idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06.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 (December 5, 2012) is 4158 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-09 == Outdated reference: A later version (-11) exists of draft-ietf-xrblock-rtcp-xr-summary-stat-03 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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 S. Zhang, Ed. 5 Expires: June 8, 2013 J. Zhao 6 STTRI 7 Q. Wu 8 Huawei 9 December 5, 2012 11 RTP Control Protocol (RTCP) Extended Report (XR) Block for Burst/Gap 12 Loss metric Reporting 13 draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06.txt 15 Abstract 17 This document defines an RTP Control Protocol (RTCP) Extended Report 18 (XR) Block that allows the reporting of Burst and Gap Loss metrics 19 for use in a range of RTP applications. 21 Status of this Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on June 8, 2013. 38 Copyright Notice 40 Copyright (c) 2012 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 1.1. Burst and Gap Loss Report Block . . . . . . . . . . . . . 3 57 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 58 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 59 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 61 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 62 3. Burst/Gap Loss Block . . . . . . . . . . . . . . . . . . . . . 6 63 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 64 3.2. Definition of Fields in Burst/Gap Loss Report Block . . . 6 65 3.3. Derived metrics based on reported metrics . . . . . . . . 9 66 4. Considerations for Voice-over-IP applications . . . . . . . . 10 67 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11 68 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 11 69 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 11 70 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 71 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 12 72 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 12 73 6.3. Contact information for registrations . . . . . . . . . . 12 74 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 75 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 14 76 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 77 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 78 10.1. Normative References . . . . . . . . . . . . . . . . . . . 16 79 10.2. Informative References . . . . . . . . . . . . . . . . . . 16 80 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 17 81 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06 . . . . . . . 17 82 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-04 . . . . . . . 17 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 85 1. Introduction 87 1.1. Burst and Gap Loss Report Block 89 This draft defines a new block type to augment those defined in 90 [RFC3611] for use in a range of RTP applications. The new block type 91 supports the reporting of the proportion of packets lost by the 92 network. The losses during loss bursts are reported, together with 93 the number of bursts and additional data allowing the calculation of 94 statistical parameters (mean and variance) of the distribution of 95 burst lengths. Some uses of these metrics depend on the availability 96 of the metric "cumulative number of packets lost" from RTCP 97 [RFC3550]. 99 This block provides information on transient IP problems. Burst/Gap 100 metrics are typically used in Cumulative reports however MAY be used 101 in Interval reports. The burstiness of packet loss affects user 102 experience, may influence any sender strategies to mitigate the 103 problem, and may also have diagnostic value. 105 The metric belongs to the class of transport-related end system 106 metrics defined in [RFC6792]. 108 The definitions of Burst, Gap, Loss and Discard are consistent with 109 definitions in [RFC3611]. To accommodate the range of jitter buffer 110 algorithms and packet discard logic that may be used by implementors, 111 the method used to distinguish between bursts and gaps may be an 112 equivalent method to that defined in [RFC3611]. The method used 113 SHOULD produce the same result as that defined in [RFC3611] for 114 conditions of burst packet loss, but MAY produce different results 115 for conditions of time varying jitter. 117 1.2. RTCP and RTCP XR Reports 119 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 120 defined an extensible structure for reporting using an RTCP Extended 121 Report (XR). This document defines a new Extended Report block for 122 use with [RFC3550] and [RFC3611]. 124 1.3. Performance Metrics Framework 126 The Performance Metrics Framework [RFC6390] provides guidance on the 127 definition and specification of performance metrics. The RTP 128 Monitoring Architectures [RFC6792] provides guideline for reporting 129 block format using RTCP XR. The Metrics Block described in this 130 document are in accordance with the guidelines in [RFC6390] and 131 [RFC6792]. 133 1.4. Applicability 135 These metrics are applicable to a range of RTP applications which 136 don't use stream repair means. 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 loss rate is high 170 enough to cause noticeable quality degradation (generally over 5 171 percent loss rate), and gaps, which are periods during which lost 172 packets are infrequent and hence quality is generally acceptable. 174 3. Burst/Gap Loss Block 176 Metrics in this block report on Burst/Gap Loss in the stream arriving 177 at the RTP system. The measurement of these metrics are made at the 178 receiving end of the RTP stream. Instances of this Metrics Block 179 refer by Synchronization source (SSRC) to the separate auxiliary 180 Measurement Information block [RFC6776] which contains measurement 181 periods (see RFC6776 section 4.2). This metric block relies on the 182 measurement period in the Measurement Information block indicating 183 the span of the report and SHOULD be sent in the same compound RTCP 184 packet as the measurement information block. If the measurement 185 period is not received in the same compound RTCP packet as this 186 metric block, this metric block MUST be discarded. 188 3.1. Report Block Structure 190 Burst/Gap Loss metrics block 192 0 1 2 3 193 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 1 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | BT=NBGL | I |C| resv. | block length = 5 | 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 197 | SSRC of Source | 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 | Threshold | Sum of Burst Durations (ms) | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 | Packets Lost in Bursts | Total... | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 | ...Packets expected in bursts | Number of bursts | Sum of| 204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 205 | ...Squares of Burst Durations (ms-squared) | 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 Figure 1: Report Block Structure 210 3.2. Definition of Fields in Burst/Gap Loss Report Block 212 Block type (BT): 8 bits 214 A Burst/Gap Loss Report Block is identified by the constant NBGL. 216 [Note to RFC Editor: please replace NBGL 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 Loss metrics 222 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 Loss Metric is not measured at a 235 particular time instant but over one or several reporting 236 intervals. Therefore Burst/Gap Loss Metric MUST NOT be chosen as 237 Sampled Metric. 239 Loss and Discard Combination flag (C): 1 bit 241 The 'C' flag is used to indicate whether combining loss/discard 242 report is needed. This field MUST be set to '1' if the burst gap 243 loss report is present in conjunction with the burst gap discard 244 report in the same compound RTCP packet and MUST be set to '0' 245 otherwise. If the burst gap discard is not sent with the burst 246 gap loss, then the receiver MUST discard the burst gap loss with 247 'C' flag set to 1. If the 'C' flag is set to 0, then receiver 248 MUST NOT discard the burst gap loss metric block when the burst 249 gap discard is not received. 251 Reserved (resv): 5 bits 253 These bits are reserved. They SHOULD be set to zero by senders 254 and MUST be ignored by receivers. 256 block length: 16 bits 258 The length of this report block in 32-bit words, minus one. For 259 the Burst/Gap Loss block, the block length is equal to 5. 261 SSRC of source: 32 bits 263 As defined in Section 4.1 of [RFC3611]. 265 Threshold: 8 bits 267 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 268 of successive packets that must be received prior to and following 269 a lost packet in order for this lost packet to be regarded as part 270 of a gap. 272 Sum of Burst Durations (ms): 24 bits 274 The total duration of bursts of lost packets in the period of the 275 report (Interval or Cumulative). 277 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 278 be reported to indicate an over-range measurement. If the 279 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 281 Packets lost in bursts: 24 bits 283 The total number of packets lost during loss bursts. 285 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 286 be reported to indicate an over-range measurement. If the 287 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 289 Total packets expected in bursts: 24 bits 291 The total number of packets expected during loss bursts (that is, 292 the sum of received packets and lost packets). 294 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 295 be reported to indicate an over-range measurement. If the 296 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 298 Number of bursts: 16 bits 300 The number of bursts in the period of the report (Interval or 301 Cumulative). 303 If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be 304 reported to indicate an over-range measurement. If the 305 measurement is unavailable, the value 0xFFFF SHOULD be reported. 307 Sum of Squares of Burst Durations (ms-squared): 36 bits 309 The sum of the squares of burst durations (where individual burst 310 durations are expressed in ms) over in the period of the report 311 (Interval or Cumulative). The units for this quantity are 312 milliseconds-squared. 314 If the measured value exceeds 0xFFFFFFFFD, the value 0xFFFFFFFFE 315 SHOULD be reported to indicate an over-range measurement. If the 316 measurement is unavailable, the value 0xFFFFFFFFF SHOULD be 317 reported. 319 3.3. Derived metrics based on reported metrics 321 The metrics described here are intended to be used as described in 322 this section, in conjunction with information from the Measurement 323 Information block [RFC6776] (which MUST be present in the same RTCP 324 packet as the Burst/Gap Loss block) and also with the metric 325 "cumulative number of packets lost" provided in standard RTCP 326 [RFC3550]. 328 These metrics provides information relevant to statistical 329 parameters, including: 331 o The fraction of packets lost during bursts (i.e., Burst Loss Rate 332 in [SUMSTAT]) 334 o The fraction of packets lost during gaps (i.e., Gap Loss Rate in 335 [SUMSTAT]) 337 o burst duration mean [SUMSTAT] 339 o burst duration variance [SUMSTAT] 341 The details on calculation these parameters in the metrics are 342 described in [SUMSTAT]. 344 4. Considerations for Voice-over-IP applications 346 This metric block is applicable to a broad range of RTP applications. 347 Where the metric is used with a Voice-overIP (VoIP) application and 348 the stream repair means is not available, the following 349 considerations apply. 351 RTCP XR views a call as being divided into bursts, which are periods 352 during which the loss rate is high enough to cause noticeable call 353 quality degradation (generally over 5 percent loss rate), and gaps, 354 which are periods during which lost packets are infrequent and hence 355 call quality is generally acceptable. 357 If Voice Activity Detection is used the Burst and Gap Duration shall 358 be determined as if silence packets had been sent, i.e. a period of 359 silence in excess of Gmin packets MUST terminate a burst condition. 361 The recommended value for the threshold Gmin in [RFC3611] results in 362 a Burst being a period of time during which the call quality is 363 degraded to a similar extent to a typical PCM Severely Errored Second 364 [PSES]. 366 5. SDP Signaling 368 [RFC3611] defines the use of SDP (Session Description Protocol) 369 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 370 without prior signaling. 372 5.1. SDP rtcp-xr-attrib Attribute Extension 374 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 375 in [RFC3611] by providing an additional value of "xr-format" to 376 signal the use of the report block defined in this document. 378 xr-format =/ xr-bgl-block 380 xr-bgl-block = "brst-gap-loss" 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 parameter, 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 NBGL in the IANA " RTP 398 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 399 the "Burst/Gap Loss Metrics Block". 401 [Note to RFC Editor: please replace NBGL 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 "brst-gap-loss" in the " 407 RTP Control Protocol Extended Reports (RTCP XR) Session Description 408 Protocol (SDP) Parameters Registry". 410 6.3. Contact information for registrations 412 The contact information for the registrations is: 414 Qin Wu (sunseawq@huawei.com) 416 101 Software Avenue, Yuhua District 417 Nanjing, Jiangsu 210012 418 China 420 7. Security Considerations 422 It is believed that this proposed RTCP XR report block introduces no 423 new security considerations beyond those described in [RFC3611]. 424 This block does not provide per-packet statistics so the risk to 425 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 426 does not apply. 428 8. Contributors 430 Geoff Hunt wrote the initial draft of this document. 432 9. Acknowledgments 434 The authors gratefully acknowledge reviews and feedback provided by 435 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 436 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 437 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 438 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 439 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada and Adam Roach. 441 10. References 443 10.1. Normative References 445 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 446 Requirement Levels", March 1997. 448 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 449 Applications", RFC 3550, July 2003. 451 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 452 Protocol Extended Reports (RTCP XR)", November 2003. 454 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 455 Description Protocol", July 2006. 457 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 458 Report Block Type for RTP Control Protocol (RTCP) Extended 459 Reports (XRs)", RFC 5725, February 2020. 461 10.2. Informative References 463 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard metric 464 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-09, 465 October 2012. 467 [PSES] "URL", http://www.its.bldrdoc.gov/projects/devglossary/ 468 _severely_errored_second.html, October 2011. 470 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 471 Development", RFC 6390, July 2011. 473 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 474 using SDES item and XR Block", RFC 6776, October 2012. 476 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 477 November 2012. 479 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 480 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-03, 481 November 2012. 483 Appendix A. Change Log 485 Note to the RFC-Editor: please remove this section prior to 486 publication as an RFC. 488 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06 490 The following are the major changes compared to previous version: 492 o SDP update based on SDP Directorate Review. 494 o Add some texts to get consistent with RFC6798 and Delay draft. 496 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-04 498 The following are the major changes compared to previous version: 500 o Outdated reference update. 502 o Editorial changes based on comments that applied to PDV and Delay 503 drafts. 505 Authors' Addresses 507 Alan Clark 508 Telchemy Incorporated 509 2905 Premiere Parkway, Suite 280 510 Duluth, GA 30097 511 USA 513 Email: alan.d.clark@telchemy.com 515 Sunshine Zhang (editor) 516 Shanghai Research Institute of China Telecom Corporation Limited 517 No.1835,South Pudong Road 518 Shanghai 200122 519 China 521 Email: zhangyx@sttri.com.cn 523 Jing Zhao 524 Shanghai Research Institute of China Telecom Corporation Limited 525 No.1835,South Pudong Road 526 Shanghai 200122 527 China 529 Email: zhaojing@sttri.com.cn 531 Qin Wu 532 Huawei 533 101 Software Avenue, Yuhua District 534 Nanjing, Jiangsu 210012 535 China 537 Email: sunseawq@huawei.com