One document matched: draft-ietf-xrblock-rtcp-xr-discard-01.xml

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<rfc category="std" docName="draft-ietf-xrblock-rtcp-xr-discard-01.txt"
     ipr="trust200902">
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  <front>
    <title abbrev="RTCP XR Discard">RTCP XR Report Block for 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="Glen Zorn" initials="G." surname="Zorn">
      <organization>Network Zen</organization>

      <address>
        <postal>
          <street>77/440 Soi Phoomjit, Rama IV Road</street>

          <street>Phra Khanong, Khlong Toie</street>

          <city>Bangkok</city>

          <code>10110</code>

          <country>Thailand</country>
        </postal>

        <phone>+66 (0) 87 502 4274</phone>

        <email>gwz@net-zen.net</email>
      </address>
    </author>

    <author fullname="Qin Wu" initials="Q." 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 month="December" year="2011" />

    <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 a simple discard count metric for use in a range of RTP
      applications.</t>
    </abstract>
  </front>

  <middle>
    <section anchor="intro" title="Introduction">
      <section title="Discard Report Block">
        <t>This draft 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 number of packets
        which are received correctly but are never played out, typically
        because they arrive too late to be played out (buffer underflow) or
        too early (buffer overflow). The metric is applicable both to systems
        which use packet loss repair techniques (such as forward error
        correction <xref target="RFC5109"></xref> or retransmission <xref
        target="RFC4588"></xref>) and to those which do not.</t>

        <t>This metric is useful for identifying the existence, and
        characterising the severity, of a packet transport problem which may
        affect users' perception of a service delivered over RTP.</t>

        <t>The metric belongs to the class of transport-related terminal
        metrics defined in <xref target="MONARCH"></xref> (work in
        progress).</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 draft defines a new Extended Report block that MUST be used as
        defined in <xref target="RFC3550"></xref> and <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>This metric is believed to be applicable to a large class of RTP
        applications which use a jitter buffer.</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 shall be regarded as discarded. A packet shall be
            classified as one of received (or OK), discarded or lost. The
            Discard Metric counts only discarded packets. 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" 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>
          </list></t>
      </section>
    </section>

    <section title="Discard Metric Report Block">
      <section title="Report Block Structure">
        <t><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 |E|  resv.  |      block length = 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SSRC of Source                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    number of packets discarded                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
          </figure></t>
      </section>

      <section title="Definition of Fields in Discard Metric Report Block">
        <t><list style="hanging">
            <t hangText="Block type (BT): 8 bits"><vspace blankLines="1" />A
            Discard Metric Report Block is identified by the constant
            ND.<vspace blankLines="1" /> [Note to RFC Editor: please replace
            ND 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 Basic
            Loss/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 to the value of a continuously measured or calculated
            that has been sampled at end of the interval (I=01) (Sampled
            Value). <vspace blankLines="1" /></t>

            <t hangText="Early indication flag (E): 1bit"><vspace
            blankLines="1" />This field is used to indicate whether packets
            are discarded due to early arrival or due to late arrival. This
            field MUST be set to '1' if packets are discarded due to too early
            arrival and MUST be set to '0' otherwise. <vspace
            blankLines="1" /></t>

            <t hangText="Reserved (resv): 5 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
            Delay block, the block length is equal to 2.<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="number of packets discarded: 32 bits"><vspace
            blankLines="1" />Number of packets discarded over the period
            (Interval or Cumulative) covered by this report. <vspace
            blankLines="1" /> If the measured value exceeds 0xFFFFFFFD, the
            value 0xFFFFFFFE SHOULD be reported to indicate an over-range
            measurement. If the measurement is unavailable, the value
            0xFFFFFFFF SHOULD be reported. <vspace blankLines="1" />Note that
            the number of packets expected in the period covered by the metric
            (whether interval or cumulative) is available from the difference
            between a pair of extended sequence numbers in the Measurement
            Identity block, so need not be repeated in this block. <vspace
            blankLines="1" /></t>
          </list></t>
      </section>
    </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-pd-block

 xr-pd-block = "pkt-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 ND in the IANA "RTCP XR
        Block Type Registry" to the "Discard Metrics Block".</t>

        <t>[Note to RFC Editor: please replace ND 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 "pkt-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:

Geoff Hunt (r.geoff.hunt@gmail.com)

Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United
Kingdom
</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="Contributors">
      <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>

    <section title="Changes from previous version">
      <t>Changed BNF for SDP following Christian Groves' and Tom Taylor's
      comments (4th and 5th May 2009), now aligned with RFC 5234 section 3.3
      "Incremental Alternatives".</t>

      <t>Updated references.</t>

      <t>Allocate 1 bit to distinguish early discard from later discard.</t>

      <t>Expand Interval Metric flag to 2 bit to allow using sampled metric.
      </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>
    </references>

    <references title="Informative References">
      <reference anchor="MONARCH">
        <front>
          <title>Monitoring Architectures for RTP</title>

          <author fullname="Qin Wu" initials="Q." surname="Wu">
            <organization></organization>
          </author>

          <date month="August" year="2011" />
        </front>

        <seriesInfo name="ID" value="draft-ietf-avtcore-monarch-04" />

        <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="RFC5725">
        <front>
          <title>RTCP XR Report Block for Post-Repair Loss metric Reporting
          </title>

          <author fullname="Ali Begen" initials="A." surname="Begen">
            <organization></organization>
          </author>

          <date month="February" year="2010" />
        </front>

        <seriesInfo name="ID" value="draft-ietf-rtcp-xr-postrepair-loss-02" />
      </reference>

      <reference anchor="RFC4588">
        <front>
          <title>RTP Retransmission Payload Format</title>

          <author fullname="J.Rey" initials="J." surname="Rey">
            <organization></organization>
          </author>

          <date month="July" year="2006" />
        </front>

        <seriesInfo name="RFC" value="4588" />

        <format type="TXT" />
      </reference>

      <reference anchor="RFC5109">
        <front>
          <title>RTP Payload Format for Generic Forward Error
          Correction</title>

          <author fullname="A.Li" initials="A." surname="Li">
            <organization></organization>
          </author>

          <date month="July" year="2006" />
        </front>

        <seriesInfo name="RFC" value="5109" />

        <format type="TXT" />
      </reference>
    </references>
  </back>
</rfc>