7003
PROPOSED STANDARD
RTP Control Protocol (RTCP) Extended Report (XR) Block for Burst/Gap Discard Metric Reporting
Authors: A. Clark, R. Huang, Q. Wu
Date: September 2013
Area: rai
Working Group: xrblock
Stream: IETF
Abstract
This document defines an RTP Control Protocol (RTCP) Extended Report (XR) block that allows the reporting of burst and gap discard metrics for use in a range of RTP applications.
RFC 7003
PROPOSED STANDARD
Errata Exist
Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 7003 Telchemy
Category: Standards Track R. Huang
ISSN: 2070-1721 Q. Wu, Ed.
Huawei
September 2013
<span class="h1">RTP Control Protocol (RTCP) Extended Report (XR) Block</span>
<span class="h1">for Burst/Gap Discard Metric Reporting</span>
Abstract
This document defines an RTP Control Protocol (RTCP) Extended Report
(XR) block that allows the reporting of burst and gap discard 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 <a href="./rfc5741#section-2">Section 2 of RFC 5741</a>.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
<a href="https://www.rfc-editor.org/info/rfc7003">http://www.rfc-editor.org/info/rfc7003</a>.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of
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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
<a href="#section-1">1</a>. Introduction ....................................................<a href="#page-2">2</a>
<a href="#section-1.1">1.1</a>. Burst/Gap Discard Metrics Block ............................<a href="#page-2">2</a>
<a href="#section-1.2">1.2</a>. RTCP and RTCP Extended Reports .............................<a href="#page-3">3</a>
<a href="#section-1.3">1.3</a>. Performance Metrics Framework ..............................<a href="#page-3">3</a>
<a href="#section-1.4">1.4</a>. Applicability ..............................................<a href="#page-3">3</a>
<a href="#section-2">2</a>. Terminology .....................................................<a href="#page-3">3</a>
<a href="#section-3">3</a>. Burst/Gap Discard Metrics Block .................................<a href="#page-4">4</a>
<a href="#section-3.1">3.1</a>. Report Block Structure .....................................<a href="#page-5">5</a>
<a href="#section-3.2">3.2</a>. Definition of Fields in Burst/Gap Discard Metrics Block ....<a href="#page-5">5</a>
<a href="#section-3.3">3.3</a>. Derived Metrics Based on Reported Metrics ..................<a href="#page-7">7</a>
<a href="#section-4">4</a>. Considerations for Voice-over-IP Applications ...................<a href="#page-7">7</a>
<a href="#section-5">5</a>. SDP Signaling ...................................................<a href="#page-8">8</a>
<a href="#section-5.1">5.1</a>. SDP rtcp-xr Attribute Extension ............................<a href="#page-8">8</a>
<a href="#section-5.2">5.2</a>. Offer/Answer Usage .........................................<a href="#page-8">8</a>
<a href="#section-6">6</a>. IANA Considerations .............................................<a href="#page-8">8</a>
<a href="#section-6.1">6.1</a>. New RTCP XR Block Type Value ...............................<a href="#page-8">8</a>
<a href="#section-6.2">6.2</a>. New RTCP XR SDP Parameter ..................................<a href="#page-9">9</a>
<a href="#section-6.3">6.3</a>. Contact Information for Registrations ......................<a href="#page-9">9</a>
<a href="#section-7">7</a>. Security Considerations .........................................<a href="#page-9">9</a>
<a href="#section-8">8</a>. Contributors ....................................................<a href="#page-9">9</a>
<a href="#section-9">9</a>. Acknowledgments .................................................<a href="#page-9">9</a>
<a href="#section-10">10</a>. References ....................................................<a href="#page-10">10</a>
<a href="#section-10.1">10.1</a>. Normative References .....................................<a href="#page-10">10</a>
<a href="#section-10.2">10.2</a>. Informative References ...................................<a href="#page-10">10</a>
<a href="#appendix-A">Appendix A</a>. Metrics Represented Using the Template from <a href="./rfc6390">RFC 6390</a>..12
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>. Burst/Gap Discard Metrics Block</span>
This document defines a new block type to augment those defined in
[<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] for use in a range of RTP applications. The new block type
supports the reporting of the proportion of packets discarded by the
jitter buffer at the receiver, using packet discard logic according
to the jitter buffer algorithms. The discards during discard bursts
are reported, together with the number of bursts. This block is
intended to be used in conjunction with [<a href="./rfc7002" title=""RTP Control Protocol (RTCP) Extended Report (XR) for Discard Count Metric Reporting"">RFC7002</a>], which provides the
total packets discarded and on which this block therefore depends.
However, the metric in [<a href="./rfc7002" title=""RTP Control Protocol (RTCP) Extended Report (XR) for Discard Count Metric Reporting"">RFC7002</a>] may be used independently of the
metrics in this block.
This block provides information on transient IP problems. Burst/gap
metrics are typically used in cumulative reports; however, they also
may be used in interval reports (see the Interval Metric flag in
<a href="#section-3.2">Section 3.2</a>). The burstiness of packet discard affects user
experience, may influence any sender strategies to mitigate the
problem, and may also have diagnostic value.
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The metric belongs to the class of transport-related end-system
metrics defined in [<a href="./rfc6792" title=""Guidelines for Use of the RTP Monitoring Framework"">RFC6792</a>].
The definitions of "burst", "gap", "loss", and "discard" are
consistent with the definitions in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>]. To accommodate the
range of jitter buffer algorithms and packet discard logic that may
be used by implementors, the method used to distinguish between
bursts and gaps shall use an equivalent method to that defined in
<a href="./rfc3611#section-4.7.2">Section 4.7.2 of [RFC3611]</a>. Note that reporting the specific jitter
buffer algorithms and/or packet discard logic is out of the scope of
this document.
<span class="h3"><a class="selflink" id="section-1.2" href="#section-1.2">1.2</a>. RTCP and RTCP Extended Reports</span>
The use of RTCP for reporting is defined in [<a href="./rfc3550" title=""RTP: A Transport Protocol for Real-Time Applications"">RFC3550</a>]. [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>]
defined an extensible structure for reporting using an RTCP Extended
Report (XR). This document defines a new Extended Report block for
use with [<a href="./rfc3550" title=""RTP: A Transport Protocol for Real-Time Applications"">RFC3550</a>] and [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>].
<span class="h3"><a class="selflink" id="section-1.3" href="#section-1.3">1.3</a>. Performance Metrics Framework</span>
The Performance Metrics Framework [<a href="./rfc6390" title=""Guidelines for Considering New Performance Metric Development"">RFC6390</a>] provides guidance on the
definition and specification of performance metrics. The RTP
Monitoring Framework [<a href="./rfc6792" title=""Guidelines for Use of the RTP Monitoring Framework"">RFC6792</a>] provides guidelines for reporting
block format using RTCP XR. The metrics block described in this
document is in accordance with the guidelines in [<a href="./rfc6390" title=""Guidelines for Considering New Performance Metric Development"">RFC6390</a>] and
[<a href="./rfc6792" title=""Guidelines for Use of the RTP Monitoring Framework"">RFC6792</a>].
<span class="h3"><a class="selflink" id="section-1.4" href="#section-1.4">1.4</a>. Applicability</span>
These metrics are applicable to a range of RTP applications that
contain de-jitter buffers [<a href="./rfc5481" title=""Packet Delay Variation Applicability Statement"">RFC5481</a>] at the receiving end to smooth
variation in packet-arrival time and don't use stream repair means,
e.g., Forward Error Correction (FEC) [<a href="./rfc5109" title=""RTP Payload Format for Generic Forward Error Correction"">RFC5109</a>] and/or retransmission
[<a href="./rfc4588" title=""RTP Retransmission Payload Format"">RFC4588</a>].
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Terminology</span>
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 <a href="./rfc2119">RFC 2119</a> [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
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In addition, the following terms are defined:
Received, Lost, and Discarded
A packet shall be 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 shall be regarded 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. A packet shall be
classified as one of received (or OK), discarded, or lost. The
metric "cumulative number of packets lost" defined in [<a href="./rfc3550" title=""RTP: A Transport Protocol for Real-Time Applications"">RFC3550</a>]
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
[<a href="./rfc7002" title=""RTP Control Protocol (RTCP) Extended Report (XR) for Discard Count Metric Reporting"">RFC7002</a>] reports a count of packets discarded from the media
stream (single SSRC within a single RTP session) arriving at the
receiver. Another metric, defined in [<a href="./rfc5725" title=""Post-Repair Loss RLE Report Block Type for RTP Control Protocol (RTCP) Extended Reports (XRs)"">RFC5725</a>], is available to
report on packets that are not recovered by any repair techniques
that may be in use. Note that the term "discard" defined here
builds on the "discard" definition in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] but extends the
concept to take into account packet duplication and reports
different types of discard counts [<a href="./rfc7002" title=""RTP Control Protocol (RTCP) Extended Report (XR) for Discard Count Metric Reporting"">RFC7002</a>].
Bursts and Gaps
The terms "burst" and "gap" are used in a manner consistent with
that of RTCP XR [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>]. 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 over 5 percent discard rate), and gaps, which are
periods during which discarded packets are infrequent and hence
quality is generally acceptable.
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Burst/Gap Discard Metrics Block</span>
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 [<a href="./rfc6776" title=""Measurement Identity and Information Reporting Using a Source Description (SDES) Item and an RTCP Extended Report (XR) Block"">RFC6776</a>], which describes
measurement periods in use (see <a href="./rfc6776#section-4.2">[RFC6776], Section 4.2</a>).
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
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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.
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. Report Block Structure</span>
The structure of the 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=20 | I | resv | Block Length = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Packets Discarded in Bursts |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Total Packets Expected in Bursts | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Definition of Fields in Burst/Gap Discard Metrics Block</span>
Block Type (BT): 8 bits
A Burst/Gap Discard Metrics Block is identified by the constant
20.
Interval Metric flag (I): 2 bits
This field is used to indicate whether the burst/gap discard
metrics are Sampled, Interval, or Cumulative metrics [<a href="./rfc6792" title=""Guidelines for Use of the RTP Monitoring Framework"">RFC6792</a>]:
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.
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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.
Reserved (resv): 6 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (see <a href="./rfc6709#section-4.2">[RFC6709], Section 4.2</a>).
Block Length: 16 bits
The length of this report block in 32-bit words, minus one. For
the Burst/Gap Discard Metrics Block, the block length is equal to
3. The block MUST be discarded if the block length is set to a
different value.
SSRC of Source: 32 bits
As defined in <a href="./rfc3611#section-4.1">Section 4.1 of [RFC3611]</a>.
Threshold: 8 bits
The Threshold is equivalent to Gmin in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>], i.e., the number
of successive packets that must not be discarded prior to and
following a discard packet in order for this discarded packet to
be regarded as part of a gap. Note that the Threshold is set in
accordance with the Gmin calculation defined in <a href="./rfc3611#section-4.7.2">Section 4.7.2 of
[RFC3611]</a>.
Packets Discarded in Bursts: 24 bits
The total number of packets discarded during discard bursts.
The measured value is 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.
Total Packets Expected in Bursts: 24 bits
The total number of packets expected during discard bursts (that
is, the sum of received packets and lost packets).
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The measured value is 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.
Reserved: 8 bits
These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See <a href="./rfc6709#section-4.2">[RFC6709], Section 4.2</a>).
<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. Derived Metrics Based on Reported Metrics</span>
The metrics described here are intended to be used in conjunction
with information from the Measurement Information Block [<a href="./rfc6776" title=""Measurement Identity and Information Reporting Using a Source Description (SDES) Item and an RTCP Extended Report (XR) Block"">RFC6776</a>] and
also with the metric "number of packets discarded" provided in the
RTCP XR Discard Count Metrics Block [<a href="./rfc7002" title=""RTP Control Protocol (RTCP) Extended Report (XR) for Discard Count Metric Reporting"">RFC7002</a>].
These metrics provide the following information relevant to
statistical parameters, including:
o The fraction of packets discarded during bursts (Burst Discard
Rate in [<a href="./rfc7004" title=""RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting"">RFC7004</a>]), which can be calculated using the metric
"Packets Discarded in Bursts" and the metric "Total Packets
Expected in Bursts" provided in the Burst/Gap Discard Metrics
Block.
o The fraction of packets discarded during gaps (Gap Discard Rate in
[<a href="./rfc7004" title=""RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting"">RFC7004</a>]), which can be calculated using the metric "Packets
Discarded in Bursts" and the metric "Total Packets Expected in
Bursts" provided in the Burst/Gap Discard Metrics Block.
The details on calculation these parameters in the metrics are
described in [<a href="./rfc7004" title=""RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting"">RFC7004</a>].
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Considerations for Voice-over-IP Applications</span>
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 over 5 percent discard rate) and gaps,
which are periods during which discarded packets are infrequent and
hence call quality is generally acceptable.
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If voice activity detection is used, the burst and gap duration shall
be 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 [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] 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.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. SDP Signaling</span>
[<a id="ref-RFC3611">RFC3611</a>] defines the use of SDP (Session Description Protocol)
[<a href="./rfc4566" title=""SDP: Session Description Protocol"">RFC4566</a>] for signaling the use of XR blocks. XR blocks MAY be used
without prior signaling.
<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. SDP rtcp-xr Attribute Extension</span>
This section augments the SDP [<a href="./rfc4566" title=""SDP: Session Description Protocol"">RFC4566</a>] attribute "rtcp-xr" defined
in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document. The
ABNF [<a href="./rfc5234" title=""Augmented BNF for Syntax Specifications: ABNF"">RFC5234</a>] syntax is as follows.
xr-format =/ xr-bgd-block
xr-bgd-block = "burst-gap-discard"
<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>. Offer/Answer Usage</span>
When SDP is used in Offer/Answer context, the SDP Offer/Answer usage
defined in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] for unilateral "rtcp-xr" attribute parameters
applies. For detailed usage in Offer/Answer for unilateral
parameters, refer to <a href="./rfc3611#section-5.2">Section 5.2 of [RFC3611]</a>.
<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. IANA Considerations</span>
New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to
[<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>].
<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. New RTCP XR Block Type Value</span>
This document assigns the block type value 20 in the IANA "RTP
Control Protocol Extended Reports (RTCP XR) Block Type Registry" to
the "Burst/Gap Discard Metrics Block".
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<span class="h3"><a class="selflink" id="section-6.2" href="#section-6.2">6.2</a>. New RTCP XR SDP Parameter</span>
This document also registers a new parameter "burst-gap-discard" in
the "RTP Control Protocol Extended Reports (RTCP XR) Session
Description Protocol (SDP) Parameters Registry".
<span class="h3"><a class="selflink" id="section-6.3" href="#section-6.3">6.3</a>. Contact Information for Registrations</span>
The contact information for the registrations is:
Qin Wu ([email protected])
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Security Considerations</span>
It is believed that this RTCP XR block introduces no new security
considerations beyond those described in [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>]. This block does
not provide per-packet statistics, so the risk to confidentiality
documented in <a href="#section-7">Section 7</a>, paragraph 3 of [<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>] does not apply.
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. Contributors</span>
Geoff Hunt wrote the initial draft of this document.
<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>. Acknowledgments</span>
The authors gratefully acknowledge reviews and feedback provided by
Bruce Adams, Philip Arden, Amit Arora, Claire Bi, Bob Biskner, Benoit
Claise, Kevin Connor, Claus Dahm, Randy Ethier, Roni Even, Stephen
Farrell, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus,
Paul Jones, Rajesh Kumar, Paul Kyzivat, Keith Lantz, Mohamed Mostafa,
Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Dan
Romascanu, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada.
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<span class="h2"><a class="selflink" id="section-10" href="#section-10">10</a>. References</span>
<span class="h3"><a class="selflink" id="section-10.1" href="#section-10.1">10.1</a>. Normative References</span>
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.
[<a id="ref-RFC3550">RFC3550</a>] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, <a href="./rfc3550">RFC 3550</a>, July 2003.
[<a id="ref-RFC3611">RFC3611</a>] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", <a href="./rfc3611">RFC 3611</a>, November
2003.
[<a id="ref-RFC4566">RFC4566</a>] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", <a href="./rfc4566">RFC 4566</a>, July 2006.
[<a id="ref-RFC5234">RFC5234</a>] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, <a href="./rfc5234">RFC 5234</a>, January 2008.
[<a id="ref-RFC5725">RFC5725</a>] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE
Report Block Type for RTP Control Protocol (RTCP) Extended
Reports (XRs)", <a href="./rfc5725">RFC 5725</a>, February 2010.
[<a id="ref-RFC6776">RFC6776</a>] Clark, A. and Q. Wu, "Measurement Identity and Information
Reporting Using a Source Description (SDES) Item and an
RTCP Extended Report (XR) Block", <a href="./rfc6776">RFC 6776</a>, October 2012.
[<a id="ref-RFC7002">RFC7002</a>] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol
(RTCP) Extended Report (XR) for Discard Count Metric
Reporting", <a href="./rfc7002">RFC 7002</a>, September 2013.
[<a id="ref-RFC7004">RFC7004</a>] Zorn, G., Schott, R., Wu, Q., Ed., and R. Huang, "RTP
Control Protocol (RTCP) Extended Report (XR) Blocks for
Summary Statistics Metrics Reporting", <a href="./rfc7004">RFC 7004</a>, September
2013.
<span class="h3"><a class="selflink" id="section-10.2" href="#section-10.2">10.2</a>. Informative References</span>
[<a id="ref-RFC4588">RFC4588</a>] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", <a href="./rfc4588">RFC 4588</a>,
July 2006.
[<a id="ref-RFC5109">RFC5109</a>] Li, A., "RTP Payload Format for Generic Forward Error
Correction", <a href="./rfc5109">RFC 5109</a>, December 2007.
<span class="grey">Clark, et al. Standards Track [Page 10]</span><span id="page-11" ></span>
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[<a id="ref-RFC5481">RFC5481</a>] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", <a href="./rfc5481">RFC 5481</a>, March 2009.
[<a id="ref-RFC6390">RFC6390</a>] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", <a href="https://www.rfc-editor.org/bcp/bcp170">BCP 170</a>, <a href="./rfc6390">RFC 6390</a>,
October 2011.
[<a id="ref-RFC6709">RFC6709</a>] Carpenter, B., Aboba, B., and S. Cheshire, "Design
Considerations for Protocol Extensions", <a href="./rfc6709">RFC 6709</a>,
September 2012.
[<a id="ref-RFC6792">RFC6792</a>] Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the
RTP Monitoring Framework", <a href="./rfc6792">RFC 6792</a>, November 2012.
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<span class="h2"><a class="selflink" id="appendix-A" href="#appendix-A">Appendix A</a>. Metrics Represented Using the Template from <a href="./rfc6390">RFC 6390</a></span>
a. Burst/Gap Discard Threshold in RTP Metric
* Metric Name: Burst/gap discard threshold in RTP
* Metric Description: The Threshold is equivalent to Gmin in
[<a href="./rfc3611" title=""RTP Control Protocol Extended Reports (RTCP XR)"">RFC3611</a>], i.e., the number of successive packets that must
not be discarded prior to and following a discard packet in
order for this discarded packet to be regarded as part of a
gap.
* Method of Measurement or Calculation: See <a href="#section-3.2">Section 3.2</a>,
Threshold definition.
* Units of Measurement: See <a href="#section-3.2">Section 3.2</a>, Threshold definition.
* Measurement Point(s) with Potential Measurement Domain: See
<a href="#section-3">Section 3</a>, 1st paragraph.
* Measurement Timing: See <a href="#section-3">Section 3</a>, 2nd paragraph for
measurement timing and <a href="#section-3.2">Section 3.2</a> for Interval Metric flag.
* Use and Applications: See <a href="#section-1.4">Section 1.4</a>.
* Reporting Model: See <a href="./rfc3611">RFC 3611</a>.
b. Packets Discarded in Bursts Metric
* Metric Name: RTP packets discarded in bursts
* Metric Description: The total number of RTP packets discarded
during discard bursts.
* Method of Measurement or Calculation: See <a href="#section-3.2">Section 3.2</a>, Packets
Discarded in Bursts definition.
* Units of Measurement: See <a href="#section-3.2">Section 3.2</a>, Packets Discarded in
Bursts definition.
* Measurement Point(s) with Potential Measurement Domain: See
<a href="#section-3">Section 3</a>, 1st paragraph.
* Measurement Timing: See <a href="#section-3">Section 3</a>, 2nd paragraph for
measurement timing and <a href="#section-3.2">Section 3.2</a> for Interval Metric flag.
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* Use and Applications: See <a href="#section-1.4">Section 1.4</a>.
* Reporting Model: See <a href="./rfc3611">RFC 3611</a>.
c. Total Packets Expected in Discard Bursts Metric
* Metric Name: Total RTP packets expected in discard bursts
* Metric Description: The total number of packets expected
during discard bursts (that is, the sum of received packets
and lost packets).
* Method of Measurement or Calculation: See <a href="#section-3.2">Section 3.2</a>, Total
Packets Expected in Bursts definition.
* Units of Measurement: See <a href="#section-3.2">Section 3.2</a>, Total Packets Expected
in Bursts definition.
* Measurement Point(s) with Potential Measurement Domain: See
<a href="#section-3">Section 3</a>, 1st paragraph.
* Measurement Timing: See <a href="#section-3">Section 3</a>, 2nd paragraph for
measurement timing and <a href="#section-3.2">Section 3.2</a> for Interval Metric flag.
* Use and Applications: See <a href="#section-1.4">Section 1.4</a>.
* Reporting Model: See <a href="./rfc3611">RFC 3611</a>.
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Authors' Addresses
Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
USA
EMail: [email protected]
Rachel Huang
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
EMail: [email protected]
Qin Wu (editor)
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
EMail: [email protected]
Clark, et al. Standards Track [Page 14]
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