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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 426, 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reference: RFC 4566 (Obsoleted by RFC 8866) ** Downref: Normative reference to an Informational RFC: RFC 6709 == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-11 == Outdated reference: A later version (-11) exists of draft-ietf-xrblock-rtcp-xr-summary-stat-05 Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 R. Huang 5 Expires: June 24, 2013 Q. Wu, Ed. 6 Huawei 7 December 21, 2012 9 RTP Control Protocol(RTCP) Extended Report (XR) Block for Burst/Gap 10 Discard metric Reporting 11 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09.txt 13 Abstract 15 This document defines an RTP Control Protocol(RTCP) Extended Report 16 (XR) Block that allows the reporting of Burst and Gap Discard metrics 17 for use in a range of RTP applications. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on June 24, 2013. 36 Copyright Notice 38 Copyright (c) 2012 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 1.1. Burst and Gap Discard Report Block . . . . . . . . . . . . 3 55 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 56 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 57 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 60 3. Burst/Gap Discard Block . . . . . . . . . . . . . . . . . . . 6 61 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 62 3.2. Definition of Fields in Burst/Gap Discard Report Block . . 6 63 3.3. Derived metrics based on reported metrics . . . . . . . . 8 64 4. Considerations for Voice-over-IP applications . . . . . . . . 9 65 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 10 66 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 10 67 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 10 68 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 69 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 11 70 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 11 71 6.3. Contact information for registrations . . . . . . . . . . 11 72 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 73 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 13 74 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 75 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 76 10.1. Normative References . . . . . . . . . . . . . . . . . . . 15 77 10.2. Informative References . . . . . . . . . . . . . . . . . . 15 78 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16 79 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 . . . . . 16 80 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 . . . . . 16 81 A.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 . . . . . 16 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 84 1. Introduction 86 1.1. Burst and Gap Discard Report Block 88 This document defines a new block type to augment those defined in 89 [RFC3611] for use in a range of RTP applications. The new block type 90 supports the reporting of the proportion of packets discarded by the 91 receiver due to jitter. The discards during discard bursts are 92 reported, together with the number of bursts. This block is intended 93 to be used in conjunction with [DISCARD] which provides the total 94 packets discarded, and on which this block therefore depends. 95 However the metric in [DISCARD] may be used independently of the 96 metrics in this block. 98 This block provides information on transient IP problems. Burst/Gap 99 metrics are typically used in Cumulative reports, however they also 100 MAY be used in Interval reports. The burstiness of packet discard 101 affects user experience, may influence any sender strategies to 102 mitigate the problem, and may also have diagnostic value. 104 The metric belongs to the class of transport-related end system 105 metrics defined in [RFC6792]. 107 The definitions of Burst, Gap, Loss and Discard are consistent with 108 definitions in [RFC3611]. To accommodate the range of jitter buffer 109 algorithms and packet discard logic that may be used by implementors, 110 the method used to distinguish between bursts and gaps may be an 111 equivalent method to that defined in[RFC3611]. 113 1.2. RTCP and RTCP XR Reports 115 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 116 defined an extensible structure for reporting using an RTCP Extended 117 Report (XR). This document defines a new Extended Report block for 118 use with [RFC3550] and [RFC3611]. 120 1.3. Performance Metrics Framework 122 The Performance Metrics Framework [RFC6390] provides guidance on the 123 definition and specification of performance metrics. The RTP 124 Monitoring Architectures [RFC6792] provides guideline for reporting 125 block format using RTCP XR. The Metrics Block described in this 126 document are in accordance with the guidelines in [RFC6390] and 127 [RFC6792]. 129 1.4. Applicability 131 These metrics are applicable to a range of RTP applications which 132 contain jitter buffers and don't use stream repair means,e.g., 133 Forward Error Correction (FEC) [RFC5109] and/or retransmission 134 [RFC4588]. 136 2. Terminology 138 2.1. Standards Language 140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 142 document are to be interpreted as described in RFC 2119 [RFC2119]. 144 In addition, the following terms are defined: 146 Received, Lost and Discarded 148 A packet shall be regarded as lost if it fails to arrive within an 149 implementation-specific time window. A packet that arrives within 150 this time window but is too early or late to be played out or 151 thrown away before playout due to packet duplication or redundancy 152 shall be regarded as discarded. A packet shall be classified as 153 one of received (or OK), discarded or lost. The metric 154 "cumulative number of packets lost" defined in [RFC3550] reports a 155 count of packets lost from the media stream (single SSRC within 156 single RTP session). Similarly the metric "number of packets 157 discarded" defined in [DISCARD] reports a count of packets 158 discarded from the media stream (single SSRC within single RTP 159 session) arriving at the receiver. Another metric defined in 160 [RFC5725] is available to report on packets which are not 161 recovered by any repair techniques which may be in use. 163 Bursts and Gaps 165 The terms Burst and Gap are used in a manner consistent with that 166 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 167 into bursts, which are periods during which the discard rate is 168 high enough to cause noticeable quality degradation (generally 169 over 5 percent discard rate), and gaps, which are periods during 170 which discarded packets are infrequent and hence quality is 171 generally acceptable. 173 3. Burst/Gap Discard Block 175 Metrics in this block report on Burst/Gap Discard in the stream 176 arriving at the RTP system. The measurement of these metrics are 177 made at the receiving end of the RTP stream. Instances of this 178 Metrics Block refer by Synchronization source (SSRC) to the separate 179 auxiliary Measurement Information block [RFC6776] which describes 180 measurement periods in use (see RFC6776 section 4.2). This Metrics 181 Block relies on the measurement period in the Measurement Information 182 block indicating the span of the report and SHOULD be sent in the 183 same compound RTCP packet as the measurement information block. If 184 the measurement period is not received in the same compound RTCP 185 packet as this Metrics Block, this Metrics Block MUST be discarded. 187 3.1. Report Block Structure 189 Burst/Gap Discard metrics block 191 0 1 2 3 192 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 1 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | BT=NBGD | I | resv. | block length = 3 | 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | SSRC of Source | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | Threshold | Packets Discarded in Bursts | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | Total Packets expected in bursts | Reserved. | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 Figure 1: Report Block Structure 205 3.2. Definition of Fields in Burst/Gap Discard Report Block 207 Block type (BT): 8 bits 209 A Burst/Gap Discard Report Block is identified by the constant 210 NBGD. 212 [Note to RFC Editor: please replace NBGD with the IANA provided 213 RTCP XR block type for this block.] 215 Interval Metric flag (I): 2 bits 217 This field is used to indicate whether the Burst/Gap Discard 218 metrics are Sampled, Interval or Cumulative metrics: 220 I=10: Interval Duration - the reported value applies to the 221 most recent measurement interval duration between successive 222 metrics reports. 224 I=11: Cumulative Duration - the reported value applies to the 225 accumulation period characteristic of cumulative measurements. 227 I=01: Sampled Value - the reported value is a sampled 228 instantaneous value. 230 In this document, Burst/Gap Discard Metrics can only be measured 231 over definite intervals, and cannot be sampled. Accordingly, the 232 value I=01, indicating a sampled value, MUST NOT be used. In 233 addition, the value I=00 is reserved and also MUST NOT be used. 234 The block MUST be discarded if the value I=01 or I=00 is received. 236 Reserved (resv): 6 bits 238 These bits are reserved. They MUST be set to zero by senders and 239 ignored by receivers (See RFC6709 section 4.2). 241 block length: 16 bits 243 The length of this report block in 32-bit words, minus one. For 244 the Burst/Gap discard block, the block length is equal to 3. The 245 block MUST be discarded if the block length is set to a different 246 value. 248 SSRC of source: 32 bits 250 As defined in Section 4.1 of [RFC3611]. 252 Threshold: 8 bits 254 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 255 of successive packets that must not be discarded prior to and 256 following a discard packet in order for this discarded packet to 257 be regarded as part of a gap. 259 Packets discarded in bursts: 24 bits 261 The total number of packets discarded during discard bursts. 263 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be 264 reported to indicate an over-range measurement. If the 265 measurement is unavailable, the value 0xFFFFFF MUST be reported. 267 Total packets expected in bursts: 24 bits 269 The total number of packets expected during discarded bursts (that 270 is, the sum of received packets and lost packets). 272 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be 273 reported to indicate an over-range measurement. If the 274 measurement is unavailable, the value 0xFFFFFF MUST be reported. 276 Reserved (resv): 8 bits 278 These bits are reserved. They MUST be set to zero by senders and 279 ignored by receivers (See RFC6709 section 4.2). 281 3.3. Derived metrics based on reported metrics 283 The metrics described here are intended to be used in conjunction 284 with information from the Measurement Information block [RFC6776] 285 (which MUST be present in the same RTCP packet as the Burst/Gap 286 Discard block) and also with the metric "number of packets discarded" 287 provided in the RTCP XR Discard Count Block [DISCARD]. The RTCP XR 288 Discard Count Block SHOULD be sent if the Burst/Gap Discard block is 289 sent, but the converse does not apply. 291 These metrics provide the following information relevant to 292 statistical parameters, including: 294 o The fraction of packets discarded during bursts (burst discard 295 rate in [SUMSTAT]), which can be calculated using the metric " 296 Packets Discarded in Bursts " and the metric " Total Packets 297 expected in Bursts " provided in the Burst/Gap Discard metrics 298 block. 300 o The fraction of packets discarded during gaps (gap discard rate in 301 [SUMSTAT]), which can be calculated using the metric " Packets 302 Discarded in Bursts " and the metric " Total Packets expected in 303 Bursts " provided in the Burst/Gap Discard metrics block. 305 The details on calculation these parameters in the metrics are 306 described in [SUMSTAT]. 308 4. Considerations for Voice-over-IP applications 310 This Metrics Block is applicable to a broad range of RTP 311 applications. Where the metric is used with a Voice-overIP (VoIP) 312 application and the stream repair means is not available, the 313 following considerations apply. 315 RTCP XR views a call as being divided into bursts, which are periods 316 during which the discard rate is high enough to cause noticeable call 317 quality degradation (generally over 5 percent discard rate), and 318 gaps, which are periods during which discarded packets are infrequent 319 and hence call quality is generally acceptable. 321 If Voice Activity Detection is used the Burst and Gap Duration shall 322 be determined as if silence packets had been sent, i.e. a period of 323 silence in excess of Gmin packets MUST terminate a burst condition. 325 The recommended value for the threshold Gmin in [RFC3611] results in 326 a Burst being a period of time during which the call quality is 327 degraded to a similar extent to a typical Pulse-Code Modulation(PCM) 328 Severely Errored Second. 330 5. SDP Signaling 332 [RFC3611] defines the use of SDP (Session Description Protocol) 333 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 334 without prior signaling. 336 5.1. SDP rtcp-xr-attrib Attribute Extension 338 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 339 in [RFC3611] by providing an additional value of "xr-format" to 340 signal the use of the report block defined in this document. 342 xr-format =/ xr-bgd-block 344 xr-bgd-block = "brst-gap-dscrd" 346 5.2. Offer/Answer Usage 348 When SDP is used in offer-answer context, the SDP Offer/Answer usage 349 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 350 applies. For detailed usage in Offer/Answer for unilateral 351 parameter, refer to section 5.2 of [RFC3611]. 353 6. IANA Considerations 355 New block types for RTCP XR are subject to IANA registration. For 356 general guidelines on IANA considerations for RTCP XR, refer to 357 [RFC3611]. 359 6.1. New RTCP XR Block Type value 361 This document assigns the block type value NBGD in the IANA " RTP 362 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 363 the "Burst/Gap Discard Metrics Block". 365 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 366 XR block type for this block.] 368 6.2. New RTCP XR SDP Parameter 370 This document also registers a new parameter "brst-gap-dscrd" in the 371 "RTP Control Protocol Extended Reports (RTCP XR) Session Description 372 Protocol (SDP) Parameters Registry". 374 6.3. Contact information for registrations 376 The contact information for the registrations is: 378 Qin Wu (sunseawq@huawei.com) 380 101 Software Avenue, Yuhua District 381 Nanjing, Jiangsu 210012 382 China 384 7. Security Considerations 386 It is believed that this proposed RTCP XR report block introduces no 387 new security considerations beyond those described in [RFC3611]. 388 This block does not provide per-packet statistics so the risk to 389 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 390 does not apply. 392 8. Contributors 394 Geoff Hunt wrote the initial draft of this document. 396 9. Acknowledgments 398 The authors gratefully acknowledge reviews and feedback provided by 399 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 400 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 401 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 402 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 403 Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Paul 404 Kyzivat,Claire Bi and Dan Romascanu. 406 10. References 408 10.1. Normative References 410 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 411 Requirement Levels", March 1997. 413 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 414 Applications", RFC 3550, July 2003. 416 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 417 Protocol Extended Reports (RTCP XR)", November 2003. 419 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 420 Description Protocol", July 2006. 422 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 423 Report Block Type for RTP Control Protocol (RTCP) Extended 424 Reports (XRs)", RFC 5725, February 2020. 426 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 427 Considerations for Protocol Extensions", RFC 6709, 428 September 2012. 430 10.2. Informative References 432 [DISCARD] Wu, Q., "RTCP XR Report Block for Discard Count metric 433 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-11, 434 December 2012. 436 [RFC4588] Rey, J., Leon, D., , A., Varsa, V., and R. Hakenberg, "RTP 437 Retransmission Payload Format", RFC 4588, July 2006. 439 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 440 Correction", RFC 5109, December 2007. 442 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 443 Development", RFC 6390, October 2011. 445 [RFC6776] Wu, Q., "Measurement Identity and information Reporting 446 using SDES item and XR Block", RFC 6776, October 2012. 448 [RFC6792] Hunt, G., "Monitoring Architectures for RTP", RFC 6792, 449 November 2012. 451 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 452 Reporting", ID draft-ietf-xrblock-rtcp-xr-summary-stat-05, 453 December 2012. 455 Appendix A. Change Log 457 Note to the RFC-Editor: please remove this section prior to 458 publication as an RFC. 460 A.1. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-09 462 The following are the major changes compared to previous version: 464 o Editorial changes based on comments received in WGLC. 466 A.2. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-08 468 The following are the major changes compared to previous version: 470 o SDP update based on SDP Directorate Review. 472 o Add some texts to get consistent with RFC6798 and Delay draft. 474 A.3. draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 476 The following are the major changes compared to previous version: 478 o Outdated reference update. 480 o Editorial changes based on comments that applied to PDV and Delay 481 drafts. 483 Authors' Addresses 485 Alan Clark 486 Telchemy Incorporated 487 2905 Premiere Parkway, Suite 280 488 Duluth, GA 30097 489 USA 491 Email: alan.d.clark@telchemy.com 493 Rachel Huang 494 Huawei Technologies Co., Ltd. 495 101 Software Avenue, Yuhua District 496 Nanjing, Jiangsu 210012 497 China 499 Email: Rachel@huawei.com 501 Qin Wu (editor) 502 Huawei 503 101 Software Avenue, Yuhua District 504 Nanjing, Jiangsu 210012 505 China 507 Email: sunseawq@huawei.com