idnits 2.17.1 draft-ietf-xrblock-independent-burst-gap-discard-01.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 (March 21, 2016) is 2952 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-20) exists of draft-ietf-payload-flexible-fec-scheme-01 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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: September 22, 2016 University of Glasgow 6 A. Clark 7 Telchemy 8 R. Huang 9 Huawei 10 March 21, 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-01 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 September 22, 2016. 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 . . . . . . . . . . . . . . . . . . . 9 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 83 1. Introduction 85 1.1. Burst-Gap Discard Metrics Block 87 This document defines a new block type that extends the metrics 88 defined in [RFC7003]. The new block type reports the proportion of 89 packets discarded in a burst by the dejitter buffer at the receiver. 90 The number of packets discarded depends on the dejitter buffer 91 algorithm implemented by the endpoint. 93 The new report block defined in this document is different from the 94 one defined in [RFC7003]. The metrics in [RFC7003] depends on the 95 metrics in the burst-gap loss metric defined in [RFC6958]. 96 Consequently, an endpoint using [RFC7003] MUST report it along with 98 [RFC6958] for it to be useful. The combined usage is useful when an 99 endpoint observes correlated packet losses and discard. However, 100 when the burst of packet losses and discards do not occur 101 simultaneously, the application may prefer a concise report block 102 that just reports the burst-gap of discarded packets. The report 103 block in this document provides the complete information and does not 104 require additional report blocks. That is, this block reports: the 105 total number of packets discarded, the total burst duration, and the 106 total number of bursts, all of these metrics are missing in 107 [RFC7003]. 109 This block provides information on transient network issues. Burst/ 110 gap metrics are typically used in cumulative reports; however, they 111 may also be used in interval reports (see the Interval Metric flag in 112 Section 3.2). The variation in the number of packet discards in a 113 burst affects the user experience. Based on the metrics reported in 114 the block, the sending endpoint may change the packetization 115 interval, vary the bitrate, etc. The report may additionally be used 116 for diagnostics [RFC6792]. The metric belongs to the class of 117 transport-related end-system metrics defined in [RFC6792]. 119 The definitions of "burst", "gap", "loss", and "discard" are 120 consistent with the definitions in [RFC3611]. To accommodate a range 121 of dejitter buffer algorithms and packet discard logic that may be 122 used by implementors, the method used to distinguish between bursts 123 and gaps shall use an equivalent method to that defined in 124 Section 4.7.2 of [RFC3611]. Note that reporting the specific 125 dejitter buffer algorithm and/or the packet discard logic is out of 126 the scope of this document. 128 1.2. RTCP and RTCP Extended Reports 130 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 131 defined an extensible structure for reporting using an RTCP Extended 132 Report (XR). This document defines a new Extended Report block for 133 use with [RFC3550] and [RFC3611]. 135 1.3. Performance Metrics Framework 137 The Performance Metrics Framework [RFC6390] provides guidance on the 138 definition and specification of performance metrics. The RTP 139 Monitoring Framework [RFC6792] provides guidelines for reporting 140 block format using RTCP XR. The metrics block described in this 141 document is in accordance with the guidelines in [RFC6390] and 142 [RFC6792]. 144 1.4. Applicability 146 These metrics are applicable to a range of RTP applications that 147 contain dejitter buffers [RFC5481] at the receiving end to smooth 148 variation in packet-arrival time and don't use stream repair means, 149 e.g., Forward Error Correction (FEC) 150 [I-D.ietf-payload-flexible-fec-scheme] and/or retransmission 151 [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 shall be regarded as "lost" if it fails to arrive within 164 an implementation-specific time window. A packet that arrives 165 within this time window but is too early to be played out, too 166 late to be played out, or thrown away before playout due to packet 167 duplication or redundancy shall be regarded as discarded. A 168 packet shall not be regarded as discarded if it arrives within 169 this time window but is dropped during decoding by some higher- 170 layer decoder, e.g., due to a decoding error. A packet shall be 171 classified as one of received (or OK), discarded, or lost. The 172 metric "cumulative number of packets lost" defined in [RFC3550] 173 reports a 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 may be in use. Note that the term "discard" defined here 181 builds on the "discard" definition in [RFC3611] but extends the 182 concept to take into account packet duplication and reports 183 different 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. [RFC3611] RECOMMENDS a Gmin 194 value of 16. 196 3. Burst/Gap Discard Metrics Block 198 Metrics in this block report on burst/gap discard in the stream 199 arriving at the RTP system. Measurements of these metrics are made 200 at the receiving end of the RTP stream. Instances of this metrics 201 block use the synchronization source (SSRC) to refer to the separate 202 auxiliary Measurement Information Block [RFC6776], which describes 203 measurement periods in use (see [RFC6776], Section 4.2). 205 This metrics block relies on the measurement period in the 206 Measurement Information Block indicating the span of the report. 207 Senders MUST send this block in the same compound RTCP packet as the 208 Measurement Information Block. Receivers MUST verify that the 209 measurement period is received in the same compound RTCP packet as 210 this metrics block. If not, this metrics block MUST be discarded. 212 3.1. Report Block Structure 214 The structure of the Burst/Gap Discard Metrics Block is as follows. 216 0 1 2 3 217 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 1 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 | BT=IBGD | I | resv | Block Length = 5 | 220 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 | SSRC of Source | 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 | Threshold | Sum of Burst Durations (ms) | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 | Packets Discarded in Bursts | Number of | 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 | Bursts | Total Packets Expected in Bursts | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 229 | Discard Count | 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 Figure 1: Report Block Structure 234 3.2. Definition of Fields in Burst/Gap Discard Metrics Block 236 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 I=01: Sampled Value - the reported value is a sampled 256 instantaneous value. 258 In this document, burst/gap discard metrics can only be measured 259 over definite intervals and cannot be sampled. Also, the value 260 I=00 is reserved for future use. Senders MUST NOT use the values 261 I=00 or I=01. If a block is received with I=00 or I=01, the 262 receiver MUST discard the block. 264 Reserved (resv): 6 bits 266 These bits are reserved. They MUST be set to zero by senders and 267 ignored by receivers (see [RFC6709], Section 4.2). 269 block length: 16 bits 271 The length of this report block in 32-bit words, minus one. For 272 the Burst/Gap Discard Metrics Block, the block length is equal to 273 5. The block MUST be discarded if the block length is set to a 274 different value. 276 SSRC of Source: 32 bits 278 As defined in Section 4.1 of [RFC3611]. 280 Threshold: 8 bits 282 The Threshold is equivalent to Gmin in [RFC3611], i.e., the number 283 of successive packets that must not be discarded prior to and 284 following a discard packet in order for this discarded packet to 285 be regarded as part of a gap. Note that the Threshold is set in 286 accordance with the Gmin calculation defined in Section 4.7.2 of 287 [RFC3611]. 289 Sum of Burst Durations (ms): 24 bits 291 The total duration of bursts of discarded packets in the period of 292 the report (Interval or Cumulative). 294 The measured value is an unsigned value. If the measured value 295 exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate 296 an over-range measurement. If the measurement is unavailable, the 297 value 0xFFFFFF MUST be reported. 299 Packets Discarded in Bursts: 24 bits 301 The total number of packets discarded during discard bursts, as 302 defined in Section 3.2 of [RFC7002]. 304 Number of Bursts: 16 bits 306 The number of discard bursts in the period of the report (Interval 307 or Cumulative). 309 The measured value is an unsigned value. If the measured value 310 exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an 311 over-range measurement. If the measurement is unavailable, the 312 value 0xFFFF MUST be reported. 314 Total Packets Expected in Bursts: 24 bits 316 The total number of packets expected during the discard bursts 317 (that is, the sum of received packets and lost packets). The 318 metric is defined in [RFC7003]. 320 Discard Count: 32 bits 322 Number of packets discarded over the period (Interval or 323 Cumulative) covered by this report, as defined in Section 3.2 of 324 [RFC7002]. 326 3.3. Derived Metrics Based on the Reported Metrics 328 The metrics described here are intended to be used in conjunction 329 with information from the Measurement Information Block [RFC6776]. 331 These metrics provide the following information relevant to 332 statistical parameters (depending on cumulative of interval 333 measures), for example: 335 o The average discarded burst size, which can be calculated by 336 dividing the metric "Packets Discarded in Bursts" by the "Number 337 of Bursts". 339 o The average burst duration, which can be calculated by dividing 340 the metric "Sum of Burst Durations (ms)" by the "Number of 341 bursts". 343 4. Considerations for Voice-over-IP Applications 345 This metrics block is applicable to a broad range of RTP 346 applications. Where the metric is used with a Voice-over-IP (VoIP) 347 application and the stream repair means is not available, the 348 following considerations apply. 350 RTCP XR views a call as being divided into bursts, which are periods 351 during which the discard rate is high enough to cause noticeable call 352 quality degradation (generally over 5 percent discard rate) and gaps, 353 which are periods during which discarded packets are infrequent and 354 hence call quality is generally acceptable. 356 If voice activity detection is used, the burst and gap duration shall 357 be determined as if silence packets had been sent, i.e., a period of 358 silence in excess of Gmin packets will terminate a burst condition. 360 The recommended value for the threshold Gmin in [RFC3611] results in 361 a burst being a period of time during which the call quality is 362 degraded to a similar extent to a typical pulse code modulation (PCM) 363 severely errored second. 365 5. SDP Signaling 367 [RFC3611] defines the use of SDP (Session Description Protocol) 368 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 369 without prior signaling. 371 5.1. SDP rtcp-xr Attribute Extension 373 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 374 in [RFC3611] by providing an additional value of "xr-format" to 375 signal the use of the report block defined in this document. The 376 ABNF [RFC5234] syntax is as follows. 378 xr-format =/ xr-ind-bgd-block 380 xr-ind-bgd-block = "ind-burst-gap-discard" 382 5.2. Offer/Answer Usage 384 When SDP is used in Offer/Answer context, the SDP Offer/Answer usage 385 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 386 applies. For detailed usage in Offer/Answer for unilateral 387 parameters, refer to Section 5.2 of [RFC3611]. 389 6. IANA Considerations 391 New block types for RTCP XR are subject to IANA registration. For 392 general guidelines on IANA considerations for RTCP XR, refer to 393 [RFC3611]. 395 6.1. New RTCP XR Block Type Value 397 This document assigns the block type value IBGD in the IANA "RTP 398 Control Protocol Extended Reports (RTCP XR) Block Type Registry" to 399 the "Burst/Gap Discard Metrics Block". 401 [Note to RFC Editor: Please replace IBGD with the IANA provided RTCP 402 XR block type for this block.] 404 6.2. New RTCP XR SDP Parameter 406 This document also registers a new parameter "ind-burst-gap-discard" 407 in the "RTP Control Protocol Extended Reports (RTCP XR) Session 408 Description Protocol (SDP) Parameters Registry". 410 6.3. Contact Information for Registrations 412 The contact information for the registrations is: 414 ART Area Directors 416 7. Security Considerations 418 It is believed that this RTCP XR block introduces no new security 419 considerations beyond those described in [RFC3611]. This block does 420 not provide per-packet statistics, so the risk to confidentiality 421 documented in Section 7, paragraph 3 of [RFC3611] does not apply. 423 8. Contributors 425 Qin Wu, Rachel Huang, and Alan Clark wrote RFC7003, which this 426 document extends. 428 9. Acknowledgments 430 The authors would like to thank Paul Kyzivat, Jan Novak, Dan 431 Romascanu for providing valuable feedback on earlier versions of this 432 draft. 434 10. References 436 10.1. Normative References 438 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 439 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 440 RFC2119, March 1997, 441 . 443 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. 444 Jacobson, "RTP: A Transport Protocol for Real-Time 445 Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, 446 July 2003, . 448 [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., 449 "RTP Control Protocol Extended Reports (RTCP XR)", RFC 450 3611, DOI 10.17487/RFC3611, November 2003, 451 . 453 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 454 Description Protocol", RFC 4566, DOI 10.17487/RFC4566, 455 July 2006, . 457 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 458 Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/ 459 RFC5234, January 2008, 460 . 462 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 463 Report Block Type for RTP Control Protocol (RTCP) Extended 464 Reports (XRs)", RFC 5725, DOI 10.17487/RFC5725, February 465 2010, . 467 [RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information 468 Reporting Using a Source Description (SDES) Item and an 469 RTCP Extended Report (XR) Block", RFC 6776, DOI 10.17487/ 470 RFC6776, October 2012, 471 . 473 [RFC7003] Clark, A., Huang, R., and Q. Wu, Ed., "RTP Control 474 Protocol (RTCP) Extended Report (XR) Block for Burst/Gap 475 Discard Metric Reporting", RFC 7003, DOI 10.17487/RFC7003, 476 September 2013, . 478 10.2. Informative References 480 [I-D.ietf-payload-flexible-fec-scheme] 481 Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP 482 Payload Format for Flexible Forward Error Correction 483 (FEC)", draft-ietf-payload-flexible-fec-scheme-01 (work in 484 progress), October 2015. 486 [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. 487 Hakenberg, "RTP Retransmission Payload Format", RFC 4588, 488 DOI 10.17487/RFC4588, July 2006, 489 . 491 [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation 492 Applicability Statement", RFC 5481, DOI 10.17487/RFC5481, 493 March 2009, . 495 [RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New 496 Performance Metric Development", BCP 170, RFC 6390, DOI 497 10.17487/RFC6390, October 2011, 498 . 500 [RFC6709] Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design 501 Considerations for Protocol Extensions", RFC 6709, DOI 502 10.17487/RFC6709, September 2012, 503 . 505 [RFC6792] Wu, Q., Ed., Hunt, G., and P. Arden, "Guidelines for Use 506 of the RTP Monitoring Framework", RFC 6792, DOI 10.17487/ 507 RFC6792, November 2012, 508 . 510 [RFC6958] Clark, A., Zhang, S., Zhao, J., and Q. Wu, Ed., "RTP 511 Control Protocol (RTCP) Extended Report (XR) Block for 512 Burst/Gap Loss Metric Reporting", RFC 6958, DOI 10.17487/ 513 RFC6958, May 2013, 514 . 516 [RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol 517 (RTCP) Extended Report (XR) Block for Discard Count Metric 518 Reporting", RFC 7002, DOI 10.17487/RFC7002, September 519 2013, . 521 Appendix A. Metrics Represented Using the Template from RFC 6390 523 a. Threshold Metric 525 * Defined in Appendix A.a of [RFC7003]. 527 b. Sum of burst durations (ms) 529 * Metric Name: Sum of Burst Durations with Discarded RTP 530 Packets. 532 * Metric Description: The total duration of bursts of discarded 533 RTP packets in the period of the report. 535 * Method of Measurement or Calculation: See Section 3.1, Sum of 536 Burst Durations definition. 538 * Units of Measurement: See Section 3.1, Sum of Burst Durations 539 definition. 541 * Measurement Point(s) with Potential Measurement Domain: See 542 Section 3, 1st paragraph. 544 * Measurement Timing: See Section 3, 2nd paragraph for 545 measurement timing and Section 3.1 for Interval Metric flag. 547 * Use and Applications: See Section 1.4. 549 * Reporting Model: See RFC 3611. 551 c. Packets Discarded in Bursts Metric 553 * Defined in Appendix A.b of [RFC7003]. 555 d. Number of bursts 557 * Metric Name: Number of discard bursts in RTP. 559 * Metric Description: The total number of bursts with discarded 560 RTP packets in the period of the report. 562 * Method of Measurement or Calculation: See Section 3.1, Number 563 of discard bursts definition. 565 * Units of Measurement: See Section 3.1 for the Number of bursts 566 definition. 568 * Measurement Point(s) with Potential Measurement Domain: See 569 Section 3, 1st paragraph. 571 * Measurement Timing: See Section 3, 2nd paragraph for 572 measurement timing and Section 3.1 for Interval Metric flag. 574 * Use and Applications: See Section 1.4. 576 * Reporting Model: See RFC 3611. 578 e. Total Packets Expected in Bursts Metric 580 * Defined in Appendix A.c of [RFC7003]. 582 f. Discard Count 584 * Defined in Appendix A.a of [RFC7002]. 586 Authors' Addresses 588 Varun Singh 589 Nemu Dialogue Systems Oy 590 Runeberginkatu 4c A 4 591 Helsinki 00100 592 Finland 594 EMail: varun.singh@iki.fi 595 URI: http://www.callstats.io/ 597 Colin Perkins 598 University of Glasgow 599 School of Computing Science 600 Glasgow G12 8QQ 601 United Kingdom 603 EMail: csp@csperkins.org 605 Alan Clark 606 Telchemy Incorporated 607 2905 Premiere Parkway, Suite 280 608 Duluth, GA 30097 609 USA 611 EMail: alan.d.clark@telchemy.com 612 Rachel Huang 613 Huawei Technologies Co., Ltd. 614 101 Software Avenue, Yuhua District 615 Nanjing, Jiangsu 210012 616 China 618 EMail: Rachel@huawei.com