idnits 2.17.1 draft-ietf-avt-rtcp-xr-discard-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.i or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) 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 lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (February 25, 2009) is 5539 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: 'RFC2119' is defined on line 293, but no explicit reference was found in the text -- No information found for draft-ietf-avt-rtcp-xr-measid - is the name correct? -- Possible downref: Normative reference to a draft: ref. 'MEASIDENT' ** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866) == Outdated reference: A later version (-12) exists of draft-ietf-pmol-metrics-framework-00 -- No information found for draft-ietf-rtcp-xr-postrepair-loss - is the name correct? Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 5 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Audio/Video Transport Working G. Hunt 3 Group BT 4 Internet-Draft A. Clark 5 Intended status: Standards Track Telchemy 6 Expires: August 29, 2009 February 25, 2009 8 RTCP XR Report Block for Discard metric Reporting 9 draft-ietf-avt-rtcp-xr-discard-01.txt 11 Status of this Memo 13 This Internet-Draft is submitted to IETF in full conformance with the 14 provisions of BCP 78 and BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on August 29, 2009. 34 Copyright Notice 36 Copyright (c) 2009 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents in effect on the date of 41 publication of this document (http://trustee.ietf.org/license-info). 42 Please review these documents carefully, as they describe your rights 43 and restrictions with respect to this document. 45 Abstract 47 This document defines an RTCP XR Report Block that allows the 48 reporting of a simple discard count metric for use in a range of RTP 49 applications. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 1.1. Discard 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. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 3. Discard Metric Report Block . . . . . . . . . . . . . . . . . 6 60 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 61 3.2. Definition of Fields in Discard Metric Report Block . . . 6 62 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 63 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 64 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 9 65 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 9 66 5.3. Contact information for registrations . . . . . . . . . . 9 67 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 68 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11 69 8. Changes from previous version . . . . . . . . . . . . . . . . 12 70 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 71 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 72 9.2. Informative References . . . . . . . . . . . . . . . . . . 13 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 75 1. Introduction 77 1.1. Discard Report Block 79 This draft defines a new block type to augment those defined in 80 [RFC3611] for use in a range of RTP applications. The new block type 81 supports the reporting of the number of packets which are received 82 correctly but are never played out, typically because they arrive too 83 late to be played out (buffer underflow) or too early (buffer 84 overflow). The metric is applicable both to systems which use packet 85 loss repair techniques (such as forward error correction [RFC5109] or 86 retransmission [RFC4588]) and to those which do not. 88 This metric is useful for identifying the existence, and 89 characterising the severity, of a packet transport problem which may 90 affect users' perception of a service delivered over RTP. 92 The metric belongs to the class of transport-related terminal metrics 93 defined in [MONARCH] (work in progress). 95 Instances of this Metrics Block refer by tag to the separate 96 auxiliary Measurement Identity block [MEASIDENT] which contains 97 information such as the SSRC of the measured stream, and RTP sequence 98 numbers and time intervals indicating the span of the report. 100 The Measurement Identity block provides extended sequence numbers for 101 the beginning and end of both Interval and Cumulative reporting 102 periods. This allows systems receiving the report to calculate the 103 number of packets expected. 105 1.2. RTCP and RTCP XR Reports 107 The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] 108 defined an extensible structure for reporting using an RTCP Extended 109 Report (XR). This draft defines a new Extended Report block that 110 MUST be used as defined in [RFC3550] and [RFC3611]. 112 1.3. Performance Metrics Framework 114 The Performance Metrics Framework [PMOLFRAME] provides guidance on 115 the definition and specification of performance metrics. Metrics 116 described in this draft either reference external definitions or 117 define metrics generally in accordance with the guidelines in 118 [PMOLFRAME]. 120 1.4. Applicability 122 This metric is believed to be applicable to a large class of RTP 123 applications which use a jitter buffer. 125 2. Definitions 127 Received, Lost and Discarded 129 A packet shall be regarded as lost if it fails to arrive within an 130 implementation-specific time window. A packet that arrives within 131 this time window but is too early or late to be played out shall 132 be regarded as discarded. A packet shall be classified as one of 133 received (or OK), discarded or lost. The Discard Metric counts 134 only discarded packets. The metric "cumulative number of packets 135 lost" defined in [RFC3550] reports a count of packets lost from 136 the media stream (single SSRC within single RTP session). 137 Similarly the metric "number of packets discarded" reports a count 138 of packets discarded from the media stream (single SSRC within 139 single RTP session) arriving at the receiver. Another metric 140 defined in [POSTREPAIRLOSS] is available to report on packets 141 which are not recovered by any repair techniques which may be in 142 use. 144 For Voice-over-IP applications of the metric, if Voice Activity 145 Detection is used then the proportion of packets lost and 146 discarded shall be determined based on transmitted packets, i.e. 147 packets that contained silence and were not transmitted shall not 148 be considered, because they do not form part of the RTP sequence. 150 3. Discard Metric Report Block 152 3.1. Report Block Structure 154 0 1 2 3 155 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 7 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 | BT=ND |I| tag | resv | block length=1 | 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | number of packets discarded | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 Figure 1: Report Block Structure 164 3.2. Definition of Fields in Discard Metric Report Block 166 block type (BT): 8 bits 168 A Discard Metric Report Block is identified by the constant ND. 170 [Note to RFC Editor: please replace ND with the IANA provided RTCP XR 171 block type for this block.] 173 Interval Metric flag (I): 1 bit 175 This field is used to indicate whether the Discard metric is an 176 Interval or a Cumulative metric, that is, whether the reported 177 value applies to the most recent measurement interval duration 178 between successive metrics reports (I=1) (the Interval Duration) 179 or to the accumulation period characteristic of cumulative 180 measurements (I=0) (the Cumulative Duration). Numerical values 181 for both these intervals are provided in the Measurement 182 Identifier block referenced by the tag field below. 184 Measurement Identifier association (tag): 3 bits 186 This field is used to identify the Measurement Identifier block 187 [MEASIDENT] which describes this measurement. The relevant 188 Measurement Identifier block has the same tag value as the Discard 189 Metric block. Note that there may be more than one Measurement 190 Identifier block per RTCP packet. 192 Reserved (resv): 4 bits 194 These bits are reserved. They SHOULD be set to zero by senders 195 and MUST be ignored by receivers. 197 block length: 16 bits 198 The length of this report block in 32-bit words minus one. For 199 the Discard Metric block, the block length is equal to 1. 201 number of packets discarded: 32 bits 203 Number of packets discarded over the period (Interval or 204 Cumulative) covered by this report. 206 If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE 207 SHOULD be reported to indicate an over-range measurement. If the 208 measurement is unavailable, the value 0xFFFFFFFF SHOULD be 209 reported. 211 Note that the number of packets expected in the period covered by 212 the metric (whether interval or cumulative) is available from the 213 difference between a pair of extended sequence numbers in the 214 Measurement Identity block, so need not be repeated in this block. 216 4. SDP Signaling 218 [RFC3611] defines the use of SDP (Session Description Protocol) 219 [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used 220 without prior signaling. 222 This section augments the SDP [RFC4566] attribute "rtcp-xr" defined 223 in [RFC3611] by providing an additional value of "xr-format" to 224 signal the use of the report block defined in this document. 226 rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF 228 (defined in RFC3611) 230 xr-format = xr-format / xr-pd-block 232 xr-pd-block = "pkt-dscrd" 234 5. IANA Considerations 236 New block types for RTCP XR are subject to IANA registration. For 237 general guidelines on IANA considerations for RTCP XR, refer to 238 [RFC3611]. 240 5.1. New RTCP XR Block Type value 242 This document assigns the block type value ND in the IANA "RTCP XR 243 Block Type Registry" to the "Concealed Seconds Metrics Block". 245 [Note to RFC Editor: please replace ND with the IANA provided RTCP XR 246 block type for this block.] 248 5.2. New RTCP XR SDP Parameter 250 This document also registers a new parameter "pkt-dscrd" in the "RTCP 251 XR SDP Parameters Registry". 253 5.3. Contact information for registrations 255 The contact information for the registrations is: 257 Geoff Hunt (geoff.hunt@bt.com) 259 Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United 260 Kingdom 262 6. Security Considerations 264 It is believed that this proposed RTCP XR report block introduces no 265 new security considerations beyond those described in [RFC3611]. 266 This block does not provide per-packet statistics so the risk to 267 confidentiality documented in Section 7, paragraph 3 of [RFC3611] 268 does not apply. 270 7. Contributors 272 The authors gratefully acknowledge the comments and contributions 273 made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin 274 Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert 275 Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith 276 Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, 277 Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada. 279 8. Changes from previous version 281 Expanded and clarified IANA Considerations section 283 Changed SDP tag for block to "pkt-dscrd" 285 9. References 287 9.1. Normative References 289 [MEASIDENT] 290 Hunt, G., "RTCP XR Measurement Identifier Block", 291 ID draft-ietf-avt-rtcp-xr-measid-01, February 2009. 293 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 294 Requirement Levels", RFC 2119, BCP 14, March 1997. 296 [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time 297 Applications", RFC 3550, July 2003. 299 [RFC3611] Friedman, T., "RTP Control Protocol Extended Reports (RTCP 300 XR)", RFC 3611, November 2003. 302 [RFC4566] Handley, M., "SDP: Session Description Protocol", 303 RFC 4566, July 2006. 305 9.2. Informative References 307 [MONARCH] Hunt, G., "Monitoring Architectures for RTP", 308 ID draft-hunt-avt-monarch-01, August 2008. 310 [PMOLFRAME] 311 Clark, A., "Framework for Performance Metric Development", 312 ID draft-ietf-pmol-metrics-framework-00, July 2008. 314 [POSTREPAIRLOSS] 315 Hunt, G., "RTCP XR Report Block for Post-Repair Loss 316 metric Reporting", 317 ID draft-ietf-rtcp-xr-postrepair-loss-01, February 2009. 319 [RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588, 320 July 2006. 322 [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error 323 Correction", RFC 5109, December 2007. 325 Authors' Addresses 327 Geoff Hunt 328 BT 329 Orion 2 PP3 330 Adastral Park 331 Martlesham Heath 332 Ipswich, Suffolk IP5 3RE 333 United Kingdom 335 Phone: +44 1473 651704 336 Email: geoff.hunt@bt.com 338 Alan Clark 339 Telchemy Incorporated 340 2905 Premiere Parkway, Suite 280 341 Duluth, GA 30097 342 USA 344 Email: alan.d.clark@telchemy.com