idnits 2.17.1 draft-ietf-avtcore-feedback-supression-rtp-16.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (March 30, 2012) is 4408 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'RFCXXXX' is mentioned on line 501, but not defined ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) -- Obsolete informational reference (is this intentional?): RFC 5117 (Obsoleted by RFC 7667) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Q. Wu 3 Internet-Draft F. Xia 4 Intended status: Standards Track R. Even 5 Expires: October 1, 2012 Huawei 6 March 30, 2012 8 RTCP Extension for Third-party Loss Report 9 draft-ietf-avtcore-feedback-supression-rtp-16 11 Abstract 13 In a large RTP session using the RTCP feedback mechanism defined in 14 RFC 4585, a feedback target may experience transient overload if some 15 event causes a large number of receivers to send feedback at once. 16 This overload is usually avoided by ensuring that feedback reports 17 are forwarded to all receivers, allowing them to avoid sending 18 duplicate feedback reports. However, there are cases where it is not 19 recommended to forward feedback reports, and this may allow feedback 20 implosion. This memo discusses these cases and defines a new RTCP 21 third-party loss report that can be used to inform receivers that the 22 feedback target is aware of some loss event, allowing them to 23 suppress feedback. Associated SDP signalling is also defined. 25 Status of this Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on October 1, 2012. 42 Copyright Notice 44 Copyright (c) 2012 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 61 2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 5 63 4. Format of RTCP Feedback Messages . . . . . . . . . . . . . . . 6 64 4.1. Transport Layer Feedback: Third-Party Loss Report 65 (TPLR) . . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 4.2. Payload Specific Feedback: Third-Party Loss Report 67 (TPLR) . . . . . . . . . . . . . . . . . . . . . . . . . . 7 68 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 69 6. Example Use Cases . . . . . . . . . . . . . . . . . . . . . . 9 70 6.1. Source Specific Multicast (SSM) use case . . . . . . . . . 9 71 6.2. Unicast based Rapid Acquisition of Multicast Stream 72 (RAMS) use case . . . . . . . . . . . . . . . . . . . . . 10 73 6.3. RTP Transport Translator use case . . . . . . . . . . . . 10 74 6.4. Multipoint Control Unit (MCU) use case . . . . . . . . . . 10 75 6.5. Mixer use case . . . . . . . . . . . . . . . . . . . . . . 11 76 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 77 8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 11 78 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12 79 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 80 10.1. Normative References . . . . . . . . . . . . . . . . . . . 13 81 10.2. Informative References . . . . . . . . . . . . . . . . . . 13 82 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 14 83 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 . . . . . . 14 84 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 . . . . . . 14 85 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 . . . . . . 15 86 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 . . . . . . 15 87 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 . . . . . . 15 88 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 . . . . . . 16 89 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 . . . . . . 16 90 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 . . . . . . 16 91 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 . . . . . . 16 92 A.10. draft-ietf-avtcore-feedback-suppression-rtp-10 . . . . . . 17 93 A.11. draft-ietf-avtcore-feedback-suppression-rtp-11 . . . . . . 17 94 A.12. draft-ietf-avtcore-feedback-suppression-rtp-12 . . . . . . 17 95 A.13. draft-ietf-avtcore-feedback-suppression-rtp-13 . . . . . . 17 96 A.14. draft-ietf-avtcore-feedback-suppression-rtp-14 . . . . . . 17 97 A.15. draft-ietf-avtcore-feedback-suppression-rtp-15 . . . . . . 18 98 A.16. draft-ietf-avtcore-feedback-suppression-rtp-16 . . . . . . 18 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 101 1. Introduction 103 RTCP feedback messages [RFC4585] allow the receivers in an RTP 104 session to report events and ask for action from the media source (or 105 a delegated feedback target when using unicast RTCP feedback with SSM 106 [RFC5760]). There are cases where multiple receivers may initiate 107 the same, or an equivalent message towards the same media source or 108 the same feedback target. When the receiver count is large, this 109 behavior may cause transient overload of the media source, the 110 network or both. This is known as a "feedback storm" or a "NACK 111 storm". One common cause of such a feedback storm is receivers 112 utilizing RTP retransmission [RFC4588] as a packet loss recovery 113 technique, sending feedback using RTCP NACK messages [RFC4585] 114 without proper dithering of the retransmission requests (e.g., not 115 implementing the RFC 4585 dithering rules or sending NACKs to a 116 feedback target that doesn't redistribute them to other receivers). 118 Another use case involves video Fast Update requests. A storm of 119 these feedback messages can occur in conversational multimedia 120 scenarios like multipoint video switching conference [RFC4587]. In 121 this scenario, the receiver may lose synchronization with the video 122 stream when speaker is changed in the middle of session. Poorly 123 designed receivers that blindly issue fast update requests (i.e., 124 Full Intra Request (FIR) described in RFC5104 [RFC5104]), can cause 125 an implosion of FIR requests from receivers to the same media source. 127 RTCP feedback storms may cause short term overload, and in extreme 128 cases to pose a possible risk of increasing network congestion on the 129 control channel (e.g. RTCP feedback), the data channel, or both. It 130 is therefore desirable to provide a way of suppressing unneeded 131 feedback. This document specifies a new third-party loss report for 132 this function. It supplements the existing the use of RTCP NACK 133 packet and further is more precise in the uses where the network is 134 active to suppress feedback. It tells receivers explicitly that 135 feedback for a particular packet or frame loss is not needed and can 136 provide an early indication before the receiver reacts to the loss 137 and invokes its packet loss repair machinery. Section 6 provides 138 some examples of when to send the Third-Party Loss Report message. 140 2. Requirements Notation 142 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 143 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 144 document are to be interpreted as described in RFC2119 [RFC2119]. 146 2.1. Glossary 148 TPLR - Third-Party Loss Report 149 TLLEI - Transport Layer Third-Party Loss Early Indication 150 PSLEI - Payload Specific Third-Party Loss Early Indication 151 FCI - Feedback Control Information [RFC4585] 152 AVPF - The Audio-Visual Profile with RTCP-based feedback [RFC4585] 153 SSRC - Synchronization Source 154 BRS - Burst/Retransmission Sources [RFC6285] 155 FIR - Full Intra Request [RFC5104] 156 PLI - Picture Loss Indication [RFC4585] 157 SSM - Source Specific Multicast [RFC5760] 158 RAMS - Unicast based Rapid Acquisition of Multicast Stream [RFC6285] 159 MCU - Multipoint Control Unit [RFC5117] 161 3. Protocol Overview 163 This document extends the RTCP feedback messages defined in the RTP/ 164 AVPF [RFC4585] defining a RTCP Third-Party Loss Report (TPLR) 165 message. The RTCP TPLR message can be used by the intermediaries to 166 inform the receiver that the sender of the RTCP TPLR has received 167 reports that the indicated packets were lost, and asks the receiver 168 not to send feedback to it regarding these packets. Intermediaries 169 are variously referred to as Distribution source, Burst/ 170 Retransmission Sources (BRS), MCUs, RTP translator, or RTP mixers, 171 depending on the precise use case described Section 6. 173 RTCP TPLR follows the similar format of message type as RTCP NACK or 174 Full Intra Request Command. However, the RTCP TPLR is defined as an 175 indication that the sender of the feedback has received reports that 176 the indicated packets were lost, while NACK [RFC4585] just indicates 177 that the sender of the NACK observed that these packets were lost. 178 The RTCP TPLR message is generated by an intermediary that may not 179 have seen the actual packet loss. It is sent following the same 180 timing rule as sending NACK defined in RFC4585 [RFC4585]. The RTCP 181 TPLR message may be sent in a regular full compound RTCP packet or in 182 an early RTCP packet, as per the RTP/AVPF rules. Intermediaries in 183 the network that receive a RTCP TPLR SHOULD NOT send their own 184 additional Third-Party Loss Report messages for the same packet 185 sequence numbers. They SHOULD simply forward the RTCP TPLR message 186 received from upstream direction to the receiver(s), additionally, 187 they may generate their own RTCP TPLR that reports a set of the 188 losses they see, which are different from ones reported in the RTCP 189 TPLR they received. The RTCP TPLR does not have the retransmission 190 request [RFC4588] semantics. 192 When a receiver gets a RTCP TPLR message, it MUST follow the rules 193 for NACK suppression in RFC4585 [RFC4585]and refrain from sending a 194 feedback request (e.g., NACK or FIR) for the missing packets reported 195 in the message,which is dealt with in the same way as receiving NACK. 197 To increase the robustness to the loss of a TPLR, The RTCP TPLR may 198 be retransmitted. If the additional TPLR arrives at receiver, the 199 receiver SHOULD deal with the additional TPLR in the same way as 200 receiving the first TPLR for the same packet and no additional 201 behavior for receiver is required. 203 A receiver may have sent a Feedback message according to the RTP/AVPF 204 scheduling algorithm of RFC4585 [RFC4585] before receiving a RTCP 205 TPLR message, but further feedback messages for those sequence 206 numbers SHOULD be suppressed after receiving the RTCP TPLR. Nodes 207 that do not understand the RTCP TPLR message will ignore it, and 208 might therefore still send feedback according to the AVPF scheduling 209 algorithm of RFC4585 [RFC4585]. The media source or intermediate 210 nodes cannot be certain that the use of a RTCP TPLR message actually 211 reduces the amount of feedback it receives. 213 4. Format of RTCP Feedback Messages 215 This document introduces two new RTCP Feedback messages for Third 216 Party Loss Report. Applications that are employing one or more loss- 217 repair methods MAY use the RTCP TPLR together with their existing 218 loss-repair methods either for every packet they expect to receive, 219 or for an application-specific subset of the RTP packets in a 220 session. 222 The following two sections each define a RTCP TPLR message. Both 223 messages are feedback messages as defined in section 6.1 of RFC4585 224 [RFC4585], and use the header format defined there. Each section 225 defines how to populate the PT, FMT,length SSRC of packet sender, 226 SSRC of media source, and FCI fields in that header. 228 4.1. Transport Layer Feedback: Third-Party Loss Report (TPLR) 230 This TPLR message is identified by RTCP packet type value PT=RTPFB 231 and FMT=TBA1. 233 Within the common packet header for feedback messages (as defined in 234 section 6.1 of RFC4585 [RFC4585]), the "SSRC of packet sender" field 235 indicates the source of the request, and the "SSRC of media source" 236 denotes the media sender of the flow for which the indicated losses 237 are being suppressed. 239 The Feedback Control Information (FCI) field MUST contain one or more 240 entries of transport layer third-party loss Early Indication (TLLEI). 241 Each entry applies to the same media source identified by the SSRC 242 contained in the SSRC of media source field of Feedback header. The 243 length field in the TLLEI feedback message MUST be set to 2+1*N, 244 where N is the number of FCI entries. 246 The FCI field for TLLEI uses the similar format of message Types 247 defined in the section 6.2.1 of RFC4585 [RFC4585]. The format is 248 shown in Figure 1. 250 0 1 2 3 251 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 | PID | BLP | 254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 Figure 1: Syntax of an FCI Entry in the TLLEI Feedback Message 258 Packet ID (PID): 16 bits 260 The PID field is used to specify a lost packet. The PID field 261 refers to the RTP sequence number of the lost packet. 263 bitmask of lost packets (BLP): 16 bits 265 The BLP allows for reporting losses of any of the 16 RTP packets 266 immediately following the RTP packet indicated by the PID. The 267 BLP's definition is identical to that given in the section 6.2.1 268 of [RFC4585]. 270 4.2. Payload Specific Feedback: Third-Party Loss Report (TPLR) 272 This TPLR message is identified by RTCP packet type value PT=PSFB and 273 FMT=TBA2, which is used to suppress FIR [RFC5104] and PLI [RFC4585]. 275 Within the common packet header for feedback messages (as defined in 276 section 6.1 of RFC4585 [RFC4585]), the "SSRC of packet sender" field 277 indicates the source of the request, and the "SSRC of media source" 278 is not used and SHALL be set to 0. The SSRCs of the media senders to 279 which this message applies are in the corresponding FCI entries. 281 The FCI field for a Payload Specific Third-Party Loss Early 282 Indication (PSLEI) consists one or more FCI entries. Each entry 283 applies to a different media Source, identified by its SSRC. the 284 content of which is depicted in Figure 2. The length field in the 285 PSLEI feedback message MUST be set to 2+1*N, where N is the number of 286 FCI entries. 288 The format is shown in Figure 2. 290 0 1 2 3 291 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | SSRC | 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 296 Figure 2: Syntax of an FCI Entry in the PSLEI Feedback Message 298 Synchronization source (SSRC):32 bits 300 The SSRC value of the media source that is already aware, or in 301 the process of being made aware, that some receiver lost 302 synchronization with the media stream and for which the PSLEI 303 receiver's own response to any such error is suppressed. 305 5. SDP Signaling 307 The Session Description Protocol (SDP) [RFC4566] attribute, rtcp-fb, 308 is defined in the Section 4 of RFC4585 [RFC4585] and may be used to 309 negotiate the capability to handle specific AVPF commands and 310 indications. The ABNF for rtcp-fb is described in section 4.2 of 311 RFC4585 [RFC4585]. In this section, we extend the rtcp-fb attribute 312 to include the commands and indications that are described for third- 313 party loss report in the present document. 315 In the ABNF [RFC5234] for rtcp-fb-val defined in RFC4585 [RFC4585], 316 the feedback type "nack", without parameters, indicates use of the 317 Generic NACK feedback format as defined in Section 6.2.1of RFC4585 318 [RFC4585]. In this document, we define two parameters that indicate 319 the third-party loss supported for use with "nack", namely: 321 o "tllei" denotes support of transport layer third-party loss early 322 indication. 324 o "pslei" denotes support of payload specific third-party loss early 325 indication. 327 The ABNF for these two parameters for "nack" is defined here (please 328 refer to section 4.2 of RFC4585 [RFC4585] for complete ABNF syntax). 330 rtcp-fb-val =/ "nack" rtcp-fb-nack-param 331 rtcp-fb-nack-param = SP "tllei" 332 ;transport layer third party 333 ; loss early indication 334 / SP "pslei" 335 ;payload specific third party 336 ; loss early indication 337 / SP token [SP byte-string] 338 ; for future commands/indications 339 token = 340 byte-string = 342 Refer to Section 4.2 of RFC4585 [RFC4585] for a detailed description 343 and the full syntax of the "rtcp-fb" attribute. 345 6. Example Use Cases 347 The operation of feedback suppression is similar for all types of RTP 348 sessions and topologies [RFC5117], however the exact messages used 349 and the scenarios in which suppression is employed differ for various 350 use cases. The following sections outline some of the intended use 351 cases for using the Third-Party Loss Report for feedback suppression 352 and give an overview of the particular mechanisms. 354 6.1. Source Specific Multicast (SSM) use case 356 In SSM RTP sessions as described in "RTP Control Protocol (RTCP) 357 Extensions for Single-Source Multicast Sessions with Unicast 358 Feedback" [RFC5760], one or more Media Sources send RTP packets to a 359 Distribution Source. The Distribution Source relays the RTP packets 360 to the receivers using a source- specific multicast group. 362 As outlined in the RFC5760 [RFC5760], there are two Unicast Feedback 363 models that may be used for reporting, the Simple Feedback model and 364 the Distribution Source Feedback Summary Model. In the simple 365 Feedback Model, there's no need for distribution source to create the 366 RTCP TPLRs, instead, RTCP NACKs are reflected by the distribution 367 source to the other Receivers. However in the Distribution Source 368 Feedback Summary model, the distribution source will not redistribute 369 the NACK for some reason(e.g., to prevent revealing the identity or 370 existence of a system sending NACK)and may send a RTCP TPLR message 371 to the systems that were unable to receive the NACK, and won't 372 receive the NACK via other means. The RTCP TPLR can be generated at 373 the distribution source when downstream loss is reported (e.g., 374 downstream loss report is received), which indicates to the receivers 375 that they should not transmit feedback messages for the same loss 376 event for a certain time. Therefore the distribution source in the 377 feedback summary model can be reasonably certain that it will help 378 the situation (i.e., unable receive the NACK) by sending this RTCP 379 TPLR message to all the relevant receivers impacted by the packet 380 loss. 382 6.2. Unicast based Rapid Acquisition of Multicast Stream (RAMS) use 383 case 385 The typical RAMS architecture [RFC6285] may have several Burst/ 386 Retransmission Sources(BRS) behind the multicast source (MS) placed 387 at the same level. These BRSes will receive the primary multicast 388 RTP stream from the media source and cache most recent packets after 389 joining multicast session. If packet loss happens at the upstream of 390 all the BRSs or the downstream of BRSes. One of the BRSes or all the 391 BRSes may send a RTCP NACK or RTCP TPLR message to the DS, where the 392 SSRC in this RTCP NACK or RTCP TPLR message is the BRS that is 393 sending the message. The DS forwards/reflects this message down on 394 the primary SSM. The details on how DS deal with this message is 395 specified in [RETRANSMISSION-FOR-SSM]. 397 6.3. RTP Transport Translator use case 399 A Transport Translator (Topo-Trn-Translator), as defined in RFC5117 400 [RFC5117] is typically forwarding the RTP and RTCP traffic between 401 RTP clients, for example converting from multicast to unicast for 402 domains that do not support multicast. The translator may suffer a 403 loss of important video packets. In this case, the translator may 404 forward RTCP TPLR message received from upstream in the same way as 405 forwarding other RTCP traffic. If the translator acting as the 406 monitor [MONARCH] is aware of packet loss, it may use the SSRC of 407 monitor as packet sender SSRC to create NACK message and send it to 408 the receivers that are not aware of packet loss. 410 6.4. Multipoint Control Unit (MCU) use case 412 When the speaker is changed in a voice-activated multipoint video 413 switching conference [RFC4587], an RTP mixer can be used to select 414 the available input streams and forward them to each participants. 415 If the MCU is doing a blind switch without waiting for a 416 synchronization point on the new stream it can send a FIR to the new 417 video source. In this case the MCU should send a FIR suppression 418 message to the new receivers. e.g., when the RTP Mixer starts to 419 receive FIR from some participants it can suppress the remaining 420 session participants from sending FIR by sending out a RTCP TPLR 421 message. 423 6.5. Mixer use case 425 A Mixer, in accordance with RFC5117 [RFC5117], aggregates multiple 426 RTP streams from other session participants and generates a new RTP 427 stream sent to the session participants. In some cases, the video 428 frames may get badly screwed up between media source and the mixer. 429 In such case, the mixer need to check if the packet loss will result 430 in PLI or FIR transmissions from most of the group by analyzing the 431 received video. If so the mixer may initiate FIR or PLI towards the 432 media source on behalf of all the session participants and send out a 433 RTCP TPLR message to these session participants that may or are 434 expected to send a PLI or FIR. Alternatively, when the mixer starts 435 to receive FIR or PLI from some participants and like to suppress the 436 remaining session participants from sending FIR or PLI by forwarding 437 the FIR/PLI from one session participant to others. 439 7. Security Considerations 441 The security considerations documented in [RFC4585] are also 442 applicable for the TPLR messages defined in this document. 444 More specifically, spoofed or maliciously created TPLR feedback 445 messages cause missing RTP packets to not be repaired in a timely 446 fashion and add risk of (undesired) feedback supression at RTCP 447 receivers that accept such TPLR messages. Any packet loss detected 448 by a receiver and where this RTP receiver also receives a TPLR 449 message for the same missing packet(s), will negatively impact the 450 application that relies on the (timely) RTP retransmission 451 capabilities. 453 A solution to prevent such attack with maliciously sent TPLR 454 messages, is to apply an authentication and integrity protection 455 framework for the feedback messages. This can be accomplished using 456 the RTP profile that combines Secure RTP [RFC3711] and AVPF into 457 SAVPF [RFC5124]. 459 Note that intermediaries that are not visible at the RTP layer that 460 wish to send the Third-Party Loss Reports on behalf of the media 461 source can only do so if they spoof the SSRC of the media source. 462 This is difficult in case SRTP is in use. If the intermediary is 463 visible at the RTP layer, this is not an issue, provided the 464 intermediary is part of the security context for the session. 466 8. IANA Consideration 468 This document instructs IANA to add two values to the '"ack" and 469 "nack" Attribute Values' sub-registry [RFC4585] of the 'Session 470 Description Protocol (SDP) Parameters' registry. 472 The value registration for the attribute value "nack": 474 Value name: tllei 475 Long name: Transport Layer Third-Party Loss Early Indication 476 Usable with: nack 477 Reference: RFC 4585. 479 Value name: pslei 480 Long name: Payload Specific Third-Party Loss Early Indication 481 Usable with: nack 482 Reference: RFC 4585. 484 The following value have been registered as one FMT value in the "FMT 485 Values for RTPFB Payload Types" registry located at the time of 486 publication at: http://www.iana.org/assignments/rtp-parameters 488 RTPFB range 489 Name Long Name Value Reference 490 -------------- --------------------------------- ----- --------- 491 TLLEI Transport Layer Third-Party TBA1 [RFCXXXX] 492 Loss Early Indication 494 The following value have been registered as one FMT value in the "FMT 495 Values for PSFB Payload Types" registry located at the time of 496 publication at: http://www.iana.org/assignments/rtp-parameters 498 PSFB range 499 Name Long Name Value Reference 500 -------------- --------------------------------- ----- -------- 501 PSLEI Payload Specific Third-Party TBA2 [RFCXXXX] 502 Loss Early Indication 504 9. Acknowledgement 506 The authors would like to thank David R Oran, Magnus Westerlund, 507 Colin Perkins, Ali C. Begen, Tom VAN CAENEGEM, Ingemar Johansson S, 508 Bill Ver Steeg, Jonathan Lennox, WeeSan Lee for their valuable 509 comments and suggestions on this document. 511 10. References 512 10.1. Normative References 514 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 515 Requirement Levels", March 1997. 517 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 518 "Extended RTP Profile for Real-time Transport Control 519 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, 520 July 2006. 522 [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. 523 Hakenberg, "RTP Retransmission Payload Format", RFC 4588, 524 July 2006. 526 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 527 Description Protocol", RFC 4566, July 2006. 529 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 530 Specifications: ABNF", STD 68, RFC 5234, January 2008. 532 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 533 "Codec Control Messages in the RTP Audio-Visual Profile 534 with Feedback (AVPF)", RFC 5104, February 2008. 536 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. 537 Norrman, "The Secure Real-time Transport Protocol (SRTP)", 538 RFC 3711, March 2004. 540 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for 541 Real-time Transport Control Protocol (RTCP)-Based Feedback 542 (RTP/SAVPF)", RFC 5124, February 2008. 544 10.2. Informative References 546 [RFC6285] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast- 547 Based Rapid Acquisition of Multicast RTP Sessions", 548 June 2011. 550 [MONARCH] Wu, Q., Hunt, G., and P. Arden, "Monitoring Architectures 551 for RTP", June 2011. 553 [RETRANSMISSION-FOR-SSM] 554 Caenegem, T., Steeg, B., and A. Begen, "Retransmission for 555 Source-Specific Multicast (SSM) Sessions", May 2011. 557 [RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, 558 January 2008. 560 [RFC4587] Even, R., "RTP Payload Format for H.261 Video Streams", 561 RFC 4587, August 2006. 563 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 564 Protocol (RTCP) Extensions for Single-Source Multicast 565 Sessions with Unicast Feedback", RFC 5760, February 2010. 567 Appendix A. Change Log 569 Note to the RFC-Editor: please remove this section prior to 570 publication as an RFC. 572 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 574 The following are the major changes compared to previous version: 576 o Remove the merge report from SSM use case and additional text to 577 address report merging issue. 579 o Revise section 3 and section 6 to address FEC packet dealing issue 580 and Leave how to repair packet loss beyond the scope. 582 o Modify the SSM use case and RAMS use case to focus on uses. 584 o Other Editorial changes. 586 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 588 The following are the major changes compared to previous version: 590 o In Section 4.1, fix typo: change Section 4.3.1.1 of section 591 [RFC5104] to section 6.2.1 of [RFC4585]. 593 o In Section 3: Clarify how to deal with downstream loss using 594 Third-party loss report and upstream loss using NACK. 596 o Update title and abstract to focus on third-party loss report. 598 o In Section 6.1: Update this section to explain how third party 599 loss report is used to deal with downstream loss. 601 o In section 6.1.2: Update this section to explain how third party 602 loss report is used to deal with downstream loss. 604 o In section 6.2: Rephrase the text to discuss how BRS deal with the 605 third-party loss report. 607 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 609 The following are the major changes compared to previous version: 611 o In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix A. 613 o Update abstract to clarify when third-party loss reports should be 614 sent instead of NACKs. 616 o Update section 3 Paragraph 2 to differentiate when a third-party 617 loss report should be used compared to a NACK. 619 o Update section 3 Paragraph 3 to explain when media source to send 620 a third-party loss. 622 o Move specific rules for section 6.1.1 and section 6.1.2 to section 623 6.1 as generic rules and delete section 6.1.1. 625 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 627 The following are the major changes compared to previous version: 628 o Reference Update. 630 o Clarify the use of the third-party loss report in section 3 and 631 section 6.1.1. 633 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 635 The following are the major changes compared to previous version: 636 o Remove 3rd and 4th paragraphs of section 6.1 and replaced them 637 with 2nd and 3rd paragraphs of section 3. 639 o Remove section 6.1.1.1. 641 o Revise the last paragraph of section 1 to clarify the rationale of 642 using new message. 644 o Update RTP transport translator case in section 6.3 to correct the 645 use of the third-party loss report. 647 o Update MCU case in section 6.4 to correct the use of the third 648 party loss report. 650 o Revise SSM use case to address multiple DS issue. 652 o References Update. 654 o Move one rationale on preventing sending unicast NACK in 655 introduction section to SSM case section. 657 o Other Editorial changes to section 6.1, 6.1.1, 6.2. 659 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 661 The following are the major changes compared to previous version: 663 o A few Editorial changes to the whole document. 665 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 667 The following are the major changes compared to previous version: 669 o Restructuring the protocol overview section to clarify the round 670 trip 672 time calculation and receiver behavior to the additional TPLR. 674 o Restructuring the SSM use case section to focus on the use of 675 TPLR. 677 o Editorial changes to the abstract, introduction, message format, 678 use cases and IANA sections. 680 o References update 682 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 684 The following are the major changes compared to previous version: 686 o Clarify which RTT is used and how timer is refreshed in the 687 section 3. 689 o Editorial changes to the Introduction, Protocol Overview, SDP 691 Signaling, Message Format, Use case,Security Consideration and 692 IANA sections. 694 o Remove Seq Nr field in the figure 2 for payload specific feedback. 696 o References reorganizing. 698 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 700 The following are the major changes compared to previous version: 702 o Clarify to suppression interval with regard to how long to receive 703 the 705 retransmitted packet. Treating TPLR in the same way as receiving 706 NACK. 708 o Replace timer based approach with timeless based approach. 710 A.10. draft-ietf-avtcore-feedback-suppression-rtp-10 712 The following are the major changes compared to previous version: 714 o Fix the definition of Synchronization source for TPLR in section 715 4.2. 717 o Associate SDP parameters tllei and pslei with "nack". 719 o Remove the packet loss recovery from TPLR loss handling part. 721 o Other typo fixed. 723 A.11. draft-ietf-avtcore-feedback-suppression-rtp-11 725 The following are the major changes compared to previous version: 727 o Additional Editorial changes. 729 A.12. draft-ietf-avtcore-feedback-suppression-rtp-12 731 The following are the major changes compared to previous version: 733 o Additional Editorial changes. 735 A.13. draft-ietf-avtcore-feedback-suppression-rtp-13 737 The following are the major changes compared to previous version: 739 o Additional Editorial changes. 741 A.14. draft-ietf-avtcore-feedback-suppression-rtp-14 743 The following are the major changes compared to previous version: 745 o Two References moving to normative refereces. 747 o Revise IANA section to clarify whether to create new registry or 748 add new value to the existing registry. 750 o Revise Security section to clarify ill effect of accepting 751 unauthenticated messages. 753 o Add a glossary to fix acronym issue. 755 o Other Editorial changes. 757 A.15. draft-ietf-avtcore-feedback-suppression-rtp-15 759 The following are the major changes compared to previous version: 761 o Some Editorial changes. 763 A.16. draft-ietf-avtcore-feedback-suppression-rtp-16 765 The following are the major changes compared to previous version: 767 o Some Editorial changes. 769 Authors' Addresses 771 Qin Wu 772 Huawei 773 101 Software Avenue, Yuhua District 774 Nanjing, Jiangsu 210012 775 China 777 Email: sunseawq@huawei.com 779 Frank Xia 780 Huawei 781 1700 Alma Dr. Suite 500 782 Plano, TX 75075 783 USA 785 Phone: +1 972-509-5599 786 Email: xiayangsong@huawei.com 787 Roni Even 788 Huawei 789 14 David Hamelech 790 Tel Aviv 64953 791 Israel 793 Email: even.roni@huawei.com