[Search] [pdf|bibtex] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02                                                      
Audio/Video Transport Working                                    G. Hunt
Group                                                                 BT
Internet-Draft                                                  A. Clark
Intended status: Standards Track                                Telchemy
Expires: November 16, 2009                                  May 15, 2009


        RTCP XR Report Block for Jitter Buffer Metric Reporting
                    draft-ietf-avt-rtcp-xr-jb-02.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 November 16, 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 November 16, 2009               [Page 1]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 2]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 3]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 4]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 5]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 6]


Internet-Draft            RTCP XR Jitter Buffer                 May 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-jb-block

   xr-jb-block = "jitter-bfr"


































Hunt & Clark            Expires November 16, 2009               [Page 7]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 8]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009               [Page 9]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009              [Page 10]


Internet-Draft            RTCP XR Jitter Buffer                 May 2009


7.  Changes since previous version

   Changed BNF for SDP following Christian Groves' and Tom Taylor's
   comments (4th and 5th May 2009), now aligned with RFC 5234 section 
   3.3 "Incremental Alternatives".

   Updated references.












































Hunt & Clark            Expires November 16, 2009              [Page 11]


Internet-Draft            RTCP XR Jitter Buffer                 May 2009


8.  References

8.1.  Normative References

   [MEASIDENT]
              Hunt, G., "RTCP XR Measurement Identifier Block",
              ID draft-ietf-avt-rtcp-xr-meas-identity-02, May 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-02, March 2009.























Hunt & Clark            Expires November 16, 2009              [Page 12]


Internet-Draft            RTCP XR Jitter Buffer                 May 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 November 16, 2009              [Page 13]