idnits 2.17.1 draft-ietf-avtcore-feedback-supression-rtp-10.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 seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (February 6, 2012) is 4462 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 487, but not defined == Unused Reference: 'RFC5226' is defined on line 501, but no explicit reference was found in the text == Unused Reference: 'RFC5740' is defined on line 529, but no explicit reference was found in the text == Unused Reference: 'MONARCH' is defined on line 537, but no explicit reference was found in the text ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) -- Obsolete informational reference (is this intentional?): RFC 5117 (Obsoleted by RFC 7667) Summary: 2 errors (**), 0 flaws (~~), 6 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: August 9, 2012 Huawei 6 February 6, 2012 8 RTCP Extension for Third-party Loss Report 9 draft-ietf-avtcore-feedback-supression-rtp-10 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 August 9, 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 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 . . . . . . . . . . . . . . . . . . . . . 8 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 . . . . . . . . . . . . . . . . . . . . . . 9 73 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 74 8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 10 75 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 76 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 77 10.1. Normative References . . . . . . . . . . . . . . . . . . . 11 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 . . . . . . 13 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 . . . . . . 14 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 . . . . . . 15 88 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 . . . . . . 16 89 A.10. draft-ietf-avtcore-feedback-suppression-rtp-10 . . . . . . 16 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 92 1. Introduction 94 RTCP feedback messages [RFC4585] allow the receivers in an RTP 95 session to report events and ask for action from the media source (or 96 a delegated feedback target when using unicast RTCP feedback with SSM 97 [RFC5760]). There are cases where multiple receivers may initiate 98 the same, or an equivalent message towards the same media source or 99 the same feedback target. When the receiver count is large, this 100 behavior may cause transient overload of the media source, the 101 network or both. This is known as a "feedback storm" or a "NACK 102 storm". One common cause of such a feedback storm is receivers 103 utilizing RTP retransmission [RFC4588] as a packet loss recovery 104 technique, sending feedback using RTCP NACK messages [RFC4585] 105 without proper dithering of the retransmission requests (e.g., not 106 implementing the RFC 4585 dithering rules or sending NACKs to a 107 feedback target that doesn't redistribute them to other receivers). 109 Another use case involves video Fast Update requests. A storm of 110 these feedback messages can occur in conversational multimedia 111 scenarios like multipoint video switching conference [RFC4587]. In 112 this scenario, the receiver may lose synchronization with the video 113 stream when speaker is changed in the middle of session. Poorly 114 designed receivers that blindly issue fast update requests (i.e., 115 Full Intra Request (FIR) described in [RFC5104]), can cause an 116 implosion of FIR requests from receivers to the same media source. 118 RTCP feedback storms may cause short term overload, and in extreme 119 cases to pose a possible risk of increasing network congestion on the 120 control channel (e.g. RTCP feedback), the data channel, or both. It 121 is therefore desirable to provide a way of suppressing unneeded 122 feedback. This document specifies a new third-party loss report for 123 this function. It supplements the existing the use of RTCP NACK 124 packet and further is more precise in the uses where the network is 125 active to suppress feedback. It tells receivers explicitly that 126 feedback for a particular packet or frame loss is not needed for a 127 period of time and can provide an early indication before the 128 receiver reacts to the loss and invokes its packet loss repair 129 machinery. Section 6 provides some examples of when to send the 130 Third Party Loss Report message. 132 2. Terminology 134 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 135 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 136 document are to be interpreted as described in [RFC2119]. 138 3. Protocol Overview 140 This document extends the RTCP feedback messages defined in the 141 Audio-Visual Profile with feedback (RTP/AVPF) [RFC4585] defining a 142 Third Party Loss Report message. The Third Party Loss Report message 143 can be used by the intermediaries to inform the receiver that the 144 sender of the Third Party Loss Report has received reports that the 145 indicated packets were lost, and asks the receiver not to send 146 feedback to it regarding these packets. Intermediaries are variously 147 referred to as Distribution source, Burst/Retransmission Sources 148 (BRS), MCUs, RTP translator, or RTP mixers, depending on the precise 149 use case described in section 6. 151 RTCP Third Party Loss Report follows the similar format of message 152 type as RTCP NACK or Full Intra Request Command. However, the Third 153 Party Loss Report is defined as an indication that the sender of the 154 feedback has received reports that the indicated packets were lost, 155 while NACK [RFC4585] just indicates that the sender of the NACK 156 observed that these packets were lost. The Third Party Loss Report 157 (TPLR) message is generated by a intermediary that may not seen the 158 actual packet loss. It is sent following the same timing rule as 159 sending NACK defined in [RFC4585]. The TPLR feedback message may be 160 sent in a regular full compound RTCP packet or in an early RTCP 161 packet, as per the RTP/AVPF rules. Intermediaries in the network 162 that receive a Third Party Loss Report SHOULD NOT send their own 163 additional Third Party Loss Report messages for the same packet 164 sequence numbers. They should simply forward the Third Party Loss 165 Report message received from upstream direction to the receiver(s), 166 additionally, they may generate their own Third Party Loss Report 167 that reports a set of the losses they see, which are different from 168 ones reported in the Third Party Loss report they received. The 169 Third Party Loss Report does not have the retransmission request 170 [RFC4588] semantics. 172 When a receiver gets a Third Party Loss Report message, it should 173 follow the rules for NACK suppression in RFC 4585 and refrain from 174 sending a feedback request (e.g., NACK or FIR) for the missing 175 packets reported in the message,which is dealt with in the same way 176 as receiving NACK. 178 To increase the robustness to the loss of a TPLR, TPLR may be 179 retransmitted. If the additional TPLR arrives at receiver, the 180 receiver should deal with the additional TPLR in the same way as 181 receiving the first TPLR for the same packet and no additional 182 behavior for receiver is required. 184 A receiver may still have sent a Feedback message according to the 185 RTP/AVPF scheduling algorithm of [RFC4585] before receiving a Third 186 Party Loss Report message, but further feedback messages for those 187 sequence numbers SHOULD be suppressed for a period of time after 188 receiving the TPLR. Nodes that do not understand the Third Party 189 Loss Report message will ignore it, and might therefore still send 190 feedback according to the AVPF scheduling algorithm of [RFC4585]. 191 The media source or intermediate nodes cannot be certain that the use 192 of a Third Party Loss Report message actually reduces the amount of 193 feedback it receives. 195 4. Format of RTCP Feedback Messages 197 This document registers two new RTCP Feedback messages for Third 198 Party Loss Report. Applications that are employing one or more loss- 199 repair methods MAY use the Third Party Loss Report together with 200 their existing loss-repair methods either for every packet they 201 expect to receive, or for an application-specific subset of the RTP 202 packets in a session. In other words, receivers MAY ignore Third 203 Party Loss Report messages, but SHOULD react to them unless they have 204 good reason to still send feedback messages despite having been 205 requested to suppress them. 207 4.1. Transport Layer Feedback: Third-party Loss Report 209 This Third Party Loss Report message is an extension to the RTCP 210 Transport Layer Feedback Report and identified by RTCP packet type 211 value PT=RTPFB and FMT=TBD. 213 Within the common packet header for feedback messages (as defined in 214 section 6.1 of [RFC4585]), the "SSRC of packet sender" field 215 indicates the source of the request, and the "SSRC of media source" 216 denotes the media sender of the flow for which the indicated losses 217 are being suppressed. 219 The FCI field MUST contain one or more entries of transport layer 220 third party loss Early Indication (TLLEI). Each entry applies to the 221 same media source identified by the SSRC contained in the SSRC of 222 media source field of Feedback header. The length of the TLLEI 223 feedback message MUST be set to 2+1*N, where N is the number of FCI 224 entries. 226 The Feedback Control Information (FCI) for TLLEI uses the similar 227 format of message Types defined in the section 6.2.1 of [RFC4585]. 228 The format is shown in Figure 1. 230 0 1 2 3 231 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 1 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 | PID | BLP | 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 Figure 1: Syntax of an FCI Entry in the TLLEI Feedback Message 238 Packet ID (PID): 16 bits 240 The PID field is used to specify a lost packet. The PID field 241 refers to the RTP sequence number of the lost packet. 243 bitmask of proceeding lost packets (BLP): 16 bits 245 The BLP allows for reporting losses of any of the 16 RTP packets 246 immediately following the RTP packet indicated by the PID. The 247 BLP's definition is identical to that given in the section 6.2.1 248 of [RFC4585]. 250 4.2. Payload Specific Feedback: Third-party Loss Report 252 This message is an extension to the RTCP Payload Specific Feedback 253 report and identified by RTCP packet type value PT=PSFB and FMT=TBD, 254 which is used to suppress FIR [RFC5104]and PLI [RFC4585]. 256 Within the common packet header for feedback messages (as defined in 257 section 6.1 of [RFC4585]), the "SSRC of packet sender" field 258 indicates the source of the request, and the "SSRC of media source" 259 is not used and SHALL be set to 0. The SSRCs of the media senders to 260 which this message applies are in the corresponding FCI entries. 262 The Feedback Control Information (FCI) for a Payload Specific Third 263 Party Loss Early Indication (PSLEI) consists one or more FCI entries. 264 Each entry applies to a different media Source, identified by its 265 SSRC. the content of which is depicted in Figure 2. The length of 266 the PSLEI feedback message MUST be set to 2+1*N, where N is the 267 number of FCI entries. 269 The format is shown in Figure 2. 271 0 1 2 3 272 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 1 273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 | SSRC | 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 Figure 2: Syntax of an FCI Entry in the PSLEI Feedback Message 279 Synchronization source (SSRC):32 bits 281 The SSRC value of the media source that has already been aware the 282 receiver lost synchronization with the video stream and signal to 283 the receiver not sending a decoder refresh point. 285 5. SDP Signaling 287 The Session Description Protocol (SDP) [RFC4566] attribute, rtcp-fb, 288 is defined in the Section 4 of [RFC4585] and may be used to negotiate 289 the capability to handle specific AVPF commands and indications. The 290 ABNF for rtcp-fb is described in section 4.2 of [RFC4585]. In this 291 section, we extend the rtcp-fb attribute to include the commands and 292 indications that are described for third party loss report in the 293 present document. 295 In the ABNF [RFC5234] for rtcp-fb-val defined in [RFC4585], the 296 feedback type "nack", without parameters, indicates use of the 297 Generic NACK feedback format as defined in Section 6.2.1of [RFC4585]. 298 In this document, we define two parameters that indicate the third 299 party loss supported for use with "nack", namely: 301 o "tllei" denotes support of transport layer third party loss early 302 indication. 304 o "pslei" denotes support of payload specific third party loss early 305 indication. 307 The ABNF for these two parameters for "nack" is defined here (please 308 refer to section 4.2 of [RFC4585] for complete ABNF syntax). 310 rtcp-fb-val =/ "nack" rtcp-fb-nack-param 311 rtcp-fb-nack-param = SP "tllei" 312 ;transport layer third party 313 ; loss early indication 314 / SP "pslei" 315 ;payload specific third party 316 ; loss early indication 317 / SP token [SP byte-string] 318 ; for future commands/indications 319 token = 320 byte-string = 322 Refer to Section 4.2 of [RFC4585] for a detailed description and the 323 full syntax of the "rtcp-fb" attribute. 325 6. Example Use Cases 327 The operation of feedback suppression is similar for all types of RTP 328 sessions and topologies [RFC5117], however the exact messages used 329 and the scenarios in which suppression is employed differ for various 330 use cases. The following sections outline some of the intended use 331 cases for using the Third Party Loss Report for feedback suppression 332 and give an overview of the particular mechanisms. 334 6.1. Source Specific Multicast (SSM) use case 336 In SSM RTP sessions as described in "RTP Control Protocol (RTCP) 337 Extensions for Single-Source Multicast Sessions with Unicast 338 Feedback" [RFC5760], one or more Media Sources send RTP packets to a 339 Distribution Source. The Distribution Source relays the RTP packets 340 to the receivers using a source- specific multicast group. 342 As outlined in the [RFC5760], there are two Unicast Feedback models 343 that may be used for reporting, the Simple Feedback model and the 344 Distribution Source Feedback Summary Model. In the simple Feedback 345 Model, there's no need for distribution source to create the Third 346 Party Loss Report, instead, NACKs are reflected by the distribution 347 source to the other Receivers. However in the Distribution Source 348 Feedback Summary model, the distribution source will not redistribute 349 the NACK for some reason(e.g., to prevent revealing the identity or 350 existence of a system sending NACK)and may send a Third Party Loss 351 Report to the systems that were unable to receive the NACK, and won't 352 receive the NACK via other means. Since the summary feedback does 353 not mandate the forwarding of NACK downstream. The Third Party Loss 354 Report can be generated at the distribution source when downstream 355 loss is told (e.g., downstream loss report is received), which 356 indicates to the receivers that they should not transmit feedback 357 messages for the same loss event for a certain time. Therefore the 358 distribution source in the feedback summary model can be reasonably 359 certain that it will help the situation by sending this Third Party 360 Loss Report message to all the relevant receivers impacted by the 361 packet loss. 363 6.2. Unicast based Rapid Acquisition of Multicast Stream (RAMS) use 364 case 366 The typical RAMS architecture [RFC6285] may have several Burst/ 367 Retransmission Sources(BRS) behind the multicast source (MS) placed 368 at the same level. These BRSes will receive the primary multicast 369 RTP stream from the media source and cache most recent packets after 370 joining multicast session. If packet loss happens at the upstream of 371 all the BRSs or the downstream of BRSes. One of the BRSes or all the 372 BRSes may send a NACK or TPLR message to the DS, where the SSRC in 373 this NACK or TPLR message is the BRS that is sending the message. 374 The DS forwards/reflects this message down on the primary SSM. The 375 details on how DS deal with this message is specified in 376 [RETRANSMISSION-FOR-SSM]. 378 6.3. RTP Transport Translator use case 380 A Transport Translator (Topo-Trn-Translator), as defined in [RFC5117] 381 is typically forwarding the RTP and RTCP traffic between RTP clients, 382 for example converting from multicast to unicast for domains that do 383 not support multicast. The translator may suffer a loss of important 384 video packets. In this case, the translator may forward TPLR message 385 received from upstream in the same way as forwarding other RTCP 386 traffic. If the translator acting as the monitor [MONARCH]is aware 387 of packet loss, it may use the SSRC of monitor as packet sender SSRC 388 to create NACK message and send it to the receivers that is not aware 389 of packet loss. 391 6.4. Multipoint Control Unit (MCU) use case 393 When the speaker is changed in a voice-activated multipoint video 394 switching conference [RFC4587], an RTP mixer can be used to select 395 the available input streams and forward them to each participants. 396 If the MCU is doing a blind switch without waiting for a 397 synchronization point on the new stream it can send a FIR to the new 398 video source. In this case the MCU should send a FIR suppression 399 message to the new receivers. e.g., when the RTP Mixer starts to 400 receive FIR from some participants it can suppress the remaining 401 session participants from sending FIR by sending out a Third party 402 Loss report message. 404 6.5. Mixer use case 406 A Mixer, in accordance with [RFC5117], aggregates multiple RTP 407 streams from other session participants and generates a new RTP 408 stream sent to the session participants. In some cases, the video 409 frames may get badly screwed up between media source and the mixer. 410 In such case, the mixer need to check if the packet loss will result 411 in PLI or FIR transmissions from most of the group by analyzing the 412 received video. If so the mixer may initiate FIR or PLI towards the 413 media source on behalf of all the session participants and send out a 414 Third party Loss report message to these session participants that 415 may or are expected to send a PLI or FIR. Alternatively, when the 416 mixer starts to receive FIR or PLI from some participants and like to 417 suppress the remaining session participants from sending FIR or PLI 418 by forwarding the FIR/PLI from one session participant to others. 420 7. Security Considerations 422 The defined messages have certain properties that have security 423 implications. These must be addressed and taken into account by 424 users of this protocol. 426 Spoofed or maliciously created feedback messages of the type defined 427 in this specification can have the following implications: 429 Sending the spurious Third Party Loss Report (e.g., the Third Party 430 Loss Report with the wrong sequence number of lost packet) that 431 causes missing RTP packets to not be repaired in a timely fashion. 433 To prevent these attacks, there is a need to apply authentication and 434 integrity protection of the feedback messages. This can be 435 accomplished against threats external to the current RTP session 436 using the RTP profile that combines Secure RTP [RFC3711] and AVPF 437 into SAVPF [RFC5124]. 439 Note that intermediaries that are not visible at the RTP layer that 440 wish to send the Third Party Loss Reports on behalf of the media 441 source can only do so if they spoof the SSRC of the media source. 442 This is difficult in case SRTP is in use. If the intermediary is 443 visible at the RTP layer, this is not an issue, provided the 444 intermediary is part of the security context for the session. 446 Also note that endpoints that receive a Third Party Loss Report would 447 be well-advised to ignore it, unless the security is in place to 448 authenticate the sender of the Third Party Loss Report. Accepting 449 Third Party Loss Report from un-authenticated sender can lead to a 450 denial of service attack, where the endpoint accepts poor quality 451 media that could be repaired. 453 8. IANA Consideration 455 For use with "nack" [RFC4585], a joint sub-registry has been set up 456 that registers the following two values: 458 The value registration for the attribute value "nack": 460 Value name: tllei 461 Long name: Transport Layer Third Party Loss Early Indication 462 Usable with: nack 463 Reference: RFC 4585. 465 Value name: pslei 466 Long name: Payload Specific Third Party 467 Usable with: nack 468 Reference: RFC 4585. 470 The following value have been registered as one FMT value in the "FMT 471 Values for RTPFB Payload Types" registry located at the time of 472 publication at: http://www.iana.org/assignments/rtp-parameters 474 RTPFB range 475 Name Long Name Value Reference 476 -------------- --------------------------------- ----- --------- 477 TLLEI Transport Layer Third Party TBA1 [RFCXXXX] 478 Loss Early Indication 480 The following value have been registered as one FMT value in the "FMT 481 Values for PSFB Payload Types" registry located at the time of 482 publication at: http://www.iana.org/assignments/rtp-parameters 484 PSFB range 485 Name Long Name Value Reference 486 -------------- --------------------------------- ----- --------- 487 PSLEI Payload Specific Third Party TBA2 [RFCXXXX] 488 Loss Early Indication 490 9. Acknowledgement 492 The authors would like to thank David R Oran, Magnus Westerlund, 493 Colin Perkins, Ali C. Begen, Tom VAN CAENEGEM, Ingemar Johansson S, 494 Bill Ver Steeg, Jonathan Lennox, WeeSan Lee for their valuable 495 comments and suggestions on this document. 497 10. References 499 10.1. Normative References 501 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 502 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 503 May 2008. 505 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 506 Requirement Levels", BCP 14, RFC 2119, March 1997. 508 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, 509 "Extended RTP Profile for Real-time Transport Control 510 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, 511 July 2006. 513 [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. 514 Hakenberg, "RTP Retransmission Payload Format", RFC 4588, 515 July 2006. 517 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 518 Description Protocol", RFC 4566, July 2006. 520 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 521 Specifications: ABNF", STD 68, RFC 5234, January 2008. 523 [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, 524 "Codec Control Messages in the RTP Audio-Visual Profile 525 with Feedback (AVPF)", RFC 5104, February 2008. 527 10.2. Informative References 529 [RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker, 530 "NACK-Oriented Reliable Multicast (NORM) Transport 531 Protocol", November 2009. 533 [RFC6285] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast- 534 Based Rapid Acquisition of Multicast RTP Sessions", 535 June 2011. 537 [MONARCH] Wu, Q., Hunt, G., and P. Arden, "Monitoring Architectures 538 for RTP", June 2011. 540 [RETRANSMISSION-FOR-SSM] 541 Caenegem, T., Steeg, B., and A. Begen, "Retransmission for 542 Source-Specific Multicast (SSM) Sessions", May 2011. 544 [RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, 545 January 2008. 547 [RFC4587] Even, R., "RTP Payload Format for H.261 Video Streams", 548 RFC 4587, August 2006. 550 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 551 Protocol (RTCP) Extensions for Single-Source Multicast 552 Sessions with Unicast Feedback", RFC 5760, February 2010. 554 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for 555 Real-time Transport Control Protocol (RTCP)-Based Feedback 556 (RTP/SAVPF)", RFC 5124, February 2008. 558 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. 559 Norrman, "The Secure Real-time Transport Protocol (SRTP)", 560 RFC 3711, March 2004. 562 Appendix A. Change Log 564 Note to the RFC-Editor: please remove this section prior to 565 publication as an RFC. 567 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 569 The following are the major changes compared to previous version: 571 o Remove the merge report from SSM use case and additional text to 572 address report merging issue. 574 o Revise section 3 and section 6 to address FEC packet dealing issue 575 and Leave how to repair packet loss beyond the scope. 577 o Modify the SSM use case and RAMS use case to focus on uses. 579 o Other Editorial changes. 581 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 583 The following are the major changes compared to previous version: 585 o In Section 4.1, fix typo: Section 4.3.1.1 of section [RFC5104]-> 586 section 6.2.1 of [RFC4585]. 588 o In Section 3: Clarify how to deal with downstream loss using Third 589 party loss report and upstream loss using NACK. 591 o Update title and abstract to focus on third party loss report. 593 o In Section 6.1: Update this section to explain how third party 594 loss report is used to deal with downstream loss. 596 o In section 6.1.2: Update this section to explain how third party 597 loss report is used to deal with downstream loss. 599 o In section 6.2: Rephrase the text to discuss how BRS deal with the 600 third party loss report. 602 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 604 The following are the major changes compared to previous version: 606 o In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix A. 608 o Update abstract to clarify when third-party loss reports should be 609 sent instead of NACKs. 611 o Update section 3 Paragraph 2 to differentiate when a third-party 612 loss report should be used compared to a NACK. 614 o Update section 3 Paragraph 3 to explain when media source to send 615 a third-party loss. 617 o Move specific rules for section 6.1.1 and section 6.1.2 to section 618 6.1 as generic rules and delete section 6.1.1. 620 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 622 The following are the major changes compared to previous version: 623 o Reference Update. 625 o Clarify the use of the third party loss report in section 3 and 626 section 6.1.1. 628 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 630 The following are the major changes compared to previous version: 631 o Remove 3rd and 4th paragraphs of section 6.1 and replaced them 632 with 2nd and 3rd paragraphs of section 3. 634 o Remove section 6.1.1.1. 636 o Revise the last paragraph of section 1 to clarify the rationale of 637 using new message. 639 o Update RTP transport translator case in section 6.3 to correct the 640 use of the third party loss report. 642 o Update MCU case in section 6.4 to correct the use of the third 643 party loss report. 645 o Revise SSM use case to address multiple DS issue. 647 o References Update. 649 o Move one rationale on preventing sending unicast NACK in 650 introduction section to SSM case section. 652 o Other Editorial changes to section 6.1, 6.1.1, 6.2. 654 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 656 The following are the major changes compared to previous version: 658 o A few Editorial changes to the whole document. 660 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 662 The following are the major changes compared to previous version: 664 o Restructuring the protocol overview section to clarify the round 665 trip time calculation and receiver behavior to the additional 666 TPLR. 668 o Restructuring the SSM use case section to focus on the use of 669 TPLR. 671 o Editorial changes to the abstract, introduction, message format, 672 use cases and IANA sections. 674 o References update 676 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 678 The following are the major changes compared to previous version: 680 o Clarify which RTT is used and how timer is refreshed in the 681 section 3. 683 o Editorial changes to the Introduction, Protocol Overview, SDP 684 Signaling, Message Format, Use case,Security Consideration and 685 IANA sections. 687 o Remove Seq Nr field in the figure 2 for payload specific feedback. 689 o References reorganizing. 691 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 693 The following are the major changes compared to previous version: 695 o Clarify to suppression interval with regard to how long to receive 696 the retransmitted packet. Treating TPLR in the same way as 697 receiving NACK .Replace timer based approach with timeless based 698 approach 700 A.10. draft-ietf-avtcore-feedback-suppression-rtp-10 702 The following are the major changes compared to previous version: 704 o Fix the definition of Synchronization source for TPLR in section 705 4.2. 706 o Associate SDP parameters tllei and pslei with "nack". 707 o Remove the packet loss recovery from TPLR loss handling part. 708 o Other typo fixed. 710 Authors' Addresses 712 Qin Wu 713 Huawei 714 101 Software Avenue, Yuhua District 715 Nanjing, Jiangsu 210012 716 China 718 Email: sunseawq@huawei.com 720 Frank Xia 721 Huawei 722 1700 Alma Dr. Suite 500 723 Plano, TX 75075 724 USA 726 Phone: +1 972-509-5599 727 Email: xiayangsong@huawei.com 728 Roni Even 729 Huawei 730 14 David Hamelech 731 Tel Aviv 64953 732 Israel 734 Email: even.roni@huawei.com