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Versions: 00 01 02 03 04 05 06 07 draft-ietf-xrblock-rtcp-xr-synchronization

Network Working Group                                          H. Asaeda
Internet-Draft                                           Keio University
Intended status: Standards Track                                R. Huang
Expires: December 17, 2011                                         Q. Wu
                                                                  Huawei
                                                           June 15, 2011


 RTCP XR Blocks for Synchronization Delay and Offset Metrics Reporting
            draft-asaeda-xrblock-rtcp-xr-synchronization-01

Abstract

   This document defines an RTCP XR Report Block and associated SDP
   parameters that allows the reporting of synchronization delay and
   offset 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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 17, 2011.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
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   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  Standards Language  . . . . . . . . . . . . . . . . . . . . 3
   3.  Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  RTP Flows Initial Synchronization Delay Report Block  . . . . . 4
     4.1.  Metric Block Structure  . . . . . . . . . . . . . . . . . . 4
     4.2.  Definition of Fields in RTP Flow Initial
           Synchronization Delay Metrics Block . . . . . . . . . . . . 4
   5.  RTP Flows General Synchronization Offset Metrics Block  . . . . 5
     5.1.  Metric Block Structure  . . . . . . . . . . . . . . . . . . 5
     5.2.  Definition of Fields in RTP Flow General
           Synchronization Offset Metrics Block  . . . . . . . . . . . 6
   6.  SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     10.1. Normative References  . . . . . . . . . . . . . . . . . . . 8
     10.2. Informative References  . . . . . . . . . . . . . . . . . . 8
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . . . 9
     A.1.  draft-asaeda-xrblock-rtcp-xr-syncronization-00  . . . . . . 9
     A.2.  draft-asaeda-xrblock-rtcp-xr-syncronization-01  . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9













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1.  Introduction

   This draft defines a new block type to augment those defined in
   [RFC3611], for use in a range of RTP applications.

   This new block type supports reporting of Initial synchronization
   delay.  Information is recorded about the difference between the
   start of RTP sessions and the time the RTP receiver acquires all
   components of RTP sessions [RFC6051].  It also supports reporting of
   the general Synchronization offset status of an arbitrary number of
   streams, with the same RTCP CNAME.  Information is recorded about the
   synchronization offset time of each RTP stream relative to the
   reference RTP stream with the same CNAME and General Synchronization
   Offset of zero.

   The metrics belong to the class of transport level metrics defined in
   [MONARCH] (work in progress).


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].


3.  Applicability

   The report blocks defined in this document could be used by dedicated
   network monitoring applications.

   When joining a layered video session in such an application, a
   receiver may not synchronize playout across the multimedia session
   until RTCP SR packets have been received on all of the component RTP
   sessions.  For unicast session, the delay due to negotiation of NAT
   pinholes, firewall holes, quality-of-service, and media security keys
   is contributed to such initial synchronization playout.  For
   multicast session, such initial synchronization delay varies with the
   session bandwidth and the number of members, the number of senders in
   the session.  The RTP flow synchronization delay block can be used to
   report the initial synchronization delay of these RTP streams beyond
   the information carried in the standard RTCP packet format.  In the
   absence of packet loss, the initial synchronization delay equals to
   the average time taken to receive the first RTCP packet in the RTP
   session with the longest RTCP reporting interval.  In the presence of
   packet loss, the media synchronization needs to wait until the



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   reporting interval has passed, and the next RTCP SR packet is sent.

   In an RTP multimedia session, there can be an arbitrary number of
   streams, with the same RTCP CNAME.  The RTP Flows General
   Synchronization Offset block can be used to report the general
   Synchronization offset status of these RTP streams beyond the
   information carried in the standard RTCP packet format.  For layered
   session or multimedia session, the first RTP packet can be chosen as
   the basic packet of reference RTP stream.


4.  RTP Flows Initial Synchronization Delay Report Block

   This block reports Initial synchronization delay beyond the
   information carried in the standard RTCP packet format.  Information
   is recorded about the the difference between the start of RTP
   sessions and the time the RTP receiver acquires all components of RTP
   sessions [RFC6051].  The components of RTP session are referred to as
   one RTP session for each media type or the media content in each
   layer contained in RTP Control Protocol (RTCP) sender report (SR)
   packets [RFC3550].

4.1.  Metric Block Structure

   The RTP Flows Initial Synchronization Delay Report Block has the
   following format:

       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=TBD    |   Reserved    |          Block length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      SSRC of Sender                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Initial Synchronization Delay                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.  Definition of Fields in RTP Flow Initial Synchronization Delay
      Metrics Block

   Block type (BT): 8 bits

      The Statistics Summary Report Block is identified by the constant
      <RFISD>.







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   Block length: 16 bits

      The constant 2, in accordance with the definition of this field in
      Section 3 of RFC 3611 [RFC3611].

   SSRC of Sender: 32 bits

      The SSRC of the RTP data packet source being reported upon by this
      report block.  (Section 4.1 of [RFC3611]).
   Initial Synchronization Delay: 32 bits

      The average delay, expressed in units of 1/65536 seconds, between
      the RTCP packets received on all of the components RTP sessions
      and the beginning of session [RFC6051].  The value is calculated
      as follows:

         The average time, expressed in units of 1/65536 seconds, taken
         to receive the first RTCP packet in the RTP session with the
         longest RTCP reporting interval [RFC6051].


5.  RTP Flows General Synchronization Offset Metrics Block

   In an RTP multimedia session, there can be an arbitrary number of
   streams, with the same RTCP CNAME.  This block reports the general
   Synchronization offset status of these RTP streams beyond the
   information carried in the standard RTCP packet format.  Information
   is recorded about the synchronization offset time of each RTP stream
   relative to the reference RTP stream with the same CNAME and General
   Synchronisation Offset of zero.


5.1.  Metric Block Structure

   The RTP Flow General Synchronization Offset Report Block has the
   following format:

       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=TBD    |   Reserved    |         Block length          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SSRC of source                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                General Synchronization Offset                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





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5.2.  Definition of Fields in RTP Flow General Synchronization Offset
      Metrics Block

   Block type (BT): 8 bits

      The RTP Flow General Synchronization Offset Report Block is
      identified by the constant <RFGSO>.

   Block length: 16 bits

      The constant 3, in accordance with the definition of this field in
      Section 3 of RFC 3611 [RFC3611].

   SSRC of Source: 32 bits

      The SSRC of the RTP data packet source being reported upon by this
      report block.  (Section 4.1 of [RFC3611]).
   General synchronization offset: 32 bits

      This field represents the synchronization offset time of one RTP
      stream in milliseconds relative to the reference RTP stream with
      the same CNAME and General Synchronisation Offset of zero
      [RFC6051] This value is calculated based on the interarrival time
      between arbitray RTP packet and the reference RTP packet with the
      same CNAME , and timestamps of this arbitray RTP packet and the
      reference RTP packet with the same CNAME.


6.  SDP Signaling

   Two new parameters are defined for the two report blocks defined in
   this document to be used with Session Description Protocol (SDP)
   [RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234].
   They have the following syntax within the "rtcp-xr" attribute
   [RFC3611]:

        rtcp-xr-attrib =  "a=rtcp-xr:"
                          [xr-format *(SP xr-format)] CRLF
              xr-format = RTP-flows-init-syn
                       / RTP-flows-general-syn

              RTP-flows-init-syn = "RTP-flows-init-syn"
                              ["=" max-size]
                 max-size = 1*DIGIT ; maximum block size in octets

              RTP-flow-general-syn = "RTP-flows-general-syn"
                                ["=" max-size]
                 max-size = 1*DIGIT ; maximum block size in octets



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   Refer to Section 5.1 of RFC 3611 [RFC3611] for a detailed description
   and the full syntax of the "rtcp-xr" attribute.


7.  IANA Considerations

   New report block types for RTCP XR are subject to IANA registration.
   For general guidelines on IANA allocations for RTCP XR, refer to
   Section 6.2 of [RFC3611].

   This document assigns two new block type values in the RTCP XR Block
   Type Registry:

      Name:       RFISD
      Long Name:  RTP Flows Initial Synchronization Delay
      Value       <RFISD>
      Reference:  Section 4
      Name:       RFGSO
      Long Name:  RTP Flows General Synchronization Offset Metrics Block
      Value       <RFGSO>
      Reference:  Section 5

   This document also registers two new SDP [RFC4566] parameters for the
   "rtcp-xr" attribute in the RTCP XR SDP Parameters Registry:

      *  "RTP-flows-init-syn"
      *  "RTP-flows-general-syn"

   The contact information for the registrations is:

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


8.  Security Considerations

   The new RTCP XR report blocks proposed in this document introduces no
   new security considerations beyond those described in [RFC3611].


9.  Acknowledgements

   The authors would like to thank Bill Ver Steeg, David R Oran, Ali
   Begen, Colin Perkins, Roni Even, Youqing Yang, Wenxiao Yu and
   Yinliang Hu for their valuable comments and suggestions on this
   document.



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10.  References

10.1.  Normative References

   [I-D.ietf-avt-rtp-svc]
              Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
              "RTP Payload Format for Scalable Video Coding",
              draft-ietf-avt-rtp-svc-27 (work in progress),
              February 2011.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2250]  Hoffman, D., Fernando, G., Goyal, V., and M. Civanlar,
              "RTP Payload Format for MPEG1/MPEG2 Video", RFC 2250,
              January 1998.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC3611]  Friedman, T., Caceres, R., and A. Clark, "RTP Control
              Protocol Extended Reports (RTCP XR)", RFC 3611,
              November 2003.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC6051]  Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP
              Flows", RFC 6051, November 2010.

10.2.  Informative References

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

   [MONARCH]  Wu, Q., "Monitoring Architectures for RTP",
              ID draft-ietf-avtcore-monarch-00, April 2011.

   [PMOL]     Clark, A., "Framework for Performance Metric Development",
              ID draft-ietf-pmol-metrics-framework-08, January 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-asaeda-xrblock-rtcp-xr-syncronization-00

   This document is separated from
   draft-wu-xrblock-rtcp-xr-quality-monitoring-01 with some editorial
   changes and focuses on RTP Flow Initial Synchronization Delay and RTP
   Flows General Synchronization Offset.

A.2.  draft-asaeda-xrblock-rtcp-xr-syncronization-01

   Separate Synchronization Delay and Offset Metrics Block into two
   independent block based on comments on the list.


Authors' Addresses

   Hitoshi Asaeda
   Keio University
   Graduate School of Media and Governance
   5322 Endo
   Fujisawa, Kanagawa  252-0882
   Japan

   Email: asaeda@wide.ad.jp


   Rachel Huang
   Huawei Technologies Co., Ltd.
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: Rachel@huawei.com


   Qin Wu
   Huawei Technologies Co., Ltd.
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: sunseawq@huawei.com





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