Audio/Video Transport Working G. Hunt Group BT Internet-Draft A. Clark Intended status: Standards Track Telchemy Expires: August 29, 2009 February 25, 2009 RTCP XR Report Block for Jitter Buffer Metric Reporting draft-ietf-avt-rtcp-xr-jb-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the 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 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. Hunt & Clark Expires August 29, 2009 [Page 1] Internet-Draft RTCP XR Jitter Buffer February 2009 Abstract This document defines an RTCP XR Report Block that allows the reporting of Jitter Buffer metrics for a range of RTP applications. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Jitter Buffer Metrics Block . . . . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2. Jitter Buffer Metrics Block . . . . . . . . . . . . . . . . . 4 2.1. Report Block Structure . . . . . . . . . . . . . . . . . . 4 2.2. Definition of Fields in Jitter Buffer Metrics Block . . . 4 3. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 8 4.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 8 4.3. Contact information for registrations . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Changes since previous version . . . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Hunt & Clark Expires August 29, 2009 [Page 2] Internet-Draft RTCP XR Jitter Buffer February 2009 1. Introduction 1.1. Jitter Buffer Metrics 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 provides information on jitter buffer configuration and performance. The metric belongs to the class of transport-related terminal 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 These metrics are applicable to a range of RTP applications. Hunt & Clark Expires August 29, 2009 [Page 3] Internet-Draft RTCP XR Jitter Buffer February 2009 2. Jitter Buffer Metrics Block This block describes the configuration and operating parameters of the jitter buffer in the receiver of the RTP end system or RTP mixer which sends the report. 2.1. Report Block Structure JB 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=NJB |I| tag |jb cfg | block length=2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | JB nominal | JB maximum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | JB high water mark | JB low water mark | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Report Block Structure 2.2. Definition of Fields in Jitter Buffer Metrics Block block type (BT): 8 bits A Jitter Buffer Metrics Report Block is identified by the constant NJB. [Note to RFC Editor: please replace NJB 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 Jitter Buffer Metrics block is an Interval or a Cumulative report, 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 Jitter Buffer Metrics block. Note that there may be more than one Hunt & Clark Expires August 29, 2009 [Page 4] Internet-Draft RTCP XR Jitter Buffer February 2009 Measurement Identifier block per RTCP packet. Jitter Buffer Configuration (jb cfg): 4 bits This field is used to identify the jitter buffer method in use at the receiver, according to the following code: bits 014-017 0 = Fixed jitter buffer 1 = Adaptive jitter buffer Other values reserved block length: 16 bits The length of this report block in 32-bit words, minus one. For the Jitter Buffer block, the block length is equal to 2. jitter buffer nominal delay (JB nominal): 16 bits This is the current nominal jitter buffer delay in milliseconds, which corresponds to the nominal jitter buffer delay for packets that arrive exactly on time. This parameter MUST be provided for both fixed and adaptive jitter buffer implementations. 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. jitter buffer maximum delay (JB maximum): 16 bits This is the current maximum jitter buffer delay in milliseconds which corresponds to the earliest arriving packet that would not be discarded. In simple queue implementations this may correspond to the nominal size. In adaptive jitter buffer implementations, this value may dynamically. This parameter MUST be provided for both fixed and adaptive jitter buffer implementations. 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. jitter buffer high water mark (JB high water mark): 16 bits Hunt & Clark Expires August 29, 2009 [Page 5] Internet-Draft RTCP XR Jitter Buffer February 2009 This is the highest value of the jitter buffer nominal delay which occurred at any time during the reporting interval. 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. jitter buffer low water mark (JB low water mark): 16 bits This is the lowest value of the jitter buffer nominal delay which occurred at any time during the reporting interval. 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. Hunt & Clark Expires August 29, 2009 [Page 6] Internet-Draft RTCP XR Jitter Buffer February 2009 3. 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-jb-block xr-jb-block = "jitter-bfr" Hunt & Clark Expires August 29, 2009 [Page 7] Internet-Draft RTCP XR Jitter Buffer February 2009 4. 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]. 4.1. New RTCP XR Block Type value This document assigns the block type value NJB in the IANA "RTCP XR Block Type Registry" to the "JB Metrics Block". [Note to RFC Editor: please replace NJB with the IANA provided RTCP XR block type for this block.] 4.2. New RTCP XR SDP Parameter This document also registers a new parameter "jitter-bfr" in the "RTCP XR SDP Parameters Registry". 4.3. Contact information for registrations The contact information for the registrations is: Geoff Hunt (geoff.hunt@bt.com) Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United Kingdom Hunt & Clark Expires August 29, 2009 [Page 8] Internet-Draft RTCP XR Jitter Buffer February 2009 5. 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. Hunt & Clark Expires August 29, 2009 [Page 9] Internet-Draft RTCP XR Jitter Buffer February 2009 6. 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. Hunt & Clark Expires August 29, 2009 [Page 10] Internet-Draft RTCP XR Jitter Buffer February 2009 7. Changes since previous version Expanded and clarified IANA Considerations section Changed SDP tag for block to "jitter-bfr" Hunt & Clark Expires August 29, 2009 [Page 11] Internet-Draft RTCP XR Jitter Buffer February 2009 8. References 8.1. Normative References [MEASIDENT] Hunt, G., "RTCP XR Measurement Identifier Block", ID 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. 8.2. 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. Hunt & Clark Expires August 29, 2009 [Page 12] Internet-Draft RTCP XR Jitter Buffer February 2009 Authors' Addresses Geoff Hunt BT Orion 2 PP3 Adastral Park Martlesham Heath Ipswich, Suffolk IP5 3RE United Kingdom Phone: +44 1473 651704 Email: geoff.hunt@bt.com Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA Email: alan.d.clark@telchemy.com Hunt & Clark Expires August 29, 2009 [Page 13]