Broadcast/Multicast Service", RFC 6064, January
3723 2011.
3725 [RFC6128] Begen, A., "RTP Control Protocol (RTCP) Port for Source-
3726 Specific Multicast (SSM) Sessions", RFC 6128, February
3727 2011.
3729 [RFC6189] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media
3730 Path Key Agreement for Unicast Secure RTP", RFC 6189,
3731 April 2011.
3733 [RFC6193] Saito, M., Wing, D., and M. Toyama, "Media Description for
3734 the Internet Key Exchange Protocol (IKE) in the Session
3735 Description Protocol (SDP)", RFC 6193, April 2011.
3737 [RFC6230] Boulton, C., Melanchuk, T., and S. McGlashan, "Media
3738 Control Channel Framework", RFC 6230, May 2011.
3740 [RFC6236] Johansson, I. and K. Jung, "Negotiation of Generic Image
3741 Attributes in the Session Description Protocol (SDP)", RFC
3742 6236, May 2011.
3744 [RFC6284] Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping
3745 between Unicast and Multicast RTP Sessions", RFC 6284,
3746 June 2011.
3748 [RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax,
3749 "Unicast-Based Rapid Acquisition of Multicast RTP
3750 Sessions", RFC 6285, June 2011.
3752 [RFC6364] Begen, A., "Session Description Protocol Elements for the
3753 Forward Error Correction (FEC) Framework", RFC 6364,
3754 October 2011.
3756 [RFC6489] Huston, G., Michaelson, G., and S. Kent, "Certification
3757 Authority (CA) Key Rollover in the Resource Public Key
3758 Infrastructure (RPKI)", BCP 174, RFC 6489, February 2012.
3760 [RFC6642] Wu, Q., Xia, F., and R. Even, "RTP Control Protocol (RTCP)
3761 Extension for a Third-Party Loss Report", RFC 6642, June
3762 2012.
3764 [RFC6679] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P.,
3765 and K. Carlberg, "Explicit Congestion Notification (ECN)
3766 for RTP over UDP", RFC 6679, August 2012.
3768 [RFC6714] Holmberg, C., Blau, S., and E. Burger, "Connection
3769 Establishment for Media Anchoring (CEMA) for the Message
3770 Session Relay Protocol (MSRP)", RFC 6714, August 2012.
3772 [RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
3773 Datagram Congestion Control Protocol UDP Encapsulation for
3774 NAT Traversal", RFC 6773, November 2012.
3776 [RFC6787] Burnett, D. and S. Shanmugham, "Media Resource Control
3777 Protocol Version 2 (MRCPv2)", RFC 6787, November 2012.
3779 [RFC6871] Gilman, R., Even, R., and F. Andreasen, "Session
3780 Description Protocol (SDP) Media Capabilities
3781 Negotiation", RFC 6871, February 2013.
3783 [RFC6947] Boucadair, M., Kaplan, H., Gilman, R., and S.
3784 Veikkolainen, "The Session Description Protocol (SDP)
3785 Alternate Connectivity (ALTC) Attribute", RFC 6947, May
3786 2013.
3788 [RFC7006] Garcia-Martin, M., Veikkolainen, S., and R. Gilman,
3789 "Miscellaneous Capabilities Negotiation in the Session
3790 Description Protocol (SDP)", RFC 7006, September 2013.
3792 [RFC7104] Begen, A., Cai, Y., and H. Ou, "Duplication Grouping
3793 Semantics in the Session Description Protocol", RFC 7104,
3794 January 2014.
3796 [RFC7195] Garcia-Martin, M. and S. Veikkolainen, "Session
3797 Description Protocol (SDP) Extension for Setting Audio and
3798 Video Media Streams over Circuit-Switched Bearers in the
3799 Public Switched Telephone Network (PSTN)", RFC 7195, May
3800 2014.
3802 [RFC7197] Begen, A., Cai, Y., and H. Ou, "Duplication Delay
3803 Attribute in the Session Description Protocol", RFC 7197,
3804 April 2014.
3806 [RFC7226] Villamizar, C., McDysan, D., Ning, S., Malis, A., and L.
3807 Yong, "Requirements for Advanced Multipath in MPLS
3808 Networks", RFC 7226, May 2014.
3810 [RFC7272] van Brandenburg, R., Stokking, H., van Deventer, O.,
3811 Boronat, F., Montagud, M., and K. Gross, "Inter-
3812 Destination Media Synchronization (IDMS) Using the RTP
3813 Control Protocol (RTCP)", RFC 7272, June 2014.
3815 [RFC7273] Williams, A., Gross, K., van Brandenburg, R., and H.
3816 Stokking, "RTP Clock Source Signalling", RFC 7273, June
3817 2014.
3819 [T.38] "Procedures for real-time Group 3 facsimile communication
3820 over IP networks", .
3822 Author's Address
3824 Suhas Nandakumar
3825 Cisco
3826 170 West Tasman Drive
3827 San Jose, CA 95134
3828 USA
3830 Email: snandaku@cisco.com