idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12.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 (April 12, 2013) is 4033 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 538, but not defined == Unused Reference: 'RFC6709' is defined on line 448, but no explicit reference was found in the text ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-11 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Audio/Video Transport Working Group A. Clark 3 Internet-Draft Telchemy 4 Intended status: Standards Track R. Huang 5 Expires: October 14, 2013 Q. Wu, Ed. 6 Huawei 7 April 12, 2013 9 RTP Control Protocol(RTCP) Extended Report (XR) Block for Burst/Gap 10 Discard metric Reporting 11 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12.txt 13 Abstract 15 This document defines an RTP Control Protocol(RTCP) Extended Report 16 (XR) Block that allows the reporting of Burst and Gap Discard metrics 17 for use in a range of RTP applications. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on October 14, 2013. 36 Copyright Notice 38 Copyright (c) 2013 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 1.1. Burst and Gap Discard Report Block . . . . . . . . . . . . 3 55 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 56 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 57 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 60 3. Burst/Gap Discard Block . . . . . . . . . . . . . . . . . . . 6 61 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 62 3.2. Definition of Fields in Burst/Gap Discard Report Block . . 6 63 3.3. Derived metrics based on reported metrics . . . . . . . . 8 64 4. Considerations for Voice-over-IP applications . . . . . . . . 10 65 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11 66 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 11 67 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 11 68 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 69 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 12 70 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 12 71 6.3. Contact information for registrations . . . . . . . . . . 12 72 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 73 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14 74 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 75 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 76 10.1. Normative References . . . . . . . . . . . . . . . . . . . 16 77 10.2. Informative References . . . . . . . . . . . . . . . . . . 16 78 Appendix A. Metrics represented using RFC6390 Template . . . . . 17 79 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 20 80 B.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12 . . . . . 20 81 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11 . . . . . 20 82 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 . . . . . 20 83 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 . . . . . 20 84 B.5. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 . . . . . 20 85 B.6. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 . . . . . 20 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 88 1. Introduction 90 1.1. Burst and Gap Discard Report Block 92 This document defines a new block type to augment those defined in 93 [RFC3611] for use in a range of RTP applications. The new block type 94 supports the reporting of the proportion of packets discarded by the 95 receiver due to jitter. The discards during discard bursts are 96 reported, together with the number of bursts. This block is intended 97 to be used in conjunction with [DISCARD] which provides the total 98 packets discarded, and on which this block therefore depends. 99 However the metric in [DISCARD] may be used independently of the 100 metrics in this block. 102 This block provides information on transient IP problems. Burst/Gap 103 metrics are typically used in Cumulative reports, however they also 104 MAY be used in Interval reports. The burstiness of packet discard 105 affects user experience, may influence any sender strategies to 106 mitigate the problem, and may also have diagnostic value. 108 The metric belongs to the class of transport-related end system 109 metrics defined in [RFC6792]. 111 The definitions of Burst, Gap, Loss and Discard are consistent with 112 definitions in [RFC3611]. To accommodate the range of jitter buffer 113 algorithms and packet discard logic that may be used by implementors, 114 the method used to distinguish between bursts and gaps may be an 115 equivalent method to that defined in[RFC3611]. 117 1.2. RTCP and RTCP XR Reports 119 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 120 defined an extensible structure for reporting using an RTCP Extended 121 Report (XR). This document defines a new Extended Report block for 122 use with [RFC3550] and [RFC3611]. 124 1.3. Performance Metrics Framework 126 The Performance Metrics Framework [RFC6390] provides guidance on the 127 definition and specification of performance metrics. The RTP 128 Monitoring Architectures [RFC6792] provides guideline for reporting 129 block format using RTCP XR. The Metrics Block described in this 130 document are in accordance with the guidelines in [RFC6390] and 131 [RFC6792]. 133 1.4. Applicability 135 These metrics are applicable to a range of RTP applications which 136 contain jitter buffers and don't use stream repair means, e.g., 137 Forward Error Correction (FEC) [RFC5109] and/or retransmission 138 [RFC4588]. 140 2. Terminology 142 2.1. Standards Language 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in RFC 2119 [RFC2119]. 148 In addition, the following terms are defined: 150 Received, Lost and Discarded 152 A packet shall be regarded as lost if it fails to arrive within an 153 implementation-specific time window. A packet that arrives within 154 this time window but is too early or late to be played out or 155 thrown away before playout due to packet duplication or redundancy 156 shall be regarded as discarded. A packet shall be classified as 157 one of received (or OK), discarded or lost. The metric 158 "cumulative number of packets lost" defined in [RFC3550] reports a 159 count of packets lost from the media stream (single SSRC within 160 single RTP session). Similarly the metric "number of packets 161 discarded" defined in [DISCARD] reports a count of packets 162 discarded from the media stream (single SSRC within single RTP 163 session) arriving at the receiver. Another metric defined in 164 [RFC5725] is available to report on packets which are not 165 recovered by any repair techniques which may be in use. 167 Bursts and Gaps 169 The terms Burst and Gap are used in a manner consistent with that 170 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 171 into bursts, which are periods during which the discard rate is 172 high enough to cause noticeable quality degradation (generally 173 over 5 percent discard rate), and gaps, which are periods during 174 which discarded packets are infrequent and hence quality is 175 generally acceptable. 177 3. Burst/Gap Discard Block 179 Metrics in this block report on Burst/Gap Discard in the stream 180 arriving at the RTP system. The measurement of these metrics are 181 made at the receiving end of the RTP stream. Instances of this 182 Metrics Block refer by Synchronization source (SSRC) to the separate 183 auxiliary Measurement Information block [RFC6776] which describes 184 measurement periods in use (see RFC6776 section 4.2). 186 This Metrics Block relies on the measurement period in the 187 Measurement Information block indicating the span of the report. 188 Senders MUST send this block in the same compound RTCP packet as the 189 measurement information block. Receivers MUST verify that the 190 measurement period is received in the same compound RTCP packet as 191 this Metrics Block. If not, this Metrics Block MUST be discarded. 193 3.1. Report Block Structure 195 Burst/Gap Discard metrics block 197 0 1 2 3 198 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 1 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | BT=NBGD | I | resv. | block length = 3 | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | SSRC of Source | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Threshold | Packets Discarded in Bursts | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | Total Packets expected in bursts | Reserved. | 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 Figure 1: Report Block Structure 211 3.2. Definition of Fields in Burst/Gap Discard Report Block 213 Block type (BT): 8 bits 215 A Burst/Gap Discard Report Block is identified by the constant 216 NBGD. 218 [Note to RFC Editor: please replace NBGD with the IANA provided 219 RTCP XR block type for this block.] 221 Interval Metric flag (I): 2 bits 223 This field is used to indicate whether the Burst/Gap Discard 224 metrics are Sampled, Interval or Cumulative metrics: 226 I=10: Interval Duration - the reported value applies to the 227 most recent measurement interval duration between successive 228 metrics reports. 230 I=11: Cumulative Duration - the reported value applies to the 231 accumulation period characteristic of cumulative measurements. 233 I=01: Sampled Value - the reported value is a sampled 234 instantaneous value. 236 In this document, Burst/Gap Discard Metrics can only be measured 237 over definite intervals, and cannot be sampled. Also, the value 238 I=00 is reserved for future use. Senders MUST NOT use the values 239 I=00 or I=01. If a block is received with I=00 or I=01, the 240 receiver MUST discard the block. 242 Reserved (resv): 6 bits 244 These bits are reserved. They MUST be set to zero by senders and 245 ignored by receivers (See RFC6709 section 4.2). 247 block length: 16 bits 249 The length of this report block in 32-bit words, minus one. For 250 the Burst/Gap discard block, the block length is equal to 3. The 251 block MUST be discarded if the block length is set to a different 252 value. 254 SSRC of source: 32 bits 256 As defined in Section 4.1 of [RFC3611]. 258 Threshold: 8 bits 260 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 261 of successive packets that must not be discarded prior to and 262 following a discard packet in order for this discarded packet to 263 be regarded as part of a gap. 265 Packets discarded in bursts: 24 bits 267 The total number of packets discarded during discard bursts. 269 The measured value is unsigned value. If the measured value 270 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 271 an over-range measurement. If the measurement is unavailable, the 272 value 0xFFFFFF MUST be reported. 274 Total packets expected in bursts: 24 bits 276 The total number of packets expected during discarded bursts (that 277 is, the sum of received packets and lost packets). 279 The measured value is unsigned value. If the measured value 280 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 281 an over-range measurement. If the measurement is unavailable, the 282 value 0xFFFFFF MUST be reported. 284 Reserved (resv): 8 bits 286 These bits are reserved. They MUST be set to zero by senders and 287 ignored by receivers (See RFC6709 section 4.2). 289 3.3. Derived metrics based on reported metrics 291 The metrics described here are intended to be used in conjunction 292 with information from the Measurement Information block [RFC6776] and 293 also with the metric "number of packets discarded" provided in the 294 RTCP XR Discard Count Block [DISCARD]. The RTCP XR Discard Count 295 Block should be sent if the Burst/Gap Discard block is sent, but the 296 converse does not apply. 298 These metrics provide the following information relevant to 299 statistical parameters, including: 301 o The fraction of packets discarded during bursts (burst discard 302 rate in [SUMSTAT]), which can be calculated using the metric " 303 Packets Discarded in Bursts " and the metric " Total Packets 304 expected in Bursts " provided in the Burst/Gap Discard metrics 305 block. 307 o The fraction of packets discarded during gaps (gap discard rate in 308 [SUMSTAT]), which can be calculated using the metric " Packets 309 Discarded in Bursts " and the metric " Total Packets expected in 310 Bursts " provided in the Burst/Gap Discard metrics block. 312 The details on calculation these parameters in the metrics are 313 described in [SUMSTAT]. 315 4. Considerations for Voice-over-IP applications 317 This Metrics Block is applicable to a broad range of RTP 318 applications. Where the metric is used with a Voice-overIP (VoIP) 319 application and the stream repair means is not available, the 320 following considerations apply. 322 RTCP XR views a call as being divided into bursts, which are periods 323 during which the discard rate is high enough to cause noticeable call 324 quality degradation (generally over 5 percent discard rate), and 325 gaps, which are periods during which discarded packets are infrequent 326 and hence call quality is generally acceptable. 328 If Voice Activity Detection is used the Burst and Gap Duration shall 329 be determined as if silence packets had been sent, i.e. a period of 330 silence in excess of Gmin packets must terminate a burst condition. 332 The recommended value for the threshold Gmin in [RFC3611] results in 333 a Burst being a period of time during which the call quality is 334 degraded to a similar extent to a typical Pulse-Code Modulation(PCM) 335 Severely Errored Second. 337 5. SDP Signaling 339 [RFC3611] defines the use of SDP (Session Description Protocol) 340 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 341 without prior signaling. 343 5.1. SDP rtcp-xr-attrib Attribute Extension 345 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 346 in [RFC3611] by providing an additional value of "xr-format" to 347 signal the use of the report block defined in this document. 349 xr-format =/ xr-bgd-block 351 xr-bgd-block = "burst-gap-discard" 353 5.2. Offer/Answer Usage 355 When SDP is used in offer-answer context, the SDP Offer/Answer usage 356 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 357 applies. For detailed usage in Offer/Answer for unilateral 358 parameter, refer to section 5.2 of [RFC3611]. 360 6. IANA Considerations 362 New block types for RTCP XR are subject to IANA registration. For 363 general guidelines on IANA considerations for RTCP XR, refer to 364 [RFC3611]. 366 6.1. New RTCP XR Block Type value 368 This document assigns the block type value NBGD in the IANA " RTP 369 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 370 the "Burst/Gap Discard Metrics Block". 372 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 373 XR block type for this block.] 375 6.2. New RTCP XR SDP Parameter 377 This document also registers a new parameter "burst-gap-discard" in 378 the "RTP Control Protocol Extended Reports (RTCP XR) Session 379 Description Protocol (SDP) Parameters Registry". 381 6.3. Contact information for registrations 383 The contact information for the registrations is: 385 Qin Wu (sunseawq@huawei.com) 387 101 Software Avenue, Yuhua District 388 Nanjing, Jiangsu 210012 389 China 391 7. Security Considerations 393 It is believed that this proposed RTCP XR report block introduces no 394 new security considerations beyond those described in [RFC3611]. 395 This block does not provide per-packet statistics so the risk to 396 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 397 does not apply. 399 8. Contributors 401 Geoff Hunt wrote the initial draft of this document. 403 9. Acknowledgments 405 The authors gratefully acknowledge reviews and feedback provided by 406 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 407 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 408 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 409 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 410 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Paul 411 Kyzivat,Claire Bi and Dan Romascanu. 413 10. References 415 10.1. Normative References 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", March 1997. 420 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 421 Applications", RFC 3550, July 2003. 423 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 424 Protocol Extended Reports (RTCP XR)", November 2003. 426 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 427 Description Protocol", July 2006. 429 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 430 Report Block Type for RTP Control Protocol (RTCP) Extended 431 Reports (XRs)", RFC 5725, February 2020. 433 10.2. Informative References 435 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard Count metric 436 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-11, 437 December 2012. 439 [RFC4588] Rey, J., Leon, D., , A., Varsa, V., and R. Hakenberg, "RTP 440 Retransmission Payload Format", RFC 4588, July 2006. 442 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 443 Correction", RFC 5109, December 2007. 445 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 446 Development", RFC 6390, October 2011. 448 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 449 Considerations for Protocol Extensions", RFC 6709, 450 September 2012. 452 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 453 using SDES item and XR Block", RFC 6776, October 2012. 455 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 456 November 2012. 458 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 459 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-11, 460 March 2013. 462 Appendix A. Metrics represented using RFC6390 Template 464 RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC 465 number, when assigned. 467 a. Threshold Metric 469 * Metric Name: Threshold in RTP 471 * Metric Description: The Threshold is equivalent to Gmin in 472 [RFC3611], i.e. the number of successive packets that must not 473 be discarded prior to and following a discard packet in order 474 for this discarded packet to be regarded as part of a gap. 476 * Method of Measurement or Calculation: See section 3.2, 477 Threshold definition [RFCXXXX]. 479 * Units of Measurement: See section 3.2, Threshold definition 480 [RFCXXXX]. 482 * Measurement Point(s) with Potential Measurement Domain: See 483 section 3, 1st paragraph [RFCXXXX]. 485 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 486 measurement timing and section 3.2 [RFCXXXX] for Interval 487 Metric flag. 489 * Use and applications: See section 1.4 [RFCXXXX]. 491 * Reporting model: See RFC3611. 493 b. Packets discarded in bursts Metric 495 * Metric Name: RTP Packets discarded in bursts 497 * Metric Description: The total number of RTP packets discarded 498 during discard bursts. 500 * Method of Measurement or Calculation: See section 3.2, Packets 501 discarded in bursts definition [RFCXXXX]. 503 * Units of Measurement: See section 3.2, Packets discarded in 504 bursts definition [RFCXXXX]. 506 * Measurement Point(s) with Potential Measurement Domain: See 507 section 3, 1st paragraph [RFCXXXX]. 509 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 510 measurement timing and section 3.2 [RFCXXXX] for Interval 511 Metric flag. 513 * Use and applications: See section 1.4 [RFCXXXX]. 515 * Reporting model: See RFC3611. 517 c. Total packets expected in bursts Metric 519 * Metric Name: Total RTP packets expected in bursts 521 * Metric Description: The total number of packets expected 522 during discarded bursts (that is, the sum of received packets 523 and lost packets). 525 * Method of Measurement or Calculation: See section 3.2, Total 526 packets expected in bursts definition [RFCXXXX]. 528 * Units of Measurement: See section 3.2, Total packets expected 529 in bursts definition [RFCXXXX]. 531 * Measurement Point(s) with Potential Measurement Domain: See 532 section 3, 1st paragraph [RFCXXXX]. 534 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 535 measurement timing and section 3.2 [RFCXXXX] for Interval 536 Metric flag. 538 * Use and applications: See section 1.4 [RFCXXXX]. 540 * Reporting model: See RFC3611. 542 Appendix B. Change Log 544 Note to the RFC-Editor: please remove this section prior to 545 publication as an RFC. 547 B.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12 549 The following are the major changes compared to previous version: 551 o Similar changes to Burst Gap loss draft to get in line with Burst 552 Gap Loss draft. 554 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11 556 The following are the major changes compared to previous version: 558 o Similar changes to Burst Gap loss draft to address IESG review 559 comments apply to this document. 561 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 563 The following are the major changes compared to previous version: 565 o Move RFC6709 as one informative reference. 567 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 569 The following are the major changes compared to previous version: 571 o Editorial changes based on comments received in WGLC. 573 B.5. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 575 The following are the major changes compared to previous version: 577 o SDP update based on SDP Directorate Review. 579 o Add some texts to get consistent with RFC6798 and Delay draft. 581 B.6. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 583 The following are the major changes compared to previous version: 585 o Outdated reference update. 587 o Editorial changes based on comments that applied to PDV and Delay 588 drafts. 590 Authors' Addresses 592 Alan Clark 593 Telchemy Incorporated 594 2905 Premiere Parkway, Suite 280 595 Duluth, GA 30097 596 USA 598 Email: alan.d.clark@telchemy.com 600 Rachel Huang 601 Huawei Technologies Co., Ltd. 602 101 Software Avenue, Yuhua District 603 Nanjing, Jiangsu 210012 604 China 606 Email: Rachel@huawei.com 608 Qin Wu (editor) 609 Huawei 610 101 Software Avenue, Yuhua District 611 Nanjing, Jiangsu 210012 612 China 614 Email: sunseawq@huawei.com