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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 7005

Audio/Video Transport Working Group                             A. Clark
Internet-Draft                                                  Telchemy
Intended status: Standards Track                                V. Singh
Expires: May 30, 2013                                   Aalto University
                                                                   Q. Wu
                                                                  Huawei
                                                       November 26, 2012


RTP Control Protocol (RTCP) Extended Report (XR) Block for Jitter Buffer
                            Metric Reporting
                  draft-ietf-xrblock-rtcp-xr-jb-02.txt

Abstract

   This document defines an RTP Control Protocol (RTCP) Extended Report
   (XR) Block that allows the reporting of Jitter Buffer metrics for a
   range of RTP applications.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 30, 2013.

Copyright Notice

   Copyright (c) 2012 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
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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


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
     3.1.  SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . .  7
     3.2.  Offer/Answer Usage . . . . . . . . . . . . . . . . . . . .  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.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 13
     A.1.  draft-ietf-xrblock-rtcp-xr-jb-02 . . . . . . . . . . . . . 13
     A.2.  draft-ietf-xrblock-rtcp-xr-jb-01 . . . . . . . . . . . . . 13
     A.3.  draft-ietf-xrblock-rtcp-xr-jb-00 . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14



















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1.  Introduction

1.1.  Jitter Buffer Metrics Block

   This document 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 end system
   metrics defined in [RFC6792].

   Instances of this Metrics Block refer by SSRC to the separate
   auxiliary Measurement Information block [RFC6776] 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 document defines a new Extended Report block for
   use with [RFC3550] and [RFC3611].

1.3.  Performance Metrics Framework

   The Performance Metrics Framework [RFC6390] provides guidance on the
   definition and specification of performance metrics.  The RTP
   Monitoring Architectures [RFC6792] provides guideline for reporting
   block format using RTCP XR.  Metrics described in this draft are in
   accordance with the guidelines in [RFC6390][RFC6792].

1.4.  Applicability

   Real-time applications employ a jitter buffer to smooth out jitter
   encountered on the path from source to destination.  These metrics
   are used to measure how the jitter buffer behave as a result of the
   jitter and applicable to a range of RTP applications.  These metrics
   reflect terminal related factor that most affects real-time
   application quality and useful to provide more precise estimation for
   user experience to the quality of real-time application performance
   and also valuable to network manager in troubleshooting network.








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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.  Instances of this Metrics Block refer by
   SSRC to the separate auxiliary Measurement Information block
   [RFC6776] which contains measurement intervals.  This metric block
   relies on the measurement interval in the Measurement Information
   block indicating the span of the report and should be sent in the
   same compound RTCP packet as the measurement information block.  If
   the measurement interval is not received in the same compound RTCP
   packet as this metric block, this metric block should be discarded.

2.1.  Report Block Structure

   JB Metrics Block

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     BT=NJB    | I |jb cfg |rsv|       block length=3          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           SSRC of Source                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          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): 2 bits

      This field is used to indicate whether the Jitter Buffer metrics
      are Sampled, Interval or Cumulative metrics:





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         I=10: Interval Duration - the reported value applies to the
         most recent measurement interval duration between successive
         metrics reports.

         I=11: Cumulative Duration - the reported value applies to the
         accumulation period characteristic of cumulative measurements.

         I=01: Sampled Value - the reported value is a sampled
         instantaneous value.


   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 014-011

            0 = Fixed jitter buffer

            1 = Adaptive jitter buffer

            Other values reserved


   Reserved (rsv): 2 bits

      These bits are reserved.  They MUST be set to zero by senders
      ignored by receivers (See RFC6709 section 4.2).


   Block Length: 16 bits

      The length of this report block in 32-bit words, minus one and
      MUST be set to 3, in accordance with the definition of this field
      in [RFC3611].  The block MUST be discarded if the block length is
      set to a different value.


   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.  It is calculated based on the time
      for packets spent in the jitter buffer.  This parameter MUST be
      provided for both fixed and adaptive jitter buffer
      implementations.




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      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

      This is the highest value of the jitter buffer nominal delay in
      milliseconds 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 in
      milliseconds 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.












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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.

3.1.  SDP rtcp-xr-attrib Attribute Extension

   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.

   xr-format =/ xr-jb-block

   xr-jb-block = "jitter-bfr"

3.2.  Offer/Answer Usage

   When SDP is used in offer-answer context, the SDP Offer/Answer usage
   defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters
   applies.  For detailed usage in Offer/Answer for unilateral
   parameter, refer to section 5.2 of [RFC3611].





























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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:

      Qin Wu (sunseawq@huawei.com)
      101 Software Avenue, Yuhua District
      Nanjing, Jiangsu  210012
      China























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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.












































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6.  Contributors

   Geoff Hunt wrote the initial draft of this document.
















































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7.  Acknowledgments

   The authors gratefully acknowledge reviews and feedback provided 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.











































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8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", March 1997.

   [RFC3550]  Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
              Applications", RFC 3550, July 2003.

   [RFC3611]  Friedman, T., Caceres, R., and A. Clark, "RTP Control
              Protocol Extended Reports (RTCP XR)", November 2003.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", July 2006.

   [RFC6709]  Carpenter, B., Aboba, B., and S. Cheshire, "Design
              Considerations for Protocol Extensions", RFC 6709,
              September 2012.

8.2.  Informative References

   [RFC6390]  Clark, A. and B. Claise, "Framework for Performance Metric
              Development", RFC 6390, October 2011.

   [RFC6776]  Wu, Q., "Measurement Identity and information Reporting
              using SDES item and XR Block", RFC 6776, August 2012.

   [RFC6792]  Hunt, G., Wu, Q., and P. Arden, "Monitoring Architectures
              for RTP", RFC 6792, November 2012.





















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Appendix A.  Change Log

   Note to the RFC-Editor: please remove this section prior to
   publication as an RFC.

A.1.  draft-ietf-xrblock-rtcp-xr-jb-02

   The following are the major changes to previous version :

   o  Add some explaination text in the SDP offer/answer section.

   o  Add some text in applicability section to explain the use to
      report jitter buffer metrics.

   o  Other editorial change changes aligning with PDV,Delay draft.

A.2.  draft-ietf-xrblock-rtcp-xr-jb-01

   The following are the major changes to previous version :

   o  Outdated reference update

   o  Add one Editor notes to ask clarification on the use of reporting
      jitter buffer metrics.

   o  Other Editorial changes.

A.3.  draft-ietf-xrblock-rtcp-xr-jb-00

   The following are the major changes to previous version :

   o  Boilerplate updates.

   o  references updates

   o  allocate 32 bit field in report block for SSRC

   o  Other editorial changes to get alignment with MONARCH draft.













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Authors' Addresses

   Alan Clark
   Telchemy Incorporated
   2905 Premiere Parkway, Suite 280
   Duluth, GA  30097
   USA

   Email: alan.d.clark@telchemy.com


   Varun Singh
   Aalto University
   School of Electrical Engineering
   Otakaari 5 A
   Espoo, FIN  02150
   Finland

   Email: varun@comnet.tkk.fi


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: sunseawq@huawei.com























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