Audio/Video Transport Working Group                              G. Hunt
Internet-Draft                                              Unaffiliated
Intended status: Standards Track                                A. Clark
Expires: April 19, 2012                                         Telchemy
                                                                K. Gross
                                                            AVA Networks
                                                                   Q. Wu
                                                                  Huawei
                                                        October 17, 2011


            RTCP XR Report Block for Delay metric Reporting
                draft-ietf-xrblock-rtcp-xr-delay-00.txt

Abstract

   This document defines an RTCP XR Report Block that allows the
   reporting of Delay metrics for use in 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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on April 19, 2012.

Copyright Notice

   Copyright (c) 2011 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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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.  Packet Delay Metrics Block . . . . . . . . . . . . . . . .  3
     1.2.  RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . .  3
     1.3.  Performance Metrics Framework  . . . . . . . . . . . . . .  3
     1.4.  Applicability  . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Standards Language . . . . . . . . . . . . . . . . . . . .  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.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 13
     A.1.  draft-ietf-xrblock-rtcp-xr-delay-00  . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14






















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1.  Introduction

1.1.  Packet Delay 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
   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).

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.


















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2.  Terminology

2.1.  Standards Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].












































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3.  Delay Block

   Metrics in this block report on packet delay in the stream arriving
   at the RTP system.

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|   resv.     |      block length = 3         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           SSRC of Source                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | 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 NPDV 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 Packet Delay Variation
      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).


   Reserved (resv): 7 bits

      These bits are reserved.  They SHOULD be set to zero by senders
      and MUST be ignored by receivers.




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   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 3.


   SSRC of source: 32 bits

      As defined in Section 4.1 of [RFC3611].


   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.



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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.

   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.


































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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-delay-block

   xr-delay-block ="delay"


































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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 assigns the block type value NDEL in the IANA "RTCP XR
   Block Type Registry" to the "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 "delay" in the "RTCP XR
   SDP Parameters Registry".

5.3.  Contact information for registrations


   The contact information for the registrations is:

   Geoff Hunt (r.geoff.hunt@gmail.com)

   Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United
   Kingdom























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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.












































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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.











































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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.

8.2.  Informative References

   [MONARCH]  Hunt, G., "Monitoring Architectures for RTP",
              ID draft-ietf-avtcore-monarch-04, August 2011.

   [PMOLFRAME]
              Clark, A. and B. Claise, "Framework for Performance Metric
              Development", ID draft-ietf-pmol-metrics-framework-12,
              July 2011.


























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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-delay-00

   The following are the major changes to previous version :

   o  Changed BNF for SDP following Christian Groves' and Tom Taylor's
      comments (4th and 5th May 2009).

   o  Updated references.






































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Authors' Addresses

   Geoff Hunt
   Unaffiliated

   Email: r.geoff.hunt@gmail.com


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

   Email: alan.d.clark@telchemy.com


   Kevin Gross
   AVA Networks

   Email: kevin.gross@comcast.net


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

   Email: sunseawq@huawei.com





















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