path: root/doc/rfc/rfc7004.txt

Internet Engineering Task Force (IETF)                           G. Zorn
Request for Comments: 7004                                   Network Zen
Category: Standards Track                                      R. Schott
ISSN: 2070-1721                                         Deutsche Telekom
                                                              Q. Wu, Ed.
                                                                R. Huang
                                                                  Huawei
                                                          September 2013


        RTP Control Protocol (RTCP) Extended Report (XR) Blocks
                for Summary Statistics Metrics Reporting

Abstract

   This document defines three RTP Control Protocol (RTCP) Extended
   Report (XR) blocks that allow the reporting of loss, duplication, and
   discard summary statistics metrics in a range of RTP applications.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7004.

Copyright Notice

   Copyright (c) 2013 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
   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.




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Table of Contents

   1. Introduction ....................................................2
      1.1. Summary Statistics Metrics .................................2
      1.2. RTCP and RTCP Extended Reports .............................3
      1.3. Performance Metrics Framework ..............................3
      1.4. Applicability ..............................................3
   2. Terminology .....................................................3
   3. Transport-Related End-System Metrics ............................4
      3.1. Burst/Gap Loss Summary Statistics Block ....................4
           3.1.1. Report Block Structure ..............................5
           3.1.2. Definition of Fields in Loss Summary
                  Statistics Block ....................................5
      3.2. Burst/Gap Discard Summary Statistics Block .................7
           3.2.1. Report Block Structure ..............................8
           3.2.2. Definition of Fields in Burst/Gap Discard
                  Summary Statistics Block ............................8
   4. Application-Level Metrics ......................................10
      4.1. Frame Impairment Statistics Summary Block .................10
           4.1.1. Report Block Structure .............................11
           4.1.2. Definition of Fields in Frame Impairment
                  Statistics Summary Block ...........................11
   5. SDP Signaling ..................................................13
      5.1. SDP rtcp-xr Attribute Extension ...........................13
      5.2. Offer/Answer Usage ........................................13
   6. IANA Considerations ............................................13
      6.1. New RTCP XR Block Type Values .............................13
      6.2. New RTCP XR SDP Parameters ................................14
      6.3. Contact Information for Registrations .....................14
   7. Security Considerations ........................................14
   8. Acknowledgements ...............................................14
   9. References .....................................................14
      9.1. Normative References ......................................14
      9.2. Informative References ....................................15
   Appendix A.  Metrics Represented Using the Template from RFC 6390 .16
















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1.  Introduction

1.1.  Summary Statistics Metrics

   This document defines three new block types to augment those defined
   in [RFC3611] for use in a range of RTP applications:

   o  Burst/Gap Loss Summary Statistics Block

   o  Burst/Gap Discard Summary Statistics Block

   o  Frame Impairment Statistics Summary Block

   The first two block types support the reporting of burst/gap loss and
   burst/gap discard summary statistics including packet loss/discard
   proportion, mean, and variance and belong to the class of transport-
   related end-system metrics defined in [RFC6792].  These two blocks
   are intended to be used in conjunction with information from the
   Burst/Gap Loss Metrics Block [RFC6958] or Burst/Gap Discard Metrics
   Block [RFC7003], on which these two blocks therefore depend.  The
   metrics in the Burst/Gap Loss Metrics Block and Burst/Gap Discard
   Metrics Block are consistent with the definitions of "burst", "gap",
   "loss", and "discard" in RTCP XR [RFC3611].

   The third block supports the reporting of detailed video statistics
   for each frame type, including the number of frames received, lost,
   and discarded of each frame type in the Group of Pictures (GOP) and
   additional data allowing the calculation of statistical parameters
   (e.g., the proportion of each frame type impaired by packet loss and
   discard).  The metrics defined in this block belong to the class of
   application-level metrics defined in [RFC6792].

1.2.  RTCP and RTCP Extended 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 RTP Monitoring Framework [RFC6792] provides guidelines for
   reporting block format using RTCP XR.  Metrics described in this
   document are in accordance with the guidelines in [RFC6792].







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1.4.  Applicability

   These metrics are applicable to a wide range of RTP applications and
   reflect transient IP problems that affect user experience.  They can
   be used to form an accurate assessment of users' quality of
   experience and influence sender strategies to mitigate the problem.

2.  Terminology

   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].

   In addition, the following term is defined:

   Frame Type

      In many cases, a video frame is compressed using different
      algorithms.  Frame type is used to identify different algorithms
      for video frames.  Two frame types used in the different video
      algorithms are the Key frame and Derived frames.  The Key frame is
      independently coded without prediction from other pictures and
      used as a reference frame for predicting other pictures.  Derived
      frames are predicatively coded and derived from a Key frame using
      a prediction algorithm.  If there is no video image compression,
      all frames are Key frames.

3.  Transport-Related End-System Metrics

3.1.  Burst/Gap Loss Summary Statistics Block

   This block extends packet loss and discard metrics defined in
   Section 4.7.1 of [RFC3611].  The metrics described here are intended
   to be used as described in this section, in conjunction with
   information from the Measurement Information Block [RFC6776] (which
   MUST be present in the same RTCP packet as the Burst/Gap Loss Metrics
   Block [RFC6958]) and also with the metric "cumulative number of
   packets lost" provided in standard RTCP [RFC3550].  Instances of this
   metrics block use the synchronization source (SSRC) to refer to the
   separate auxiliary Measurement Information Block [RFC6776], which
   describes measurement periods in use (see [RFC6776], Section 4.2).
   This metrics block relies on the measurement period 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 period is not received in the
   same compound RTCP packet as this metrics block, this metrics block
   MUST be discarded.




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   The metrics carried in this metrics block provide information
   relevant to statistical parameters, including Burst Loss Rate, Gap
   Loss Rate, Burst Duration Mean, and Burst Duration Variance, and are
   measured at the receiving end of the RTP stream using burst/gap loss
   metrics defined in [RFC6958] and other information that is sent
   together with this report block.

3.1.1.  Report Block Structure

   The structure of the Burst/Gap Loss Summary Statistics Block is as
   follows.

    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=17    | I | Reserved  |        Block Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         SSRC of Source                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Burst Loss Rate        |         Gap Loss Rate         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Burst Duration Mean     |    Burst Duration Variance    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.1.2.  Definition of Fields in Loss Summary Statistics Block

   Block Type (BT): 8 bits

      A Burst/Gap Loss Summary Statistics Block is identified by the
      constant 17.

   Interval Metric flag (I): 2 bits

      This field is used to indicate whether the burst/gap loss summary
      statistics metrics are Sampled, Interval, or Cumulative metrics:

         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.

      In this document, the value I=00 is the reserved value and MUST
      NOT be used.



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   Reserved: 6 bits

      This field is reserved for future definition.  In the absence of
      such a definition, the bits in this field MUST be set to zero and
      ignored by the receiver (see [RFC6709], Section 4.2).

   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

      As defined in Section 4.1 of RFC 3611 [RFC3611].

   Burst Loss Rate: 16 bits

      The fraction of packets lost during bursts since the beginning of
      reception, expressed as a fixed point number with the binary point
      immediately after the left-most bit.  This value is calculated by
      dividing Packets Lost in Bursts by Total Packets Expected in
      Bursts, multiplying the result of the division by 32768 (0x8000),
      and keeping only the integer part.  The maximum value is thus
      0x8000.  Representing this as a formula:

      integer-part( (Packets Lost in Bursts / Total Packets Expected in
      Bursts) * 0x8000 )

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

   Gap Loss Rate: 16 bits

      The fraction of packets lost during gaps since the beginning of
      reception expressed as a fixed point number with the binary point
      immediately after the left-most bit.  This value is calculated by
      dividing the difference between number of packets lost and Packets
      Lost in Bursts by the difference between Packets Expected and
      Total Packets Expected in Bursts, multiplying the result of the
      division by 32768 (0x8000), and keeping only the integer part.
      The maximum value is thus 0x8000.  Representing this as a formula:

      integer-part ( (number of packets lost - Packets Lost in Bursts)/
      (Packets Expected - Total Packets Expected in Bursts) * 0x8000 )

      where "number of packets lost" is obtained from standard RTCP
      [RFC3550] and Packets Expected is calculated as the difference
      between "extended last sequence number" and "extended first



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      sequence number" (Interval or Cumulative) provided in the
      Measurement Identity and Information Block [RFC6776].

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

      Note that if the metric is to be calculated on an Interval basis,
      a difference must be taken between the current and preceding
      values of "cumulative number of packets lost" in RTCP to obtain
      the "number of packets lost" for the reporting interval.

   Burst Duration Mean: 16 bits

      The mean burst duration is obtained as the quotient:

      mean = Sum of Burst Durations / Number of Bursts

      where "Sum of Burst Durations" and "Number of Bursts" is obtained
      from the RTCP XR Burst/Gap Loss Metrics Block [RFC6958].

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

   Burst Duration Variance: 16 bits

      The variance of the burst duration is obtained using the standard
      result:

      var = ( Sum of Squares of Burst Durations - Number of Bursts *
      mean^2 ) / (Number of Bursts - 1)

      where "Sum of Squares of Burst Durations" and "Number of Bursts"
      is obtained from the RTCP XR Burst/Gap Loss Metrics Block
      [RFC6958].

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

3.2.  Burst/Gap Discard Summary Statistics Block

   This block extends packet loss and discard metrics defined in
   Section 4.7.1 of [RFC3611].  The metrics described here are intended
   to be used as described in this section, in conjunction with
   information from the Measurement Identity Block [RFC6776] (which MUST
   be present in the same RTCP packet as the Burst/Gap Discard Summary
   Statistics Block).





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   These metrics provide information relevant to statistical parameters,
   including Burst Discard Rate and Gap Discard Rate, and are measured
   at the receiving end of the RTP stream using burst/gap discard
   metrics defined in [RFC7003] and other information that is sent
   together with this report block.

   Instances of this metrics block use the synchronization source (SSRC)
   to refer to the separate auxiliary Measurement Information block
   [RFC6776] that describes measurement periods in use (see [RFC6776],
   Section 4.2).  This metrics block relies on the measurement period 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 period is not
   received in the same compound RTCP packet as this metrics block, this
   metrics block MUST be discarded.

3.2.1.  Report Block Structure

   The structure of the Burst/Gap Discard Summary Statistics Block is as
   follows.

    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=18    | I |  Reserved |        Block Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          SSRC of Source                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Burst Discard Rate   |        Gap Discard Rate       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.2.2.  Definition of Fields in Burst/Gap Discard Summary Statistics
        Block

   Block Type (BT): 8 bits

      A Burst/Gap Discard Summary Statistics Block is identified by the
      constant 18.

   Interval Metric flag (I): 2 bits

      This field is used to indicate whether the burst/gap discard
      summary statistics metrics are Sampled, Interval, or Cumulative
      metrics:

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



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         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.

      In this document, the value I=00 is the reserved value and MUST
      NOT be used.

   Reserved: 6 bits

      This field is reserved for future definition.  In the absence of
      such a definition, the bits in this field MUST be set to zero and
      ignored by the receiver (see [RFC6709], Section 4.2).

   Block Length: 16 bits

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

   SSRC of Source: 32 bits

      As defined in Section 4.1 of RFC3611 [RFC3611].

   Burst Discard Rate: 16 bits

      The fraction of packets discarded during bursts since the
      beginning of reception, expressed as a fixed point number with the
      binary point immediately after the left-most bit.  This value is
      calculated by dividing Packets Discarded in Bursts by Total
      Packets Expected in Bursts, multiplying the result of the division
      by 32768 (0x8000), and keeping only the integer part, according to
      the formula:

      integer-part( (Packets Discarded in Bursts / Total Packets
      Expected in Bursts) * 0x8000 )

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

   Gap Discard Rate: 16 bits

      The fraction of packets discarded during gaps since the beginning
      of reception expressed as a fixed point number with the binary
      point immediately after the left-most bit.  This value is
      calculated by dividing the difference between number of packets
      discarded and Packets Discarded in Bursts by the difference
      between Packets Expected and Total Packets Expected in Bursts,



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      multiplying the result of the division by 32768 (0x8000), and
      keeping only the integer part.  The maximum value is thus 0x8000.
      Representing this as a formula:

      integer-part( (number of packets discarded - Packets Discarded in
      Bursts) /(Packets Expected - Total Packets Expected in Bursts) *
      0x8000 )

      where "number of packets discarded" is obtained from the RTCP XR
      Discard Count Block [RFC7002] and filled with the sum of packets
      discarded due to early arrival (DT=1) and packets discarded due to
      late arrival (DT=2) and Packets Expected is calculated as the
      difference between "extended last sequence number" and "extended
      first sequence number" (Interval or Cumulative) provided in the
      Measurement Information Block [RFC6776].  In order for the Burst/
      Gap Discard Summary Statistics Block to be meaningful, 2 instances
      of the Discard Count Block with DT=1 and DT=2 MUST be included in
      the same RTCP XR packet as the Burst/Gap Discard Summary
      Statistics Block.

      If the measurement is unavailable, the value 0xFFFF MUST be
      reported.

4.  Application-Level Metrics

4.1.  Frame Impairment Statistics Summary Block

   This block extends the statistics summary report mechanism defined in
   Section 4.6 of [RFC3611] and reports statistics on which frame types
   were affected beyond the information carried in the Statistics
   Summary Report Block RTCP packet specified in Section 4.6 of
   [RFC3611].  Information is measured at the receiving end of the RTP
   stream and recorded about the number of frames received, lost frames,
   duplicated frames, and lost partial frames.  Such information can be
   useful for network management and video quality monitoring.
















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4.1.1.  Report Block Structure

   The structure of the Frame Impairment Statistics Summary Block is as
   follows.

    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=19    |T|   Reserved  |        Block Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        SSRC of Source                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          begin_seq            |             end_seq           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      discarded_frames                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          dup_frames                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      full_lost_frames                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      partial_lost_frames                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.1.2.  Definition of Fields in Frame Impairment Statistics Summary
        Block

   Block Type (BT): 8 bits

      A Frame Impairment Statistics Summary Block is identified by the
      constant 19.

   Frame type indicator (T): 1 bit

      This field is used to indicate the frame type to be reported.  The
      bit is set to 0 if the full_lost_frames, partial_lost_frames,
      dup_frames, and discarded_frames fields contain Key frame
      (reference frame) counts or 1 if they contain Derived frame
      counts.  Note that if both the Key frame and Derivation frame
      report are sent, they should be sent in the same RTCP compound
      packet using two Frame Impairment Statistics Summary Blocks.

   Reserved: 7 bits

      This field is reserved for future definition.  In the absence of
      such a definition, the bits in this field MUST be set to zero and
      ignored by the receiver (see [RFC6709], Section 4.2).





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   Block Length: 16 bits

      The constant 6, in accordance with the definition of this field in
      Section 3 of RFC 3611 [RFC3611].

   SSRC of Source: 32 bits

      As defined in Section 4.1 of RFC 3611 [RFC3611].

   begin_seq: 16 bits

      As defined in Section 4.1 of RFC 3611 [RFC3611].

   end_seq: 16 bits

      As defined in Section 4.1 of RFC 3611 [RFC3611].

   Number of discarded frames (discarded_frames): 32 bits

      Number of frames discarded in the above sequence number interval.

   Number of duplicate frames (dup_frames): 32 bits

      Number of duplicate frames received in the above sequence number
      interval.

   Number of full lost frames (full_lost_frames): 32 bits

      A frame is either split across multiple packets or carried in only
      one packet.  If the whole frame or all the packets of the frame
      are lost, this frame is regarded as one full_lost_frame.  The
      full_lost_frames can be inferred from packet(s) that comprise the
      frame.  The full_lost_frames is equivalent to the number of full
      lost frames in the above sequence number interval.

   Number of partial lost frames (partial_lost_frames): 32 bits

      When a frame is split across multiple packets and some packets of
      the frame are lost, this frame is regarded as one
      partial_lost_frame.  The partial_lost_frames can be inferred from
      packets that comprise the frame.  The value of the
      partial_lost_frames field is equivalent to the number of partial
      lost frames in the above sequence number interval.








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5.  SDP Signaling

   RFC 3611 defines the use of SDP (Session Description Protocol)
   [RFC4566] for signaling the use of XR blocks.  However, XR blocks MAY
   be used without prior signaling (see Section 5 of [RFC3611]).

5.1.  SDP rtcp-xr Attribute Extension

   This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
   in Section 5.1 of [RFC3611] by providing three additional values of
   "xr-format" to signal the use of the report block defined in this
   document.  The ABNF [RFC5234] syntax is as follows.

   xr-format =/ xr-bglss-block
              / xr-bgdss-block
              / xr-fiss-block
   xr-bglss-block = "burst-gap-loss-stat"
   xr-bgdss-block = "burst-gap-discard-stat"
   xr-fiss-block  = "frame-impairment-stat"

5.2.  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 of Offer/Answer for unilateral
   parameter, refer to section 5.2 of [RFC3611].

6.  IANA Considerations

   New block types for RTCP XR are subject to IANA registration.  For
   general guidelines on IANA considerations for RTCP XR, refer to RFC
   3611.

6.1.  New RTCP XR Block Type Values

   This document assigns three new block type values in the "RTP Control
   Protocol Extended Reports (RTCP XR) Block Type Registry":

         Name:       BGLSS
         Long Name:  Burst/Gap Loss Summary Statistics Block
         Value       17
         Reference:  Section 3.1

         Name:       BGDSS
         Long Name:  Burst/Gap Discard Summary Statistics Block
         Value       18
         Reference:  Section 3.2




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         Name:       FISS
         Long Name:  Frame Impairment Statistics Summary Block
         Value       19
         Reference:  Section 4.1

6.2.  New RTCP XR SDP Parameters

   This document also registers three new SDP [RFC4566] parameters for
   the "rtcp-xr" attribute in the "RTP Control Protocol Extended Reports
   (RTCP XR) Session Description Protocol (SDP) Parameters Registry":

   *  "burst-gap-loss-stat"
   *  "burst-gap-discard-stat"
   *  "frame-impairment-stat"

6.3.  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

7.  Security Considerations

   The new RTCP XR blocks in this document do not introduce any new
   security considerations beyond those described in [RFC3611].

8.  Acknowledgements

   The authors would like to thank Bill Ver Steeg, David R. Oran, Ali
   Begen, Colin Perkins, Roni Even, Youqing Yang, Wenxiao Yu, Yinliang
   Hu, Jing Zhao, Ray van Brandenburg, Claire Bi, Dan Romascanu, Alfred
   Morton, Jr., Klaas Wierenga, Barry Leiba, Robert Sparks, Ralph Droms,
   and Benoit Claise for their valuable comments and suggestions on this
   document.

9.  References

9.1.  Normative References

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

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



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   [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.

   [RFC6776]  Clark, A. and Q. Wu, "Measurement Identity and Information
              Reporting Using a Source Description (SDES) Item and an
              RTCP Extended Report (XR) Block", RFC 6776, October 2012.

   [RFC6958]  Clark, A., Zhang, S., Zhao, J., and Q. Wu, "RTP Control
              Protocol (RTCP) Extended Report (XR) Block for Burst/Gap
              Loss Metric Reporting", RFC 6958, May 2013.

   [RFC7002]  Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol
              (RTCP) Extended Report (XR) Block for Discard Count Metric
              Reporting", RFC 7002, September 2013.

   [RFC7003]  Clark, A., Huang, R., and Q. Wu, Ed., "RTP Control
              Protocol (RTCP) Extended Report (XR) Block for Burst/Gap
              Discard Metric Reporting", RFC 7003, September 2013.

9.2.  Informative References

   [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
              Performance Metric Development", BCP 170, RFC 6390,
              October 2011.

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

   [RFC6792]  Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
              RTP Monitoring Framework", RFC 6792, November 2012.













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Appendix A.  Metrics Represented Using the Template from RFC 6390

   a.  Burst Loss Rate Metric

       *  Metric Name: RTP Burst Loss Rate

       *  Metric Description: The fraction of packets lost during bursts
          since the beginning of reception for RTP traffic.

       *  Method of Measurement or Calculation: See Section 3.1.2, Burst
          Loss Rate definition.

       *  Units of Measurement: See Section 3.1.2, Burst Loss Rate
          definition.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.1, 2nd paragraph.

       *  Measurement Timing: See Section 3.1, 1st paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   b.  Gap Loss Rate Metric

       *  Metric Name: RTP Gap Loss Rate

       *  Metric Description: The fraction of packets lost during gaps
          since the beginning of reception for RTP traffic.

       *  Method of Measurement or Calculation: See Section 3.1.2, Gap
          Loss Rate definition.

       *  Units of Measurement: See Section 3.1.2, Gap Loss Rate
          definition.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.1, 2nd paragraph.

       *  Measurement Timing: See Section 3.1, 1st paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.




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   c.  Burst Duration Mean Metric

       *  Metric Name: RTP Burst Duration Mean

       *  Metric Description: The mean duration of the burst periods
          that have occurred since the beginning of reception for RTP
          traffic.

       *  Method of Measurement or Calculation: See Section 3.1.2, Burst
          Loss Rate definition.

       *  Units of Measurement: This metric is expressed in
          milliseconds.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.1, 2nd paragraph.

       *  Measurement Timing: See Section 3.1, 1st paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   d.  Burst Duration Variance Metric

       *  Metric Name: RTP Burst Duration Variance

       *  Metric Description: The variance duration of the burst periods
          that have occurred since the beginning of reception for RTP
          traffic.

       *  Method of Measurement or Calculation: See Section 3.1.2, Burst
          Duration Variance definition.

       *  Units of Measurement: See Section 3.1.2, Burst Duration
          Variance definition.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.1, 2nd paragraph.

       *  Measurement Timing: See Section 3.1, 1st paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.




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   e.  Burst Discard Rate Metric

       *  Metric Name: RTP Burst Discard Rate

       *  Metric Description: The fraction of packets discarded during
          bursts since the beginning of reception for RTP traffic.

       *  Method of Measurement or Calculation: See Section 3.2.2, Burst
          Discard Rate definition.

       *  Units of Measurement: See Section 3.2.2, Burst Discard Rate
          definition.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.2, 2nd paragraph.

       *  Measurement Timing: See Section 3.2, 3rd paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   f.  Gap Discard Rate Metric

       *  Metric Name: RTP Gap Discard Rate

       *  Metric Description: The fraction of packets discarded during
          gaps since the beginning of reception for RTP traffic.

       *  Method of Measurement or Calculation: See Section 3.2.2, Gap
          Discard Rate definition.

       *  Units of Measurement: See Section 3.2.2, Gap Discard Rate
          definition.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 3.2, 2nd paragraph.

       *  Measurement Timing: See Section 3.2, 3rd paragraph for
          measurement timing and Section 3.1.2 for Interval Metric flag.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.






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   g.  Number of Discarded Frames Metric

       *  Metric Name: Number of discarded frames in RTP

       *  Metric Description: Number of frames discarded in a certain
          sequence number interval for RTP traffic.

       *  Method of Measurement or Calculation: See Section 4.1.2,
          Number of discarded frames definition.  This metric is
          directly measured and can be inferred from packet(s) that
          comprise the frame.

       *  Units of Measurement: This metric is expressed as a 32-bit
          unsigned integer value.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 4.1, 1st paragraph.

       *  Measurement Timing: See Section 4.1, Number of discarded
          frames definition.  This metric relies on the sequence number
          interval and RTCP RR packet of [RFC3550] to determine
          measurement timing.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   h.  Number of Duplicate Frames Metric

       *  Metric Name: Number of duplicate frames in RTP

       *  Metric Description: Number of frames duplicated in a certain
          sequence number interval for RTP traffic.

       *  Method of Measurement or Calculation: See Section 4.1.2,
          Number of duplicate frames definition.  This metric is
          directly measured and can be inferred from packet(s) that
          comprise the frame.

       *  Units of Measurement: This metric is expressed as a 32-bit
          unsigned integer value.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 4.1, 1st paragraph.

       *  Measurement Timing: See Section 4.1, Number of duplicate
          frames definition.  This metric relies on the sequence number
          interval to determine measurement timing.



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       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   i.  Number of Full Lost Frames Metric

       *  Metric Name: Number of full lost frames in RTP

       *  Metric Description: A frame is either split across multiple
          RTP packets or carried in only one RTP packet.  If the whole
          frame or all the packets of the frame is lost, this frame is
          regarded as one full_lost_frame.

       *  Method of Measurement or Calculation: See Section 4.1.2,
          Number of full lost frames definition.

       *  Units of Measurement: This metric is expressed as a 32-bit
          unsigned integer value.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 4.1, 1st paragraph.

       *  Measurement Timing: See Section 4.1, Number of full lost
          frames definition.  This metric relies on the sequence number
          interval to determine measurement timing.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

   j.  Number of Partial Lost Frames Metric

       *  Metric Name: Number of partial lost frames in RTP

       *  Metric Description: When a frame is split across multiple RTP
          packets and some RTP packets of the frame are lost, this frame
          is regarded as one partial_lost_frame.

       *  Method of Measurement or Calculation: See Section 4.1.2,
          Number of partial lost frames definition.

       *  Units of Measurement: This metric is expressed as a 32-bit
          unsigned integer value.

       *  Measurement Point(s) with Potential Measurement Domain: See
          Section 4.1, 1st paragraph.





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       *  Measurement Timing: See Section 4.1, Number of partial lost
          frames definition.  This metric relies on the sequence number
          interval to determine measurement timing.

       *  Use and Applications: See Section 1.4.

       *  Reporting Model: See RFC 3611.

Authors' Addresses

   Glen Zorn
   Network Zen
   227/358 Thanon Sanphawut
   Bang Na, Bangkok  10260
   Thailand

   Phone: +66 (0) 909-201060
   EMail: glenzorn@gmail.com


   Roland Schott
   Deutsche Telekom
   Deutsche-Telekom-Allee 7
   Darmstadt  64295
   Germany

   EMail: Roland.Schott@telekom.de


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

   EMail: sunseawq@huawei.com


   Rachel Huang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing  210012
   China

   EMail: Rachel@huawei.com






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