idnits 2.17.1 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05.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 date (July 30, 2012) is 4288 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-05 == Outdated reference: A later version (-10) exists of draft-ietf-xrblock-rtcp-xr-meas-identity-09 == Outdated reference: A later version (-22) exists of draft-ietf-avtcore-monarch-12 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 G. Hunt 3 Internet-Draft Unaffiliated 4 Intended status: Standards Track A. Clark 5 Expires: January 31, 2013 Telchemy 6 R. Huang 7 Q. Wu, Ed. 8 Huawei 9 July 30, 2012 11 RTCP XR Report Block for Burst/Gap Discard metric Reporting 12 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05.txt 14 Abstract 16 This document defines an RTCP XR Report Block that allows the 17 reporting of Burst and Gap Discard metrics for use in a range of RTP 18 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 January 31, 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. Burst and Gap Discard Report Block . . . . . . . . . . . . 3 56 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 57 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 58 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4 61 3. Burst/Gap Discard Block . . . . . . . . . . . . . . . . . . . 5 62 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 63 3.2. Definition of Fields in Burst/Gap Discard Report Block . . 5 64 3.3. Derived metrics based on reported metrics . . . . . . . . 7 65 4. Considerations for Voice-over-IP applications . . . . . . . . 8 66 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 67 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 68 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10 69 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 70 6.3. Contact information for registrations . . . . . . . . . . 10 71 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 72 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 73 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 74 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 75 9.2. Informative References . . . . . . . . . . . . . . . . . . 13 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 78 1. Introduction 80 1.1. Burst and Gap Discard Report Block 82 This document defines a new block type to augment those defined in 83 [RFC3611] for use in a range of RTP applications. The new block type 84 supports the reporting of the proportion of packets discarded by the 85 receiver due to jitter. The discards during discard bursts are 86 reported, together with the number of bursts. This block is intended 87 to be used in conjunction with [DISCARD] which provides the total 88 packets discarded, and on which this block therefore depends. 89 However the metric in [DISCARD] may be used independently of the 90 metrics in this block. 92 This block provides information on transient IP problems. Burst/Gap 93 metrics are typically used in Cumulative reports however MAY be used 94 in Interval reports. The burstiness of packet discard affects user 95 experience, may influence any sender strategies to mitigate the 96 problem, and may also have diagnostic value. 98 The metric belongs to the class of transport-related terminal metrics 99 defined in [MONARCH]. 101 The definitions of Burst, Gap, Loss and Discard are consistent with 102 definitions in [RFC3611]. To accommodate the range of jitter buffer 103 algorithms and packet discard logic that may be used by implementors, 104 the method used to distinguish between bursts and gaps may be an 105 equivalent method to that defined in[RFC3611]. 107 1.2. RTCP and RTCP XR Reports 109 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 110 defined an extensible structure for reporting using an RTCP Extended 111 Report (XR). This document defines a new Extended Report block. The 112 use of Extended Report blocks is defined by [RFC3611]. 114 1.3. Performance Metrics Framework 116 The Performance Metrics Framework [RFC6390] provides guidance on the 117 definition and specification of performance metrics. Metrics 118 described in this draft either reference external definitions or 119 define metrics generally in accordance with the guidelines in 120 [RFC6390]. 122 1.4. Applicability 124 These metrics are applicable to a range of RTP applications which 125 don't use stream repair means. 127 2. Terminology 129 2.1. Standards Language 131 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 132 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 133 document are to be interpreted as described in RFC 2119 [RFC2119]. 135 In addition, the following terms are defined: 137 Received, Lost and Discarded 139 A packet shall be regarded as lost if it fails to arrive within an 140 implementation-specific time window. A packet that arrives within 141 this time window but is too early or late to be played out or 142 thrown away before playout due to packet duplication or redundancy 143 shall be regarded as discarded. A packet shall be classified as 144 one of received (or OK), discarded or lost. The metric 145 "cumulative number of packets lost" defined in [RFC3550] reports a 146 count of packets lost from the media stream (single SSRC within 147 single RTP session). Similarly the metric "number of packets 148 discarded" defined in [DISCARD] reports a count of packets 149 discarded from the media stream (single SSRC within single RTP 150 session) arriving at the receiver. Another metric defined in 151 [RFC5725] is available to report on packets which are not 152 recovered by any repair techniques which may be in use. 154 Bursts and Gaps 156 The terms Burst and Gap are used in a manner consistent with that 157 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 158 into bursts, which are periods during which the discard rate is 159 high enough to cause noticeable quality degradation (generally 160 over 5 percent discard rate), and gaps, which are periods during 161 which discarded packets are infrequent and hence quality is 162 generally acceptable. 164 3. Burst/Gap Discard Block 166 Metrics in this block report on Burst/Gap Discard in the stream 167 arriving at the RTP system. 169 3.1. Report Block Structure 171 Burst/Gap Discard metrics block 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=NBGD | I | resv. | block length = 3 | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | SSRC of Source | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | Threshold | Packets Discarded in Bursts | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 | Total Packets expected in bursts | Reserved. | 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 Figure 1: Report Block Structure 187 3.2. Definition of Fields in Burst/Gap Discard Report Block 189 Block type (BT): 8 bits 191 A Burst/Gap Discard Report Block is identified by the constant 192 NBGD. 194 [Note to RFC Editor: please replace NBGD with the IANA provided 195 RTCP XR block type for this block.] 197 Interval Metric flag (I): 2 bits 199 This field is used to indicate whether the Burst/Gap Discard 200 metrics are Sampled, Interval or Cumulative metrics, that is, 201 whether the reported values applies to the most recent measurement 202 interval duration between successive metrics reports (I=10) (the 203 Interval Duration) or to the accumulation period characteristic of 204 cumulative measurements (I=11) (the Cumulative Duration) or is a 205 sampled instantaneous value (I=01) (Sampled Value). In this 206 document, Burst/Gap Discard Metric is not measured at a particular 207 time instant but over one or several reporting intervals. 208 Therefore Burst/Gap Discard Metric MUST NOT be chosen as Sampled 209 Metric. 211 Reserved (resv): 6 bits 213 These bits are reserved. They SHOULD be set to zero by senders 214 and MUST be ignored by receivers. 216 block length: 16 bits 218 The length of this report block in 32-bit words, minus one. For 219 the Burst/Gap discard block, the block length is equal to 3. 221 SSRC of source: 32 bits 223 As defined in Section 4.1 of [RFC3611]. 225 Threshold: 8 bits 227 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 228 of successive packets that must not be discarded prior to and 229 following a discard packet in order for this discarded packet to 230 be regarded as part of a gap. 232 Packets discarded in bursts: 24 bits 234 The total number of packets discarded during discard bursts. 236 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 237 be reported to indicate an over-range measurement. If the 238 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 240 Total packets expected in bursts: 24 bits 242 The total number of packets expected during discarded bursts (that 243 is, the sum of received packets and lost packets). 245 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 246 be reported to indicate an over-range measurement. If the 247 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 249 Reserved (resv): 8 bits 251 These bits are reserved. They SHOULD be set to zero by senders 252 and MUST be ignored by receivers. 254 3.3. Derived metrics based on reported metrics 256 The metrics described here are intended to be used in conjunction 257 with information from the Measurement Information block [MEASID], 258 discard block [DISCARD] (which MUST be present in the same RTCP 259 packet as the Burst/Gap Discard block). 261 These metrics provides the following information relevant to 262 statistical parameters, including: 264 o The fraction of packets discarded during bursts (burst discard 265 rate in [SUMSTAT]) 267 o The fraction of packets discarded during gaps (gap discard rate in 268 [SUMSTAT]) 270 The details on calculation these parameters in the metrics are 271 described in [SUMSTAT]. 273 4. Considerations for Voice-over-IP applications 275 This metric block is applicable to a broad range of RTP applications. 276 Where the metric is used with a Voice-overIP (VoIP) application and 277 the stream repair means is not available, the following 278 considerations apply. 280 RTCP XR views a call as being divided into bursts, which are periods 281 during which the discard rate is high enough to cause noticeable call 282 quality degradation (generally over 5 percent discard rate), and 283 gaps, which are periods during which discarded packets are infrequent 284 and hence call quality is generally acceptable. 286 If Voice Activity Detection is used the Burst and Gap Duration shall 287 be determined as if silence packets had been sent, i.e. a period of 288 silence in excess of Gmin packets MUST terminate a burst condition. 290 The recommended value for the threshold Gmin in [RFC3611] results in 291 a Burst being a period of time during which the call quality is 292 degraded to a similar extent to a typical PCM Severely Errored Second 293 [PSES]. 295 5. SDP Signaling 297 [RFC3611] defines the use of SDP (Session Description Protocol) 298 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 299 without prior signaling. 301 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 302 in [RFC3611] by providing an additional value of "xr-format" to 303 signal the use of the report block defined in this document. 305 rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF 307 (defined in [RFC3611]) 309 xr-format =/ xr-bgd-block 311 xr-bgd-block = "brst-gap-dscrd" 313 6. IANA Considerations 315 New block types for RTCP XR are subject to IANA registration. For 316 general guidelines on IANA considerations for RTCP XR, refer to 317 [RFC3611]. 319 6.1. New RTCP XR Block Type value 321 This document assigns the block type value NBGD in the IANA "RTCP XR 322 Block Type Registry" to the "Burst/Gap Discard Metrics Block". 324 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 325 XR block type for this block.] 327 6.2. New RTCP XR SDP Parameter 329 This document also registers a new parameter "brst-gap-dscrd" in the 330 "RTCP XR SDP Parameters Registry". 332 6.3. Contact information for registrations 334 The contact information for the registrations is: 336 Qin Wu (sunseawq@huawei.com) 338 101 Software Avenue, Yuhua District 339 Nanjing, Jiangsu 210012 340 China 342 7. Security Considerations 344 It is believed that this proposed RTCP XR report block introduces no 345 new security considerations beyond those described in [RFC3611]. 346 This block does not provide per-packet statistics so the risk to 347 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 348 does not apply. 350 8. Acknowledgments 352 The authors gratefully acknowledge the comments and contributions 353 made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin 354 Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert 355 Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith 356 Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, 357 Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada. 359 9. References 361 9.1. Normative References 363 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 364 Requirement Levels", March 1997. 366 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 367 Applications", RFC 3550, July 2003. 369 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 370 Protocol Extended Reports (RTCP XR)", November 2003. 372 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 373 Description Protocol", July 2006. 375 [RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE 376 Report Block Type for RTP Control Protocol (RTCP) Extended 377 Reports (XRs)", RFC 5725, February 2020. 379 9.2. Informative References 381 [DISCARD] Hunt, G., "RTCP XR Report Block for Discard metric 382 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-05, 383 July 2012. 385 [MEASID] Wu, Q., "Measurement Identity and information Reporting 386 using SDES item and XR Block", 387 ID draft-ietf-xrblock-rtcp-xr-meas-identity-09, July 2012. 389 [MONARCH] Hunt, G., "Monitoring Architectures for RTP", 390 ID draft-ietf-avtcore-monarch-12, June 2012. 392 [PSES] "URL", http://www.its.bldrdoc.gov/projects/devglossary/ 393 _severely_errored_second.html, October 2011. 395 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 396 Development", RFC 6390, October 2011. 398 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 399 Reporting", ID draft-zorn-xrblock-rtcp-xr-al-stat-06, 400 July 2012. 402 Authors' Addresses 404 Geoff Hunt 405 Unaffiliated 407 Email: r.geoff.hunt@gmail.com 409 Alan Clark 410 Telchemy Incorporated 411 2905 Premiere Parkway, Suite 280 412 Duluth, GA 30097 413 USA 415 Email: alan.d.clark@telchemy.com 417 Rachel Huang 418 Huawei Technologies Co., Ltd. 419 101 Software Avenue, Yuhua District 420 Nanjing, Jiangsu 210012 421 China 423 Email: Rachel@huawei.com 425 Qin Wu (editor) 426 Huawei 427 101 Software Avenue, Yuhua District 428 Nanjing, Jiangsu 210012 429 China 431 Email: sunseawq@huawei.com