Audio/Video Transport Working G. Hunt Group BT Internet-Draft A. Clark Intended status: Standards Track Telchemy Expires:
April 28,August 29, 2009 OctoberFebruary 25, 20082009 RTCP XR Report Block for Delay metric Reporting draft-ietf-avt-rtcp-xr-delay-00.txtdraft-ietf-avt-rtcp-xr-delay-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or sheThis Internet-Draft is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed,submitted to IETF in accordancefull conformance with Section 6the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 28,August 29, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document defines an RTCP XR Report Block that allows the reporting of Delay metrics for use in a range of RTP applications. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Delay Report Block . . . . . . . . . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Delay Block . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 3.2. Definition of Fields in Delay Metrics Report Block . . . . 5 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 9 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 9 5.3. Contact information for registrations . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11 8. ReferencesChanges from previous version . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . 12 8.1. Normative References. . . . . . . . . . . . . . . . 13 9.1. Normative References . . . 12 8.2. Informative References. . . . . . . . . . . . . . . . 13 9.2. Informative References . . 12 Authors' Addresses. . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements. . . . . . . . . . 14 1. Introduction 1.1. Delay Report Block This draft defines a new block type to augment those defined in [RFC3611] for use in a range of RTP applications. The new block type supports the reporting of the mean, minimum and maximum values of the network round-trip delay between RTP interfaces in peer RTP end systems as measured, for example, using the RTCP method described in [RFC3550]. It also supports reporting of the component of the round- trip delay internal to the local RTP system. The network metrics belong to the class of packet transport delay metrics defined in [MONARCH] (work in progress). Instances of this Metrics Block refer by tag to the separate auxiliary Measurement Identity block [MEASIDENT] which contains information such as the SSRC of the measured stream, and RTP sequence numbers and time intervals indicating the span of the report. 1.2. RTCP and RTCP XR Reports The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] defined an extensible structure for reporting using an RTCP Extended Report (XR). This draft defines a new Extended Report block that MUST be used as defined in [RFC3550] and [RFC3611]. 1.3. Performance Metrics Framework The Performance Metrics Framework [PMOLFRAME] provides guidance on the definition and specification of performance metrics. Metrics described in this draft either reference external definitions or define metrics generally in accordance with the guidelines in [PMOLFRAME]. 1.4. Applicability This metric is believed to be applicable to all RTP applications. 2. Definitions Numeric formats This report block makes use of binary fractions. The terminology used is S X:Y where S indicates a two's complement signed representation, X the number of bits prior to the decimal place and Y the number of bits after the decimal place. Hence 8:8 represents an unsigned number in the range 0.0 to 255.996 with a granularity of 0.0039. S7:8 would represent the range -128.000 to +127.996. 0:16 represents a proper binary fraction with range 0.0 to 1 - 1/65536 = 0.9999847 though note that use of flag values at the top of the numeric range slightly reduces this upper limit. For example, if the 16- bit values 0xfffe and 0xffff are used as flags for "over-range" and "unavailable" conditions, a 0:16 quantity has range 0.0 to 1 - 3/65536 = 0.9999542 3. Delay Block 3.1. Report Block Structure Delay metrics block 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BT=NDEL |I| tag | resv | block length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mean Network Round Trip Delay | End System Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Min Network Round Trip Delay | Max Network Round Trip Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Report Block Structure 3.2. Definition of Fields in Delay Metrics Report Block block type (BT): 8 bits A Delay Report Block is identified by the constant NDEL. [Note to RFC Editor: please replace NDEL with the IANA provided RTCP XR block type for this block.] Interval Metric flag (I): 1 bit This field is used to indicate whether the Delay metric block is an Interval or a Cumulative metric block, that is, whether the reported values apply to the most recent measurement interval duration between successive metrics reports (I=1) (the Interval Duration) or to the accumulation period characteristic of cumulative measurements (I=0) (the Cumulative Duration). Numerical values for both these intervals are provided in the Measurement Identifier block referenced by the tag field below. Measurement Identifier association (tag): 3 bits This field is used to identify the Measurement Identifier block [MEASIDENT] which describes this measurement. The relevant Measurement Identifier block has the same tag value as the Delay block. Note that there may be more than one Measurement Identifier block per RTCP packet. Reserved (resv): 4 bits These bits are reserved. They SHOULD be set to zero by senders and MUST be ignored by receivers. block length: 16 bits The length of this report block in 32-bit words, minus one. For the Delay block, the block length is equal to 2. Mean Network Round Trip Delay (ms): 16 bits The Mean Network Round Trip Delay is the mean value of the RTP-to- RTP interface round trip delay in ms over the measurement period, typically determined using RTCP SR/RR. If only one measurement of Round Trip Delay is available for the timespan of the report (whether Interval or Cumulative), this single value should be reported as the mean value. If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. End System Delay (ms): 16 bits The End System Delay is the internal round trip delay within the reporting endpoint, calculated using the nominal value of the jitter buffer delay plus the accumulation/ encoding and decoding / playout delay associated with the codec being used. If the measured or estimated value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. Min Network Round Trip Delay (ms): 16 bits The Min Network Round Trip Delay is the minimum value of the RTP- to-RTP interface round trip delay in ms over the measurement period, typically determined using RTCP SR/RR. If only one measurement of Round Trip Delay is available for the timespan of the report (whether Interval or Cumulative), this single value should be reported as the minimum value. If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. Max Network Round Trip Delay (ms): 16 bits The Max Network Round Trip Delay is the maximum value of the RTP- to-RTP interface round trip delay in ms over the measurement period, typically determined using RTCP SR/RR. If only one measurement of Round Trip Delay is available for the timespan of the report (whether Interval or Cumulative), this single value should be reported as the maximum value. If the measured value exceeds 0xFFFD, the value 0xFFFE SHOULD be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF SHOULD be reported. 4. SDP Signaling [RFC3611] defines the use of SDP (Session Description Protocol) [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling. This section augments the SDP [RFC4566] attribute "rtcp-xr" defined in [RFC3611] by providing an additional value of "xr-format" to signal the use of the report block defined in this document. rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF (defined in [RFC3611]) xr-format = xr-format / xr-delay-block xr-delay-block = "xr-delay""delay" 5. IANA Considerations New block types for RTCP XR are subject to IANA registration. For general guidelines on IANA considerations for RTCP XR, refer to [RFC3611]. 5.1. New RTCP XR Block Type value This document creates a newassigns the block type withinvalue NDEL in the IANA "RTCP XR Block Type Registry" calledto the Delay Block, and"Delay Metrics Block". [Note to RFC Editor: please replace NDEL with the IANA provided RTCP XR block type for this block.] 5.2. New RTCP XR SDP Parameter This document also registers a new parameter xr-delay within"delay" in the "RTCP XR SDP Parameters Registry". 5.3. Contact information for registrations The contact information for the registrations is: Geoff Hunt (email@example.com) Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United Kingdom 6. Security Considerations It is believed that this proposed RTCP XR report block introduces no new security considerations beyond those described in [RFC3611]. This block does not provide per-packet statistics so the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply. 7. Contributors The authors gratefully acknowledge the comments and contributions made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada. 8. Changes from previous version Expanded and clarified IANA Considerations section. Changed SDP tag for block to "delay". 9. References 188.8.131.52. Normative References [MEASIDENT] Hunt, G., "RTCP XR Measurement Identifier Block", ID draft-ietf-avt-rtcp-xr-measid-00, August 2008.draft-ietf-avt-rtcp-xr-measid-01, February 2009. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997. [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003. [RFC3611] Friedman, T., "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003. [RFC4566] Handley, M., "SDP: Session Description Protocol", RFC 4566, July 2006. 184.108.40.206. Informative References [MONARCH] Hunt, G., "Monitoring Architectures for RTP", ID draft-hunt-avt-monarch-01, August 2008. [PMOLFRAME] Clark, A., "Framework for Performance Metric Development", ID draft-ietf-pmol-metrics-framework-00, July 2008. Authors' Addresses Geoff Hunt BT Orion 1 PP92 PP3 Adastral Park Martlesham Heath Ipswich, Suffolk IP4 2THIP5 3RE United Kingdom Phone: +44 1473 608325651704 Email: firstname.lastname@example.org Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA Email: email@example.com Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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