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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-20) exists of draft-ietf-payload-flexible-fec-scheme-02 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Audio/Video Transport Working Group V. Singh 3 Internet-Draft callstats.io 4 Intended status: Standards Track C. Perkins 5 Expires: February 5, 2017 University of Glasgow 6 A. Clark 7 Telchemy 8 R. Huang 9 Huawei 10 August 4, 2016 12 RTP Control Protocol (RTCP) Extended Report (XR) Block for Independent 13 Reporting of Burst/Gap Discard Metric 14 draft-ietf-xrblock-independent-burst-gap-discard-03 16 Abstract 18 This document defines an RTP Control Protocol (RTCP) Extended Report 19 (XR) block that allows the reporting of burst and gap discard metrics 20 independently of the burst and gap loss metrics for use in a range of 21 RTP applications. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on February 5, 2017. 40 Copyright Notice 42 Copyright (c) 2016 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 1.1. Burst-Gap Discard Metrics Block . . . . . . . . . . . . . 2 59 1.2. RTCP and RTCP Extended Reports . . . . . . . . . . . . . 3 60 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 61 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 63 3. Burst/Gap Discard Metrics Block . . . . . . . . . . . . . . . 5 64 3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5 65 3.2. Definition of Fields in Burst/Gap Discard Metrics Block . 5 66 3.3. Derived Metrics Based on the Reported Metrics . . . . . . 7 67 4. Considerations for Voice-over-IP Applications . . . . . . . . 8 68 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 69 5.1. SDP rtcp-xr Attribute Extension . . . . . . . . . . . . . 8 70 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 8 71 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 72 6.1. New RTCP XR Block Type Value . . . . . . . . . . . . . . 9 73 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 9 74 6.3. Contact Information for Registrations . . . . . . . . . . 9 75 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 76 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10 77 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 78 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 79 10.1. Normative References . . . . . . . . . . . . . . . . . . 10 80 10.2. Informative References . . . . . . . . . . . . . . . . . 11 81 Appendix A. Metrics Represented Using the Template from RFC 6390 13 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 84 1. Introduction 86 1.1. Burst-Gap Discard Metrics Block 88 This document defines a new block type that extends the metrics 89 defined in [RFC7003]. The new block type reports the proportion of 90 packets discarded in a burst by the de-jitter buffer at the receiver. 91 The number of packets discarded depends on the de-jitter buffer 92 algorithm implemented by the endpoint. 94 The new report block defined in this document is different from the 95 one defined in [RFC7003]. The metrics in [RFC7003] depends on the 96 metrics in the burst-gap loss metric defined in [RFC6958]. 98 Consequently, an endpoint that sends a Burst/Gap Discard Metrics 99 Block [RFC7003] also needs to send a Burst/Gap Loss Metrics Block 100 [RFC6958]. The combined usage is useful when an endpoint observes 101 correlated packet losses and discard. However, when the burst of 102 packet losses and discards do not occur simultaneously, the 103 application could prefer to send a concise report block that just 104 reports the burst-gap of discarded packets. The report block in this 105 document provides the complete information and does not require 106 additional report blocks. That is, this block reports: the total 107 number of packets discarded, the total burst duration, and the total 108 number of bursts, all of these metrics are missing in [RFC7003]. 110 This block provides information on transient network issues. Burst/ 111 gap metrics are typically used in cumulative reports; however, they 112 can also be used in interval reports (see the Interval Metric flag in 113 Section 3.2). The variation in the number of packet discards in a 114 burst affects the user experience. Based on the metrics reported in 115 the block, the sending endpoint can change the packetization 116 interval, vary the bitrate, etc. The report can additionally be used 117 for diagnostics [RFC6792]. The metric belongs to the class of 118 transport-related end-system metrics defined in [RFC6792]. 120 The definitions of "burst", "gap", "loss", and "discard" are 121 consistent with the definitions in [RFC3611]. To accommodate a range 122 of de-jitter buffer algorithms and packet discard logic that can be 123 used by implementers, the method used to distinguish between bursts 124 and gaps use an equivalent method to that defined in Section 4.7.2 of 125 [RFC3611]. Note that reporting the specific de-jitter buffer 126 algorithm and/or the packet discard logic is out of the scope of this 127 document. 129 1.2. RTCP and RTCP Extended Reports 131 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 132 defined an extensible structure for reporting using an RTCP Extended 133 Report (XR). This document defines a new Extended Report block for 134 use with [RFC3550] and [RFC3611]. 136 1.3. Performance Metrics Framework 138 The Performance Metrics Framework [RFC6390] provides guidance on the 139 definition and specification of performance metrics. The RTP 140 Monitoring Framework [RFC6792] provides guidelines for reporting 141 block format using RTCP XR. The metrics block described in this 142 document is in accordance with the guidelines in [RFC6390] and 143 [RFC6792]. 145 1.4. Applicability 147 These metrics are applicable to a range of RTP applications that 148 contain de-jitter buffers at the receiver to smooth variation in 149 packet-arrival time and don't use stream repair means, e.g., Forward 150 Error Correction (FEC) [I-D.ietf-payload-flexible-fec-scheme] and/or 151 retransmission [RFC4588]. 153 2. Terminology 155 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 156 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 157 document are to be interpreted as described in RFC 2119 [RFC2119]. 159 In addition, the following terms are defined: 161 Received, Lost, and Discarded 163 A packet is regarded as "lost" if it fails to arrive within an 164 implementation-specific time window. A packet that arrives within 165 this time window but is too early to be played out, too late to be 166 played out, or thrown away before play-out due to packet 167 duplication or redundancy is be recorded as discarded. A packet 168 SHALL NOT be regarded as discarded if it arrives within this time 169 window but is dropped during decoding by some higher-layer 170 decoder, e.g., due to a decoding error. Each packet is classified 171 as one of received (or OK), discarded, or lost. The metric 172 "cumulative number of packets lost" defined in [RFC3550] reports a 173 count of packets lost from the media stream (single 174 synchronization source (SSRC) within a single RTP session). 175 Similarly, the metric "number of packets discarded" defined in 176 [RFC7002] reports a count of packets discarded from the media 177 stream (single SSRC within a single RTP session) arriving at the 178 receiver. Another metric, defined in [RFC5725], is available to 179 report on packets that are not recovered by any repair techniques 180 that are in use. Note that the term "discard" defined here builds 181 on the "discard" definition in [RFC3611] but extends the concept 182 to take into account packet duplication and reports different 183 types of discard counts [RFC7002]. 185 Bursts and Gaps 187 The terms "burst" and "gap" are used in a manner consistent with 188 that of RTCP XR [RFC3611]. RTCP XR views an RTP stream as being 189 divided into bursts, which are periods during which the discard 190 rate is high enough to cause noticeable quality degradation 191 (generally over 5 percent discard rate), and gaps, which are 192 periods during which discarded packets are infrequent and hence 193 quality is generally acceptable. 195 3. Burst/Gap Discard Metrics Block 197 Metrics in this block report on burst/gap discard in the stream 198 arriving at the RTP system. Measurements of these metrics are made 199 at the receiving end of the RTP stream. Instances of this metrics 200 block use the synchronization source (SSRC) to refer to the separate 201 auxiliary Measurement Information Block [RFC6776], which describes 202 measurement periods in use (see [RFC6776], Section 4.2). 204 This metrics block relies on the measurement period in the 205 Measurement Information Block indicating the span of the report. 206 Senders MUST send this block in the same compound RTCP packet as the 207 Measurement Information Block. Receivers MUST verify that the 208 measurement period is received in the same compound RTCP packet as 209 this metrics block. If not, this metrics block MUST be discarded. 211 3.1. Report Block Structure 213 The structure of the Burst/Gap Discard Metrics Block is as follows. 215 0 1 2 3 216 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 1 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | BT=IBGD | I | resv | Block Length = 5 | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | SSRC of Source | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | Threshold | Sum of Burst Durations (ms) | 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 | Packets Discarded in Bursts | Number of | 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 | Bursts | Total Packets Expected in Bursts | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | Discard Count | 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 Figure 1: Report Block Structure 233 3.2. Definition of Fields in Burst/Gap Discard Metrics Block 235 Block Type (BT): 8 bits 237 A Burst/Gap Discard Metrics Block is identified by the constant 238 IBGD. 240 [Note to RFC Editor: Please replace IBGD with the IANA provided 241 RTCP XR block type for this block.] 243 Interval Metric flag (I): 2 bits 245 This field is used to indicate whether the burst/gap discard 246 metrics are Sampled, Interval, or Cumulative metrics [RFC6792]: 248 I=10: Interval Duration - the reported value applies to the 249 most recent measurement interval duration between successive 250 metrics reports. 252 I=11: Cumulative Duration - the reported value applies to the 253 accumulation period characteristic of cumulative measurements. 255 In this document, burst/gap discard metrics can only be measured 256 over definite intervals and cannot be sampled. Also, the value 257 I=00 is reserved for future use. Senders MUST NOT use the values 258 I=00 or I=01. If a block is received with I=00 or I=01, the 259 receiver MUST discard the block. 261 Reserved (resv): 6 bits 263 These bits are reserved. They MUST be set to zero by senders and 264 ignored by receivers (see [RFC6709], Section 4.2). 266 block length: 16 bits 268 The length of this report block in 32-bit words, minus one. For 269 the Burst/Gap Discard Metrics Block, the block length is equal to 270 5. The block MUST be discarded if the block length is set to a 271 different value. 273 SSRC of Source: 32 bits 275 As defined in Section 4.1 of [RFC3611]. 277 Threshold: 8 bits 279 The Threshold is equivalent to Gmin in [RFC3611], i.e., the number 280 of successive packets that have to be received prior to, and 281 following, a discarded packet in order for that discarded packet 282 to be regarded as part of a gap. Note that the Threshold is set 283 in accordance with the Gmin calculation defined in Section 4.7.2 284 of [RFC3611]. 286 Sum of Burst Durations (ms): 24 bits 287 The total duration of bursts of discarded packets in the period of 288 the report (Interval or Cumulative). 290 The measured value is an unsigned value. If the measured value 291 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 292 an over-range measurement. If the measurement is unavailable, the 293 value 0xFFFFFF MUST be reported. 295 Packets Discarded in Bursts: 24 bits 297 The total number of packets discarded during discard bursts, as 298 defined in Section 3.2 of [RFC7002]. 300 Number of Bursts: 16 bits 302 The number of discard bursts in the period of the report (Interval 303 or Cumulative). 305 The measured value is an unsigned value. If the measured value 306 exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an 307 over-range measurement. If the measurement is unavailable, the 308 value 0xFFFF MUST be reported. 310 Total Packets Expected in Bursts: 24 bits 312 The total number of packets expected during the discard bursts 313 (that is, the sum of received packets and lost packets). The 314 metric is defined in [RFC7003]. 316 Discard Count: 32 bits 318 Number of packets discarded over the period (Interval or 319 Cumulative) covered by this report, as defined in Section 3.2 of 320 [RFC7002]. 322 3.3. Derived Metrics Based on the Reported Metrics 324 The metrics described here are intended to be used in conjunction 325 with information from the Measurement Information Block [RFC6776]. 327 These metrics provide the following information relevant to 328 statistical parameters (depending on cumulative of interval 329 measures), for example: 331 o The average discarded burst size, which can be calculated by 332 dividing the metric "Packets Discarded in Bursts" by the "Number 333 of Bursts". 335 o The average burst duration, which can be calculated by dividing 336 the metric "Sum of Burst Durations (ms)" by the "Number of 337 bursts". 339 4. Considerations for Voice-over-IP Applications 341 This metrics block is applicable to a broad range of RTP 342 applications. Where the metric is used with a Voice-over-IP (VoIP) 343 application and the stream repair means is not available, the 344 following considerations apply. 346 RTCP XR views a call as being divided into bursts, which are periods 347 during which the discard rate is high enough to cause noticeable call 348 quality degradation (generally over 5 percent discard rate) and gaps, 349 which are periods during which discarded packets are infrequent and 350 hence call quality is generally acceptable. 352 If voice activity detection is used, the burst and gap duration is 353 determined as if silence packets had been sent, i.e., a period of 354 silence in excess of Gmin packets will terminate a burst condition. 356 The RECOMMENDED value for the threshold Gmin in [RFC3611] results in 357 a burst being a period of time during which the call quality is 358 degraded to a similar extent to a typical pulse code modulation (PCM) 359 severely errored second. 361 5. SDP Signaling 363 [RFC3611] defines the use of SDP (Session Description Protocol) 364 [RFC4566] for signaling the use of XR blocks. XR blocks can be used 365 without prior signaling. 367 5.1. SDP rtcp-xr Attribute Extension 369 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 370 in [RFC3611] by providing an additional value of "xr-format" to 371 signal the use of the report block defined in this document. The 372 ABNF [RFC5234] syntax is as follows. 374 xr-format =/ xr-ind-bgd-block 376 xr-ind-bgd-block = "ind-burst-gap-discard" 378 5.2. Offer/Answer Usage 380 When SDP is used in Offer/Answer context, the SDP Offer/Answer usage 381 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 382 applies. For detailed usage in Offer/Answer for unilateral 383 parameters, refer to Section 5.2 of [RFC3611]. 385 6. IANA Considerations 387 New block types for RTCP XR are subject to IANA registration. For 388 general guidelines on IANA considerations for RTCP XR, refer to 389 [RFC3611]. 391 6.1. New RTCP XR Block Type Value 393 This document assigns the block type value IBGD in the IANA "RTP 394 Control Protocol Extended Reports (RTCP XR) Block Type Registry" to 395 the "Burst/Gap Discard Metrics Block". 397 [Note to RFC Editor: Please replace IBGD with the IANA provided RTCP 398 XR block type for this block.] 400 6.2. New RTCP XR SDP Parameter 402 This document also registers a new parameter "ind-burst-gap-discard" 403 in the "RTP Control Protocol Extended Reports (RTCP XR) Session 404 Description Protocol (SDP) Parameters Registry". 406 6.3. Contact Information for Registrations 408 The contact information for the registrations is: 410 ART Area Directors 412 7. Security Considerations 414 This block does not provide per-packet statistics, so the risk to 415 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 416 does not apply. However the gap indicated within this block could be 417 used to detect the timing of other events on the path between the 418 sender and receiver. For example, a competing multimedia stream 419 might cause a discard burst for the duration of the stream, allowing 420 the receiver of this block to know when the competing stream was 421 active. This risk is not a significant threat since the only 422 information leaked is the timing of the discard, not the cause. 424 Where this is a concern, the implementation SHOULD apply encryption 425 and authentication to this report block. For example, this can be 426 achieved by using the Audio-Visual Profile with Feedback (AVPF) 427 profile together with the Secure RTP profile, as defined in 428 [RFC3711]; an appropriate combination of those two profiles ("SAVPF") 429 is specified in [RFC5124]. Besides this, it is believed that this 430 RTCP XR block introduces no new security considerations beyond those 431 described in [RFC3611]. 433 8. Contributors 435 Qin Wu, Rachel Huang, and Alan Clark wrote RFC7003, which this 436 document extends. 438 9. Acknowledgments 440 The authors would like to thank Ben Campbell, Stephen Farrell, Paul 441 Kyzivat, Shucheng LIU, Jan Novak, and Dan Romascanu for providing 442 valuable feedback on earlier versions of this draft. 444 10. References 446 10.1. Normative References 448 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 449 Requirement Levels", BCP 14, RFC 2119, 450 DOI 10.17487/RFC2119, March 1997, 451 . 453 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. 454 Jacobson, "RTP: A Transport Protocol for Real-Time 455 Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, 456 July 2003, . 458 [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., 459 "RTP Control Protocol Extended Reports (RTCP XR)", 460 RFC 3611, DOI 10.17487/RFC3611, November 2003, 461 . 463 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. 464 Norrman, "The Secure Real-time Transport Protocol (SRTP)", 465 RFC 3711, DOI 10.17487/RFC3711, March 2004, 466 . 468 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 469 Description Protocol", RFC 4566, DOI 10.17487/RFC4566, 470 July 2006, . 472 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for 473 Real-time Transport Control Protocol (RTCP)-Based Feedback 474 (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February 475 2008, . 477 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 478 Specifications: ABNF", STD 68, RFC 5234, 479 DOI 10.17487/RFC5234, January 2008, 480 . 482 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 483 Report Block Type for RTP Control Protocol (RTCP) Extended 484 Reports (XRs)", RFC 5725, DOI 10.17487/RFC5725, February 485 2010, . 487 [RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information 488 Reporting Using a Source Description (SDES) Item and an 489 RTCP Extended Report (XR) Block", RFC 6776, 490 DOI 10.17487/RFC6776, October 2012, 491 . 493 [RFC7003] Clark, A., Huang, R., and Q. Wu, Ed., "RTP Control 494 Protocol (RTCP) Extended Report (XR) Block for Burst/Gap 495 Discard Metric Reporting", RFC 7003, DOI 10.17487/RFC7003, 496 September 2013, . 498 10.2. Informative References 500 [I-D.ietf-payload-flexible-fec-scheme] 501 Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP 502 Payload Format for Flexible Forward Error Correction 503 (FEC)", draft-ietf-payload-flexible-fec-scheme-02 (work in 504 progress), March 2016. 506 [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. 507 Hakenberg, "RTP Retransmission Payload Format", RFC 4588, 508 DOI 10.17487/RFC4588, July 2006, 509 . 511 [RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New 512 Performance Metric Development", BCP 170, RFC 6390, 513 DOI 10.17487/RFC6390, October 2011, 514 . 516 [RFC6709] Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design 517 Considerations for Protocol Extensions", RFC 6709, 518 DOI 10.17487/RFC6709, September 2012, 519 . 521 [RFC6792] Wu, Q., Ed., Hunt, G., and P. Arden, "Guidelines for Use 522 of the RTP Monitoring Framework", RFC 6792, 523 DOI 10.17487/RFC6792, November 2012, 524 . 526 [RFC6958] Clark, A., Zhang, S., Zhao, J., and Q. Wu, Ed., "RTP 527 Control Protocol (RTCP) Extended Report (XR) Block for 528 Burst/Gap Loss Metric Reporting", RFC 6958, 529 DOI 10.17487/RFC6958, May 2013, 530 . 532 [RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol 533 (RTCP) Extended Report (XR) Block for Discard Count Metric 534 Reporting", RFC 7002, DOI 10.17487/RFC7002, September 535 2013, . 537 Appendix A. Metrics Represented Using the Template from RFC 6390 539 a. Threshold Metric 541 * Defined in Appendix A.a of [RFC7003]. 543 b. Sum of burst durations (ms) 545 * Metric Name: Sum of Burst Durations with Discarded RTP 546 Packets. 548 * Metric Description: The total duration of bursts of discarded 549 RTP packets in the period of the report. 551 * Method of Measurement or Calculation: See Section 3.1, Sum of 552 Burst Durations definition. 554 * Units of Measurement: See Section 3.1, Sum of Burst Durations 555 definition. 557 * Measurement Point(s) with Potential Measurement Domain: See 558 Section 3, 1st paragraph. 560 * Measurement Timing: See Section 3, 2nd paragraph for 561 measurement timing and Section 3.1 for Interval Metric flag. 563 * Use and Applications: See Section 1.4. 565 * Reporting Model: See RFC 3611. 567 c. Packets Discarded in Bursts Metric 569 * Defined in Appendix A.b of [RFC7003]. 571 d. Number of bursts 573 * Metric Name: Number of discard bursts in RTP. 575 * Metric Description: The total number of bursts with discarded 576 RTP packets in the period of the report. 578 * Method of Measurement or Calculation: See Section 3.1, Number 579 of discard bursts definition. 581 * Units of Measurement: See Section 3.1 for the Number of bursts 582 definition. 584 * Measurement Point(s) with Potential Measurement Domain: See 585 Section 3, 1st paragraph. 587 * Measurement Timing: See Section 3, 2nd paragraph for 588 measurement timing and Section 3.1 for Interval Metric flag. 590 * Use and Applications: See Section 1.4. 592 * Reporting Model: See RFC 3611. 594 e. Total Packets Expected in Bursts Metric 596 * Defined in Appendix A.c of [RFC7003]. 598 f. Discard Count 600 * Defined in Appendix A.a of [RFC7002]. 602 Authors' Addresses 604 Varun Singh 605 Nemu Dialogue Systems Oy 606 Runeberginkatu 4c A 4 607 Helsinki 00100 608 Finland 610 EMail: varun.singh@iki.fi 611 URI: http://www.callstats.io/ 613 Colin Perkins 614 University of Glasgow 615 School of Computing Science 616 Glasgow G12 8QQ 617 United Kingdom 619 EMail: csp@csperkins.org 621 Alan Clark 622 Telchemy Incorporated 623 2905 Premiere Parkway, Suite 280 624 Duluth, GA 30097 625 USA 627 EMail: alan.d.clark@telchemy.com 628 Rachel Huang 629 Huawei Technologies Co., Ltd. 630 101 Software Avenue, Yuhua District 631 Nanjing, Jiangsu 210012 632 China 634 EMail: Rachel@huawei.com