idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11.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 11, 2013) is 4025 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 537, but not defined == Unused Reference: 'RFC6709' is defined on line 447, but no explicit reference was found in the text ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-11 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 13, 2013 Q. Wu, Ed. 6 Huawei 7 April 11, 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-11.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 13, 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-11 . . . . . 20 81 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 . . . . . 20 82 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 . . . . . 20 83 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 . . . . . 20 84 B.5. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 . . . . . 20 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 87 1. Introduction 89 1.1. Burst and Gap Discard Report Block 91 This document defines a new block type to augment those defined in 92 [RFC3611] for use in a range of RTP applications. The new block type 93 supports the reporting of the proportion of packets discarded by the 94 receiver due to jitter. The discards during discard bursts are 95 reported, together with the number of bursts. This block is intended 96 to be used in conjunction with [DISCARD] which provides the total 97 packets discarded, and on which this block therefore depends. 98 However the metric in [DISCARD] may be used independently of the 99 metrics in this block. 101 This block provides information on transient IP problems. Burst/Gap 102 metrics are typically used in Cumulative reports, however they also 103 MAY be used in Interval reports. The burstiness of packet discard 104 affects user experience, may influence any sender strategies to 105 mitigate the problem, and may also have diagnostic value. 107 The metric belongs to the class of transport-related end system 108 metrics defined in [RFC6792]. 110 The definitions of Burst, Gap, Loss and Discard are consistent with 111 definitions in [RFC3611]. To accommodate the range of jitter buffer 112 algorithms and packet discard logic that may be used by implementors, 113 the method used to distinguish between bursts and gaps may be an 114 equivalent method to that defined in[RFC3611]. 116 1.2. RTCP and RTCP XR Reports 118 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 119 defined an extensible structure for reporting using an RTCP Extended 120 Report (XR). This document defines a new Extended Report block for 121 use with [RFC3550] and [RFC3611]. 123 1.3. Performance Metrics Framework 125 The Performance Metrics Framework [RFC6390] provides guidance on the 126 definition and specification of performance metrics. The RTP 127 Monitoring Architectures [RFC6792] provides guideline for reporting 128 block format using RTCP XR. The Metrics Block described in this 129 document are in accordance with the guidelines in [RFC6390] and 130 [RFC6792]. 132 1.4. Applicability 134 These metrics are applicable to a range of RTP applications which 135 contain jitter buffers and don't use stream repair means, e.g., 136 Forward Error Correction (FEC) [RFC5109] and/or retransmission 137 [RFC4588]. 139 2. Terminology 141 2.1. Standards Language 143 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 144 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 145 document are to be interpreted as described in RFC 2119 [RFC2119]. 147 In addition, the following terms are defined: 149 Received, Lost and Discarded 151 A packet shall be regarded as lost if it fails to arrive within an 152 implementation-specific time window. A packet that arrives within 153 this time window but is too early or late to be played out or 154 thrown away before playout due to packet duplication or redundancy 155 shall be regarded as discarded. A packet shall be classified as 156 one of received (or OK), discarded or lost. The metric 157 "cumulative number of packets lost" defined in [RFC3550] reports a 158 count of packets lost from the media stream (single SSRC within 159 single RTP session). Similarly the metric "number of packets 160 discarded" defined in [DISCARD] reports a count of packets 161 discarded from the media stream (single SSRC within single RTP 162 session) arriving at the receiver. Another metric defined in 163 [RFC5725] is available to report on packets which are not 164 recovered by any repair techniques which may be in use. 166 Bursts and Gaps 168 The terms Burst and Gap are used in a manner consistent with that 169 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 170 into bursts, which are periods during which the discard rate is 171 high enough to cause noticeable quality degradation (generally 172 over 5 percent discard rate), and gaps, which are periods during 173 which discarded packets are infrequent and hence quality is 174 generally acceptable. 176 3. Burst/Gap Discard Block 178 Metrics in this block report on Burst/Gap Discard in the stream 179 arriving at the RTP system. The measurement of these metrics are 180 made at the receiving end of the RTP stream. Instances of this 181 Metrics Block refer by Synchronization source (SSRC) to the separate 182 auxiliary Measurement Information block [RFC6776] which describes 183 measurement periods in use (see RFC6776 section 4.2). This Metrics 184 Block relies on the measurement period in the Measurement Information 185 block indicating the span of the report and MUST be sent in the same 186 compound RTCP packet as the measurement information block. If the 187 measurement period is not received in the same compound RTCP packet 188 as this Metrics Block, this Metrics Block MUST be discarded. 190 3.1. Report Block Structure 192 Burst/Gap Discard metrics block 194 0 1 2 3 195 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 1 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 197 | BT=NBGD | I | resv. | block length = 3 | 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 | SSRC of Source | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 | Threshold | Packets Discarded in Bursts | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 | Total Packets expected in bursts | Reserved. | 204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 Figure 1: Report Block Structure 208 3.2. Definition of Fields in Burst/Gap Discard Report Block 210 Block type (BT): 8 bits 212 A Burst/Gap Discard Report Block is identified by the constant 213 NBGD. 215 [Note to RFC Editor: please replace NBGD with the IANA provided 216 RTCP XR block type for this block.] 218 Interval Metric flag (I): 2 bits 220 This field is used to indicate whether the Burst/Gap Discard 221 metrics are Sampled, Interval or Cumulative metrics: 223 I=10: Interval Duration - the reported value applies to the 224 most recent measurement interval duration between successive 225 metrics reports. 227 I=11: Cumulative Duration - the reported value applies to the 228 accumulation period characteristic of cumulative measurements. 230 I=01: Sampled Value - the reported value is a sampled 231 instantaneous value. 233 In this document, Burst/Gap Discard Metrics can only be measured 234 over definite intervals, and cannot be sampled. Accordingly, the 235 value I=01, indicating a sampled value, MUST NOT be sent, and MUST 236 be discarded when received. In addition, the value I=00 is 237 reserved and also MUST NOT be sent, and MUST be discarded when 238 received. 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. 263 Packets discarded in bursts: 24 bits 265 The total number of packets discarded during discard bursts. 267 The measured value is unsigned value. If the measured value 268 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 269 an over-range measurement. If the measurement is unavailable, the 270 value 0xFFFFFF MUST be reported. 272 Total packets expected in bursts: 24 bits 274 The total number of packets expected during discarded bursts (that 275 is, the sum of received packets and lost packets). 277 The measured value is unsigned value. If the measured value 278 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 279 an over-range measurement. If the measurement is unavailable, the 280 value 0xFFFFFF MUST be reported. 282 Reserved (resv): 8 bits 284 These bits are reserved. They MUST be set to zero by senders and 285 ignored by receivers (See RFC6709 section 4.2). 287 3.3. Derived metrics based on reported metrics 289 The metrics described here are intended to be used in conjunction 290 with information from the Measurement Information block [RFC6776] 291 (which must be present in the same RTCP packet as the Burst/Gap 292 Discard block) and also with the metric "number of packets discarded" 293 provided in the RTCP XR Discard Count Block [DISCARD]. The RTCP XR 294 Discard Count Block should be sent if the Burst/Gap Discard block is 295 sent, but the converse does not apply. 297 These metrics provide the following information relevant to 298 statistical parameters, including: 300 o The fraction of packets discarded during bursts (burst discard 301 rate in [SUMSTAT]), which can be calculated using the metric " 302 Packets Discarded in Bursts " and the metric " Total Packets 303 expected in Bursts " provided in the Burst/Gap Discard metrics 304 block. 306 o The fraction of packets discarded during gaps (gap discard rate in 307 [SUMSTAT]), which can be calculated using the metric " Packets 308 Discarded in Bursts " and the metric " Total Packets expected in 309 Bursts " provided in the Burst/Gap Discard metrics block. 311 The details on calculation these parameters in the metrics are 312 described in [SUMSTAT]. 314 4. Considerations for Voice-over-IP applications 316 This Metrics Block is applicable to a broad range of RTP 317 applications. Where the metric is used with a Voice-overIP (VoIP) 318 application and the stream repair means is not available, the 319 following considerations apply. 321 RTCP XR views a call as being divided into bursts, which are periods 322 during which the discard rate is high enough to cause noticeable call 323 quality degradation (generally over 5 percent discard rate), and 324 gaps, which are periods during which discarded packets are infrequent 325 and hence call quality is generally acceptable. 327 If Voice Activity Detection is used the Burst and Gap Duration shall 328 be determined as if silence packets had been sent, i.e. a period of 329 silence in excess of Gmin packets must terminate a burst condition. 331 The recommended value for the threshold Gmin in [RFC3611] results in 332 a Burst being a period of time during which the call quality is 333 degraded to a similar extent to a typical Pulse-Code Modulation(PCM) 334 Severely Errored Second. 336 5. SDP Signaling 338 [RFC3611] defines the use of SDP (Session Description Protocol) 339 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 340 without prior signaling. 342 5.1. SDP rtcp-xr-attrib Attribute Extension 344 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 345 in [RFC3611] by providing an additional value of "xr-format" to 346 signal the use of the report block defined in this document. 348 xr-format =/ xr-bgd-block 350 xr-bgd-block = "burst-gap-dscrd" 352 5.2. Offer/Answer Usage 354 When SDP is used in offer-answer context, the SDP Offer/Answer usage 355 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 356 applies. For detailed usage in Offer/Answer for unilateral 357 parameter, refer to section 5.2 of [RFC3611]. 359 6. IANA Considerations 361 New block types for RTCP XR are subject to IANA registration. For 362 general guidelines on IANA considerations for RTCP XR, refer to 363 [RFC3611]. 365 6.1. New RTCP XR Block Type value 367 This document assigns the block type value NBGD in the IANA " RTP 368 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 369 the "Burst/Gap Discard Metrics Block". 371 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 372 XR block type for this block.] 374 6.2. New RTCP XR SDP Parameter 376 This document also registers a new parameter "burst-gap-dscrd" in the 377 "RTP Control Protocol Extended Reports (RTCP XR) Session Description 378 Protocol (SDP) Parameters Registry". 380 6.3. Contact information for registrations 382 The contact information for the registrations is: 384 Qin Wu (sunseawq@huawei.com) 386 101 Software Avenue, Yuhua District 387 Nanjing, Jiangsu 210012 388 China 390 7. Security Considerations 392 It is believed that this proposed RTCP XR report block introduces no 393 new security considerations beyond those described in [RFC3611]. 394 This block does not provide per-packet statistics so the risk to 395 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 396 does not apply. 398 8. Contributors 400 Geoff Hunt wrote the initial draft of this document. 402 9. Acknowledgments 404 The authors gratefully acknowledge reviews and feedback provided by 405 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 406 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 407 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 408 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 409 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Paul 410 Kyzivat,Claire Bi and Dan Romascanu. 412 10. References 414 10.1. Normative References 416 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 417 Requirement Levels", March 1997. 419 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 420 Applications", RFC 3550, July 2003. 422 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 423 Protocol Extended Reports (RTCP XR)", November 2003. 425 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 426 Description Protocol", July 2006. 428 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 429 Report Block Type for RTP Control Protocol (RTCP) Extended 430 Reports (XRs)", RFC 5725, February 2020. 432 10.2. Informative References 434 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard Count metric 435 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-11, 436 December 2012. 438 [RFC4588] Rey, J., Leon, D., , A., Varsa, V., and R. Hakenberg, "RTP 439 Retransmission Payload Format", RFC 4588, July 2006. 441 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 442 Correction", RFC 5109, December 2007. 444 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 445 Development", RFC 6390, October 2011. 447 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 448 Considerations for Protocol Extensions", RFC 6709, 449 September 2012. 451 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 452 using SDES item and XR Block", RFC 6776, October 2012. 454 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 455 November 2012. 457 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 458 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-11, 459 March 2013. 461 Appendix A. Metrics represented using RFC6390 Template 463 RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC 464 number, when assigned. 466 a. Threshold Metric 468 * Metric Name: Threshold in RTP 470 * Metric Description: The Threshold is equivalent to Gmin in 471 [RFC3611], i.e. the number of successive packets that must not 472 be discarded prior to and following a discard packet in order 473 for this discarded packet to be regarded as part of a gap. 475 * Method of Measurement or Calculation: See section 3.2, 476 Threshold definition [RFCXXXX]. 478 * Units of Measurement: See section 3.2, Threshold definition 479 [RFCXXXX]. 481 * Measurement Point(s) with Potential Measurement Domain: See 482 section 3, 1st paragraph [RFCXXXX]. 484 * Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for 485 measurement timing and section 3.2 [RFCXXXX] for Interval 486 Metric flag. 488 * Use and applications: See section 1.4 [RFCXXXX]. 490 * Reporting model: See RFC3611. 492 b. Packets discarded in bursts Metric 494 * Metric Name: RTP Packets discarded in bursts 496 * Metric Description: The total number of RTP packets discarded 497 during discard bursts. 499 * Method of Measurement or Calculation: See section 3.2, Packets 500 discarded in bursts definition [RFCXXXX]. 502 * Units of Measurement: See section 3.2, Packets discarded in 503 bursts definition [RFCXXXX]. 505 * Measurement Point(s) with Potential Measurement Domain: See 506 section 3, 1st paragraph [RFCXXXX]. 508 * Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for 509 measurement timing and section 3.2 [RFCXXXX] for Interval 510 Metric flag. 512 * Use and applications: See section 1.4 [RFCXXXX]. 514 * Reporting model: See RFC3611. 516 c. Total packets expected in bursts Metric 518 * Metric Name: Total RTP packets expected in bursts 520 * Metric Description: The total number of packets expected 521 during discarded bursts (that is, the sum of received packets 522 and lost packets). 524 * Method of Measurement or Calculation: See section 3.2, Total 525 packets expected in bursts definition [RFCXXXX]. 527 * Units of Measurement: See section 3.2, Total packets expected 528 in bursts definition [RFCXXXX]. 530 * Measurement Point(s) with Potential Measurement Domain: See 531 section 3, 1st paragraph [RFCXXXX]. 533 * Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for 534 measurement timing and section 3.2 [RFCXXXX] for Interval 535 Metric flag. 537 * Use and applications: See section 1.4 [RFCXXXX]. 539 * Reporting model: See RFC3611. 541 Appendix B. Change Log 543 Note to the RFC-Editor: please remove this section prior to 544 publication as an RFC. 546 B.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-11 548 The following are the major changes compared to previous version: 550 o Similar changes to Burst Gap loss draft to address IESG review 551 comments apply to this document. 553 B.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-10 555 The following are the major changes compared to previous version: 557 o Move RFC6709 as one informative reference. 559 B.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 561 The following are the major changes compared to previous version: 563 o Editorial changes based on comments received in WGLC. 565 B.4. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 567 The following are the major changes compared to previous version: 569 o SDP update based on SDP Directorate Review. 571 o Add some texts to get consistent with RFC6798 and Delay draft. 573 B.5. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 575 The following are the major changes compared to previous version: 577 o Outdated reference update. 579 o Editorial changes based on comments that applied to PDV and Delay 580 drafts. 582 Authors' Addresses 584 Alan Clark 585 Telchemy Incorporated 586 2905 Premiere Parkway, Suite 280 587 Duluth, GA 30097 588 USA 590 Email: alan.d.clark@telchemy.com 592 Rachel Huang 593 Huawei Technologies Co., Ltd. 594 101 Software Avenue, Yuhua District 595 Nanjing, Jiangsu 210012 596 China 598 Email: Rachel@huawei.com 600 Qin Wu (editor) 601 Huawei 602 101 Software Avenue, Yuhua District 603 Nanjing, Jiangsu 210012 604 China 606 Email: sunseawq@huawei.com