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rfc:rfc8015

Internet Engineering Task Force (IETF) V. Singh Request for Comments: 8015 callstats.io Category: Standards Track C. Perkins ISSN: 2070-1721 University of Glasgow

                                                              A. Clark
                                                              Telchemy
                                                              R. Huang
                                                                Huawei
                                                         November 2016
       RTP Control Protocol (RTCP) Extended Report (XR) Block
       for Independent Reporting of Burst/Gap Discard Metrics

Abstract

 This document defines an RTP Control Protocol (RTCP) Extended Report
 (XR) block that allows the reporting of burst/gap discard metrics
 independently of the burst/gap loss metrics for use 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 7841.
 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/rfc8015.

Singh, et al. Standards Track [Page 1] RFC 8015 RTCP XR Burst/Gap Discard November 2016

Copyright Notice

 Copyright (c) 2016 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.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   1.1.  Independent Burst/Gap Discard Metrics Block . . . . . . .   3
   1.2.  RTCP and RTCP Extended Reports  . . . . . . . . . . . . .   4
   1.3.  Performance Metrics Framework . . . . . . . . . . . . . .   4
   1.4.  Applicability . . . . . . . . . . . . . . . . . . . . . .   4
 2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
 3.  Independent Burst/Gap Discard Metrics Block . . . . . . . . .   5
   3.1.  Report Block Structure  . . . . . . . . . . . . . . . . .   6
   3.2.  Definition of Fields in the Independent Burst/Gap Discard
         Metrics Block . . . . . . . . . . . . . . . . . . . . . .   6
   3.3.  Derived Metrics Based on the Reported Metrics . . . . . .   8
 4.  Considerations for Voice-over-IP Applications . . . . . . . .   9
 5.  SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . .   9
   5.1.  SDP rtcp-xr Attribute Extension . . . . . . . . . . . . .   9
   5.2.  Offer/Answer Usage  . . . . . . . . . . . . . . . . . . .   9
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   6.1.  New RTCP XR Block Type Value  . . . . . . . . . . . . . .  10
   6.2.  New RTCP XR SDP Parameter . . . . . . . . . . . . . . . .  10
   6.3.  Contact Information for Registrations . . . . . . . . . .  10
 7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
 8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
   8.2.  Informative References  . . . . . . . . . . . . . . . . .  12
 Appendix A.  Metrics Represented Using the Template from RFC 6390  13
 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
 Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  14
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

Singh, et al. Standards Track [Page 2] RFC 8015 RTCP XR Burst/Gap Discard November 2016

1. Introduction

1.1. Independent Burst/Gap Discard Metrics Block

 This document defines a new block type that extends the metrics
 defined in [RFC7003].  The new block type reports the proportion of
 packets discarded in a burst by the de-jitter buffer at the receiver.
 The number of packets discarded depends on the de-jitter buffer
 algorithm implemented by the endpoint.
 The new report block defined in this document is different from the
 one defined in [RFC7003].  The metrics in [RFC7003] depend on the
 metrics in the burst/gap loss metric defined in [RFC6958].
 Consequently, an endpoint that sends a Burst/Gap Discard Metrics
 Block [RFC7003] also needs to send a Burst/Gap Loss Metrics Block
 [RFC6958].  The combined usage is useful when an endpoint observes
 correlated packet losses and discard.  However, when the burst of
 packet losses and discards do not occur simultaneously, the
 application could prefer to send a concise report block that just
 reports the burst/gap of discarded packets.  The report block in this
 document provides the complete information and does not require
 additional report blocks.  That is, this block reports the total
 number of packets discarded, the total burst duration, and the total
 number of bursts.  All of these metrics are missing in [RFC7003].
 This block provides information on transient network issues.  Burst/
 gap metrics are typically used in cumulative reports; however, they
 can also be used in interval reports (see the Interval Metric flag in
 Section 3.2).  The variation in the number of packet discards in a
 burst affects the user experience.  Based on the metrics reported in
 the block, the sending endpoint can change the packetization
 interval, vary the bitrate, etc.  The report can additionally be used
 for diagnostics [RFC6792].  The metric belongs to the class of
 transport-related end-system metrics defined in [RFC6792].
 The definitions of "burst", "gap", "loss", and "discard" are
 consistent with the definitions in [RFC3611].  To accommodate a range
 of de-jitter buffer algorithms and packet discard logic that can be
 used by implementers, the method used to distinguish between bursts
 and gaps uses an equivalent method to that defined in Section 4.7.2
 of [RFC3611].  Note that reporting the specific de-jitter buffer
 algorithm and/or the packet discard logic is out of the scope of this
 document.

Singh, et al. Standards Track [Page 3] RFC 8015 RTCP XR Burst/Gap Discard November 2016

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 Performance Metrics Framework [RFC6390] provides guidance on the
 definition and specification of performance metrics.  The RTP
 Monitoring Framework [RFC6792] provides guidelines for reporting the
 block format using RTCP XR.  The metrics block described in this
 document is in accordance with the guidelines in [RFC6390] and
 [RFC6792].

1.4. Applicability

 These metrics are applicable to a range of RTP applications that
 contain de-jitter buffers at the receiver to smooth variation in
 packet-arrival time and don't use stream repair means, e.g., Forward
 Error Correction (FEC) [FLEX_FEC] and/or retransmission [RFC4588].

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 terms are defined:
 Received, Lost, and Discarded
    A packet is regarded as "lost" if it fails to arrive within an
    implementation-specific time window.  A packet that arrives within
    this time window but is too early to be played out, too late to be
    played out, or thrown away before playout due to packet
    duplication or redundancy is be recorded as "discarded".  A packet
    SHALL NOT be regarded as "discarded" if it arrives within this
    time window but is dropped during decoding by some higher-layer
    decoder, e.g., due to a decoding error.  Each packet is classified
    as one of "received" (or "OK"), "discarded", or "lost".  The
    metric "cumulative number of packets lost" defined in [RFC3550]
    reports a count of packets lost from the media stream (single
    synchronization source (SSRC) within a single RTP session).
    Similarly, the metric "number of packets discarded" defined in
    [RFC7002] reports a count of packets discarded from the media
    stream (single SSRC within a single RTP session) arriving at the

Singh, et al. Standards Track [Page 4] RFC 8015 RTCP XR Burst/Gap Discard November 2016

    receiver.  Another metric, defined in [RFC5725], is available to
    report on packets that are not recovered by any repair techniques
    that are in use.  Note that the term "discard" defined here builds
    on the "discard" definition in [RFC3611] but extends the concept
    to take into account packet duplication and reports different
    types of discard counts [RFC7002].
 Bursts and Gaps
    The terms "burst" and "gap" are used in a manner consistent with
    that of RTCP XR [RFC3611].  RTCP XR views an RTP stream as being
    divided into bursts, which are periods during which the discard
    rate is high enough to cause noticeable quality degradation
    (generally a discard rate over 5 percent), and gaps, which are
    periods during which discarded packets are infrequent, and hence
    quality is generally acceptable.

3. Independent Burst/Gap Discard Metrics Block

 Metrics in this block report on burst/gap discard in the stream
 arriving at the RTP system.  Measurements of these metrics are made
 at the receiving end of the RTP stream.  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.
 Senders MUST send this block in the same compound RTCP packet as the
 Measurement Information Block.  Receivers MUST verify that the
 measurement period is received in the same compound RTCP packet as
 this metrics block.  If not, this metrics block MUST be discarded.

Singh, et al. Standards Track [Page 5] RFC 8015 RTCP XR Burst/Gap Discard November 2016

3.1. Report Block Structure

 The structure of the Independent Burst/Gap Discard Metrics 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=35     | I |   resv    |      Block Length = 5         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        SSRC of Source                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   Threshold   |         Sum of Burst Durations (ms)           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Packets Discarded in Bursts          |    Number of  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Bursts     |           Total Packets Expected in Bursts    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Discard Count                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   Figure 1: Report Block Structure

3.2. Definition of Fields in the Independent Burst/Gap Discard Metrics

    Block
 Block Type (BT): 8 bits
    An Independent Burst/Gap Discard Metrics Block is identified by
    the constant 35.
 Interval Metric flag (I): 2 bits
    This field is used to indicate whether the burst/gap discard
    metrics are Sampled, Interval, or Cumulative metrics [RFC6792]:
       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.
    In this document, burst/gap discard metrics can only be measured
    over definite intervals and cannot be sampled.  Also, the value
    I=00 is reserved for future use.  Senders MUST NOT use the values
    I=00 or I=01.  If a block is received with I=00 or I=01, the
    receiver MUST discard the block.

Singh, et al. Standards Track [Page 6] RFC 8015 RTCP XR Burst/Gap Discard November 2016

 Reserved (resv): 6 bits
    These bits are reserved.  They MUST be set to zero by senders and
    ignored by receivers (see [RFC6709], Section 4.2).
 Block Length: 16 bits
    The length of this report block in 32-bit words, minus one.  For
    the Independent Burst/Gap Discard Metrics Block, the block length
    is equal to 5.  The block MUST be discarded if the block length is
    set to a different value.
 SSRC of Source: 32 bits
    As defined in Section 4 of [RFC3611].
 Threshold: 8 bits
    The Threshold is equivalent to Gmin in [RFC3611], i.e., the number
    of successive packets that have to be received prior to, and
    following, a discarded packet in order for that discarded packet
    to be regarded as part of a gap.  Note that the Threshold is set
    in accordance with the Gmin calculation defined in Section 4.7.2
    of [RFC3611].
 Sum of Burst Durations (ms): 24 bits
    The total duration of bursts of discarded packets in the period of
    the report (Interval or Cumulative).
    The measured value is an unsigned value.  If the measured value
    exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate
    an over-range measurement.  If the measurement is unavailable, the
    value 0xFFFFFF MUST be reported.
 Packets Discarded in Bursts: 24 bits
    The total number of packets discarded during discard bursts, as
    defined in Section 3.2 of [RFC7002].

Singh, et al. Standards Track [Page 7] RFC 8015 RTCP XR Burst/Gap Discard November 2016

 Number of Bursts: 16 bits
    The number of discard bursts in the period of the report (Interval
    or Cumulative).
    The measured value is an unsigned value.  If the measured value
    exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an
    over-range measurement.  If the measurement is unavailable, the
    value 0xFFFF MUST be reported.
 Total Packets Expected in Bursts: 24 bits
    The total number of packets expected during the discard bursts
    (that is, the sum of received packets and lost packets).  The
    metric is defined in [RFC7003].
 Discard Count: 32 bits
    Number of packets discarded over the period (Interval or
    Cumulative) covered by this report, as defined in Section 3.2 of
    [RFC7002].

3.3. Derived Metrics Based on the Reported Metrics

 The metrics described here are intended to be used in conjunction
 with information from the Measurement Information Block [RFC6776].
 These metrics provide the following information relevant to
 statistical parameters (depending on cumulative of interval
 measures), for example:
 o  The average discarded burst size, which can be calculated by
    dividing the metric "Packets Discarded in Bursts" by the "Number
    of Bursts".
 o  The average burst duration, which can be calculated by dividing
    the metric "Sum of Burst Durations (ms)" by the "Number of
    Bursts".

Singh, et al. Standards Track [Page 8] RFC 8015 RTCP XR Burst/Gap Discard November 2016

4. Considerations for Voice-over-IP Applications

 This metrics block is applicable to a broad range of RTP
 applications.  Where the metric is used with a Voice-over-IP (VoIP)
 application and the stream repair means is not available, the
 following considerations apply.
 RTCP XR views a call as being divided into bursts, which are periods
 during which the discard rate is high enough to cause noticeable call
 quality degradation (generally a discard rate over 5 percent) and
 gaps, which are periods during which discarded packets are
 infrequent, and hence call quality is generally acceptable.
 If voice activity detection is used, the burst/gap duration is
 determined as if silence packets had been sent, i.e., a period of
 silence in excess of Gmin packets will terminate a burst condition.
 The RECOMMENDED value for the threshold Gmin in [RFC3611] results in
 a burst being a period of time during which the call quality is
 degraded to a similar extent to a typical pulse code modulation (PCM)
 severely errored second.

5. SDP Signaling

 [RFC3611] defines the use of SDP (Session Description Protocol)
 [RFC4566] for signaling the use of XR blocks.  XR blocks can be used
 without prior signaling.

5.1. SDP rtcp-xr Attribute Extension

 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.  The
 ABNF [RFC5234] syntax is as follows.
 xr-format =/ xr-ind-bgd-block
 xr-ind-bgd-block = "ind-burst-gap-discard"

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 in Offer/Answer for unilateral
 parameters, refer to Section 5.2 of [RFC3611].

Singh, et al. Standards Track [Page 9] RFC 8015 RTCP XR Burst/Gap Discard November 2016

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
 [RFC3611].

6.1. New RTCP XR Block Type Value

 This document assigns the block type value 35 in the IANA "RTP
 Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
 the "Independent Burst/Gap Discard Metrics Block".

6.2. New RTCP XR SDP Parameter

 This document also registers a new parameter "ind-burst-gap-discard"
 in the "RTP Control Protocol Extended Reports (RTCP XR) Session
 Description Protocol (SDP) Parameters Registry".

6.3. Contact Information for Registrations

 The contact information for the registrations is:
    ART Area Directors <art-ads@ietf.org>

7. Security Considerations

 This block does not provide per-packet statistics, so the risk to
 confidentiality documented in Section 7, paragraph 3 of [RFC3611]
 does not apply.  However, the gap indicated within this block could
 be used to detect the timing of other events on the path between the
 sender and receiver.  For example, a competing multimedia stream
 might cause a discard burst for the duration of the stream, allowing
 the receiver of this block to know when the competing stream was
 active.  This risk is not a significant threat since the only
 information leaked is the timing of the discard, not the cause.
 Where this is a concern, the implementation SHOULD apply encryption
 and authentication to this report block.  For example, this can be
 achieved by using the Audio-Visual Profile with Feedback (AVPF)
 profile together with the Secure RTP profile, as defined in
 [RFC3711]; an appropriate combination of those two profiles ("SAVPF")
 is specified in [RFC5124].  Besides this, it is believed that this
 RTCP XR block introduces no new security considerations beyond those
 described in [RFC3611].

Singh, et al. Standards Track [Page 10] RFC 8015 RTCP XR Burst/Gap Discard November 2016

8. References

8.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
            Jacobson, "RTP: A Transport Protocol for Real-Time
            Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
            July 2003, <http://www.rfc-editor.org/info/rfc3550>.
 [RFC3611]  Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed.,
            "RTP Control Protocol Extended Reports (RTCP XR)",
            RFC 3611, DOI 10.17487/RFC3611, November 2003,
            <http://www.rfc-editor.org/info/rfc3611>.
 [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
            Norrman, "The Secure Real-time Transport Protocol (SRTP)",
            RFC 3711, DOI 10.17487/RFC3711, March 2004,
            <http://www.rfc-editor.org/info/rfc3711>.
 [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
            Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
            July 2006, <http://www.rfc-editor.org/info/rfc4566>.
 [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for
            Real-time Transport Control Protocol (RTCP)-Based Feedback
            (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
            2008, <http://www.rfc-editor.org/info/rfc5124>.
 [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234,
            DOI 10.17487/RFC5234, January 2008,
            <http://www.rfc-editor.org/info/rfc5234>.
 [RFC5725]  Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE
            Report Block Type for RTP Control Protocol (RTCP) Extended
            Reports (XRs)", RFC 5725, DOI 10.17487/RFC5725, February
            2010, <http://www.rfc-editor.org/info/rfc5725>.
 [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,
            DOI 10.17487/RFC6776, October 2012,
            <http://www.rfc-editor.org/info/rfc6776>.

Singh, et al. Standards Track [Page 11] RFC 8015 RTCP XR Burst/Gap Discard November 2016

 [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, DOI 10.17487/RFC7003,
            September 2013, <http://www.rfc-editor.org/info/rfc7003>.

8.2. Informative References

 [FLEX_FEC]
            Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP
            Payload Format for Flexible Forward Error Correction
            (FEC)", Work in Progress, draft-ietf-payload-flexible-fec-
            scheme-03, October 2016.
 [RFC4588]  Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
            Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
            DOI 10.17487/RFC4588, July 2006,
            <http://www.rfc-editor.org/info/rfc4588>.
 [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
            Performance Metric Development", BCP 170, RFC 6390,
            DOI 10.17487/RFC6390, October 2011,
            <http://www.rfc-editor.org/info/rfc6390>.
 [RFC6709]  Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design
            Considerations for Protocol Extensions", RFC 6709,
            DOI 10.17487/RFC6709, September 2012,
            <http://www.rfc-editor.org/info/rfc6709>.
 [RFC6792]  Wu, Q., Ed., Hunt, G., and P. Arden, "Guidelines for Use
            of the RTP Monitoring Framework", RFC 6792,
            DOI 10.17487/RFC6792, November 2012,
            <http://www.rfc-editor.org/info/rfc6792>.
 [RFC6958]  Clark, A., Zhang, S., Zhao, J., and Q. Wu, Ed., "RTP
            Control Protocol (RTCP) Extended Report (XR) Block for
            Burst/Gap Loss Metric Reporting", RFC 6958,
            DOI 10.17487/RFC6958, May 2013,
            <http://www.rfc-editor.org/info/rfc6958>.
 [RFC7002]  Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol
            (RTCP) Extended Report (XR) Block for Discard Count Metric
            Reporting", RFC 7002, DOI 10.17487/RFC7002, September
            2013, <http://www.rfc-editor.org/info/rfc7002>.

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Appendix A. Metrics Represented Using the Template from RFC 6390

 a.  Threshold Metric
  • Defined in item a of Appendix A of [RFC7003].
 b.  Sum of Burst Durations (ms)
  • Metric Name: Sum of Burst Durations with Discarded RTP

Packets.

  • Metric Description: The total duration of bursts of discarded

RTP packets in the period of the report.

  • Method of Measurement or Calculation: See Section 3.2, Sum of

Burst Durations definition.

  • Units of Measurement: See Section 3.2, Sum of Burst Durations

definition.

  • Measurement Point(s) with Potential Measurement Domain: See

Section 3, first paragraph.

  • Measurement Timing: See Section 3, second paragraph for

measurement timing and Section 3.2 for Interval Metric flag.

  • Use and Applications: See Section 1.4.
  • Reporting Model: See [RFC3611].
 c.  Packets Discarded in Bursts Metric
  • Defined in item b of Appendix A of [RFC7003].
 d.  Number of Bursts
  • Metric Name: Number of discard bursts in RTP.
  • Metric Description: The total number of bursts with discarded

RTP packets in the period of the report.

  • Method of Measurement or Calculation: See Section 3.2, Number

of Bursts definition.

  • Units of Measurement: See Section 3.2 for the Number of Bursts

definition.

Singh, et al. Standards Track [Page 13] RFC 8015 RTCP XR Burst/Gap Discard November 2016

  • Measurement Point(s) with Potential Measurement Domain: See

Section 3, first paragraph.

  • Measurement Timing: See Section 3, second paragraph for

measurement timing and Section 3.2 for Interval Metric flag.

  • Use and Applications: See Section 1.4.
  • Reporting Model: See [RFC3611].
 e.  Total Packets Expected in Bursts Metric
  • Defined in item c of Appendix A of [RFC7003].
 f.  Discard Count
  • Defined in Appendix A of [RFC7002].

Acknowledgments

 The authors would like to thank Ben Campbell, Stephen Farrell, Paul
 Kyzivat, Shucheng LIU, Jan Novak, and Dan Romascanu for providing
 valuable feedback on this document.

Contributors

 Qin Wu, Rachel Huang, and Alan Clark wrote RFC 7003, which this
 document extends.

Singh, et al. Standards Track [Page 14] RFC 8015 RTCP XR Burst/Gap Discard November 2016

Authors' Addresses

 Varun Singh
 CALLSTATS I/O Oy
 Runeberginkatu 4c A 4
 Helsinki  00100
 Finland
 Email: varun@callstats.io
 URI:   https://www.callstats.io/about
 Colin Perkins
 University of Glasgow
 School of Computing Science
 Glasgow  G12 8QQ
 United Kingdom
 Email: csp@csperkins.org
 Alan Clark
 Telchemy Incorporated
 2905 Premiere Parkway, Suite 280
 Duluth, GA  30097
 United States of America
 Email: alan.d.clark@telchemy.com
 Rachel Huang
 Huawei Technologies Co., Ltd.
 101 Software Avenue, Yuhua District
 Nanjing, Jiangsu  210012
 China
 Email: Rachel@huawei.com

Singh, et al. Standards Track [Page 15]

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