idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-discard-13.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 seems to use 'NOT RECOMMENDED' as an RFC 2119 keyword, but does not include the phrase in its RFC 2119 key words list. -- The document date (April 27, 2013) is 4010 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) == Missing Reference: 'RFCXXXX' is mentioned on line 451, but not defined == Unused Reference: 'RFC6709' is defined on line 393, 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reference: RFC 4566 (Obsoleted by RFC 8866) ** Downref: Normative reference to an Informational RFC: RFC 6709 == Outdated reference: A later version (-06) exists of draft-ietf-avtext-rtp-duplication-02 Summary: 2 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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 G. Zorn 5 Expires: October 29, 2013 Network Zen 6 Q. Wu 7 Huawei 8 April 27, 2013 10 RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count 11 metric Reporting 12 draft-ietf-xrblock-rtcp-xr-discard-13.txt 14 Abstract 16 This document defines an RTP Control Protocol(RTCP) Extended Report 17 (XR) Block that allows the reporting of a simple discard count metric 18 for use in a range of RTP applications. 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on October 29, 2013. 37 Copyright Notice 39 Copyright (c) 2013 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 1.1. Discard Count Report Block . . . . . . . . . . . . . . . . 3 56 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 57 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 58 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 59 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 61 3. Discard Count Metric Report Block . . . . . . . . . . . . . . 6 62 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 63 3.2. Definition of Fields in Discard Count Metric Report 64 Block . . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 66 4.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9 67 4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9 68 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 69 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10 70 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 71 5.3. Contact information for registrations . . . . . . . . . . 10 72 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 73 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12 74 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 75 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 76 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 77 9.2. Informative References . . . . . . . . . . . . . . . . . . 14 78 Appendix A. Metrics represented using RFC6390 Template . . . . . 15 79 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 16 80 B.1. draft-ietf-xrblock-rtcp-xr-discard-13 . . . . . . . . . . 16 81 B.2. draft-ietf-xrblock-rtcp-xr-discard-12 . . . . . . . . . . 16 82 B.3. draft-ietf-xrblock-rtcp-xr-discard-11 . . . . . . . . . . 16 83 B.4. draft-ietf-xrblock-rtcp-xr-discard-10 . . . . . . . . . . 16 84 B.5. draft-ietf-xrblock-rtcp-xr-discard-09 . . . . . . . . . . 16 85 B.6. draft-ietf-xrblock-rtcp-xr-discard-08 . . . . . . . . . . 16 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 88 1. Introduction 90 1.1. Discard Count Report Block 92 This document defines a new block type to augment those defined in 93 [RFC3611] for use in a range of RTP applications. The new block type 94 supports the reporting of the number of packets which are received 95 correctly but are never played out, typically because they arrive too 96 late to be played out (buffer underflow) or too early (buffer 97 overflow). The metric is applicable both to systems which use packet 98 loss repair techniques (such as forward error correction [RFC5109] or 99 retransmission [RFC4588]) and to those which do not. 101 This metric is useful for identifying the existence, and 102 characterizing the severity, of a packet transport problem which may 103 affect users' perception of a service delivered over RTP. 105 This block may be used in conjunction with [BGDISCARD] which provides 106 additional information on the pattern of discarded packets. However 107 the metric in [BGDISCARD] may be used independently of the metrics in 108 this block. 110 In case of Discard Count Metrics Block sent together with Burst Gap 111 Discard Metrics Block defined in [BGDISCARD] to the media sender or 112 RTP based network management system, information carried in the 113 Discard Count Metrics Block and Burst Gap Discard Metrics Block 114 allows them calculate the some bust gap summary statistics, e.g., gap 115 discard rate. 117 The metric belongs to the class of transport-related end system 118 metrics defined in [RFC6792]. 120 1.2. RTCP and RTCP XR Reports 122 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 123 defined an extensible structure for reporting using an RTCP Extended 124 Report (XR). This document defines a new Extended Report block for 125 use with [RFC3550] and [RFC3611]. 127 1.3. Performance Metrics Framework 129 The Performance Metrics Framework [RFC6390] provides guidance on the 130 definition and specification of performance metrics. The RTP 131 Monitoring Architectures [RFC6792] provides guideline for reporting 132 block format using RTCP XR. The metrics block described in this 133 document are in accordance with the guidelines in [RFC6390] and 134 [RFC6792]. 136 1.4. Applicability 138 This metric is believed to be applicable to a large class of RTP 139 applications which use a jitter buffer. 141 Discards due to late or early arriving packets affects user 142 experience. The reporting of discards alerts senders and other 143 receivers to the need to adjust their transmission or reception 144 strategies. The reports allow network managers to diagnose these 145 user experience problems. 147 The ability to detect duplicate packets can be used by managers to 148 detect network layer or sender behavior which may indicate network or 149 device issues. Based on the reports, these issues may be addressed 150 prior to any impact on user experience. 152 2. Terminology 154 2.1. Standards Language 156 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 157 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 158 document are to be interpreted as described in RFC 2119 [RFC2119]. 160 In addition, the following terms are defined: 162 Received, Lost and Discarded 164 A packet shall be regarded as lost if it fails to arrive within an 165 implementation-specific time window. A packet that arrives within 166 this time window but is either too early to be played out or too 167 late to be played out or thrown away before playout due to packet 168 duplication or redundancy shall be regarded as discarded. A 169 packet shall not be regarded as discarded if it arrives within 170 this time window but is dropped during decoding by some higher 171 layer decoder, e.g., due to a decoding error. A packet shall be 172 classified as one of received (or OK), discarded or lost. The 173 Discard Count Metric counts only discarded packets. The metric 174 "cumulative number of packets lost" defined in [RFC3550] reports a 175 count of packets lost from the media stream (single 176 Synchronization source (SSRC) within single RTP session). 177 Similarly the metric "number of packets discarded" reports a count 178 of packets discarded from the media stream (single SSRC within 179 single RTP session) arriving at the receiver. Another metric 180 defined in [RFC5725] is available to report on packets which are 181 not recovered by any repair techniques which may be in use. 183 3. Discard Count Metric Report Block 185 Metrics in this block report on the number of packets discarded in 186 the stream arriving at the RTP end system. The measurement of these 187 metrics is made at the receiving end of the RTP stream. Instances of 188 this metrics block refer by SSRC to the separate auxiliary 189 Measurement Information Block [RFC6776] which describes measurement 190 Intervals in use. This metrics block relies on the measurement 191 interval in the Measurement Information Block indicating the span of 192 the report and MUST be sent in the same compound RTCP packet as the 193 measurement information block. If the measurement interval is not 194 received in the same compound RTCP packet as this metrics block, this 195 metrics block MUST be discarded. 197 3.1. Report Block Structure 199 0 1 2 3 200 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 1 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | BT=PDC | I |DT | resv.| block length = 2 | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | SSRC of Source | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | number of packets discarded | 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 Figure 1: Report Block Structure 211 3.2. Definition of Fields in Discard Count Metric Report Block 213 Block type (BT): 8 bits 215 A Discard Count Metric Report Block is identified by the constant 216 PDC. 218 [Note to RFC Editor: please replace PDC with the IANA provided 219 RTCP XR block type for this block.] 221 Interval Metric Flag (I): 2 bits 223 This field indicates whether the reported metric is an interval, 224 cumulative, or sampled metric [RFC6792]: 226 I=10: Interval Duration - the reported value applies to the 227 most recent measurement interval duration between successive 228 metrics reports. 230 I=11: Cumulative Duration - the reported value applies to the 231 accumulation period characteristic of cumulative measurements. 233 I=01: Sampled Value - the reported value is a sampled 234 instantaneous value. 236 In this document, the Discard Count Metric can only be measured 237 over definite intervals, and cannot be sampled. Accordingly, the 238 value I=01, indicating a sampled value, MUST NOT be sent, and MUST 239 be discarded when received. In addition, the value I=00 is 240 reserved and also MUST NOT be sent, and MUST be discarded when 241 received. 243 Discard Type (DT): 2bits 245 This field is used to identify the discard type used in this 246 report block. The discard type is defined as follows: 248 00: Report packet discarded or being thrown away before playout 249 due to packets duplication. 251 01: Report packet discarded due to too early to be played out. 253 10: Report packet discarded due to too late to be played out. 255 The value DT=11 is reserved for future definition and MUST NOT be 256 Sent,and MUST be discarded when received. 258 An endpoint MAY report any combination of discard types in each 259 reporting interval by including several Discard Count Metric 260 Report Blocks in a single RTCP XR packet. 262 Some systems send duplicate RTP packets for robustness or error 263 resilience. This is NOT RECOMMENDED since it breaks RTCP packet 264 statistics. If duplication is desired for error resilience, the 265 mechanism described in [RTPDUP] can be used, since this will not 266 cause breakage of RTP streams or RTCP statistics. 268 Reserved (resv): 4 bits 270 These bits are reserved. They MUST be set to zero by senders and 271 ignored by receivers (See RFC6709 section 4.2). 273 block length: 16 bits 275 The length of this report block in 32-bit words, minus one, in 276 accordance with the definition in [RFC3611]. This field MUST be 277 set to 2 to match the fixed length of the report block. The block 278 MUST be discarded if the block length is set to a different value. 280 SSRC of source: 32 bits 282 As defined in Section 4.1 of [RFC3611]. 284 number of packets discarded: 32 bits 286 Number of packets discarded over the period (Interval or 287 Cumulative) covered by this report. 289 The measured value is unsigned value. If the measured value 290 exceeds 0xFFFFFFFD, the value 0xFFFFFFFE MUST be reported to 291 indicate an over-range measurement. If the measurement is 292 unavailable, the value 0xFFFFFFFF MUST be reported. 294 Note that the number of packets expected in the period associated 295 with this metric (whether interval or cumulative) is available 296 from the difference between a pair of extended sequence numbers in 297 the Measurement Information block [RFC6776], so need not be 298 repeated in this block. 300 4. SDP Signaling 302 [RFC3611] defines the use of SDP (Session Description Protocol) 303 [RFC4566] for signaling the use of XR blocks. However XR blocks MAY 304 be used without prior signaling (see section 5 of RFC3611). 306 4.1. SDP rtcp-xr-attrib Attribute Extension 308 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 309 in [RFC3611] by providing an additional value of "xr-format" to 310 signal the use of the report block defined in this document. 312 xr-format =/ xr-pdc-block 313 xr-pdc-block = "pkt-discard-count" 315 4.2. Offer/Answer Usage 317 When SDP is used in offer-answer context, the SDP Offer/Answer usage 318 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 319 applies. For detailed usage of Offer/Answer for unilateral 320 parameter, refer to section 5.2 of [RFC3611]. 322 5. IANA Considerations 324 New block types for RTCP XR are subject to IANA registration. For 325 general guidelines on IANA considerations for RTCP XR, refer to 326 [RFC3611]. 328 5.1. New RTCP XR Block Type value 330 This document assigns the block type value PDC in the IANA " RTP 331 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 332 the "Discard Count Metrics Block". 334 [Note to RFC Editor: please replace PDC with the IANA provided RTCP 335 XR block type for this block.] 337 5.2. New RTCP XR SDP Parameter 339 This document also registers a new parameter "pkt-discard-count" in 340 the " RTP Control Protocol Extended Reports (RTCP XR) Session 341 Description Protocol (SDP) Parameters Registry ". 343 5.3. Contact information for registrations 345 The following contact information is provided for all 346 registrations in this document: 348 Qin Wu (sunseawq@huawei.com) 350 101 Software Avenue, Yuhua District 351 Nanjing, Jiangsu 210012 352 China 354 6. Security Considerations 356 It is believed that this proposed RTCP XR report block introduces no 357 new security considerations beyond those described in [RFC3611]. 358 This block does not provide per-packet statistics so the risk to 359 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 360 does not apply. 362 7. Contributors 364 Geoff Hunt wrote the initial draft of this document. 366 8. Acknowledgments 368 The authors gratefully acknowledge reviews and feedback provided by 369 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 370 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 371 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 372 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 373 Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada, Kevin 374 Gross, Varun Singh, Claire Bi, Roni Even, Dan Romascanu and Jonathan 375 Lennox. 377 9. References 379 9.1. Normative References 381 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 382 Requirement Levels", March 1997. 384 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 385 Applications", RFC 3550, July 2003. 387 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 388 Protocol Extended Reports (RTCP XR)", November 2003. 390 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 391 Description Protocol", July 2006. 393 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 394 Considerations for Protocol Extensions", RFC 6709, 395 September 2012. 397 [RFC6776] Hunt, G., "Measurement Identity and information Reporting 398 using SDES item and XR Block", RFC 6776, October 2012. 400 9.2. Informative References 402 [BGDISCARD] 403 Hunt, G., "RTCP XR Report Block for Burst Gap Discard 404 metric Reporting", 405 ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-14, 406 April 2013. 408 [RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588, 409 July 2006. 411 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 412 Correction", RFC 5109, July 2006. 414 [RFC5725] Begen, A., "RTCP XR Report Block for Post-Repair Loss 415 metric Reporting", RFC 5725, February 2010. 417 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 418 Development", RFC 6390, October 2011. 420 [RFC6792] Wu, Q., "Monitoring Architectures for RTP", RFC 6792, 421 November 2012. 423 [RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams", 424 ID draft-ietf-avtext-rtp-duplication-02, March 2013. 426 Appendix A. Metrics represented using RFC6390 Template 428 RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC 429 number, when assigned. 431 a. Number of packets discarded Metric 433 * Metric Name: Number of RTP packets discarded Metric 435 * Metric Description: Number of RTP packets discarded over the 436 period covered by this report. 438 * Method of Measurement or Calculation: See section 3.2, number 439 of packets discarded definition [RFCXXXX]. 441 * Units of Measurement: See section 3.2, number of packets 442 discarded definition [RFCXXXX]. 444 * Measurement Point(s) with Potential Measurement Domain: See 445 section 3, 1st paragraph [RFCXXXX]. 447 * Measurement Timing: See section 3, 1st paragraph [RFCXXXX] for 448 measurement timing and section 3.2 [RFCXXXX] for Interval 449 Metric flag. 451 * Use and applications: See section 1.4 [RFCXXXX]. 453 * Reporting model: See RFC3611. 455 Appendix B. Change Log 457 Note to the RFC-Editor: please remove this section prior to 458 publication as an RFC. 460 B.1. draft-ietf-xrblock-rtcp-xr-discard-13 462 The following are the major changes compared to previous version: 464 o Some editorial changes to get in line with burst gap drafts. 466 B.2. draft-ietf-xrblock-rtcp-xr-discard-12 468 The following are the major changes compared to previous version: 470 o Incorporate some changes to burst gap draft that applies to this 471 document. 473 o Use RFC6390 template to the metrics in the appendix. 475 B.3. draft-ietf-xrblock-rtcp-xr-discard-11 477 The following are the major changes compared to previous version: 479 o Editorial change t based on SDP Directorate and Colin's Review. 481 B.4. draft-ietf-xrblock-rtcp-xr-discard-10 483 The following are the major changes compared to previous version: 485 o Editorial change to get in line with recently discussed drafts. 487 o Remove DT=3 based on the discussion to summary statistics draft. 489 B.5. draft-ietf-xrblock-rtcp-xr-discard-09 491 The following are the major changes compared to previous version: 493 o SDP Duplicated Parameter Deleting. 495 B.6. draft-ietf-xrblock-rtcp-xr-discard-08 497 The following are the major changes compared to previous version: 499 o Outdated reference update. 501 o Editorial changes based on comments that applied to PDV and Delay 502 drafts. 504 Authors' Addresses 506 Alan Clark 507 Telchemy Incorporated 508 2905 Premiere Parkway, Suite 280 509 Duluth, GA 30097 510 USA 512 Email: alan.d.clark@telchemy.com 514 Glen Zorn 515 Network Zen 516 77/440 Soi Phoomjit, Rama IV Road 517 Phra Khanong, Khlong Toie 518 Bangkok 10110 519 Thailand 521 Phone: +66 (0) 87 502 4274 522 Email: gwz@net-zen.net 524 Qin Wu 525 Huawei 526 101 Software Avenue, Yuhua District 527 Nanjing, Jiangsu 210012 528 China 530 Email: sunseawq@huawei.com