idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-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 (April 15, 2013) is 4028 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 536, but not defined == Unused Reference: 'RFC6709' is defined on line 446, but no explicit reference was found in the text ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-11 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 17, 2013 Q. Wu, Ed. 6 Huawei 7 April 15, 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-13.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 17, 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-13 . . . . . 20 81 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12 . . . . . 20 82 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11 . . . . . 20 83 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 . . . . . 20 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 86 1. Introduction 88 1.1. Burst and Gap Discard Report Block 90 This document defines a new block type to augment those defined in 91 [RFC3611] for use in a range of RTP applications. The new block type 92 supports the reporting of the proportion of packets discarded by the 93 receiver due to jitter. The discards during discard bursts are 94 reported, together with the number of bursts. This block is intended 95 to be used in conjunction with [DISCARD] which provides the total 96 packets discarded, and on which this block therefore depends. 97 However the metric in [DISCARD] may be used independently of the 98 metrics in this block. 100 This block provides information on transient IP problems. Burst/Gap 101 metrics are typically used in Cumulative reports, however they also 102 may be used in Interval reports. The burstiness of packet discard 103 affects user experience, may influence any sender strategies to 104 mitigate the problem, and may also have diagnostic value. 106 The metric belongs to the class of transport-related end system 107 metrics defined in [RFC6792]. 109 The definitions of Burst, Gap, Loss and Discard are consistent with 110 definitions in [RFC3611]. To accommodate the range of jitter buffer 111 algorithms and packet discard logic that may be used by implementors, 112 the method used to distinguish between bursts and gaps may be an 113 equivalent method to that defined in[RFC3611]. 115 1.2. RTCP and RTCP XR Reports 117 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 118 defined an extensible structure for reporting using an RTCP Extended 119 Report (XR). This document defines a new Extended Report block for 120 use with [RFC3550] and [RFC3611]. 122 1.3. Performance Metrics Framework 124 The Performance Metrics Framework [RFC6390] provides guidance on the 125 definition and specification of performance metrics. The RTP 126 Monitoring Architectures [RFC6792] provides guideline for reporting 127 block format using RTCP XR. The Metrics Block described in this 128 document are in accordance with the guidelines in [RFC6390] and 129 [RFC6792]. 131 1.4. Applicability 133 These metrics are applicable to a range of RTP applications which 134 contain jitter buffers and don't use stream repair means, e.g., 135 Forward Error Correction (FEC) [RFC5109] and/or retransmission 136 [RFC4588]. 138 2. Terminology 140 2.1. Standards Language 142 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 143 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 144 document are to be interpreted as described in RFC 2119 [RFC2119]. 146 In addition, the following terms are defined: 148 Received, Lost and Discarded 150 A packet shall be regarded as lost if it fails to arrive within an 151 implementation-specific time window. A packet that arrives within 152 this time window but is too early or late to be played out or 153 thrown away before playout due to packet duplication or redundancy 154 shall be regarded as discarded. A packet shall be classified as 155 one of received (or OK), discarded or lost. The metric 156 "cumulative number of packets lost" defined in [RFC3550] reports a 157 count of packets lost from the media stream (single SSRC within 158 single RTP session). Similarly the metric "number of packets 159 discarded" defined in [DISCARD] reports a count of packets 160 discarded from the media stream (single SSRC within single RTP 161 session) arriving at the receiver. Another metric defined in 162 [RFC5725] is available to report on packets which are not 163 recovered by any repair techniques which may be in use. 165 Bursts and Gaps 167 The terms Burst and Gap are used in a manner consistent with that 168 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 169 into bursts, which are periods during which the discard rate is 170 high enough to cause noticeable quality degradation (generally 171 over 5 percent discard rate), and gaps, which are periods during 172 which discarded packets are infrequent and hence quality is 173 generally acceptable. 175 3. Burst/Gap Discard Block 177 Metrics in this block report on Burst/Gap Discard in the stream 178 arriving at the RTP system. The measurement of these metrics are 179 made at the receiving end of the RTP stream. Instances of this 180 Metrics Block refer by Synchronization source (SSRC) to the separate 181 auxiliary Measurement Information block [RFC6776] which describes 182 measurement periods in use (see RFC6776 section 4.2). 184 This Metrics Block relies on the measurement period in the 185 Measurement Information block indicating the span of the report. 186 Senders MUST send this block in the same compound RTCP packet as the 187 measurement information block. Receivers MUST verify that the 188 measurement period is received in the same compound RTCP packet as 189 this Metrics Block. If not, this Metrics Block MUST be discarded. 191 3.1. Report Block Structure 193 Burst/Gap Discard metrics block 195 0 1 2 3 196 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 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | BT=NBGD | I | resv. | block length = 3 | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | SSRC of Source | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | Threshold | Packets Discarded in Bursts | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Total Packets expected in bursts | Reserved. | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 Figure 1: Report Block Structure 209 3.2. Definition of Fields in Burst/Gap Discard Report Block 211 Block type (BT): 8 bits 213 A Burst/Gap Discard Report Block is identified by the constant 214 NBGD. 216 [Note to RFC Editor: please replace NBGD with the IANA provided 217 RTCP XR block type for this block.] 219 Interval Metric flag (I): 2 bits 221 This field is used to indicate whether the Burst/Gap Discard 222 metrics are Sampled, Interval or Cumulative metrics: 224 I=10: Interval Duration - the reported value applies to the 225 most recent measurement interval duration between successive 226 metrics reports. 228 I=11: Cumulative Duration - the reported value applies to the 229 accumulation period characteristic of cumulative measurements. 231 I=01: Sampled Value - the reported value is a sampled 232 instantaneous value. 234 In this document, Burst/Gap Discard Metrics can only be measured 235 over definite intervals, and cannot be sampled. Also, the value 236 I=00 is reserved for future use. Senders MUST NOT use the values 237 I=00 or I=01. If a block is received with I=00 or I=01, the 238 receiver MUST discard the block. 240 Reserved (resv): 6 bits 242 These bits are reserved. They MUST be set to zero by senders and 243 ignored by receivers (See RFC6709 section 4.2). 245 block length: 16 bits 247 The length of this report block in 32-bit words, minus one. For 248 the Burst/Gap discard block, the block length is equal to 3. The 249 block MUST be discarded if the block length is set to a different 250 value. 252 SSRC of source: 32 bits 254 As defined in Section 4.1 of [RFC3611]. 256 Threshold: 8 bits 258 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 259 of successive packets that must not be discarded prior to and 260 following a discard packet in order for this discarded packet to 261 be regarded as part of a gap. Note that the threshold is 262 calculated in accordance with Gmin Calculation defined in section 263 4.7.2 of RFC3611. 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]. 296 These metrics provide the following information relevant to 297 statistical parameters, including: 299 o The fraction of packets discarded during bursts (burst discard 300 rate in [SUMSTAT]), which can be calculated using the metric " 301 Packets Discarded in Bursts " and the metric " Total Packets 302 expected in Bursts " provided in the Burst/Gap Discard metrics 303 block. 305 o The fraction of packets discarded during gaps (gap discard rate in 306 [SUMSTAT]), which can be calculated using the metric " Packets 307 Discarded in Bursts " and the metric " Total Packets expected in 308 Bursts " provided in the Burst/Gap Discard metrics block. 310 The details on calculation these parameters in the metrics are 311 described in [SUMSTAT]. 313 4. Considerations for Voice-over-IP applications 315 This Metrics Block is applicable to a broad range of RTP 316 applications. Where the metric is used with a Voice-overIP (VoIP) 317 application and the stream repair means is not available, the 318 following considerations apply. 320 RTCP XR views a call as being divided into bursts, which are periods 321 during which the discard rate is high enough to cause noticeable call 322 quality degradation (generally over 5 percent discard rate), and 323 gaps, which are periods during which discarded packets are infrequent 324 and hence call quality is generally acceptable. 326 If Voice Activity Detection is used, the Burst and Gap Duration shall 327 be determined as if silence packets had been sent, i.e. a period of 328 silence in excess of Gmin packets will terminate a burst condition. 330 The recommended value for the threshold Gmin in [RFC3611] results in 331 a Burst being a period of time during which the call quality is 332 degraded to a similar extent to a typical Pulse-Code Modulation(PCM) 333 Severely Errored Second. 335 5. SDP Signaling 337 [RFC3611] defines the use of SDP (Session Description Protocol) 338 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 339 without prior signaling. 341 5.1. SDP rtcp-xr-attrib Attribute Extension 343 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 344 in [RFC3611] by providing an additional value of "xr-format" to 345 signal the use of the report block defined in this document. 347 xr-format =/ xr-bgd-block 349 xr-bgd-block = "burst-gap-discard" 351 5.2. Offer/Answer Usage 353 When SDP is used in offer-answer context, the SDP Offer/Answer usage 354 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 355 applies. For detailed usage in Offer/Answer for unilateral 356 parameter, refer to section 5.2 of [RFC3611]. 358 6. IANA Considerations 360 New block types for RTCP XR are subject to IANA registration. For 361 general guidelines on IANA considerations for RTCP XR, refer to 362 [RFC3611]. 364 6.1. New RTCP XR Block Type value 366 This document assigns the block type value NBGD in the IANA " RTP 367 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 368 the "Burst/Gap Discard Metrics Block". 370 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 371 XR block type for this block.] 373 6.2. New RTCP XR SDP Parameter 375 This document also registers a new parameter "burst-gap-discard" in 376 the "RTP Control Protocol Extended Reports (RTCP XR) Session 377 Description Protocol (SDP) Parameters Registry". 379 6.3. Contact information for registrations 381 The contact information for the registrations is: 383 Qin Wu (sunseawq@huawei.com) 385 101 Software Avenue, Yuhua District 386 Nanjing, Jiangsu 210012 387 China 389 7. Security Considerations 391 It is believed that this proposed RTCP XR report block introduces no 392 new security considerations beyond those described in [RFC3611]. 393 This block does not provide per-packet statistics so the risk to 394 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 395 does not apply. 397 8. Contributors 399 Geoff Hunt wrote the initial draft of this document. 401 9. Acknowledgments 403 The authors gratefully acknowledge reviews and feedback provided by 404 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 405 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 406 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 407 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 408 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Paul 409 Kyzivat,Claire Bi and Dan Romascanu. 411 10. References 413 10.1. Normative References 415 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 416 Requirement Levels", March 1997. 418 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 419 Applications", RFC 3550, July 2003. 421 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 422 Protocol Extended Reports (RTCP XR)", November 2003. 424 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 425 Description Protocol", July 2006. 427 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 428 Report Block Type for RTP Control Protocol (RTCP) Extended 429 Reports (XRs)", RFC 5725, February 2020. 431 10.2. Informative References 433 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard Count metric 434 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-11, 435 December 2012. 437 [RFC4588] Rey, J., Leon, D., , A., Varsa, V., and R. Hakenberg, "RTP 438 Retransmission Payload Format", RFC 4588, July 2006. 440 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 441 Correction", RFC 5109, December 2007. 443 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 444 Development", RFC 6390, October 2011. 446 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 447 Considerations for Protocol Extensions", RFC 6709, 448 September 2012. 450 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 451 using SDES item and XR Block", RFC 6776, October 2012. 453 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 454 November 2012. 456 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 457 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-11, 458 March 2013. 460 Appendix A. Metrics represented using RFC6390 Template 462 RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC 463 number, when assigned. 465 a. Threshold Metric 467 * Metric Name: Threshold in RTP 469 * Metric Description: The Threshold is equivalent to Gmin in 470 [RFC3611], i.e. the number of successive packets that must not 471 be discarded prior to and following a discard packet in order 472 for this discarded packet to be regarded as part of a gap. 474 * Method of Measurement or Calculation: See section 3.2, 475 Threshold definition [RFCXXXX]. 477 * Units of Measurement: See section 3.2, Threshold definition 478 [RFCXXXX]. 480 * Measurement Point(s) with Potential Measurement Domain: See 481 section 3, 1st paragraph [RFCXXXX]. 483 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 484 measurement timing and section 3.2 [RFCXXXX] for Interval 485 Metric flag. 487 * Use and applications: See section 1.4 [RFCXXXX]. 489 * Reporting model: See RFC3611. 491 b. Packets discarded in bursts Metric 493 * Metric Name: RTP Packets discarded in bursts 495 * Metric Description: The total number of RTP packets discarded 496 during discard bursts. 498 * Method of Measurement or Calculation: See section 3.2, Packets 499 discarded in bursts definition [RFCXXXX]. 501 * Units of Measurement: See section 3.2, Packets discarded in 502 bursts definition [RFCXXXX]. 504 * Measurement Point(s) with Potential Measurement Domain: See 505 section 3, 1st paragraph [RFCXXXX]. 507 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 508 measurement timing and section 3.2 [RFCXXXX] for Interval 509 Metric flag. 511 * Use and applications: See section 1.4 [RFCXXXX]. 513 * Reporting model: See RFC3611. 515 c. Total packets expected in bursts Metric 517 * Metric Name: Total RTP packets expected in bursts 519 * Metric Description: The total number of packets expected 520 during discarded bursts (that is, the sum of received packets 521 and lost packets). 523 * Method of Measurement or Calculation: See section 3.2, Total 524 packets expected in bursts definition [RFCXXXX]. 526 * Units of Measurement: See section 3.2, Total packets expected 527 in bursts definition [RFCXXXX]. 529 * Measurement Point(s) with Potential Measurement Domain: See 530 section 3, 1st paragraph [RFCXXXX]. 532 * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for 533 measurement timing and section 3.2 [RFCXXXX] for Interval 534 Metric flag. 536 * Use and applications: See section 1.4 [RFCXXXX]. 538 * Reporting model: See RFC3611. 540 Appendix B. Change Log 542 Note to the RFC-Editor: please remove this section prior to 543 publication as an RFC. 545 B.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-13 547 The following are the major changes compared to previous version: 549 o Additional editorial changes to Burst Gap discard draft to get in 550 line with Burst Gap Loss draft. 552 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-12 554 The following are the major changes compared to previous version: 556 o Similar changes to Burst Gap loss draft to get in line with Burst 557 Gap Loss draft. 559 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11 561 The following are the major changes compared to previous version: 563 o Similar changes to Burst Gap loss draft to address IESG review 564 comments apply to this document. 566 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 568 The following are the major changes compared to previous version: 570 o Move RFC6709 as one informative reference. 572 Authors' Addresses 574 Alan Clark 575 Telchemy Incorporated 576 2905 Premiere Parkway, Suite 280 577 Duluth, GA 30097 578 USA 580 Email: alan.d.clark@telchemy.com 582 Rachel Huang 583 Huawei Technologies Co., Ltd. 584 101 Software Avenue, Yuhua District 585 Nanjing, Jiangsu 210012 586 China 588 Email: Rachel@huawei.com 590 Qin Wu (editor) 591 Huawei 592 101 Software Avenue, Yuhua District 593 Nanjing, Jiangsu 210012 594 China 596 Email: sunseawq@huawei.com