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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 (September 11, 2012) is 4242 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-14) exists of draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05 == Outdated reference: A later version (-10) exists of draft-ietf-xrblock-rtcp-xr-meas-identity-06 == Outdated reference: A later version (-22) exists of draft-ietf-avtcore-monarch-12 == Outdated reference: A later version (-06) exists of draft-ietf-avtext-rtp-duplication-00 Summary: 1 error (**), 0 flaws (~~), 6 warnings (==), 1 comment (--).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: March 15, 2013 Network Zen 6 Q. Wu 7 Huawei 8 September 11, 2012 10 RTCP XR Report Block for Discard Count metric Reporting 11 draft-ietf-xrblock-rtcp-xr-discard-07.txt 13 Abstract 15 This document defines an RTCP XR Report Block that allows the 16 reporting of a simple discard count metric for use in a range of RTP 17 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 March 15, 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. Discard Count 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. Discard Count Metric Report Block . . . . . . . . . . . . . . 6 61 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 62 3.2. Definition of Fields in Discard Count Metric Report 63 Block . . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 66 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10 67 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 68 5.3. Contact information for registrations . . . . . . . . . . 10 69 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 70 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12 71 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 72 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 73 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 74 9.2. Informative References . . . . . . . . . . . . . . . . . . 14 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 77 1. Introduction 79 1.1. Discard Count Report Block 81 This document defines a new block type to augment those defined in 82 [RFC3611] for use in a range of RTP applications. The new block type 83 supports the reporting of the number of packets which are received 84 correctly but are never played out, typically because they arrive too 85 late to be played out (buffer underflow) or too early (buffer 86 overflow). The metric is applicable both to systems which use packet 87 loss repair techniques (such as forward error correction [RFC5109] or 88 retransmission [RFC4588]) and to those which do not. 90 This metric is useful for identifying the existence, and 91 characterising the severity, of a packet transport problem which may 92 affect users' perception of a service delivered over RTP. 94 This block may be used in conjunction with [BGDISCARD] which provides 95 additional information on the pattern of discarded packets. However 96 the metric in [BGDISCARD] may be used independently of the metrics in 97 this block. 99 In case of Discard count metric block sent together with Burst gap 100 discard metric block defined in [BGDISCARD] to the media sender or 101 RTP based network management system, information carried in the 102 discard count metric block and Burst gap discard metric block allows 103 them calculate the some bust gap summary statistics, e.g., gap 104 discard rate. 106 The metric belongs to the class of transport-related terminal metrics 107 defined in [MONARCH]. 109 1.2. RTCP and RTCP XR Reports 111 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 112 defined an extensible structure for reporting using an RTCP Extended 113 Report (XR). This document defines a new Extended Report block. The 114 use of Extended Report blocks is defined by [RFC3611]. 116 1.3. Performance Metrics Framework 118 The Performance Metrics Framework [RFC6390] provides guidance on the 119 definition and specification of performance metrics. The RTP 120 Monitoring Architectures [MONARCH] provides guideline for reporting 121 block format using RTCP XR. The Metrics Block described in this 122 document are in accordance with the guidelines in [RFC6390] and 123 [MONARCH]. 125 1.4. Applicability 127 This metric is believed to be applicable to a large class of RTP 128 applications which use a jitter buffer. 130 Discards due to late or early arriving packets affects user 131 experience. The reporting of discards alerts senders and other 132 receivers to the need to adjust their transmission or reception 133 strategies. The reports allow network managers to diagnose these 134 user experience problems. 136 The ability to detect duplicate packets can be used by managers to 137 detect network layer or sender behavior which may indicate network or 138 device issues. Based on the reports, these issues may be addressed 139 prior to any impact on user experience. 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 Discard Count 159 Metric counts only discarded packets. The metric "cumulative 160 number of packets lost" defined in [RFC3550] reports a count of 161 packets lost from the media stream (single SSRC within single RTP 162 session). Similarly the metric "number of packets discarded" 163 reports a count of packets discarded from the media stream (single 164 SSRC within single RTP session) arriving at the receiver. Another 165 metric defined in [RFC5725] is available to report on packets 166 which are not recovered by any repair techniques which may be in 167 use. 169 3. Discard Count Metric Report Block 171 3.1. Report Block Structure 173 0 1 2 3 174 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 | BT=PDC | I |DT | resv.| block length = 2 | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | SSRC of Source | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | number of packets discarded | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 Figure 1: Report Block Structure 185 3.2. Definition of Fields in Discard Count Metric Report Block 187 Block type (BT): 8 bits 189 A Discard Count Metric Report Block is identified by the constant 190 PDC. 192 [Note to RFC Editor: please replace PDC with the IANA provided 193 RTCP XR block type for this block.] 195 Interval Metric flag (I): 2 bits 197 This field indicates whether the reported metric is an interval, 198 cumulative, or sampled metric [MONARCH]. The Discard Count Metric 199 value can be reported as either an interval metric (I=10) or a 200 cumulative metric (I=11). It does not make sense to report the 201 Discard Count Metric as a sampled metric, so the value I=01 MUST 202 NOT be used. The value I=00 is reserved, and MUST NOT be used. 204 Discard Type (DT): 2bits 206 This field is used to identify the discard type used in this 207 report block. The discard type is defined as follows: 209 00: Report packet discarded or being thrown away before playout 210 due to packets duplication. 212 01: Report packet discarded due to too early to be played out. 214 10: Report packet discarded due to too late to be played out. 216 11: Report the total number of discarded packets due to both 217 early and late to be played out. 219 An endpoint MAY report only one of the above four discard types 220 blocks in an compound RTCP report in a reporting interval. It MAY 221 also report a combination of discard types in a compound RTCP 222 report but not all combinations are valid. The endpoint MAY 223 report duplicate packet discard (DT=0) block with any other 224 discard (DT=1, 2, or 3) block. Additionally, an endpoint MUST NOT 225 report combined discard (DT=3) block with early discard (DT=1) or 226 late discard (DT=2) report block. 228 Some systems send duplicate RTP packets for robustness or error 229 resilience. This is NOT RECOMMENDED since it breaks RTCP packet 230 statistics. If duplication is desired for error resilience, the 231 mechanism described in [RTPDUP] can be used, since this will not 232 cause breakage of RTP streams or RTCP statistics. 234 Reserved (resv): 4 bits 236 These bits are reserved. They MUST be set to zero by senders and 237 ignored by receivers. 239 block length: 16 bits 241 The length of this report block in 32-bit words, minus one. For 242 the Discard Count block, the block length is equal to 2. 244 SSRC of source: 32 bits 246 As defined in Section 4.1 of [RFC3611]. 248 number of packets discarded: 32 bits 250 Number of packets discarded over the period (Interval or 251 Cumulative) covered by this report. 253 If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE 254 MUST be reported to indicate an over-range measurement. If the 255 measurement is unavailable, the value 0xFFFFFFFF MUST be reported. 257 Note that the number of packets expected in the period associated 258 with this metric (whether interval or cumulative) is available 259 from the difference between a pair of extended sequence numbers in 260 the Measurement Information block [MEASI], so need not be repeated 261 in this block. 263 4. SDP Signaling 265 [RFC3611] defines the use of SDP (Session Description Protocol) 266 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 267 without prior signaling. 269 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 270 in [RFC3611] by providing an additional value of "xr-format" to 271 signal the use of the report block defined in this document. 273 rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF 275 (defined in [RFC3611]) 277 xr-format =/ xr-pdc-block 279 xr-pdc-block = "pkt-dscrd-count" 281 5. IANA Considerations 283 New block types for RTCP XR are subject to IANA registration. For 284 general guidelines on IANA considerations for RTCP XR, refer to 285 [RFC3611]. 287 5.1. New RTCP XR Block Type value 289 This document assigns the block type value PDC in the IANA "RTCP XR 290 Block Type Registry" to the "Discard Count Metrics Block". 292 [Note to RFC Editor: please replace PDC with the IANA provided RTCP 293 XR block type for this block.] 295 5.2. New RTCP XR SDP Parameter 297 This document also registers a new parameter "pkt-dscrd" in the "RTCP 298 XR SDP Parameters Registry". 300 5.3. Contact information for registrations 302 The following contact information is provided for all 303 registrations in this document: 305 Qin Wu (sunseawq@huawei.com) 307 101 Software Avenue, Yuhua District 308 Nanjing, Jiangsu 210012 309 China 311 6. Security Considerations 313 It is believed that this proposed RTCP XR report block introduces no 314 new security considerations beyond those described in [RFC3611]. 315 This block does not provide per-packet statistics so the risk to 316 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 317 does not apply. 319 7. Contributors 321 Geoff Hunt wrote the initial draft of this document. 323 8. Acknowledgments 325 The authors gratefully acknowledge the comments and contributions 326 made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin 327 Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert 328 Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith 329 Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, 330 Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada,Kevin 331 Gross, Varun Singh,Claire Bi, Roni Even, Dan Romascanu. 333 9. References 335 9.1. Normative References 337 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 338 Requirement Levels", March 1997. 340 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 341 Applications", RFC 3550, July 2003. 343 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 344 Protocol Extended Reports (RTCP XR)", November 2003. 346 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 347 Description Protocol", July 2006. 349 9.2. Informative References 351 [BGDISCARD] 352 Hunt, G., "RTCP XR Report Block for Burst Gap Discard 353 metric Reporting", 354 ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05, 355 July 2012. 357 [MEASI] Hunt, G., "Measurement Identity and information Reporting 358 using SDES item and XR Block", 359 ID draft-ietf-xrblock-rtcp-xr-meas-identity-06, 360 April 2012. 362 [MONARCH] Wu, Q., "Monitoring Architectures for RTP", 363 ID draft-ietf-avtcore-monarch-12, April 2012. 365 [RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588, 366 July 2006. 368 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 369 Correction", RFC 5109, July 2006. 371 [RFC5725] Begen, A., "RTCP XR Report Block for Post-Repair Loss 372 metric Reporting", RFC 5725, February 2010. 374 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 375 Development", RFC 6390, October 2011. 377 [RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams", 378 ID draft-ietf-avtext-rtp-duplication-00, July 2012. 380 Authors' Addresses 382 Alan Clark 383 Telchemy Incorporated 384 2905 Premiere Parkway, Suite 280 385 Duluth, GA 30097 386 USA 388 Email: alan.d.clark@telchemy.com 390 Glen Zorn 391 Network Zen 392 77/440 Soi Phoomjit, Rama IV Road 393 Phra Khanong, Khlong Toie 394 Bangkok 10110 395 Thailand 397 Phone: +66 (0) 87 502 4274 398 Email: gwz@net-zen.net 400 Qin Wu 401 Huawei 402 101 Software Avenue, Yuhua District 403 Nanjing, Jiangsu 210012 404 China 406 Email: sunseawq@huawei.com