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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 (December 19, 2012) is 4146 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) == Unused Reference: 'RFC6709' is defined on line 374, 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reference: RFC 4566 (Obsoleted by RFC 8866) ** Downref: Normative reference to an Informational RFC: RFC 6709 == Outdated reference: A later version (-14) exists of draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06 == Outdated reference: A later version (-06) exists of draft-ietf-avtext-rtp-duplication-00 Summary: 2 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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: June 22, 2013 Network Zen 6 Q. Wu 7 Huawei 8 December 19, 2012 10 RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count 11 metric Reporting 12 draft-ietf-xrblock-rtcp-xr-discard-11.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 June 22, 2013. 37 Copyright Notice 39 Copyright (c) 2012 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. Change Log . . . . . . . . . . . . . . . . . . . . . 15 79 A.1. draft-ietf-xrblock-rtcp-xr-discard-11 . . . . . . . . . . 15 80 A.2. draft-ietf-xrblock-rtcp-xr-discard-10 . . . . . . . . . . 15 81 A.3. draft-ietf-xrblock-rtcp-xr-discard-09 . . . . . . . . . . 15 82 A.4. draft-ietf-xrblock-rtcp-xr-discard-08 . . . . . . . . . . 15 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 85 1. Introduction 87 1.1. Discard Count Report Block 89 This document 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 number of packets which are received 92 correctly but are never played out, typically because they arrive too 93 late to be played out (buffer underflow) or too early (buffer 94 overflow). The metric is applicable both to systems which use packet 95 loss repair techniques (such as forward error correction [RFC5109] or 96 retransmission [RFC4588]) and to those which do not. 98 This metric is useful for identifying the existence, and 99 characterizing the severity, of a packet transport problem which may 100 affect users' perception of a service delivered over RTP. 102 This block may be used in conjunction with [BGDISCARD] which provides 103 additional information on the pattern of discarded packets. However 104 the metric in [BGDISCARD] may be used independently of the metrics in 105 this block. 107 In case of Discard count Metrics Block sent together with Burst gap 108 discard Metrics Block defined in [BGDISCARD] to the media sender or 109 RTP based network management system, information carried in the 110 discard count Metrics Block and Burst gap discard Metrics Block 111 allows them calculate the some bust gap summary statistics, e.g., gap 112 discard rate. 114 The metric belongs to the class of transport-related end system 115 metrics defined in [RFC6792]. 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 This metric is believed to be applicable to a large class of RTP 136 applications which use a jitter buffer. 138 Discards due to late or early arriving packets affects user 139 experience. The reporting of discards alerts senders and other 140 receivers to the need to adjust their transmission or reception 141 strategies. The reports allow network managers to diagnose these 142 user experience problems. 144 The ability to detect duplicate packets can be used by managers to 145 detect network layer or sender behavior which may indicate network or 146 device issues. Based on the reports, these issues may be addressed 147 prior to any impact on user experience. 149 2. Terminology 151 2.1. Standards Language 153 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 154 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 155 document are to be interpreted as described in RFC 2119 [RFC2119]. 157 In addition, the following terms are defined: 159 Received, Lost and Discarded 161 A packet shall be regarded as lost if it fails to arrive within an 162 implementation-specific time window. A packet that arrives within 163 this time window but is too early or late to be played out or 164 thrown away before playout due to packet duplication or redundancy 165 shall be regarded as discarded. A packet shall be classified as 166 one of received (or OK), discarded or lost. The Discard Count 167 Metric counts only discarded packets. The metric "cumulative 168 number of packets lost" defined in [RFC3550] reports a count of 169 packets lost from the media stream (single SSRC within single RTP 170 session). Similarly the metric "number of packets discarded" 171 reports a count of packets discarded from the media stream (single 172 SSRC within single RTP session) arriving at the receiver. Another 173 metric defined in [RFC5725] is available to report on packets 174 which are not recovered by any repair techniques which may be in 175 use. 177 3. Discard Count Metric Report Block 179 Metrics in this block report on the number of packets discarded in 180 the stream arriving at the RTP end system. The measurement of these 181 metrics is made at the receiving end of the RTP stream. Instances of 182 this Metrics Block refer by SSRC to the separate auxiliary 183 Measurement Information block [RFC6776] which describes measurement 184 Intervals in use. This Metrics Block relies on the measurement 185 interval in the Measurement Information block indicating the span of 186 the report and should be sent in the same compound RTCP packet as the 187 measurement information block. If the measurement interval is not 188 received in the same compound RTCP packet as this Metrics Block, this 189 Metrics Block should be discarded. 191 3.1. Report Block Structure 193 0 1 2 3 194 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 1 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | BT=PDC | I |DT | resv.| block length = 2 | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | SSRC of Source | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | number of packets discarded | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 Figure 1: Report Block Structure 205 3.2. Definition of Fields in Discard Count Metric Report Block 207 Block type (BT): 8 bits 209 A Discard Count Metric Report Block is identified by the constant 210 PDC. 212 [Note to RFC Editor: please replace PDC with the IANA provided 213 RTCP XR block type for this block.] 215 Interval Metric Flag (I): 2 bits 217 This field indicates whether the reported metric is an interval, 218 cumulative, or sampled metric [RFC6792]. The Discard Count Metric 219 can only be measured over definite intervals, and cannot be 220 sampled. Accordingly, the value I=01, indicating a sampled value, 221 MUST NOT be used. The value I=00 is reserved for future 222 definition, and MUST NOT be used. 224 Discard Type (DT): 2bits 226 This field is used to identify the discard type used in this 227 report block. The discard type is defined as follows: 229 00: Report packet discarded or being thrown away before playout 230 due to packets duplication. 232 01: Report packet discarded due to too early to be played out. 234 10: Report packet discarded due to too late to be played out. 236 The value DT=11 is reserved for future definition and MUST NOT be 237 used. 239 An endpoint MAY report any combination of discard types in each 240 reporting interval by including several Discard Count Metric 241 Report Blocks in a single RTCP XR packet. 243 Some systems send duplicate RTP packets for robustness or error 244 resilience. This is NOT RECOMMENDED since it breaks RTCP packet 245 statistics. If duplication is desired for error resilience, the 246 mechanism described in [RTPDUP] can be used, since this will not 247 cause breakage of RTP streams or RTCP statistics. 249 Reserved (resv): 4 bits 251 These bits are reserved. They MUST be set to zero by senders and 252 ignored by receivers (See RFC6709 section 4.2). 254 block length: 16 bits 256 The length of this report block in 32-bit words, minus one, in 257 accordance with the definition in[RFC3611] . This field MUST be 258 set to 2 to match the fixed length of the report block. The block 259 MUST be discarded if the block length is set to a different value. 261 SSRC of source: 32 bits 263 As defined in Section 4.1 of [RFC3611]. 265 number of packets discarded: 32 bits 267 Number of packets discarded over the period (Interval or 268 Cumulative) covered by this report. 270 If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE 271 MUST be reported to indicate an over-range measurement. If the 272 measurement is unavailable, the value 0xFFFFFFFF MUST be reported. 274 Note that the number of packets expected in the period associated 275 with this metric (whether interval or cumulative) is available 276 from the difference between a pair of extended sequence numbers in 277 the Measurement Information block [RFC6776], so need not be 278 repeated in this block. 280 4. SDP Signaling 282 [RFC3611] defines the use of SDP (Session Description Protocol) 283 [RFC4566] for signaling the use of XR blocks. However XR blocks MAY 284 be used without prior signaling (see section 5 of RFC3611). 286 4.1. SDP rtcp-xr-attrib Attribute Extension 288 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 289 in [RFC3611] by providing an additional value of "xr-format" to 290 signal the use of the report block defined in this document. 292 xr-format =/ xr-pdc-block 294 xr-pdc-block = "pkt-dscrd-count" 296 4.2. Offer/Answer Usage 298 When SDP is used in offer-answer context, the SDP Offer/Answer usage 299 defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters 300 applies. For detailed usage of Offer/Answer for unilateral 301 parameter, refer to section 5.2 of [RFC3611]. 303 5. IANA Considerations 305 New block types for RTCP XR are subject to IANA registration. For 306 general guidelines on IANA considerations for RTCP XR, refer to 307 [RFC3611]. 309 5.1. New RTCP XR Block Type value 311 This document assigns the block type value PDC in the IANA " RTP 312 Control Protocol Extended Reports (RTCP XR) Block Type Registry " to 313 the "Discard Count Metrics Block". 315 [Note to RFC Editor: please replace PDC with the IANA provided RTCP 316 XR block type for this block.] 318 5.2. New RTCP XR SDP Parameter 320 This document also registers a new parameter "pkt-dscrd-count" in the 321 " RTP Control Protocol Extended Reports (RTCP XR) Session Description 322 Protocol (SDP) Parameters Registry ". 324 5.3. Contact information for registrations 326 The following contact information is provided for all 327 registrations in this document: 329 Qin Wu (sunseawq@huawei.com) 331 101 Software Avenue, Yuhua District 332 Nanjing, Jiangsu 210012 333 China 335 6. Security Considerations 337 It is believed that this proposed RTCP XR report block introduces no 338 new security considerations beyond those described in [RFC3611]. 339 This block does not provide per-packet statistics so the risk to 340 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 341 does not apply. 343 7. Contributors 345 Geoff Hunt wrote the initial draft of this document. 347 8. Acknowledgments 349 The authors gratefully acknowledge reviews and feedback provided by 350 Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, 351 Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, 352 Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, 353 Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi 354 Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada,Kevin 355 Gross, Varun Singh, Claire Bi, Roni Even, Dan Romascanu and Jonathan 356 Lennox. 358 9. References 360 9.1. Normative References 362 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 363 Requirement Levels", March 1997. 365 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 366 Applications", RFC 3550, July 2003. 368 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 369 Protocol Extended Reports (RTCP XR)", November 2003. 371 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 372 Description Protocol", July 2006. 374 [RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design 375 Considerations for Protocol Extensions", RFC 6709, 376 September 2012. 378 [RFC6776] Hunt, G., "Measurement Identity and information Reporting 379 using SDES item and XR Block", RFC 6776, October 2012. 381 9.2. Informative References 383 [BGDISCARD] 384 Hunt, G., "RTCP XR Report Block for Burst Gap Discard 385 metric Reporting", 386 ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06, 387 October 2012. 389 [RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588, 390 July 2006. 392 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 393 Correction", RFC 5109, July 2006. 395 [RFC5725] Begen, A., "RTCP XR Report Block for Post-Repair Loss 396 metric Reporting", RFC 5725, February 2010. 398 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 399 Development", RFC 6390, October 2011. 401 [RFC6792] Wu, Q., "Monitoring Architectures for RTP", RFC 6792, 402 November 2012. 404 [RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams", 405 ID draft-ietf-avtext-rtp-duplication-00, July 2012. 407 Appendix A. Change Log 409 Note to the RFC-Editor: please remove this section prior to 410 publication as an RFC. 412 A.1. draft-ietf-xrblock-rtcp-xr-discard-11 414 The following are the major changes compared to previous version: 416 o Editorial change t based on SDP Directorate and Colin's Review. 418 A.2. draft-ietf-xrblock-rtcp-xr-discard-10 420 The following are the major changes compared to previous version: 422 o Editorial change to get in line with recently discussed drafts. 424 o Remove DT=3 based on the discussion to summary statistics draft. 426 A.3. draft-ietf-xrblock-rtcp-xr-discard-09 428 The following are the major changes compared to previous version: 430 o SDP Duplicated Parameter Deleting. 432 A.4. draft-ietf-xrblock-rtcp-xr-discard-08 434 The following are the major changes compared to previous version: 436 o Outdated reference update. 438 o Editorial changes based on comments that applied to PDV and Delay 439 drafts. 441 Authors' Addresses 443 Alan Clark 444 Telchemy Incorporated 445 2905 Premiere Parkway, Suite 280 446 Duluth, GA 30097 447 USA 449 Email: alan.d.clark@telchemy.com 451 Glen Zorn 452 Network Zen 453 77/440 Soi Phoomjit, Rama IV Road 454 Phra Khanong, Khlong Toie 455 Bangkok 10110 456 Thailand 458 Phone: +66 (0) 87 502 4274 459 Email: gwz@net-zen.net 461 Qin Wu 462 Huawei 463 101 Software Avenue, Yuhua District 464 Nanjing, Jiangsu 210012 465 China 467 Email: sunseawq@huawei.com