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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-15) exists of draft-ietf-xrblock-rtcp-xr-discard-02 == Outdated reference: A later version (-10) exists of draft-ietf-xrblock-rtcp-xr-meas-identity-05 == Outdated reference: A later version (-22) exists of draft-ietf-avtcore-monarch-12 == Outdated reference: A later version (-06) exists of draft-zorn-xrblock-rtcp-xr-al-stat-05 Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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 G. Hunt 3 Internet-Draft Unaffiliated 4 Intended status: Standards Track A. Clark 5 Expires: January 11, 2013 Telchemy 6 R. Huang 7 Q. Wu, Ed. 8 Huawei 9 July 10, 2012 11 RTCP XR Report Block for Burst/Gap Discard metric Reporting 12 draft-ietf-xrblock-rtcp-xr-burst-gap-discard-04.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 11, 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. 126 2. Terminology 128 2.1. Standards Language 130 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 131 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 132 document are to be interpreted as described in RFC 2119 [RFC2119]. 134 In addition, the following terms are defined: 136 Received, Lost and Discarded 138 A packet shall be regarded as lost if it fails to arrive within an 139 implementation-specific time window. A packet that arrives within 140 this time window but is too early or late to be played out or 141 thrown away before playout (e.g., packet duplication or 142 redundancy) shall be regarded as discarded. A packet shall be 143 classified as one of received (or OK), discarded or lost. 145 Bursts and Gaps 147 The terms Burst and Gap are used in a manner consistent with that 148 of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided 149 into bursts, which are periods during which the discard rate is 150 high enough to cause noticeable quality degradation (generally 151 over 5 percent discard rate), and gaps, which are periods during 152 which discarded packets are infrequent and hence quality is 153 generally acceptable. 155 3. Burst/Gap Discard Block 157 Metrics in this block report on Burst/Gap Discard in the stream 158 arriving at the RTP system. 160 3.1. Report Block Structure 162 Burst/Gap Discard metrics block 164 0 1 2 3 165 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 7 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | BT=NBGD | I | resv. | block length = 3 | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 | SSRC of Source | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 | Threshold | Packets Discarded in Bursts | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | Total Packets expected in bursts | Reserved. | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 Figure 1: Report Block Structure 178 3.2. Definition of Fields in Burst/Gap Discard Report Block 180 Block type (BT): 8 bits 182 A Burst/Gap Discard Report Block is identified by the constant 183 NBGD. 185 [Note to RFC Editor: please replace NBGD with the IANA provided 186 RTCP XR block type for this block.] 188 Interval Metric flag (I): 2 bits 190 This field is used to indicate whether the Burst/Gap Discard 191 metrics are Sampled, Interval or Cumulative metrics, that is, 192 whether the reported values applies to the most recent measurement 193 interval duration between successive metrics reports (I=10) (the 194 Interval Duration) or to the accumulation period characteristic of 195 cumulative measurements (I=11) (the Cumulative Duration) or is a 196 sampled instantaneous value (I=01) (Sampled Value). 198 Reserved (resv): 6 bits 200 These bits are reserved. They SHOULD be set to zero by senders 201 and MUST be ignored by receivers. 203 block length: 16 bits 205 The length of this report block in 32-bit words, minus one. For 206 the Delay block, the block length is equal to 3. 208 SSRC of source: 32 bits 210 As defined in Section 4.1 of [RFC3611]. 212 Threshold: 8 bits 214 The Threshold is equivalent to Gmin in [RFC3611], i.e. the number 215 of successive packets that must not be discarded prior to and 216 following a discard packet in order for this discarded packet to 217 be regarded as part of a gap. 219 Packets discarded in bursts: 24 bits 221 The total number of packets discarded during discard bursts. 223 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 224 be reported to indicate an over-range measurement. If the 225 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 227 Total packets expected in bursts: 24 bits 229 The total number of packets expected during discarded bursts (that 230 is, the sum of received packets and lost packets). 232 If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD 233 be reported to indicate an over-range measurement. If the 234 measurement is unavailable, the value 0xFFFFFF SHOULD be reported. 236 Reserved (resv): 8 bits 238 These bits are reserved. They SHOULD be set to zero by senders 239 and MUST be ignored by receivers. 241 3.3. Derived metrics based on reported metrics 243 The metrics described here are intended to be used in conjunction 244 with information from the Measurement Information block [MEASID], 245 discard block [DISCARD] (which MUST be present in the same RTCP 246 packet as the Burst/Gap Discard block). 248 These metrics provides the following information relevant to 249 statistical parameters, including: 251 o The fraction of packets discarded during bursts (burst discard 252 rate in [SUMSTAT]) 254 o The fraction of packets discarded during gaps (gap discard rate in 255 [SUMSTAT]) 257 The details on calculation these parameters in the metrics are 258 described in [SUMSTAT]. 260 4. Considerations for Voice-over-IP applications 262 This metric block is applicable to a broad range of RTP applications. 263 Where the metric is used with a Voice-overIP (VoIP) application, the 264 following considerations apply. 266 RTCP XR views a call as being divided into bursts, which are periods 267 during which the discard rate is high enough to cause noticeable call 268 quality degradation (generally over 5 percent discard rate), and 269 gaps, which are periods during which discarded packets are infrequent 270 and hence call quality is generally acceptable. 272 If Voice Activity Detection is used the Burst and Gap Duration shall 273 be determined as if silence packets had been sent, i.e. a period of 274 silence in excess of Gmin packets MUST terminate a burst condition. 276 The recommended value for the threshold Gmin in [RFC3611] results in 277 a Burst being a period of time during which the call quality is 278 degraded to a similar extent to a typical PCM Severely Errored Second 279 [PSES]. 281 5. SDP Signaling 283 [RFC3611] defines the use of SDP (Session Description Protocol) 284 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 285 without prior signaling. 287 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 288 in [RFC3611] by providing an additional value of "xr-format" to 289 signal the use of the report block defined in this document. 291 rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF 293 (defined in [RFC3611]) 295 xr-format =/ xr-bgd-block 297 xr-bgd-block = "brst-gap-dscrd" 299 6. IANA Considerations 301 New block types for RTCP XR are subject to IANA registration. For 302 general guidelines on IANA considerations for RTCP XR, refer to 303 [RFC3611]. 305 6.1. New RTCP XR Block Type value 307 This document assigns the block type value NBGD in the IANA "RTCP XR 308 Block Type Registry" to the "Burst/Gap Discard Metrics Block". 310 [Note to RFC Editor: please replace NBGD with the IANA provided RTCP 311 XR block type for this block.] 313 6.2. New RTCP XR SDP Parameter 315 This document also registers a new parameter "brst-gap-dscrd" in the 316 "RTCP XR SDP Parameters Registry". 318 6.3. Contact information for registrations 320 The contact information for the registrations is: 322 Qin Wu (sunseawq@huawei.com) 324 101 Software Avenue, Yuhua District 325 Nanjing, Jiangsu 210012 326 China 328 7. Security Considerations 330 It is believed that this proposed RTCP XR report block introduces no 331 new security considerations beyond those described in [RFC3611]. 332 This block does not provide per-packet statistics so the risk to 333 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 334 does not apply. 336 8. Acknowledgments 338 The authors gratefully acknowledge the comments and contributions 339 made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin 340 Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert 341 Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith 342 Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, 343 Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada. 345 9. References 347 9.1. Normative References 349 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 350 Requirement Levels", March 1997. 352 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 353 Applications", RFC 3550, July 2003. 355 [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control 356 Protocol Extended Reports (RTCP XR)", November 2003. 358 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 359 Description Protocol", July 2006. 361 9.2. Informative References 363 [DISCARD] Hunt, G., "RTCP XR Report Block for Discard metric 364 Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-02, 365 April 2012. 367 [MEASID] Wu, Q., "Measurement Identity and information Reporting 368 using SDES item and XR Block", 369 ID draft-ietf-xrblock-rtcp-xr-meas-identity-05, 370 April 2012. 372 [MONARCH] Hunt, G., "Monitoring Architectures for RTP", 373 ID draft-ietf-avtcore-monarch-12, April 2012. 375 [PSES] "URL", http://www.its.bldrdoc.gov/projects/devglossary/ 376 _severely_errored_second.html, October 2011. 378 [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric 379 Development", RFC 6390, October 2011. 381 [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics 382 Reporting", ID draft-zorn-xrblock-rtcp-xr-al-stat-05, 383 February 2012. 385 Authors' Addresses 387 Geoff Hunt 388 Unaffiliated 390 Email: r.geoff.hunt@gmail.com 392 Alan Clark 393 Telchemy Incorporated 394 2905 Premiere Parkway, Suite 280 395 Duluth, GA 30097 396 USA 398 Email: alan.d.clark@telchemy.com 400 Rachel Huang 401 Huawei Technologies Co., Ltd. 402 101 Software Avenue, Yuhua District 403 Nanjing, Jiangsu 210012 404 China 406 Email: Rachel@huawei.com 408 Qin Wu (editor) 409 Huawei 410 101 Software Avenue, Yuhua District 411 Nanjing, Jiangsu 210012 412 China 414 Email: sunseawq@huawei.com