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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: June 1, 2012 Huawei 6 November 29, 2011 8 RTCP Extension for Third-party Loss Report 9 draft-ietf-avtcore-feedback-supression-rtp-09 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 June 1, 2012. 42 Copyright Notice 44 Copyright (c) 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4 62 4. Format of RTCP Feedback Messages . . . . . . . . . . . . . . . 5 63 4.1. Transport Layer Feedback: Third-party Loss Report . . . . 5 64 4.2. Payload Specific Feedback: Third-party Loss Report . . . . 6 65 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 7 66 6. Example Use Cases . . . . . . . . . . . . . . . . . . . . . . 8 67 6.1. Source Specific Multicast (SSM) use case . . . . . . . . . 8 68 6.2. Unicast based Rapid Acquisition of Multicast Stream 69 (RAMS) use case . . . . . . . . . . . . . . . . . . . . . 9 70 6.3. RTP Transport Translator use case . . . . . . . . . . . . 9 71 6.4. Multipoint Control Unit (MCU) use case . . . . . . . . . . 9 72 6.5. Mixer use case . . . . . . . . . . . . . . . . . . . . . . 10 73 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 74 8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 11 75 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 76 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 77 10.1. Normative References . . . . . . . . . . . . . . . . . . . 12 78 10.2. Informative References . . . . . . . . . . . . . . . . . . 12 79 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 13 80 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 . . . . . . 13 81 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 . . . . . . 14 82 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 . . . . . . 14 83 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 . . . . . . 14 84 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 . . . . . . 15 85 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 . . . . . . 15 86 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 . . . . . . 15 87 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 . . . . . . 16 88 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 . . . . . . 16 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 91 1. Introduction 93 RTCP feedback messages [RFC4585] allow the receivers in an RTP 94 session to report events and ask for action from the media source (or 95 a delegated feedback target when using unicast RTCP feedback with SSM 96 [RFC5760]). There are cases where multiple receivers may initiate 97 the same, or an equivalent message towards the same media source. 98 When the receiver count is large, this behavior may cause transient 99 overload of the media source, the network or both. This is known as 100 a "feedback storm" or a "NACK storm". One common cause of such a 101 feedback storm is receivers utilizing RTP retransmission [RFC4588] as 102 a packet loss recovery technique, sending feedback using RTCP NACK 103 messages [RFC4585] without proper dithering of the retransmission 104 requests (e.g., not implementing the RFC 4585 dithering rules or 105 sending NACKs to a middlebox that doesn't redistribute them to other 106 receivers). 108 Another use case involves video Fast Update requests. A storm of 109 these feedback messages can occur in conversational multimedia 110 scenarios like multipoint video switching conference [RFC4587]. In 111 this scenario, the receiver may lose synchronization with the video 112 stream when speaker is changed in the middle of session. Poorly 113 designed receivers that blindly issue fast update requests (i.e., 114 Full Intra Request (FIR) described in [RFC5104]), can cause an 115 implosion of FIR requests from receivers to the same media source. 117 RTCP feedback storms may cause short term overload, and in extreme 118 cases to pose a possible risk of increasing network congestion on the 119 control channel (e.g. RTCP feedback), the data channel, or both. It 120 is therefore desirable to provide a way of suppressing unneeded 121 feedback. 123 One approach to this, suggested in [DVB-IPTV], involves sending a 124 NACK message to the other clients (or receiver) in the same group as 125 the sender of NACK. However NACK is defined as a receiver report 126 sent from a receiver observing a packet loss, therefore it only 127 inform others that sender of NACK detected loss while the case where 128 the sender of the feedback has received reports that the indicated 129 packets were lost is not covered. This document specifies a new 130 third-party loss report for this function. It supplements the 131 existing the use of RTCP NACK packet and further is more precise in 132 the uses where the network is active to suppress feedback. It tells 133 receivers explicitly that feedback for a particular packet or frame 134 loss is not needed for a period of time and can provide an early 135 indication before the receiver reacts to the loss and invokes its 136 packet loss repair machinery. Section 6 provides some examples of 137 when to send the Third Party Loss Report message. 139 2. Terminology 141 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 142 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 143 document are to be interpreted as described in [RFC2119]. 145 3. Protocol Overview 147 This document extends the RTCP feedback messages defined in the 148 Audio-Visual Profile with feedback (RTP/AVPF) [RFC4585] defining a 149 Third Party Loss Report message. The Third Party Loss Report message 150 can be used by the intermediaries to inform the receiver that the 151 sender of the Third Party Loss Report has received reports that the 152 indicated packets were lost, and asks the receiver not to send 153 feedback to it regarding these packets. 155 RTCP Third Party Loss Report follows the similar format of message 156 type as RTCP NACK or Full Intra Request Command. However, the Third 157 Party Loss Report is defined as an indication that the sender of the 158 feedback has received reports that the indicated packets were lost, 159 while NACK [RFC4585] just indicates that the sender of the NACK 160 observed that these packets were lost. The Third Party Loss Report 161 (TPLR) message is generated by a RTP system that may not seen the 162 actual packet loss. It is sent following the same timing rule as 163 sending NACK defined in [RFC4585]. The TPLR feedback message may be 164 sent in a regular full compound RTCP packet or in an early RTCP 165 packet, as per the RTP/AVPF rules. RTP Systems in the network that 166 receive a Third Party Loss Report SHOULD NOT send their own 167 additional Third Party Loss Report messages for the same packet 168 sequence numbers. They should simply forward the Third Party Loss 169 Report message received from upstream direction, additionally, they 170 may generate their own Third Party Loss Report that reports a set of 171 the losses they see, which are different from ones reported in the 172 Third Party Loss report they received. The Third Party Loss Report 173 does not have the retransmission request [RFC4588] semantics. 175 When a receiver gets a Third Party Loss Report message, it should 176 follow the rules for NACK suppression in RFC 4585 and refrain from 177 sending a feedback request (e.g., NACK or FIR) for the missing 178 packets reported in the message,which is dealt with in the same way 179 as receiving NACK. 181 To increase the robustness to the loss of a TPLR or of a transmission 182 RTP data packet, TPLR or the RTP packet for the same missing Packet 183 may be retransmitted when RTP systems are aware that the same packet 184 loss occurs again. If the additional TPLR arrives at receiver, the 185 receiver should deal with the additional TPLR in the same way as 186 receiving the first TPLR for the same packet and no additional 187 behavior for receiver is required. When the retransmitted packet is 188 received by the receiver,it should take its normal behavior as if 189 there is no current feedback suppression. 191 A receiver may still have sent a Feedback message according to the 192 RTP/AVPF scheduling algorithm of [RFC4585] before receiving a Third 193 Party Loss Report message, but further feedback messages for those 194 sequence numbers SHOULD be suppressed for a period of time after 195 receiving the TPLR. Nodes that do not understand the Third Party 196 Loss Report message will ignore it, and might therefore still send 197 feedback according to the AVPF scheduling algorithm of [RFC4585]. 198 The media source or intermediate nodes cannot be certain that the use 199 of a Third Party Loss Report message actually reduces the amount of 200 feedback it receives. 202 Since Third Party Loss Report interacts strongly with repair timing, 203 it has to work together with feedback to not adversely impact the 204 repair of lost source packets. In order not to incur a lot of NACK 205 requests due to additional TPLR described above, it is recommended 206 that the RTP system sending TPLR should be implemented more closer to 207 the media source. When the loss was detected and repair initiated 208 much closer to the media source, the delay for the receiver to 209 recover from packet loss can be reduced through the combination of 210 intermediary feedback to the source and Third Party Loss Report 211 downstream. 213 4. Format of RTCP Feedback Messages 215 This document registers 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 Third Party Loss Report together with 218 their existing loss-repair methods either for every packet they 219 expect to receive, or for an application-specific subset of the RTP 220 packets in a session. In other words, receivers MAY ignore Third 221 Party Loss Report messages, but SHOULD react to them unless they have 222 good reason to still send feedback messages despite having been 223 requested to suppress them. 225 4.1. Transport Layer Feedback: Third-party Loss Report 227 This Third Party Loss Report message is an extension to the RTCP 228 Transport Layer Feedback Report and identified by RTCP packet type 229 value PT=RTPFB and FMT=TBD. 231 Within the common packet header for feedback messages (as defined in 232 section 6.1 of [RFC4585]), the "SSRC of packet sender" field 233 indicates the source of the request, and the "SSRC of media source" 234 denotes the media sender of the flow for which the indicated losses 235 are being suppressed . 237 The FCI field MUST contain one or more entries of transport layer 238 third party loss Early Indication (TLLEI). Each entry applies to the 239 same media source identified by the SSRC contained in the SSRC of 240 media source field of Feedback header. The length of the TLLEI 241 feedback message MUST be set to 2+1*N, where N is the number of FCI 242 entries. 244 The Feedback Control Information (FCI) for TLLEI uses the similar 245 format of message Types defined in the section 6.2.1 of [RFC4585]. 246 The format is shown in Figure 1. 248 0 1 2 3 249 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 1 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 | PID | BLP | 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 Figure 1: Syntax of an FCI Entry in the TLLEI Feedback Message 256 Packet ID (PID): 16 bits 258 The PID field is used to specify a lost packet. The PID field 259 refers to the RTP sequence number of the lost packet. 261 bitmask of proceeding lost packets (BLP): 16 bits 263 The BLP allows for reporting losses of any of the 16 RTP packets 264 immediately following the RTP packet indicated by the PID. The 265 BLP's definition is identical to that given in [RFC4585]. 267 4.2. Payload Specific Feedback: Third-party Loss Report 269 This message is an extension to the RTCP Payload Specific Feedback 270 report and identified by RTCP packet type value PT=PSFB and FMT=TBD, 271 which is used to suppress FIR [RFC5104]or PLI [RFC4585]. 273 Within the common packet header for feedback messages (as defined in 274 section 6.1 of [RFC4585]), the "SSRC of packet sender" field 275 indicates the source of the request, and the "SSRC of media source" 276 is not used and SHALL be set to 0. The SSRCs of the media senders to 277 which this message applies are in the corresponding FCI entries. 279 The Feedback Control Information (FCI) for a Payload Specific Third 280 Party Loss Early Indication (PSLEI) consists one or more FCI entries. 281 Each entry applies to a different media Source, identified by its 282 SSRC. the content of which is depicted in Figure 2. The length of 283 the PSLEI feedback message MUST be set to 2+1*N, where N is the 284 number of FCI entries. 286 The format is shown in Figure 2. 288 0 1 2 3 289 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 1 290 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 291 | SSRC | 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 Figure 2: Syntax of an FCI Entry in the PSLEI Feedback Message 296 Synchronization source (SSRC):32 bits 298 The SSRC value of the media source that is requested to send a 299 decoder refresh point or that is indicated that it lost 300 synchronization with the video stream. 302 5. SDP Signaling 304 A new feedback value "tplr" needs to be defined for the Third Party 305 Loss Report message to be used with Session Description Protocol 306 (SDP) [RFC4566] using the Augmented Backus-Naur Form (ABNF) 307 [RFC4585]. 309 The "tplr" feedback value SHOULD be used with parameters that 310 indicate the third party loss supported. In this document, we define 311 two such parameter, namely: 313 o "tllei" denotes support of transport layer third party loss early 314 indication. 316 o "pslei" denotes support of payload specific third party loss early 317 indication. 319 In the ABNF [RFC5234] for rtcp-fb-val defined in [RFC4585], there is 320 a placeholder called rtcp-fb-id to define new feedback types. "tplr" 321 is defined as a new feedback type in this document, and the ABNF for 322 the parameters for tplr is defined here (please refer to section 4.2 323 of [RFC4585] for complete ABNF syntax). 325 rtcp-fb-val =/ "tplr" rtcp-fb-tplr-param 326 rtcp-fb-tplr-param = SP "tllei" 327 ;transport layer third party 328 ; loss early indication 329 / SP "pslei" 330 ;payload specific third party 331 ; loss early indication 332 / SP token [SP byte-string] 333 ; for future commands/indications 334 token = 335 byte-string = 337 Refer to Section 4.2 of [RFC4585] for a detailed description and the 338 full syntax of the "rtcp-fb" attribute. 340 6. Example Use Cases 342 The operation of feedback suppression is similar for all types of RTP 343 sessions and topologies [RFC5117], however the exact messages used 344 and the scenarios in which suppression is employed differ for various 345 use cases. The following sections outline some of the intended use 346 cases for using the Third Party Loss Report for feedback suppression 347 and give an overview of the particular mechanisms. 349 6.1. Source Specific Multicast (SSM) use case 351 In SSM RTP sessions as described in [RFC5760], one or more Media 352 Sources send RTP packets to a Distribution Source. The Distribution 353 Source relays the RTP packets to the receivers using a source- 354 specific multicast group. 356 As outlined in the [RFC5760], there are two Unicast Feedback models 357 that may be used for reporting, the Simple Feedback model and the 358 Distribution Source Feedback Summary Model. In the simple Feedback 359 Model, there's no need for distribution source to create the Third 360 Party Loss Report, instead, NACKs are reflected by the distribution 361 source to the other Receivers. However in the Distribution Source 362 Feedback Summary model, the distribution source will not redistribute 363 the NACK for some reason(e.g., to prevent revealing the identity or 364 existence of a system sending NACK)and may send a Third Party Loss 365 Report to the systems that were unable to receive the NACK, and won't 366 receive the NACK via other means. since the summary feedback does not 367 mandate the forwarding of NACK downstream. The Third Party Loss 368 Report can be generated at the distribution source when downstream 369 loss is told (e.g., downstream loss report is received), which 370 indicates to the receivers that they should not transmit feedback 371 messages for the same loss event for a certain time. Therefore the 372 distribution source in the feedback summary model can be reasonably 373 certain that it will help the situation by sending this Third Party 374 Loss Report message to all the relevant receivers impacted by the 375 packet loss. 377 6.2. Unicast based Rapid Acquisition of Multicast Stream (RAMS) use 378 case 380 The typical RAMS architecture [RFC6285] may have several Burst/ 381 Retransmission Sources(BRS) behind the multicast source (MS) placed 382 at the same level. These BRSes will receive the primary multicast 383 RTP stream from the media source and cache most recent packets after 384 joining multicast session. If packet loss happens at the upstream of 385 all the BRSs or the downstream of BRSes. One of the BRSes or all the 386 BRSes may send a NACK or TPLR message to the DS, where the SSRC in 387 this NACK or TPLR message is the BRS that is sending the message. 388 The DS forwards/reflects this message down on the primary SSM. The 389 details on how DS deal with this message is specified in 390 [RETRANSMISSION-FOR-SSM]. 392 6.3. RTP Transport Translator use case 394 A Transport Translator (Topo-Trn-Translator), as defined in [RFC5117] 395 is typically forwarding the RTP and RTCP traffic between RTP clients, 396 for example converting from multicast to unicast for domains that do 397 not support multicast. The translator may suffer a loss of important 398 video packets. In this case, the translator may forward TPLR message 399 received from upstream in the same way as forwarding other RTCP 400 traffic. If the translator acting as quality monitor [Monarch]is 401 aware of packet loss, it may use the SSRC of monitor as packet sender 402 SSRC to create NACK message and send it to the receivers that is not 403 aware of packet loss. 405 6.4. Multipoint Control Unit (MCU) use case 407 When the speaker is changed in a voice-activated multipoint video 408 switching conference [RFC4587], an RTP mixer can be used to select 409 the available input streams and forward them to each participants. 410 If the MCU is doing a blind switch without waiting for a 411 synchronization point on the new stream it can send a FIR to the new 412 video source. In this case the MCU should send a FIR suppression 413 message to the new receivers. e.g.,when the RTP Mixer starts to 414 receive FIR from some participants it can suppress the remaining 415 session participants from sending FIR by sending out a Third party 416 Loss report message. 418 6.5. Mixer use case 420 A Mixer, in accordance with [RFC5117], aggregates multiple RTP 421 streams from other session participants and generates a new RTP 422 stream sent to the session participants. In some cases, the video 423 frames may get badly screwed up between media source and the mixer. 424 In such case, the mixer need to check if the packet loss will result 425 in PLI or FIR transmissions from most of the group by analyzing the 426 received video. If so the mixer may initiate FIR or PLI towards the 427 media source on behalf of all the session participants and send out a 428 Third party Loss report message to these session participants that 429 may or are expected to send a PLI or FIR. Alternatively, when the 430 mixer starts to receive FIR or PLI from some participants and like to 431 suppress the remaining session participants from sending FIR or PLI 432 by forwarding the FIR/PLI from one session participant to others. 434 7. Security Considerations 436 The defined messages have certain properties that have security 437 implications. These must be addressed and taken into account by 438 users of this protocol. 440 Spoofed or maliciously created feedback messages of the type defined 441 in this specification can have the following implications: 443 Sending the spurious Third Party Loss Report (e.g., the Third Party 444 Loss Report with the wrong sequence number of lost packet) that 445 causes missing RTP packets to not be repaired in a timely fashion. 447 To prevent these attacks, there is a need to apply authentication and 448 integrity protection of the feedback messages. This can be 449 accomplished against threats external to the current RTP session 450 using the RTP profile that combines Secure RTP [RFC3711] and AVPF 451 into SAVPF [RFC5124]. 453 Note that middleboxes that are not visible at the RTP layer that wish 454 to send the Third Party Loss Reports on behalf of the media source 455 can only do so if they spoof the SSRC of the media source. This is 456 difficult in case SRTP is in use. If the middlebox is visible at the 457 RTP layer, this is not an issue, provided the middlebox is part of 458 the security context for the session. 460 Also note that endpoints that receive a Third Party Loss Report would 461 be well-advised to ignore it, unless the security is in place to 462 authenticate the sender of the Third Party Loss Report. Accepting 463 Third Party Loss Report from un-authenticated sender can lead to a 464 denial of service attack, where the endpoint accepts poor quality 465 media that could be repaired. 467 8. IANA Consideration 469 The new value "TPLR" has been registered with IANA in the "rtcp-fb" 470 Attribute Values registry located at the time of publication at: 471 http://www.iana.org/assignments/sdp-parameters 473 Value name: tplr 474 Long Name: Third Party Loss Reports 475 Reference: This document 477 A new registry " Third Party Loss Report Messages" has been created 478 to hold "tplr" parameters located at time of publication at: 479 http://www.iana.org/assignments/sdp-parameters 481 New registration in this registry follows the "Specification 482 required" policy as defined by [RFC5226]. In addition, they are 483 required to indicate any additional RTCP feedback types, such as 484 "nack" and "ack". 486 The following value have been registered as one FMT value in the "FMT 487 Values for RTPFB Payload Types" registry located at the time of 488 publication at: http://www.iana.org/assignments/rtp-parameters 490 RTPFB range 491 Name Long Name Value Reference 492 -------------- --------------------------------- ----- --------- 493 TLLEI Transport Layer Third Party TBA1 [RFCXXXX] 494 Loss Early Indication 496 The following value have been registered as one FMT value in the "FMT 497 Values for PSFB Payload Types" registry located at the time of 498 publication at: http://www.iana.org/assignments/rtp-parameters 500 PSFB range 501 Name Long Name Value Reference 502 -------------- --------------------------------- ----- --------- 503 PSLEI Payload Specific Third Party TBA2 [RFCXXXX] 504 Loss Early Indication 506 9. Acknowledgement 508 The authors would like to thank David R Oran, Magnus Westerlund, 509 Colin Perkins, Ali C. Begen, Tom VAN CAENEGEM, Ingemar Johansson S, 510 Bill Ver Steeg, Jonathan Lennox, WeeSan Lee for their valuable 511 comments and suggestions on this document. 513 10. References 515 10.1. Normative References 517 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 518 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 519 May 2008. 521 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 522 Requirement Levels", BCP 14, RFC 2119, March 1997. 524 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 525 "Extended RTP Profile for Real-time Transport Control 526 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, 527 July 2006. 529 [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. 530 Hakenberg, "RTP Retransmission Payload Format", RFC 4588, 531 July 2006. 533 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 534 Description Protocol", RFC 4566, July 2006. 536 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 537 Specifications: ABNF", STD 68, RFC 5234, January 2008. 539 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 540 "Codec Control Messages in the RTP Audio-Visual Profile 541 with Feedback (AVPF)", RFC 5104, February 2008. 543 10.2. Informative References 545 [RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker, 546 "NACK-Oriented Reliable Multicast (NORM) Transport 547 Protocol", November 2009. 549 [DVB-IPTV] 550 ETSI Standard, "Digital Video Broadcasting(DVB); Transport 551 of MPEG-2 TS Based DVB Services over IP Based Networks", 552 ETSI TS 102 034, V1.4.1 , August 2009. 554 [RFC6285] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast- 555 Based Rapid Acquisition of Multicast RTP Sessions", 556 June 2011. 558 [Monarch] Wu, Q., Hunt, G., and P. Arden, "Monitoring Architectures 559 for RTP", June 2011. 561 [RETRANSMISSION-FOR-SSM] 562 Caenegem, T., Steeg, B., and A. Begen, "Retransmission for 563 Source-Specific Multicast (SSM) Sessions", May 2011. 565 [RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, 566 January 2008. 568 [RFC4587] Even, R., "RTP Payload Format for H.261 Video Streams", 569 RFC 4587, August 2006. 571 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 572 Protocol (RTCP) Extensions for Single-Source Multicast 573 Sessions with Unicast Feedback", RFC 5760, February 2010. 575 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for 576 Real-time Transport Control Protocol (RTCP)-Based Feedback 577 (RTP/SAVPF)", RFC 5124, February 2008. 579 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. 580 Norrman, "The Secure Real-time Transport Protocol (SRTP)", 581 RFC 3711, March 2004. 583 Appendix A. Change Log 585 Note to the RFC-Editor: please remove this section prior to 586 publication as an RFC. 588 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 590 The following are the major changes compared to previous version: 592 o Remove the merge report from SSM use case and additional text to 593 address report merging issue. 595 o Revise section 3 and section 6 to address FEC packet dealing issue 596 and Leave how to repair packet loss beyond the scope. 598 o Modify the SSM use case and RAMS use case to focus on uses. 600 o Other Editorial changes. 602 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 604 The following are the major changes compared to previous version: 606 o In Section 4.1, fix typo: Section 4.3.1.1 of section [RFC5104]-> 607 section 6.2.1 of [RFC4585]. 609 o In Section 3: Clarify how to deal with downstream loss using Third 610 party loss report and upstream loss using NACK. 612 o Update title and abstract to focus on third party loss report. 614 o In Section 6.1: Update this section to explain how third party 615 loss report is used to deal with downstream loss. 617 o In section 6.1.2: Update this section to explain how third party 618 loss report is used to deal with downstream loss. 620 o In section 6.2: Rephrase the text to discuss how BRS deal with the 621 third party loss report. 623 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 625 The following are the major changes compared to previous version: 627 o In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix A. 629 o Update abstract to clarify when third-party loss reports should be 630 sent instead of NACKs. 632 o Update section 3 Paragraph 2 to differentiate when a third-party 633 loss report should be used compared to a NACK. 635 o Update section 3 Paragraph 3 to explain when media source to send 636 a third-party loss. 638 o Move specific rules for section 6.1.1 and section 6.1.2 to section 639 6.1 as generic rules and delete section 6.1.1. 641 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 643 The following are the major changes compared to previous version: 644 o Reference Update. 646 o Clarify the use of the third party loss report in section 3 and 647 section 6.1.1. 649 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 651 The following are the major changes compared to previous version: 652 o Remove 3rd and 4th paragraphs of section 6.1 and replaced them 653 with 2nd and 3rd paragraphs of section 3. 655 o Remove section 6.1.1.1. 657 o Revise the last paragraph of section 1 to clarify the rationale of 658 using new message. 660 o Update RTP transport translator case in section 6.3 to correct the 661 use of the third party loss report. 663 o Update MCU case in section 6.4 to correct the use of the third 664 party loss report. 666 o Revise SSM use case to address multiple DS issue. 668 o References Update. 670 o Move one rationale on preventing sending unicast NACK in 671 introduction section to SSM case section. 673 o Other Editorial changes to section 6.1, 6.1.1, 6.2. 675 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 677 The following are the major changes compared to previous version: 679 o A few Editorial changes to the whole document. 681 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 683 The following are the major changes compared to previous version: 685 o Restructuring the protocol overview section to clarify the round 686 trip time calculation and receiver behavior to the additional 687 TPLR. 689 o Restructuring the SSM use case section to focus on the use of 690 TPLR. 692 o Editorial changes to the abstract, introduction, message format, 693 use cases and IANA sections. 695 o References update 697 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 699 The following are the major changes compared to previous version: 701 o Clarify which RTT is used and how timer is refreshed in the 702 section 3. 704 o Editorial changes to the Introduction, Protocol Overview, SDP 705 Signaling, Message Format, Use case,Security Consideration and 706 IANA sections. 708 o Remove Seq Nr field in the figure 2 for payload specific feedback. 710 o References reorganizing. 712 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 714 The following are the major changes compared to previous version: 716 o Clarify to suppression interval with regard to how long to receive 717 the retransmitted packet. Treating TPLR in the same way as 718 receiving NACK .Replace timer based approach with timeless based 719 approach 721 Authors' Addresses 723 Qin Wu 724 Huawei 725 101 Software Avenue, Yuhua District 726 Nanjing, Jiangsu 210012 727 China 729 Email: sunseawq@huawei.com 731 Frank Xia 732 Huawei 733 1700 Alma Dr. Suite 500 734 Plano, TX 75075 735 USA 737 Phone: +1 972-509-5599 738 Email: xiayangsong@huawei.com 739 Roni Even 740 Huawei 741 14 David Hamelech 742 Tel Aviv 64953 743 Israel 745 Email: even.roni@huawei.com