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Versions: 00 01 02                                                      
Audio/Video Transport Working Group                       R. Brandenburg
Internet-Draft                                                       TNO
Intended status: Standards Track                                K. Gross
Expires: January 14, 2013                                   AVA Networks
                                                                   Q. Wu
                                                                  Huawei
                                                              F. Boronat
                                                             M. Montagud
                                                                   UPVLC
                                                           July 13, 2012


        RTCP XR Report Block for One Way Delay metric Reporting
             draft-wu-xrblock-rtcp-xr-one-way-delay-02.txt

Abstract

   This document defines an RTCP XR Report Block that allows the
   reporting of One Way 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 January 14, 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
   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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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   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 One Way 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.  One Way Delay Block  . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Report Block Structure . . . . . . . . . . . . . . . . . .  5
     3.2.  Definition of Fields in One Way Delay Metrics Report
           Block  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Clock synchronization for one way delay metrics  . . . . . . .  7
   5.  One way delay calculation based on measurement method in
       RFC2679  . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  SDP Signaling  . . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
     7.1.  New RTCP XR Block Type value . . . . . . . . . . . . . . . 10
     7.2.  New RTCP XR SDP Parameter  . . . . . . . . . . . . . . . . 10
     7.3.  Contact information for registrations  . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13



















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1.  Introduction

1.1.  Packet One Way Delay Metrics Block

   [I-D.ietf-xrblock-rtcp-xr-delay] defines the new block type
   supporting the reporting of the mean, minimum and maximum values of
   the network round-trip delay between media source(source) and media
   receiver(destination).  However none of these metrics allow a
   receiver to report one way delay from source to destination or the
   other way around.  As described in [RFC2679], the path from a source
   to a destination may be different than the path from the destination
   back to the source.  Even when the two paths are symmetric, they may
   have radically different performance characteristics.  Therefore the
   measurement of one-way delay can not be roughly estimated by the
   round-trip delay for many applications in the asymmetric network and
   even symmetric network.

   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, maximum values of one
   way network delay between RTP interfaces in peer RTP end systems, as
   measured, for example, using the method described in [RFC2679].

   This metrics belong to the class of transport metrics defined in
   [MONARCH].

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.  The
   use of Extended Report blocks is defined by [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 [MONARCH] provides guideline for reporting
   block format using RTCP XR.  The Metrics Block described in this
   document are in accordance with the guidelines in [RFC6390] and
   [MONARCH].

1.4.  Applicability

   These metrics are applicable to a range of delay-sensitive RTP
   applications in which this report block would be useful, such as some
   IDMS use cases (e.g., video wall, network games, networked
   loudspeakers, etc., see Draft IDMS [IDMS]).



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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.  One Way Delay Block

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

3.1.  Report Block Structure

   One Way 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=OWD    | I |  resv.    |      block length = 4         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           SSRC of Source                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Median-One-way-Network-Delay               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Max-One-way-Network-Delay                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Min-One-way-Network-Delay                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1: Report Block Structure

3.2.  Definition of Fields in One Way Delay Metrics Report Block

   Block type (BT): 8 bits

      A One way Delay Report Block is identified by the constant OWD.

      [Note to RFC Editor: please replace OWD 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 One Way Metrics are
      Sampled, Interval or Cumulative metrics [MONARCH], that is,
      whether the reported values applies to the most recent measurement
      interval duration between successive metrics reports (I=10) (the
      Interval Duration), to the accumulation period characteristic of
      cumulative measurements (I=11) (the Cumulative Duration) or is a
      sampled instantaneous value (I=01).







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   Reserved (resv): 6 bits

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


   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 4.


   SSRC of source: 32 bits

      The SSRC of the media source shall be set to the value of the SSRC
      identifier carried in the RTP header [RFC3550] of the RTP packet
      to which the XR relates.


   Median-One-way-Network-Delay: 32 bits

      The Mean One way Delay is the mean value of the RTP-to- RTP
      interface one way delay in units of 1/65536 seconds over the
      measurement period.  It can be calculated using RTCP SR/RR or RTP
      media packet according to section 3.6 of [RFC2679].  For details
      on one way delay calculation, see Section 5.


   Max-One-way-Network-Delay: 32 bits

      The Max One Way Delay is the maximum value of the RTP- to-RTP
      interface one way delay in units of 1/65536 seconds over the
      measurement period.  It can be calculated using RTCP SR/RR or RTP
      media packet according to section 3.6 of [RFC2679].  For details
      on one way delay calculation, see Section 5.


   Min-One-way-Network-Delay: 32 bits

      The Max One Way Delay is the minimum value of the RTP- to-RTP
      interface one way delay in units of 1/65536 seconds over the
      measurement period.  It can be calculated using RTCP SR/RR or RTP
      media packet according to section 3.6 of [RFC2679].  For details
      on one way delay calculation, see Section 5.







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4.  Clock synchronization for one way delay metrics

   This subsection provides informative guidance on use of methodology
   for one way delay metrics measurement.

   As specified in the methodology of [RFC2679], it is important for
   media source (Src) and media receiver (Dst) to synchronize very
   closely since one way delay values will often be as low as the 100
   usec to 10 msec range.  In order to arrange Src and Des synchronized
   before measurement method is applied, a participant at the Dst can
   indicate which synchronization source is being used at the moment.  A
   participant can also indicate any other synchronization sources
   available to it.  This allows multiple participants in an RTP session
   to use the same or a similar clock synchronization source for their
   session.




































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5.  One way delay calculation based on measurement method in RFC2679

   TBC.
















































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6.  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-one-way-delay-block

   xr-one-way-delay-block ="one way delay"


































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7.  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].

7.1.  New RTCP XR Block Type value

   This document assigns the block type value OWD in the IANA "RTCP XR
   Block Type Registry" to the "One Way Delay Metrics Block".

   [Note to RFC Editor: please replace OWD with the IANA provided RTCP
   XR block type for this block.]

7.2.  New RTCP XR SDP Parameter

   This document also registers a new parameter "one way delay" in the
   "RTCP XR SDP Parameters Registry".

7.3.  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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8.  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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9.  References

9.1.  Normative References

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

   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, September 1999.

   [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.

9.2.  Informative References

   [I-D.ietf-xrblock-rtcp-xr-delay]
              Hunt, G., Clark, A., Gross, K., and Q. Wu, "RTCP XR Report
              Block for Delay metric Reporting",
              ID draft-ietf-xrblock-rtcp-xr-delay-06, May 2012.

   [IDMS]     Brandenburg, R., Stokking, H., and M. Deventer, "RTCP for
              inter-destination media synchronization",
              ID draft-ietf-avtcore-idms-05, June 2012.

   [MONARCH]  Hunt, G., "Monitoring Architectures for RTP",
              ID draft-ietf-avtcore-monarch-17, June 2012.

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
















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Authors' Addresses

   R.van Brandenburg
   TNO

   Email: ray.vanbrandenburg@tno.nl


   Kevin Gross
   AVA Networks

   Email: kevin.gross@avanw.com


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

   Email: sunseawq@huawei.com


   Fernando Boronat Segu
   Universitat Politecnica de Valencia
   IGIC Institute, Campus de Gandia, C/ Paraninfo, 1, Grao de Gandia
   Valencia  46730
   Spain

   Email: fboronat@dcom.upv.es


   M. Montagud
   Universitat Politecnica de Valencia
   IGIC Institute, Campus de Gandia, C/ Paraninfo, 1, Grao de Gandia
   Valencia  46730
   Spain

   Email: mamontor@posgrado.upv.es












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