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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 6843

Audio/Video Transport Working Group                             A. Clark
Internet-Draft                                                  Telchemy
Intended status: Standards Track                                K. Gross
Expires: March 3, 2013                                      AVA Networks
                                                                   Q. Wu
                                                                  Huawei
                                                         August 30, 2012


            RTCP XR Report Block for Delay metric Reporting
                draft-ietf-xrblock-rtcp-xr-delay-08.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
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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 March 3, 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
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   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.



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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.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 14
     A.1.  draft-ietf-xrblock-rtcp-xr-delay-08  . . . . . . . . . . . 14
     A.2.  draft-ietf-xrblock-rtcp-xr-delay-07  . . . . . . . . . . . 14
     A.3.  draft-ietf-xrblock-rtcp-xr-delay-06  . . . . . . . . . . . 14
     A.4.  draft-ietf-xrblock-rtcp-xr-delay-05  . . . . . . . . . . . 14
     A.5.  draft-ietf-xrblock-rtcp-xr-delay-04  . . . . . . . . . . . 14
     A.6.  draft-ietf-xrblock-rtcp-xr-delay-03  . . . . . . . . . . . 14
     A.7.  draft-ietf-xrblock-rtcp-xr-delay-02  . . . . . . . . . . . 15
     A.8.  draft-ietf-xrblock-rtcp-xr-delay-01  . . . . . . . . . . . 15
     A.9.  draft-ietf-xrblock-rtcp-xr-delay-00  . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16

















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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].

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 [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 RTP applications in which
   this report block would be useful, such as multimedia conferencing
   and streaming audio and video.  Knowledge of the round-trip delay and
   delay characteristics can aid other receivers in sizing their receive
   buffers and selecting a playout delay.  The same information is also
   valuable to network managers in troubleshooting network and user
   experience issues.











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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.  Instances of this Metrics Block refer by
   Synchronization source (SSRC) to the separate auxiliary Measurement
   Information block [MEASI] 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.

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 = 6         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           SSRC of Source                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  Mean Network Round Trip Delay                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Min Network Round Trip Delay                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Max Network Round Trip Delay                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |               End System Delay - Seconds (bit 0-31)           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |              End System Delay - Fraction (bit 0-31)           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                     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 NDEL with the IANA provided
      RTCP XR block type for this block.]





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   Interval Metric flag (I): 2 bit

      This field is used to indicate whether the Delay metrics are
      Sampled, Interval or Cumulative metrics, that is, whether the
      reported values applies to the most recent measurement interval
      duration between successive metrics reports (I=10) (the Interval
      Duration) or to the accumulation period characteristic of
      cumulative measurements (I=11) (the Cumulative Duration) or is a
      sampled instantaneous value (I=01) (Sampled Value).


   Reserved (resv): 6 bits

      These bits are reserved.  They MUST be set to zero by senders and
      SHOULD 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 6.


   SSRC of source: 32 bits

      As defined in Section 4.1 of [RFC3611].


   Mean Network Round Trip Delay: 32 bits

      The Mean Network Round Trip Delay is the mean value of the RTP-to-
      RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds.  This value is typically
      determined using RTCP SR/RR (See RFC 3550 section 6.4.1).

      If only one measurement of Round Trip Delay is available for the
      timespan of the report (i.e.,the measurement period) (whether
      Interval or Cumulative), this single value SHOULD be reported as
      the mean value.

      If the measurement is unavailable, the value of this field with
      all bits set to 1 MUST be reported.


   Min Network Round Trip Delay: 32 bits

      The Min Network Round Trip Delay is the minimum value of the RTP-
      to-RTP interface round trip delay over the measurement period,



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      expressed in units of 1/65536 seconds.  This value is typically
      determined using RTCP SR/RR.

      If only one measurement of Round Trip Delay is available for the
      timespan of the report (i.e.,the measurement period) (whether
      Interval or Cumulative), this single value SHOULD be reported as
      the minimum value.

      If the measurement is unavailable, the value of this field with
      all bits set to 1 MUST be reported.

   Max Network Round Trip Delay: 32 bits

      The Max Network Round Trip Delay is the maximum value of the RTP-
      to-RTP interface round trip delay over the measurement period,
      expressed in units of 1/65536 seconds.  This value is typically
      determined using RTCP SR/RR.

      If only one measurement of Round Trip Delay is available for the
      timespan of the report (i.e.,the measurement period) (whether
      Interval or Cumulative), this single value SHOULD be reported as
      the maximum value.

      If the measurement is unavailable, the value of this field with
      all bits set to 1 MUST be reported.


   End System Delay: 64 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.  The value of
      this field is represented using a 64-bit NTP-format timestamp as
      defined in [RFC5905], which is 64-bit unsigned fixed-point number
      with the integer part in the first 32 bits and the fractional part
      in the last 32 bits.

      If the measurement is unavailable, the value of this field with
      all bits set to 1 MUST 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:

      Qin Wu (sunseawq@huawei.com)

      101 Software Avenue, Yuhua District
      Nanjing, Jiangsu  210012
      China






















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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

   Geoff Hunt wrote the initial version of this document.
















































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8.  Acknowledgments

   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,Jing
   Zhao,Kevin Gross, Colin Perkins, Charles Eckel, Glen Zorn,Shida
   Schubert.









































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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.

   [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.

   [RFC5905]  Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
              Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, June 2010.

9.2.  Informative References

   [MEASI]    Hunt, G., "Measurement Identity and information Reporting
              using SDES item and XR Block",
              ID draft-ietf-xrblock-rtcp-xr-meas-identity-09, July 2012.

   [MONARCH]  Hunt, G., "Monitoring Architectures for RTP",
              ID draft-ietf-avtcore-monarch-18, August 2012.

   [RFC6390]  Clark, A. and B. Claise, "Framework for Performance Metric
              Development", RFC 6390, October 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-08

   The following are the major changes to previous version :

   o  Move Geoff Hunt from author list to Contributors section based on
      his suggestion.

A.2.  draft-ietf-xrblock-rtcp-xr-delay-07

   The following are the major changes to previous version :

   o  Editorial changes.

   o  Reference updates.

A.3.  draft-ietf-xrblock-rtcp-xr-delay-06

   The following are the major changes to previous version :

   o  Editorial changes.

A.4.  draft-ietf-xrblock-rtcp-xr-delay-05

   The following are the major changes to previous version :

   o  One typo fixed.

A.5.  draft-ietf-xrblock-rtcp-xr-delay-04

   The following are the major changes to previous version :

   o  Revise the definition of sampled metric to get alignment with
      MONARCH.

   o  Clarify sending the metric block in the same RTCP compound packet
      as the measurement information block.

A.6.  draft-ietf-xrblock-rtcp-xr-delay-03

   The following are the major changes to previous version :

   o  Allocate 64 bit for end system delay and represent it using 64 bit
      NTP-Timestamp.



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   o  Other editorial changes.

A.7.  draft-ietf-xrblock-rtcp-xr-delay-02

   The following are the major changes to previous version :

   o  Allocate 32bits for each metrics and change unit for each metric
      from ms to 1/65536 seconds.

A.8.  draft-ietf-xrblock-rtcp-xr-delay-01

   The following are the major changes to previous version :

   o  Updated references.

   o  Allocate one more bit for Interval metric flag to indicate sampled
      metric can be used.

   o  add a few clarification text for failure mode.

A.9.  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

   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@avanw.com


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

   Email: sunseawq@huawei.com



























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