One document matched: draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05.xml
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docName="draft-ietf-xrblock-rtcp-xr-burst-gap-discard-05.txt"
ipr="trust200902">
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<front>
<title abbrev="RTCP XR Burst/Gap Discard">RTCP XR Report Block for
Burst/Gap Discard metric Reporting</title>
<author fullname="Geoff Hunt" initials="G." surname="Hunt">
<organization>Unaffiliated</organization>
<address>
<email>r.geoff.hunt@gmail.com</email>
</address>
</author>
<author fullname="Alan Clark" initials="A." surname="Clark">
<organization abbrev="Telchemy">Telchemy Incorporated</organization>
<address>
<postal>
<street>2905 Premiere Parkway, Suite 280</street>
<city>Duluth</city>
<region>GA</region>
<code>30097</code>
<country>USA</country>
</postal>
<email>alan.d.clark@telchemy.com</email>
</address>
</author>
<author fullname="Rachel Huang" initials="R" surname="Huang">
<organization abbrev="Huawei">Huawei Technologies Co.,
Ltd.</organization>
<address>
<postal>
<street>101 Software Avenue, Yuhua District</street>
<city>Nanjing</city>
<region>Jiangsu</region>
<code>210012</code>
<country>China</country>
</postal>
<email>Rachel@huawei.com</email>
</address>
</author>
<author fullname="Qin Wu" initials="Q." role="editor" surname="Wu">
<organization>Huawei</organization>
<address>
<postal>
<street>101 Software Avenue, Yuhua District</street>
<city>Nanjing</city>
<region>Jiangsu</region>
<code>210012</code>
<country>China</country>
</postal>
<email>sunseawq@huawei.com</email>
</address>
</author>
<date year="2012" />
<area>Real-time Applications and Infrastructure Area</area>
<workgroup>Audio/Video Transport Working Group</workgroup>
<keyword>RFC</keyword>
<keyword>Request for Comments</keyword>
<keyword>I-D</keyword>
<keyword>Internet-Draft</keyword>
<keyword>Real Time Control Protocol</keyword>
<abstract>
<t>This document defines an RTCP XR Report Block that allows the
reporting of Burst and Gap Discard metrics for use in a range of RTP
applications.</t>
</abstract>
</front>
<middle>
<section anchor="intro" title="Introduction">
<section title="Burst and Gap Discard Report Block">
<t>This document defines a new block type to augment those defined in
<xref target="RFC3611"></xref> for use in a range of RTP applications.
The new block type supports the reporting of the proportion of packets
discarded by the receiver due to jitter. The discards during discard
bursts are reported, together with the number of bursts. This block is
intended to be used in conjunction with <xref target="DISCARD"></xref>
which provides the total packets discarded, and on which this block
therefore depends. However the metric in <xref
target="DISCARD"></xref> may be used independently of the metrics in
this block.</t>
<t>This block provides information on transient IP problems. Burst/Gap
metrics are typically used in Cumulative reports however MAY be used
in Interval reports. The burstiness of packet discard affects user
experience, may influence any sender strategies to mitigate the
problem, and may also have diagnostic value.</t>
<t>The metric belongs to the class of transport-related terminal
metrics defined in <xref target="MONARCH"></xref>.</t>
<t>The definitions of Burst, Gap, Loss and Discard are consistent with
definitions in <xref target="RFC3611"></xref>. 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 may be an equivalent method to that defined in<xref
target="RFC3611"></xref>.</t>
</section>
<section title="RTCP and RTCP XR Reports">
<t>The use of RTCP for reporting is defined in <xref
target="RFC3550"></xref>. <xref target="RFC3611"></xref> defined an
extensible structure for reporting using an RTCP Extended Report (XR).
This document defines a new Extended Report block. The use of Extended
Report blocks is defined by <xref target="RFC3611"></xref>.</t>
</section>
<section title="Performance Metrics Framework">
<t>The Performance Metrics Framework <xref target="RFC6390"></xref>
provides guidance on the definition and specification of performance
metrics. Metrics described in this draft either reference external
definitions or define metrics generally in accordance with the
guidelines in <xref target="RFC6390"></xref>.</t>
</section>
<section title="Applicability">
<t>These metrics are applicable to a range of RTP applications which
don't use stream repair means.</t>
</section>
</section>
<section title="Terminology">
<section title="Standards Language">
<t>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 <xref
target="RFC2119">RFC 2119</xref>.</t>
<t>In addition, the following terms are defined:</t>
<t><list style="hanging">
<t hangText="Received, Lost and Discarded"><vspace
blankLines="1" />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 or late to
be played out or thrown away before playout due to packet
duplication or redundancy shall be regarded as discarded. A packet
shall be classified as one of received (or OK), discarded or lost.
The metric "cumulative number of packets lost" defined in <xref
target="RFC3550"></xref> reports a count of packets lost from the
media stream (single SSRC within single RTP session). Similarly
the metric "number of packets discarded" defined in <xref
target="DISCARD"></xref> reports a count of packets discarded from
the media stream (single SSRC within single RTP session) arriving
at the receiver. Another metric defined in <xref
target="RFC5725"></xref> is available to report on packets which
are not recovered by any repair techniques which may be in use.
<vspace blankLines="1" /></t>
<t hangText="Bursts and Gaps"><vspace blankLines="1" />The terms
Burst and Gap are used in a manner consistent with that of RTCP XR
[RFC3611]. RTCP XR views a 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. <vspace blankLines="1" /></t>
</list></t>
</section>
</section>
<section title="Burst/Gap Discard Block">
<t>Metrics in this block report on Burst/Gap Discard in the stream
arriving at the RTP system.</t>
<section title="Report Block Structure">
<t>Burst/Gap Discard metrics block<figure
title="Figure 1: Report Block Structure">
<artwork>
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NBGD | I | resv. | block length = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Packets Discarded in Bursts |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Total Packets expected in bursts | Reserved. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
</figure></t>
</section>
<section title="Definition of Fields in Burst/Gap Discard Report Block">
<t><list style="hanging">
<t hangText="Block type (BT): 8 bits"><vspace blankLines="1" />A
Burst/Gap Discard Report Block is identified by the constant
NBGD.<vspace blankLines="1" />[Note to RFC Editor: please replace
NBGD with the IANA provided RTCP XR block type for this
block.]<vspace blankLines="1" /></t>
<t hangText="Interval Metric flag (I): 2 bits"><vspace
blankLines="1" />This field is used to indicate whether the
Burst/Gap Discard metrics are Sampled, Interval or Cumulative
metrics, that is, whether the reported values applies to the most
recent measurement interval duration between successive metrics
reports (I=10) (the Interval Duration) or to the accumulation
period characteristic of cumulative measurements (I=11) (the
Cumulative Duration) or is a sampled instantaneous value (I=01)
(Sampled Value). In this document, Burst/Gap Discard Metric is not
measured at a particular time instant but over one or several
reporting intervals. Therefore Burst/Gap Discard Metric MUST NOT
be chosen as Sampled Metric. <vspace blankLines="1" /></t>
<t hangText="Reserved (resv): 6 bits"><vspace
blankLines="1" />These bits are reserved. They SHOULD be set to
zero by senders and MUST be ignored by receivers.<vspace
blankLines="1" /></t>
<t hangText="block length: 16 bits"><vspace blankLines="1" /> The
length of this report block in 32-bit words, minus one. For the
Burst/Gap discard block, the block length is equal to 3.<vspace
blankLines="1" /></t>
<t hangText="SSRC of source: 32 bits"><vspace blankLines="1" />As
defined in Section 4.1 of <xref target="RFC3611"></xref>.<vspace
blankLines="1" /></t>
<t hangText="Threshold: 8 bits"><vspace blankLines="1" />The
Threshold is equivalent to Gmin in <xref target="RFC3611"></xref>,
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. <vspace
blankLines="1" /></t>
<t hangText="Packets discarded in bursts: 24 bits"><vspace
blankLines="1" />The total number of packets discarded during
discard bursts.<vspace blankLines="1" />If the measured value
exceeds 0xFFFFFD, the value 0xFFFFFE SHOULD be reported to
indicate an over-range measurement. If the measurement is
unavailable, the value 0xFFFFFF SHOULD be reported. <vspace
blankLines="1" /></t>
<t hangText="Total packets expected in bursts: 24 bits"><vspace
blankLines="1" />The total number of packets expected during
discarded bursts (that is, the sum of received packets and lost
packets). <vspace blankLines="1" />If the measured value exceeds
0xFFFFFD, the value 0xFFFFFE SHOULD be reported to indicate an
over-range measurement. If the measurement is unavailable, the
value 0xFFFFFF SHOULD be reported. <vspace blankLines="1" /></t>
<t hangText="Reserved (resv): 8 bits"><vspace
blankLines="1" />These bits are reserved. They SHOULD be set to
zero by senders and MUST be ignored by receivers.<vspace
blankLines="1" /></t>
</list></t>
</section>
<section title="Derived metrics based on reported metrics">
<t>The metrics described here are intended to be used in conjunction
with information from the Measurement Information block <xref
target="MEASID"></xref>, discard block <xref target="DISCARD"></xref>
(which MUST be present in the same RTCP packet as the Burst/Gap
Discard block).</t>
<t>These metrics provides the following information relevant to
statistical parameters, including:<list style="symbols">
<t>The fraction of packets discarded during bursts (burst discard
rate in <xref target="SUMSTAT"></xref>)</t>
<t>The fraction of packets discarded during gaps (gap discard rate
in <xref target="SUMSTAT"></xref>)</t>
</list></t>
<t>The details on calculation these parameters in the metrics are
described in <xref target="SUMSTAT"></xref>.</t>
</section>
</section>
<section title="Considerations for Voice-over-IP applications">
<t>This metric block is applicable to a broad range of RTP applications.
Where the metric is used with a Voice-overIP (VoIP) application and the
stream repair means is not available, the following considerations
apply.</t>
<t>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.</t>
<t>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 MUST terminate a burst condition.</t>
<t>The recommended value for the threshold Gmin in <xref
target="RFC3611"></xref> results in a Burst being a period of time
during which the call quality is degraded to a similar extent to a
typical PCM Severely Errored Second <xref target="PSES"></xref>.</t>
</section>
<section title="SDP Signaling">
<t>[RFC3611] defines the use of SDP (Session Description Protocol) <xref
target="RFC4566"></xref> for signaling the use of XR blocks. XR blocks
MAY be used without prior signaling.</t>
<t>This section augments the SDP <xref target="RFC4566"></xref>
attribute "rtcp-xr" defined in <xref target="RFC3611"></xref> by
providing an additional value of "xr-format" to signal the use of the
report block defined in this document.<figure>
<artwork>
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF
(defined in [RFC3611])
xr-format =/ xr-bgd-block
xr-bgd-block = "brst-gap-dscrd"
</artwork>
</figure></t>
</section>
<section title="IANA Considerations">
<t>New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to <xref
target="RFC3611"></xref>.</t>
<section title="New RTCP XR Block Type value">
<t>This document assigns the block type value NBGD in the IANA "RTCP
XR Block Type Registry" to the "Burst/Gap Discard Metrics Block".</t>
<t>[Note to RFC Editor: please replace NBGD with the IANA provided
RTCP XR block type for this block.]</t>
</section>
<section title="New RTCP XR SDP Parameter">
<t>This document also registers a new parameter "brst-gap-dscrd" in
the "RTCP XR SDP Parameters Registry".</t>
</section>
<section title="Contact information for registrations">
<t><figure>
<artwork>
The contact information for the registrations is:
Qin Wu (sunseawq@huawei.com)
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
</artwork>
</figure><vspace blankLines="1" /></t>
</section>
</section>
<section title="Security Considerations">
<t>It is believed that this proposed RTCP XR report block introduces no
new security considerations beyond those described in <xref
target="RFC3611"></xref>. This block does not provide per-packet
statistics so the risk to confidentiality documented in Section 7,
paragraph 3 of <xref target="RFC3611"></xref> does not apply.</t>
</section>
<section title="Acknowledgments">
<t>The authors gratefully acknowledge the comments and contributions
made by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin
Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert
Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith
Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi
Raviraj, Albrecht Schwarz, Tom Taylor, and Hideaki Yamada.</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="RFC2119">
<front>
<title abbrev="RFC Key Words">Key words for use in RFCs to Indicate
Requirement Levels</title>
<author fullname="Scott Bradner" initials="S." surname="Bradner">
<organization>Harvard University</organization>
<address>
<postal>
<street>1350 Mass. Ave.</street>
<street>Cambridge</street>
<street>MA 02138</street>
</postal>
<phone>- +1 617 495 3864</phone>
<email>sob@harvard.edu</email>
</address>
</author>
<date month="March" year="1997" />
<area>General</area>
<keyword>keyword</keyword>
<abstract>
<t>In many standards track documents several words are used to
signify the requirements in the specification. These words are
often capitalized. This document defines these words as they
should be interpreted in IETF documents. Authors who follow these
guidelines should incorporate this phrase near the beginning of
their document: <list>
<t>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.</t>
</list></t>
<t>Note that the force of these words is modified by the
requirement level of the document in which they are used.</t>
</abstract>
</front>
</reference>
<reference anchor="RFC3611">
<front>
<title>RTP Control Protocol Extended Reports (RTCP XR)</title>
<author fullname="T. Friedman" initials="T." surname="Friedman">
<organization></organization>
</author>
<author fullname="R. Caceres" initials="R." surname="Caceres">
<organization></organization>
</author>
<author fullname="A. Clark" initials="A." surname="Clark">
<organization></organization>
</author>
<date month="November" year="2003" />
<abstract>
<t>This document defines the Extended Report (XR) packet type for
the RTP Control Protocol (RTCP), and defines how the use of XR
packets can be signaled by an application if it employs the
Session Description Protocol (SDP). XR packets are composed of
report blocks, and seven block types are defined here. The purpose
of the extended reporting format is to convey information that
supplements the six statistics that are contained in the report
blocks used by RTCP's Sender Report (SR) and Receiver Report (RR)
packets. Some applications, such as multicast inference of network
characteristics (MINC) or voice over IP (VoIP) monitoring, require
other and more detailed statistics. In addition to the block types
defined here, additional block types may be defined in the future
by adhering to the framework that this document provides.</t>
</abstract>
</front>
</reference>
<reference anchor="RFC4566">
<front>
<title>SDP: Session Description Protocol</title>
<author fullname="M. Handley" initials="M." surname="Handley">
<organization></organization>
</author>
<author fullname="V. Jacobson" initials="V." surname="Jacobson">
<organization></organization>
</author>
<author fullname="C. Perkins" initials="C." surname="Perkins">
<organization></organization>
</author>
<date month="July" year="2006" />
<abstract>
<t>This memo defines the Session Description Protocol (SDP). SDP
is intended for describing multimedia sessions for the purposes of
session announcement, session invitation, and other forms of
multimedia session initiation. [STANDARDS-TRACK]</t>
</abstract>
</front>
</reference>
<reference anchor="RFC3550">
<front>
<title>RTP: A Transport Protocol for Real-Time Applications</title>
<author fullname="Henning Schulzrinne" initials="H."
surname="Schulzrinne">
<organization>Columbia University</organization>
</author>
<date month="July" year="2003" />
</front>
<seriesInfo name="RFC" value="3550" />
<format type="TXT" />
</reference>
<reference anchor="RFC5725">
<front>
<title>Post-Repair Loss RLE Report Block Type for RTP Control
Protocol (RTCP) Extended Reports (XRs)</title>
<author fullname="Ali Begen" initials="A." surname="Begen">
<organization></organization>
</author>
<author fullname="Dong Hsu" initials="D." surname="Hsu">
<organization></organization>
</author>
<author fullname="Michael Lague" initials="M." surname="Lague">
<organization></organization>
</author>
<date month="February" year="2020" />
</front>
<seriesInfo name="RFC" value="5725" />
<format type="TXT" />
</reference>
</references>
<references title="Informative References">
<reference anchor="DISCARD">
<front>
<title>RTCP XR Report Block for Discard metric Reporting</title>
<author fullname="Geoff Hunt" initials="G." surname="Hunt">
<organization></organization>
</author>
<date month="July" year="2012" />
</front>
<seriesInfo name="ID" value="draft-ietf-xrblock-rtcp-xr-discard-05" />
<format type="TXT" />
</reference>
<reference anchor="SUMSTAT">
<front>
<title>RTCP XR for Summary Statistics Metrics Reporting</title>
<author fullname="Glen Zorn" initials="G." surname="Zorn">
<organization></organization>
</author>
<date month="July" year="2012" />
</front>
<seriesInfo name="ID" value="draft-zorn-xrblock-rtcp-xr-al-stat-06" />
<format type="TXT" />
</reference>
<reference anchor="MEASID">
<front>
<title>Measurement Identity and information Reporting using SDES
item and XR Block</title>
<author fullname="Qin Wu" initials="Q." surname="Wu">
<organization></organization>
</author>
<date month="July" year="2012" />
</front>
<seriesInfo name="ID"
value="draft-ietf-xrblock-rtcp-xr-meas-identity-09" />
<format type="TXT" />
</reference>
<reference anchor="MONARCH">
<front>
<title>Monitoring Architectures for RTP</title>
<author fullname="Geoff Hunt" initials="G." surname="Hunt">
<organization></organization>
</author>
<date month="June" year="2012" />
</front>
<seriesInfo name="ID" value="draft-ietf-avtcore-monarch-12" />
<format type="TXT" />
</reference>
<reference anchor="RFC6390">
<front>
<title>Framework for Performance Metric Development</title>
<author fullname="Alan Clark" initials="A." surname="Clark">
<organization></organization>
</author>
<author fullname="Benoit Claise " initials="B." surname="Claise">
<organization></organization>
</author>
<date month="October" year="2011" />
</front>
<seriesInfo name="RFC" value="6390" />
</reference>
<reference anchor="PSES">
<front>
<title>URL</title>
<author>
<organization></organization>
</author>
<date month="October" year="2011" />
</front>
<seriesInfo name=""
value="http://www.its.bldrdoc.gov/projects/devglossary/_severely_errored_second.html" />
</reference>
</references>
</back>
</rfc>
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