idnits 2.17.1 draft-ietf-avtcore-feedback-supression-rtp-13.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- 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 (February 23, 2012) is 4417 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 491, 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: August 26, 2012 Huawei 6 February 23, 2012 8 RTCP Extension for Third-party Loss Report 9 draft-ietf-avtcore-feedback-supression-rtp-13 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 26, 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. Requirements Notation . . . . . . . . . . . . . . . . . . . . 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 . . . . . . 13 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 . . . . . . 15 89 A.10. draft-ietf-avtcore-feedback-suppression-rtp-10 . . . . . . 16 90 A.11. draft-ietf-avtcore-feedback-suppression-rtp-11 . . . . . . 16 91 A.12. draft-ietf-avtcore-feedback-suppression-rtp-12 . . . . . . 16 92 A.13. draft-ietf-avtcore-feedback-suppression-rtp-13 . . . . . . 16 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 95 1. Introduction 97 RTCP feedback messages [RFC4585] allow the receivers in an RTP 98 session to report events and ask for action from the media source (or 99 a delegated feedback target when using unicast RTCP feedback with SSM 100 [RFC5760]). There are cases where multiple receivers may initiate 101 the same, or an equivalent message towards the same media source or 102 the same feedback target. When the receiver count is large, this 103 behavior may cause transient overload of the media source, the 104 network or both. This is known as a "feedback storm" or a "NACK 105 storm". One common cause of such a feedback storm is receivers 106 utilizing RTP retransmission [RFC4588] as a packet loss recovery 107 technique, sending feedback using RTCP NACK messages [RFC4585] 108 without proper dithering of the retransmission requests (e.g., not 109 implementing the RFC 4585 dithering rules or sending NACKs to a 110 feedback target that doesn't redistribute them to other receivers). 112 Another use case involves video Fast Update requests. A storm of 113 these feedback messages can occur in conversational multimedia 114 scenarios like multipoint video switching conference [RFC4587]. In 115 this scenario, the receiver may lose synchronization with the video 116 stream when speaker is changed in the middle of session. Poorly 117 designed receivers that blindly issue fast update requests (i.e., 118 Full Intra Request (FIR) described in RFC5104 [RFC5104]), can cause 119 an implosion of FIR requests from receivers to the same media source. 121 RTCP feedback storms may cause short term overload, and in extreme 122 cases to pose a possible risk of increasing network congestion on the 123 control channel (e.g. RTCP feedback), the data channel, or both. It 124 is therefore desirable to provide a way of suppressing unneeded 125 feedback. This document specifies a new third-party loss report for 126 this function. It supplements the existing the use of RTCP NACK 127 packet and further is more precise in the uses where the network is 128 active to suppress feedback. It tells receivers explicitly that 129 feedback for a particular packet or frame loss is not needed for a 130 period of time and can provide an early indication before the 131 receiver reacts to the loss and invokes its packet loss repair 132 machinery. Section 6 provides some examples of when to send the 133 Third Party Loss Report message. 135 2. Requirements Notation 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 139 document are to be interpreted as described in RFC2119 [RFC2119]. 141 3. Protocol Overview 143 This document extends the RTCP feedback messages defined in the 144 Audio-Visual Profile with feedback (RTP/AVPF) [RFC4585] defining a 145 Third Party Loss Report message. The Third Party Loss Report message 146 can be used by the intermediaries to inform the receiver that the 147 sender of the Third Party Loss Report has received reports that the 148 indicated packets were lost, and asks the receiver not to send 149 feedback to it regarding these packets. Intermediaries are variously 150 referred to as Distribution source, Burst/Retransmission Sources 151 (BRS), MCUs, RTP translator, or RTP mixers, depending on the precise 152 use case described in section 6. 154 RTCP Third Party Loss Report follows the similar format of message 155 type as RTCP NACK or Full Intra Request Command. However, the Third 156 Party Loss Report is defined as an indication that the sender of the 157 feedback has received reports that the indicated packets were lost, 158 while NACK [RFC4585] just indicates that the sender of the NACK 159 observed that these packets were lost. The Third Party Loss Report 160 (TPLR) message is generated by an intermediary that may not seen the 161 actual packet loss. It is sent following the same timing rule as 162 sending NACK defined in RFC4585 [RFC4585]. The TPLR feedback message 163 may be sent in a regular full compound RTCP packet or in an early 164 RTCP packet, as per the RTP/AVPF rules. Intermediaries in the 165 network that receive a Third Party Loss Report SHOULD NOT send their 166 own additional Third Party Loss Report messages for the same packet 167 sequence numbers. They SHOULD simply forward the Third Party Loss 168 Report message received from upstream direction to the receiver(s), 169 additionally, they may generate their own Third Party Loss Report 170 that reports a set of the losses they see, which are different from 171 ones reported in the Third Party Loss report they received. The 172 Third Party Loss Report does not have the retransmission request 173 [RFC4588] semantics. 175 When a receiver gets a Third Party Loss Report message, it MUST 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, TPLR may be 182 retransmitted. If the additional TPLR arrives at receiver, the 183 receiver SHOULD deal with the additional TPLR in the same way as 184 receiving the first TPLR for the same packet and no additional 185 behavior for receiver is required. 187 A receiver may have sent a Feedback message according to the RTP/AVPF 188 scheduling algorithm of RFC4585 [RFC4585] before receiving a Third 189 Party Loss Report message, but further feedback messages for those 190 sequence numbers SHOULD be suppressed for a period of time after 191 receiving the TPLR. Nodes that do not understand the Third Party 192 Loss Report message will ignore it, and might therefore still send 193 feedback according to the AVPF scheduling algorithm of RFC4585 194 [RFC4585]. The media source or intermediate nodes cannot be certain 195 that the use of a Third Party Loss Report message actually reduces 196 the amount of feedback it receives. 198 4. Format of RTCP Feedback Messages 200 This document registers two new RTCP Feedback messages for Third 201 Party Loss Report. Applications that are employing one or more loss- 202 repair methods MAY use the Third Party Loss Report together with 203 their existing loss-repair methods either for every packet they 204 expect to receive, or for an application-specific subset of the RTP 205 packets in a session. In other words, receivers MAY ignore Third 206 Party Loss Report messages, but SHOULD react to them unless they have 207 good reason to still send feedback messages despite having been 208 requested to suppress them. 210 4.1. Transport Layer Feedback: Third-party Loss Report 212 This Third Party Loss Report message is an extension to the RTCP 213 Transport Layer Feedback Report and identified by RTCP packet type 214 value PT=RTPFB and FMT=TBD. 216 Within the common packet header for feedback messages (as defined in 217 section 6.1 of RFC4585 [RFC4585]), the "SSRC of packet sender" field 218 indicates the source of the request, and the "SSRC of media source" 219 denotes the media sender of the flow for which the indicated losses 220 are being suppressed. 222 The FCI field MUST contain one or more entries of transport layer 223 third party loss Early Indication (TLLEI). Each entry applies to the 224 same media source identified by the SSRC contained in the SSRC of 225 media source field of Feedback header. The length of the TLLEI 226 feedback message MUST be set to 2+1*N, where N is the number of FCI 227 entries. 229 The Feedback Control Information (FCI) for TLLEI uses the similar 230 format of message Types defined in the section 6.2.1 of RFC4585 231 [RFC4585]. The format is shown in Figure 1. 233 0 1 2 3 234 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 1 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 | PID | BLP | 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 Figure 1: Syntax of an FCI Entry in the TLLEI Feedback Message 241 Packet ID (PID): 16 bits 243 The PID field is used to specify a lost packet. The PID field 244 refers to the RTP sequence number of the lost packet. 246 bitmask of lost packets (BLP): 16 bits 248 The BLP allows for reporting losses of any of the 16 RTP packets 249 immediately following the RTP packet indicated by the PID. The 250 BLP's definition is identical to that given in the section 6.2.1 251 of [RFC4585]. 253 4.2. Payload Specific Feedback: Third-party Loss Report 255 This message is an extension to the RTCP Payload Specific Feedback 256 report and identified by RTCP packet type value PT=PSFB and FMT=TBD, 257 which is used to suppress FIR [RFC5104] and PLI [RFC4585]. 259 Within the common packet header for feedback messages (as defined in 260 section 6.1 of RFC4585 [RFC4585]), the "SSRC of packet sender" field 261 indicates the source of the request, and the "SSRC of media source" 262 is not used and SHALL be set to 0. The SSRCs of the media senders to 263 which this message applies are in the corresponding FCI entries. 265 The Feedback Control Information (FCI) for a Payload Specific Third 266 Party Loss Early Indication (PSLEI) consists one or more FCI entries. 267 Each entry applies to a different media Source, identified by its 268 SSRC. the content of which is depicted in Figure 2. The length of 269 the PSLEI feedback message MUST be set to 2+1*N, where N is the 270 number of FCI entries. 272 The format is shown in Figure 2. 274 0 1 2 3 275 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 1 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | SSRC | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 280 Figure 2: Syntax of an FCI Entry in the PSLEI Feedback Message 282 Synchronization source (SSRC):32 bits 284 The SSRC value of the media source that is already aware, or in 285 the process of being made aware, that some receiver lost 286 synchronization with the media stream and for which the PSLEI 287 receiver's own response to any such error is suppressed. 289 5. SDP Signaling 291 The Session Description Protocol (SDP) [RFC4566] attribute, rtcp-fb, 292 is defined in the Section 4 of RFC4585 [RFC4585] and may be used to 293 negotiate the capability to handle specific AVPF commands and 294 indications. The ABNF for rtcp-fb is described in section 4.2 of 295 RFC4585 [RFC4585]. In this section, we extend the rtcp-fb attribute 296 to include the commands and indications that are described for third 297 party loss report in the present document. 299 In the ABNF [RFC5234] for rtcp-fb-val defined in RFC4585 [RFC4585], 300 the feedback type "nack", without parameters, indicates use of the 301 Generic NACK feedback format as defined in Section 6.2.1of RFC4585 302 [RFC4585]. In this document, we define two parameters that indicate 303 the third party loss supported for use with "nack", namely: 305 o "tllei" denotes support of transport layer third party loss early 306 indication. 308 o "pslei" denotes support of payload specific third party loss early 309 indication. 311 The ABNF for these two parameters for "nack" is defined here (please 312 refer to section 4.2 of RFC4585 [RFC4585] for complete ABNF syntax). 314 rtcp-fb-val =/ "nack" rtcp-fb-nack-param 315 rtcp-fb-nack-param = SP "tllei" 316 ;transport layer third party 317 ; loss early indication 318 / SP "pslei" 319 ;payload specific third party 320 ; loss early indication 321 / SP token [SP byte-string] 322 ; for future commands/indications 323 token = 324 byte-string = 326 Refer to Section 4.2 of RFC4585 [RFC4585] for a detailed description 327 and the full syntax of the "rtcp-fb" attribute. 329 6. Example Use Cases 331 The operation of feedback suppression is similar for all types of RTP 332 sessions and topologies [RFC5117], however the exact messages used 333 and the scenarios in which suppression is employed differ for various 334 use cases. The following sections outline some of the intended use 335 cases for using the Third Party Loss Report for feedback suppression 336 and give an overview of the particular mechanisms. 338 6.1. Source Specific Multicast (SSM) use case 340 In SSM RTP sessions as described in "RTP Control Protocol (RTCP) 341 Extensions for Single-Source Multicast Sessions with Unicast 342 Feedback" [RFC5760], one or more Media Sources send RTP packets to a 343 Distribution Source. The Distribution Source relays the RTP packets 344 to the receivers using a source- specific multicast group. 346 As outlined in the RFC5760 [RFC5760], there are two Unicast Feedback 347 models that may be used for reporting, the Simple Feedback model and 348 the Distribution Source Feedback Summary Model. In the simple 349 Feedback Model, there's no need for distribution source to create the 350 Third Party Loss Report, instead, NACKs are reflected by the 351 distribution source to the other Receivers. However in the 352 Distribution Source Feedback Summary model, the distribution source 353 will not redistribute the NACK for some reason(e.g., to prevent 354 revealing the identity or existence of a system sending NACK)and may 355 send a Third Party Loss Report to the systems that were unable to 356 receive the NACK, and won't receive the NACK via other means. The 357 Third Party Loss Report can be generated at the distribution source 358 when downstream loss is told (e.g., downstream loss report is 359 received), which indicates to the receivers that they should not 360 transmit feedback messages for the same loss event for a certain 361 time. Therefore the distribution source in the feedback summary 362 model can be reasonably certain that it will help the situation 363 (i.e., unable receive the NACK) by sending this Third Party Loss 364 Report message to all the relevant receivers impacted by the packet 365 loss. 367 6.2. Unicast based Rapid Acquisition of Multicast Stream (RAMS) use 368 case 370 The typical RAMS architecture [RFC6285] may have several Burst/ 371 Retransmission Sources(BRS) behind the multicast source (MS) placed 372 at the same level. These BRSes will receive the primary multicast 373 RTP stream from the media source and cache most recent packets after 374 joining multicast session. If packet loss happens at the upstream of 375 all the BRSs or the downstream of BRSes. One of the BRSes or all the 376 BRSes may send a NACK or TPLR message to the DS, where the SSRC in 377 this NACK or TPLR message is the BRS that is sending the message. 378 The DS forwards/reflects this message down on the primary SSM. The 379 details on how DS deal with this message is specified in 380 [RETRANSMISSION-FOR-SSM]. 382 6.3. RTP Transport Translator use case 384 A Transport Translator (Topo-Trn-Translator), as defined in RFC5117 385 [RFC5117] is typically forwarding the RTP and RTCP traffic between 386 RTP clients, for example converting from multicast to unicast for 387 domains that do not support multicast. The translator may suffer a 388 loss of important video packets. In this case, the translator may 389 forward TPLR message received from upstream in the same way as 390 forwarding other RTCP traffic. If the translator acting as the 391 monitor [MONARCH] is aware of packet loss, it may use the SSRC of 392 monitor as packet sender SSRC to create NACK message and send it to 393 the receivers that is not aware of packet loss. 395 6.4. Multipoint Control Unit (MCU) use case 397 When the speaker is changed in a voice-activated multipoint video 398 switching conference [RFC4587], an RTP mixer can be used to select 399 the available input streams and forward them to each participants. 400 If the MCU is doing a blind switch without waiting for a 401 synchronization point on the new stream it can send a FIR to the new 402 video source. In this case the MCU should send a FIR suppression 403 message to the new receivers. e.g., when the RTP Mixer starts to 404 receive FIR from some participants it can suppress the remaining 405 session participants from sending FIR by sending out a Third party 406 Loss report message. 408 6.5. Mixer use case 410 A Mixer, in accordance with RFC5117 [RFC5117], aggregates multiple 411 RTP streams from other session participants and generates a new RTP 412 stream sent to the session participants. In some cases, the video 413 frames may get badly screwed up between media source and the mixer. 414 In such case, the mixer need to check if the packet loss will result 415 in PLI or FIR transmissions from most of the group by analyzing the 416 received video. If so the mixer may initiate FIR or PLI towards the 417 media source on behalf of all the session participants and send out a 418 Third party Loss report message to these session participants that 419 may or are expected to send a PLI or FIR. Alternatively, when the 420 mixer starts to receive FIR or PLI from some participants and like to 421 suppress the remaining session participants from sending FIR or PLI 422 by forwarding the FIR/PLI from one session participant to others. 424 7. Security Considerations 426 The defined messages have certain properties that have security 427 implications. These must be addressed and taken into account by 428 users of this protocol. 430 Spoofed or maliciously created feedback messages of the type defined 431 in this specification can have the following implications: 433 Sending the spurious Third Party Loss Report (e.g., the Third Party 434 Loss Report with the wrong sequence number of lost packet) that 435 causes missing RTP packets to not be repaired in a timely fashion. 437 To prevent these attacks, there is a need to apply authentication and 438 integrity protection of the feedback messages. This can be 439 accomplished against threats external to the current RTP session 440 using the RTP profile that combines Secure RTP [RFC3711] and AVPF 441 into SAVPF [RFC5124]. 443 Note that intermediaries that are not visible at the RTP layer that 444 wish to send the Third Party Loss Reports on behalf of the media 445 source can only do so if they spoof the SSRC of the media source. 446 This is difficult in case SRTP is in use. If the intermediary is 447 visible at the RTP layer, this is not an issue, provided the 448 intermediary is part of the security context for the session. 450 Also note that endpoints that receive a Third Party Loss Report would 451 be well-advised to ignore it, unless the security is in place to 452 authenticate the sender of the Third Party Loss Report. Accepting 453 Third Party Loss Report from un-authenticated sender can lead to a 454 denial of service attack, where the endpoint accepts poor quality 455 media that could be repaired. 457 8. IANA Consideration 459 For use with "nack" [RFC4585], a joint sub-registry has been set up 460 that registers the following two values: 462 The value registration for the attribute value "nack": 464 Value name: tllei 465 Long name: Transport Layer Third Party Loss Early Indication 466 Usable with: nack 467 Reference: RFC 4585. 469 Value name: pslei 470 Long name: Payload Specific Third Party 471 Usable with: nack 472 Reference: RFC 4585. 474 The following value have been registered as one FMT value in the "FMT 475 Values for RTPFB Payload Types" registry located at the time of 476 publication at: http://www.iana.org/assignments/rtp-parameters 478 RTPFB range 479 Name Long Name Value Reference 480 -------------- --------------------------------- ----- --------- 481 TLLEI Transport Layer Third Party TBA1 [RFCXXXX] 482 Loss Early Indication 484 The following value have been registered as one FMT value in the "FMT 485 Values for PSFB Payload Types" registry located at the time of 486 publication at: http://www.iana.org/assignments/rtp-parameters 488 PSFB range 489 Name Long Name Value Reference 490 -------------- --------------------------------- ----- -------- 491 PSLEI Payload Specific Third Party TBA2 [RFCXXXX] 492 Loss Early Indication 494 9. Acknowledgement 496 The authors would like to thank David R Oran, Magnus Westerlund, 497 Colin Perkins, Ali C. Begen, Tom VAN CAENEGEM, Ingemar Johansson S, 498 Bill Ver Steeg, Jonathan Lennox, WeeSan Lee for their valuable 499 comments and suggestions on this document. 501 10. References 503 10.1. Normative References 505 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 506 Requirement Levels", 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 [RFC6285] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast- 530 Based Rapid Acquisition of Multicast RTP Sessions", 531 June 2011. 533 [MONARCH] Wu, Q., Hunt, G., and P. Arden, "Monitoring Architectures 534 for RTP", June 2011. 536 [RETRANSMISSION-FOR-SSM] 537 Caenegem, T., Steeg, B., and A. Begen, "Retransmission for 538 Source-Specific Multicast (SSM) Sessions", May 2011. 540 [RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, 541 January 2008. 543 [RFC4587] Even, R., "RTP Payload Format for H.261 Video Streams", 544 RFC 4587, August 2006. 546 [RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control 547 Protocol (RTCP) Extensions for Single-Source Multicast 548 Sessions with Unicast Feedback", RFC 5760, February 2010. 550 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for 551 Real-time Transport Control Protocol (RTCP)-Based Feedback 552 (RTP/SAVPF)", RFC 5124, February 2008. 554 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. 555 Norrman, "The Secure Real-time Transport Protocol (SRTP)", 556 RFC 3711, March 2004. 558 Appendix A. Change Log 560 Note to the RFC-Editor: please remove this section prior to 561 publication as an RFC. 563 A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 565 The following are the major changes compared to previous version: 567 o Remove the merge report from SSM use case and additional text to 568 address report merging issue. 570 o Revise section 3 and section 6 to address FEC packet dealing issue 571 and Leave how to repair packet loss beyond the scope. 573 o Modify the SSM use case and RAMS use case to focus on uses. 575 o Other Editorial changes. 577 A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 579 The following are the major changes compared to previous version: 581 o In Section 4.1, fix typo: change Section 4.3.1.1 of section 582 [RFC5104] to section 6.2.1 of [RFC4585]. 584 o In Section 3: Clarify how to deal with downstream loss using Third 585 party loss report and upstream loss using NACK. 587 o Update title and abstract to focus on third party loss report. 589 o In Section 6.1: Update this section to explain how third party 590 loss report is used to deal with downstream loss. 592 o In section 6.1.2: Update this section to explain how third party 593 loss report is used to deal with downstream loss. 595 o In section 6.2: Rephrase the text to discuss how BRS deal with the 596 third party loss report. 598 A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 600 The following are the major changes compared to previous version: 602 o In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix A. 604 o Update abstract to clarify when third-party loss reports should be 605 sent instead of NACKs. 607 o Update section 3 Paragraph 2 to differentiate when a third-party 608 loss report should be used compared to a NACK. 610 o Update section 3 Paragraph 3 to explain when media source to send 611 a third-party loss. 613 o Move specific rules for section 6.1.1 and section 6.1.2 to section 614 6.1 as generic rules and delete section 6.1.1. 616 A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 618 The following are the major changes compared to previous version: 619 o Reference Update. 621 o Clarify the use of the third party loss report in section 3 and 622 section 6.1.1. 624 A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 626 The following are the major changes compared to previous version: 627 o Remove 3rd and 4th paragraphs of section 6.1 and replaced them 628 with 2nd and 3rd paragraphs of section 3. 630 o Remove section 6.1.1.1. 632 o Revise the last paragraph of section 1 to clarify the rationale of 633 using new message. 635 o Update RTP transport translator case in section 6.3 to correct the 636 use of the third party loss report. 638 o Update MCU case in section 6.4 to correct the use of the third 639 party loss report. 641 o Revise SSM use case to address multiple DS issue. 643 o References Update. 645 o Move one rationale on preventing sending unicast NACK in 646 introduction section to SSM case section. 648 o Other Editorial changes to section 6.1, 6.1.1, 6.2. 650 A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 652 The following are the major changes compared to previous version: 654 o A few Editorial changes to the whole document. 656 A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 658 The following are the major changes compared to previous version: 660 o Restructuring the protocol overview section to clarify the round 661 trip 663 time calculation and receiver behavior to the additional TPLR. 665 o Restructuring the SSM use case section to focus on the use of 666 TPLR. 668 o Editorial changes to the abstract, introduction, message format, 669 use cases and IANA sections. 671 o References update 673 A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 675 The following are the major changes compared to previous version: 677 o Clarify which RTT is used and how timer is refreshed in the 678 section 3. 680 o Editorial changes to the Introduction, Protocol Overview, SDP 682 Signaling, Message Format, Use case,Security Consideration and 683 IANA sections. 685 o Remove Seq Nr field in the figure 2 for payload specific feedback. 687 o References reorganizing. 689 A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 691 The following are the major changes compared to previous version: 693 o Clarify to suppression interval with regard to how long to receive 694 the 695 retransmitted packet. Treating TPLR in the same way as receiving 696 NACK. 698 o Replace timer based approach with timeless based 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. 707 o Associate SDP parameters tllei and pslei with "nack". 709 o Remove the packet loss recovery from TPLR loss handling part. 711 o Other typo fixed. 713 A.11. draft-ietf-avtcore-feedback-suppression-rtp-11 715 The following are the major changes compared to previous version: 717 o Additional Editorial changes. 719 A.12. draft-ietf-avtcore-feedback-suppression-rtp-12 721 The following are the major changes compared to previous version: 723 o Additional Editorial changes. 725 A.13. draft-ietf-avtcore-feedback-suppression-rtp-13 727 The following are the major changes compared to previous version: 729 o Additional Editorial changes. 731 Authors' Addresses 733 Qin Wu 734 Huawei 735 101 Software Avenue, Yuhua District 736 Nanjing, Jiangsu 210012 737 China 739 Email: sunseawq@huawei.com 740 Frank Xia 741 Huawei 742 1700 Alma Dr. Suite 500 743 Plano, TX 75075 744 USA 746 Phone: +1 972-509-5599 747 Email: xiayangsong@huawei.com 749 Roni Even 750 Huawei 751 14 David Hamelech 752 Tel Aviv 64953 753 Israel 755 Email: even.roni@huawei.com