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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) == Unused Reference: 'RFC6709' is defined on line 478, but no explicit reference was found in the text ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) ** Downref: Normative reference to an Informational RFC: RFC 6709 == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-11 == Outdated reference: A later version (-11) exists of draft-ietf-xrblock-rtcp-xr-summary-stat-05 Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 S. Zhang, Ed. 5 Expires: June 24, 2013 J. Zhao 6 STTRI 7 Q. Wu 8 Huawei 9 December 21, 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-07.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 24, 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 . . . . . . . . 11 67 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 12 68 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 12 69 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 12 70 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 71 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 13 72 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 13 73 6.3. Contact information for registrations . . . . . . . . . . 13 74 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 75 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15 76 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 77 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 78 10.1. Normative References . . . . . . . . . . . . . . . . . . . 17 79 10.2. Informative References . . . . . . . . . . . . . . . . . . 17 80 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 18 81 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-07 . . . . . . . 18 82 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06 . . . . . . . 18 83 A.3. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-04 . . . . . . . 18 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 86 1. Introduction 88 1.1. Burst and Gap Loss Report Block 90 This draft defines a new block type to augment those defined in 91 [RFC3611] for use in a range of RTP applications. The new block type 92 supports the reporting of the proportion of packets lost by the 93 network. The losses during loss bursts are reported, together with 94 the number of bursts and additional data allowing the calculation of 95 statistical parameters (mean and variance) of the distribution of 96 burst lengths. Some uses of these metrics depend on the availability 97 of the metric "cumulative number of packets lost" from RTCP 98 [RFC3550]. 100 This block provides information on transient IP problems. Burst/Gap 101 metrics are typically used in Cumulative reports, however they also 102 MAY be used in Interval reports. The burstiness of packet loss 103 affects user experience, may influence any sender strategies to 104 mitigate the problem, and may also have diagnostic value. 106 The metric belongs to the class of transport-related end system 107 metrics defined in [RFC6792]. 109 The definitions of Burst, Gap, Loss and Discard are consistent with 110 definitions in [RFC3611]. To accommodate the range of jitter buffer 111 algorithms and packet discard logic that may be used by implementors, 112 the method used to distinguish between bursts and gaps may be an 113 equivalent method to that defined in [RFC3611]. The method used 114 SHOULD produce the same result as that defined in [RFC3611] for 115 conditions of burst packet loss, but MAY produce different results 116 for conditions of time varying jitter. 118 1.2. RTCP and RTCP XR Reports 120 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 121 defined an extensible structure for reporting using an RTCP Extended 122 Report (XR). This document defines a new Extended Report block for 123 use with [RFC3550] and [RFC3611]. 125 1.3. Performance Metrics Framework 127 The Performance Metrics Framework [RFC6390] provides guidance on the 128 definition and specification of performance metrics. The RTP 129 Monitoring Architectures [RFC6792] provides guideline for reporting 130 block format using RTCP XR. The Metrics Block described in this 131 document are in accordance with the guidelines in [RFC6390] and 132 [RFC6792]. 134 1.4. Applicability 136 These metrics are applicable to a range of RTP applications which 137 contain jitter buffers and don't use stream repair means,e.g., 138 Forward Error Correction (FEC) [RFC5109] and/or retransmission 139 [RFC4588]. 141 2. Terminology 143 2.1. Standards Language 145 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 146 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 147 document are to be interpreted as described in RFC 2119 [RFC2119]. 149 In addition, the following terms are defined: 151 Received, Lost and Discarded 153 A packet shall be regarded as lost if it fails to arrive within an 154 implementation-specific time window. A packet that arrives within 155 this time window but is too early or late to be played out or 156 thrown away before playout due to packet duplication or redundancy 157 shall be regarded as discarded. A packet shall be classified as 158 one of received (or OK), discarded or lost. The metric 159 "cumulative number of packets lost" defined in [RFC3550] reports a 160 count of packets lost from the media stream (single SSRC within 161 single RTP session). Similarly the metric "number of packets 162 discarded" defined in [DISCARD] reports a count of packets 163 discarded from the media stream (single SSRC within single RTP 164 session) arriving at the receiver. Another metric defined in 165 [RFC5725] is available to report on packets which are not 166 recovered by any repair techniques which may be in use. 168 Bursts and Gaps 170 The terms Burst and Gap are used in a manner consistent with that 171 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 172 into bursts, which are periods during which the loss rate is high 173 enough to cause noticeable quality degradation (generally over 5 174 percent loss rate), and gaps, which are periods during which lost 175 packets are infrequent and hence quality is generally acceptable. 177 3. Burst/Gap Loss Block 179 Metrics in this block report on Burst/Gap Loss in the stream arriving 180 at the RTP system. The measurement of these metrics are made at the 181 receiving end of the RTP stream. Instances of this Metrics Block 182 refer by Synchronization source (SSRC) to the separate auxiliary 183 Measurement Information block [RFC6776] which describes measurement 184 periods in use(see RFC6776 section 4.2). This Metrics Block relies 185 on the measurement period in the Measurement Information block 186 indicating the span of the report and SHOULD be sent in the same 187 compound RTCP packet as the measurement information block. If the 188 measurement period is not received in the same compound RTCP packet 189 as this Metrics Block, this Metrics Block MUST be discarded. 191 3.1. Report Block Structure 193 Burst/Gap Loss metrics block 195 0 1 2 3 196 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | BT=NBGL | I |C| resv. | block length = 5 | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | SSRC of Source | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | Threshold | Sum of Burst Durations (ms) | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Packets Lost in Bursts | Total... | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | ...Packets expected in bursts | Number of bursts | Sum of| 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 | ...Squares of Burst Durations (ms-squared) | 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 Figure 1: Report Block Structure 213 3.2. Definition of Fields in Burst/Gap Loss Report Block 215 Block type (BT): 8 bits 217 A Burst/Gap Loss Report Block is identified by the constant NBGL. 219 [Note to RFC Editor: please replace NBGL with the IANA provided 220 RTCP XR block type for this block.] 222 Interval Metric flag (I): 2 bits 224 This field is used to indicate whether the Burst/Gap Loss metrics 225 are Sampled, Interval or Cumulative metrics: 227 I=10: Interval Duration - the reported value applies to the 228 most recent measurement interval duration between successive 229 metrics reports. 231 I=11: Cumulative Duration - the reported value applies to the 232 accumulation period characteristic of cumulative measurements. 234 I=01: Sampled Value - the reported value is a sampled 235 instantaneous value. 237 In this document, Burst/Gap Loss Metrics can only be measured over 238 definite intervals, and cannot be sampled. Accordingly, the value 239 I=01, indicating a sampled value, MUST NOT be used. In addition, 240 the value I=00 is reserved and also MUST NOT be used. The block 241 MUST be discarded if the value I=01 or I=00 is received. 243 Loss and Discard Combination flag (C): 1 bit 245 The 'C' flag is used to indicate whether combining loss/discard 246 report is needed. This field MUST be set to '1' if the burst gap 247 loss report is present in conjunction with the burst gap discard 248 report in the same compound RTCP packet and MUST be set to '0' 249 otherwise. If the burst gap discard is not sent with the burst 250 gap loss, then the receiver MUST discard the burst gap loss with 251 'C' flag set to 1. If the 'C' flag is set to 0, then receiver 252 MUST NOT discard the burst gap loss Metrics Block when the burst 253 gap discard is not received. 255 Reserved (resv): 5 bits 257 These bits are reserved. They MUST be set to zero by senders and 258 ignored by receivers (See RFC6709 section 4.2). The block MUST be 259 discarded if the block length is set to a different value. 261 block length: 16 bits 263 The length of this report block in 32-bit words, minus one. For 264 the Burst/Gap Loss block, the block length is equal to 5. The 265 block MUST be discarded if the block length is set to a different 266 value. 268 SSRC of source: 32 bits 270 As defined in Section 4.1 of [RFC3611]. 272 Threshold: 8 bits 274 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 275 of successive packets that must be received prior to and following 276 a lost packet in order for this lost packet to be regarded as part 277 of a gap. 279 Sum of Burst Durations (ms): 24 bits 281 The total duration of bursts of lost packets in the period of the 282 report (Interval or Cumulative). 284 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be 285 reported to indicate an over-range measurement. If the 286 measurement is unavailable, the value 0xFFFFFF MUST be reported. 288 Packets lost in bursts: 24 bits 290 The total number of packets lost during loss bursts. 292 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be 293 reported to indicate an over-range measurement. If the 294 measurement is unavailable, the value 0xFFFFFF MUST be reported. 296 Total packets expected in bursts: 24 bits 298 The total number of packets expected during loss bursts (that is, 299 the sum of received packets and lost packets). 301 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be 302 reported to indicate an over-range measurement. If the 303 measurement is unavailable, the value 0xFFFFFF MUST be reported. 305 Number of bursts: 16 bits 307 The number of bursts in the period of the report (Interval or 308 Cumulative). 310 If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be 311 reported to indicate an over-range measurement. If the 312 measurement is unavailable, the value 0xFFFF MUST be reported. 314 Sum of Squares of Burst Durations (ms-squared): 36 bits 316 The sum of the squares of burst durations (where individual burst 317 durations are expressed in ms) over in the period of the report 318 (Interval or Cumulative). The units for this quantity are 319 milliseconds-squared. 321 If the measured value exceeds 0xFFFFFFFFD, the value 0xFFFFFFFFE 322 MUST be reported to indicate an over-range measurement. If the 323 measurement is unavailable, the value 0xFFFFFFFFF MUST be 324 reported. 326 3.3. Derived metrics based on reported metrics 328 The metrics described here are intended to be used as described in 329 this section, in conjunction with information from the Measurement 330 Information block [RFC6776] (which MUST be present in the same RTCP 331 packet as the Burst/Gap Loss block) and also with the metric 332 "cumulative number of packets lost" provided in standard RTCP 333 [RFC3550]. 335 These metrics provide information relevant to statistical parameters, 336 including: 338 o The fraction of packets lost during bursts (i.e., Burst Loss Rate 339 in [SUMSTAT]), which can be calculated using the metric " Packets 340 Loss in Bursts " and the metric " Total Packets expected in Bursts 341 " provided in the Burst/Gap Loss metrics block. 343 o The fraction of packets lost during gaps (i.e., Gap Loss Rate in 344 [SUMSTAT]), which can be calculated using the metric " Packets 345 Loss in Bursts " and the metric " Total Packets expected in Bursts 346 " provided in the Burst/Gap Loss metrics block. 348 o burst duration mean [SUMSTAT], which can be calculated using the 349 metric " Packets Loss in Bursts " and the metric " Total Packets 350 expected in Bursts " provided in the Burst/Gap Loss metrics block. 352 o burst duration variance [SUMSTAT], which can be calculated using 353 the metric " Packets Loss in Bursts " and the metric " Total 354 Packets expected in Bursts " provided in the Burst/Gap Loss 355 metrics block. 357 The details on calculation these parameters in the metrics are 358 described in [SUMSTAT]. 360 4. Considerations for Voice-over-IP applications 362 This Metrics Block is applicable to a broad range of RTP 363 applications. Where the metric is used with a Voice-overIP (VoIP) 364 application and the stream repair means is not available, the 365 following considerations apply. 367 RTCP XR views a call as being divided into bursts, which are periods 368 during which the loss rate is high enough to cause noticeable call 369 quality degradation (generally over 5 percent loss rate), and gaps, 370 which are periods during which lost packets are infrequent and hence 371 call quality is generally acceptable. 373 If Voice Activity Detection is used the Burst and Gap Duration shall 374 be determined as if silence packets had been sent, i.e. a period of 375 silence in excess of Gmin packets MUST terminate a burst condition. 377 The recommended value for the threshold Gmin in [RFC3611] results in 378 a Burst being a period of time during which the call quality is 379 degraded to a similar extent to a typical Pulse-Code Modulation(PCM) 380 Severely Errored Second. 382 5. SDP Signaling 384 [RFC3611] defines the use of SDP (Session Description Protocol) 385 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 386 without prior signaling. 388 5.1. SDP rtcp-xr-attrib Attribute Extension 390 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 391 in [RFC3611] by providing an additional value of "xr-format" to 392 signal the use of the report block defined in this document. 394 xr-format =/ xr-bgl-block 396 xr-bgl-block = "brst-gap-loss" 398 5.2. Offer/Answer Usage 400 When SDP is used in offer-answer context, the SDP Offer/Answer usage 401 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 402 applies. For detailed usage in Offer/Answer for unilateral 403 parameter, refer to section 5.2 of [RFC3611]. 405 6. IANA Considerations 407 New block types for RTCP XR are subject to IANA registration. For 408 general guidelines on IANA considerations for RTCP XR, refer to 409 [RFC3611]. 411 6.1. New RTCP XR Block Type value 413 This document assigns the block type value NBGL in the IANA " RTP 414 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 415 the "Burst/Gap Loss Metrics Block". 417 [Note to RFC Editor: please replace NBGL with the IANA provided RTCP 418 XR block type for this block.] 420 6.2. New RTCP XR SDP Parameter 422 This document also registers a new parameter "brst-gap-loss" in the " 423 RTP Control Protocol Extended Reports (RTCP XR) Session Description 424 Protocol (SDP) Parameters Registry". 426 6.3. Contact information for registrations 428 The contact information for the registrations is: 430 Qin Wu (sunseawq@huawei.com) 432 101 Software Avenue, Yuhua District 433 Nanjing, Jiangsu 210012 434 China 436 7. Security Considerations 438 It is believed that this proposed RTCP XR report block introduces no 439 new security considerations beyond those described in [RFC3611]. 440 This block does not provide per-packet statistics so the risk to 441 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 442 does not apply. 444 8. Contributors 446 Geoff Hunt wrote the initial draft of this document. 448 9. Acknowledgments 450 The authors gratefully acknowledge reviews and feedback provided by 451 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 452 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 453 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 454 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 455 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Adam Roach and 456 Dan Romascanu.. 458 10. References 460 10.1. Normative References 462 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 463 Requirement Levels", March 1997. 465 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 466 Applications", RFC 3550, July 2003. 468 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 469 Protocol Extended Reports (RTCP XR)", November 2003. 471 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 472 Description Protocol", July 2006. 474 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 475 Report Block Type for RTP Control Protocol (RTCP) Extended 476 Reports (XRs)", RFC 5725, February 2020. 478 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 479 Considerations for Protocol Extensions", RFC 6709, 480 September 2012. 482 10.2. Informative References 484 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard metric 485 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-11, 486 December 2012. 488 [RFC4588] Rey, J., Leon, D., , A., Varsa, V., and R. Hakenberg, "RTP 489 Retransmission Payload Format", RFC 4588, July 2006. 491 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 492 Correction", RFC 5109, December 2007. 494 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 495 Development", RFC 6390, July 2011. 497 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 498 using SDES item and XR Block", RFC 6776, October 2012. 500 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 501 November 2012. 503 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 504 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-05, 505 December 2012. 507 Appendix A. Change Log 509 Note to the RFC-Editor: please remove this section prior to 510 publication as an RFC. 512 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-07 514 The following are the major changes compared to previous version: 516 o Editorial changes based on comments in the WGLC. 518 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-06 520 The following are the major changes compared to previous version: 522 o SDP update based on SDP Directorate Review. 524 o Add some texts to get consistent with RFC6798 and Delay draft. 526 A.3. draft-ietf-xrblock-rtcp-xr-burst-gap-loss-04 528 The following are the major changes compared to previous version: 530 o Outdated reference update. 532 o Editorial changes based on comments that applied to PDV and Delay 533 drafts. 535 Authors' Addresses 537 Alan Clark 538 Telchemy Incorporated 539 2905 Premiere Parkway, Suite 280 540 Duluth, GA 30097 541 USA 543 Email: alan.d.clark@telchemy.com 545 Sunshine Zhang (editor) 546 Shanghai Research Institute of China Telecom Corporation Limited 547 No.1835,South Pudong Road 548 Shanghai 200122 549 China 551 Email: zhangyx@sttri.com.cn 553 Jing Zhao 554 Shanghai Research Institute of China Telecom Corporation Limited 555 No.1835,South Pudong Road 556 Shanghai 200122 557 China 559 Email: zhaojing@sttri.com.cn 561 Qin Wu 562 Huawei 563 101 Software Avenue, Yuhua District 564 Nanjing, Jiangsu 210012 565 China 567 Email: sunseawq@huawei.com