One document matched: draft-dhesikan-tsvwg-rtcweb-qos-05.xml

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<rfc category="std" docName="draft-dhesikan-tsvwg-rtcweb-qos-05"
     ipr="trust200902">
  <front>
    <title abbrev="RTCWeb QoS">DSCP and other packet markings for RTCWeb
    QoS</title>

    <author fullname="Subha Dhesikan" initials="S." surname="Dhesikan">
      <organization>Cisco</organization>

      <address>
        <email>sdhesika@cisco.com</email>
      </address>
    </author>

    <author fullname="Dan Druta" initials="D." role="editor" surname="Druta">
      <organization>ATT</organization>

      <address>
        <email>dd5826@att.com</email>
      </address>
    </author>

    <!--
   <author fullname="Cullen Jennings" initials="C."
    surname="Jennings">
      <organization>Cisco</organization>
      <address>
        <email>fluffy@cisco.com</email>
      </address>
    </author>
-->

    <author fullname="Paul Jones" initials="P." surname="Jones">
      <organization>Cisco</organization>

      <address>
        <email>paulej@packetizer.com</email>
      </address>
    </author>

    <author fullname="James Polk" initials="J." surname="Polk">
      <organization>Cisco</organization>

      <address>
        <email>jmpolk@cisco.com</email>
      </address>
    </author>

    <date day="02" month="March" year="2014" />

    <abstract>
      <t>Many networks, such as service provider and enterprise networks, can
      provide per packet treatments based on Differentiated Services Code
      Points (DSCP) on a per hop basis. This document provides the recommended
      DSCP values for browsers to use for various classes of traffic. </t>
    </abstract>
  </front>

  <middle>
    <section title="Introduction">
      <t> Differentiated Services Code Points (DSCP)<xref target="RFC2474" />
      style packet marking can help provide QoS in some environments. There are
      many use cases where such marking does not help, but it seldom makes
      things worse if packets are marked appropriately. In other words, if too many packets, say all
      audio or all audio and video, are marked for a given network condition then it can prevent desirable results. Either too
      much other traffic will be starved, or there is not enough capacity for
      the preferentially marked packets (i.e., audio and/or video).</t>

      <t>This draft proposes how a WebRTC applications can
      mark packets. This draft does not contradict or redefine any advice from
      previous IETF RFCs but simply provides a simple set of recommendations
      for implementers based on the previous RFCs.</t>

      <t>There are some environments where priority markings frequently help.
      These include:</t>

      <t>1. Private networks (Wide Area).</t>
      
      <t>2. If the congested link is the broadband uplink in a Cable or DSL
      scenario, often residential routers/NAT support preferential treatment
      based on DSCP.</t>

      <t>3. If the congested link is a local WiFi network, marking may
      help.</t>

      <t>Traditionally DSCP values have been thought of as being site
      specific, with each site selecting its own code points for each QoS
      level. However in the RTCWeb use cases, the browsers need to set them to
      something when there is no site specific information. This document
      describes a reasonable default set of DSCP code point values drawn from
      existing RFCs and common usage. These code points are solely defaults.
      Future drafts may define mechanisms for site specific mappings to
      override the values provided in this draft.</t>

      <t>This draft defines some inputs that the browser in an WebRTC application can look at to
      determine how to set the various packet markings and defines the 
      mapping from abstract QoS policies (data type, priority level) to those
      packet markings.</t>
    </section>

    <section title="Relation to Other Standards">
      <t>This specification does not change or override the advice in any
      other standards about setting packet markings. It simply provides a
     summary of them and provides the context of how they
      relate into the RTCWeb context. 
      In some cases, such as DSCP where the normative RFC
      leaves open multiple options to choose from, this clarifies which choice
      should be used in the RTCWeb context. This document also specifies the
      inputs that are needed by browser to provide to the media engine. </t>
<t> The DSCP value set by the endpoint is not always trusted by the network. 
  Therefore, the DSCP value may be remarked to any other DSCP, even to best effort 
  at the network edge through policy. The mitigation for such action is through an authorization 
  mechanism. Such authorization mechanism is outside the scope of this document. 
    </t>
    </section>

    <section title="Terminology">
      <t>The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
      in this document are to be interpreted as described in <xref
      target="RFC2119" />.</t>
    </section>

    <section title="Inputs">
      <t>
        The following are the inputs that the browser provides to the media engine:
        <list style="symbols">
         <t>Data Type:  The browser provides this input as it knows if the flow is audio, interactive video with or without audio, non-interactive video with or without audio, or data. 
         </t>
            <t>
              Priority: Another input is the relative treatment of
                  the stream within that data type.  Many applications have multiple
                  video flows and often some are more important than others. Likewise, in a videoconference where the audio and video streams of the conference is of the same data type, the audio stream may be more important than the video stream. 
                  JavaScript applications can tell the browser whether a
                  particular media flow is high, medium, low or very low importance to the
                  application.
             </t>      
            </list>
        Multiplexing behaviour of multiple media streams onto a single 5-tuple is covered in draft-ietf-mmusic-sdp-mux-attributes and is not in the scope for this document.

        </t>
    </section>

    <section title="DSCP Mappings">
      <t>Below is a table of DSCP markings for each data type of interest to
   RTCWeb. These DSCPs for each data type listed are a reasonable
      default set of code point values taken from <xref target="RFC4594" />. A
      web browser SHOULD use these values to mark the appropriate media
      packets. More information on EF can be found in <xref target="RFC3246"
      />.  More information on AF can be found in <xref target="RFC2597"
      />. </t>

      <texttable anchor="table-dscp">
        <ttcol align="center">Data Type</ttcol>

        <ttcol align="center">Very Low</ttcol>
        
        <ttcol align="center">Low</ttcol>

        <ttcol align="center">Medium</ttcol>

        <ttcol align="center">High</ttcol>

        <c>Audio</c>

        <c>CS1 (8)</c>

        <c>BE (0)</c>

        <c>EF (46)</c>

        <c>EF (46)</c>
        
        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c>Interactive Video with or without audio</c>

        <c>CS1 (8)</c>

        <c>BE (0)</c>

        <c>AF42, AF43 (36, 38)</c>

        <c>AF41, AF42 (34, 36)</c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>
        
        <c>Non-Interactive Video with or without audio</c>

        <c>CS1 (8)</c>

        <c>BE (0)</c>

        <c>AF32, AF33 (28, 30)</c>

        <c>AF31, AF32 (26, 28)</c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>

        <c> </c>
        
        <c>Data</c>

        <c>CS1 (8)</c>

        <c>BE (0)</c>

        <c>AF1x (10, 12, 14)</c>

        <c>AF2x (18, 20, 22)</c>
      </texttable>

   <t>
      
    The columns "very low", "low", "Medium" and "high" are the priority levels. The browser app SHOULD first select the data type of the stream. Within the data type, the priority of the stream SHOULD be selected. All packets within a stream SHOULD have the same priority. In some cases, the selected cell may have  multiple DSCP values, such as AF41 and AF42. These offer different drop pecedences. One may select difference drop precedences for the different packets in the stream. Therefore, all packets in the stream SHOULD be marked with the same priority but can have difference drop precedences.
  </t>
  <t>

    The combination of data type and priority provides specificity and helps in selecting the right DSCP value for the stream. In some cases, the different drop precedence values provides additional granularity in classifying packets within a stream. For example: In a video conference, the video stream may be medium priority. If so, either AF42 or AF43 may be selected. If the I frames in the stream are more important than the P frames then the I frames can be marked with AF42 and the P frames marked with AF43.
  </t>
  <t>
    The above table assumes that packets marked with CS1 is treated as "less than best effort".  However, the treatment of CS1 is implementation dependent. If an implementation treats CS1 as other than "less than best effort", then the priority of the packets may be changed from what is intended.
  </t>

<t> 
  If a packet enters a QoS domain that has no support for the above defined Data Types/Application classes, 
  then the network node at the edge will remark the DSCP value based on policies. 
  
  Subsequently, if the packet enters a QoS domain that supports a larger number of Data types/Application (service) classes, there may not be sufficient information in the packet to restore the original markings. Mechanisms for restoring such original DSCP is outside the scope of this document. 
</t>
  </section>
   
    
    
    <section title="Security Considerations">
      <t> This draft does not add any additional security implication other than 
        the normal application use of DSCP. For security implications on use of DSCP, 
        please refer to Section 6 of RFC 4594 . Please also see work-in-progress draft 
        draft-ietf-rtcweb-security-04 as an additional reference. 
</t>
    </section>

    <section title="IANA Considerations">
      <t>This specification does not require any actions from IANA.</t>
    </section>

   <section title="Downward References">
      <t>This specification contains a downwards reference to <xref
      target="RFC4594"/> however the parts of that RFC used by this
      specification are sufficiently stable for this downward reference.</t>
    </section>

    <section title="Acknowledgements">
      <t>Cullen Jennings was one of the authors of this text in the original
      individual submission but was unceremoniously kicked off by the chairs
      when it became a WG version. Thanks for hints on code to do this from
      Paolo Severini, Jim Hasselbrook, Joe Marcus, and Erik Nordmark.</t>
    </section>

   <section title="Document History">
      <t>Note to RFC Editor: Please remove this section.</t>

      <t> This document was originally an individual submission in RTCWeb
      WG. The RTCWeb working group selected it to be become a WG document. Later
      the transport ADs requested that this be moved to the TSVWG WG as that
      seemed to be a better match. This document is now being submitted as
      individual submission to the TSVWG with the hope that WG will select it as
      a WG draft and move it forward to an RFC. </t>

    </section>


    
  </middle>

  <back>
    <references title="Normative References">
      <reference anchor="RFC4594">
        <front>
          <title>Configuration Guidelines for DiffServ Service Classes</title>

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

          <author fullname="K. Chan" initials="K." surname="Chan">
            <organization></organization>
          </author>

          <author fullname="F. Baker" initials="F." surname="Baker">
            <organization></organization>
          </author>

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

        <seriesInfo name="RFC" value="4594" />

        <format octets="144044"
                target="http://www.rfc-editor.org/rfc/rfc4594.txt" type="TXT" />
      </reference>

 
      <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>
        </front>

        <seriesInfo name="BCP" value="14" />

        <seriesInfo name="RFC" value="2119" />

        <format octets="4723"
                target="http://www.rfc-editor.org/rfc/rfc2119.txt" type="TXT" />

        <format octets="17491"
                target="http://xml.resource.org/public/rfc/html/rfc2119.html"
                type="HTML" />

        <format octets="5777"
                target="http://xml.resource.org/public/rfc/xml/rfc2119.xml"
                type="XML" />
      </reference>
    </references>

    <references title="Informative References">
     
     <reference anchor="RFC3246">
        <front>
          <title>An Expedited Forwarding PHB (Per-Hop Behavior)</title>

          <author fullname="B. Davie" initials="B." surname="Davie">
            <organization></organization>
          </author>

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

          <author fullname="J.C.R. Bennet" initials="J.C.R." surname="Bennet">
            <organization></organization>
          </author>

          <author fullname="K. Benson" initials="K." surname="Benson">
            <organization></organization>
          </author>

          <author fullname="J.Y. Le Boudec" initials="J.Y."
                  surname="Le Boudec">
            <organization></organization>
          </author>

          <author fullname="W. Courtney" initials="W." surname="Courtney">
            <organization></organization>
          </author>

          <author fullname="S. Davari" initials="S." surname="Davari">
            <organization></organization>
          </author>

          <author fullname="V. Firoiu" initials="V." surname="Firoiu">
            <organization></organization>
          </author>

          <author fullname="D. Stiliadis" initials="D." surname="Stiliadis">
            <organization></organization>
          </author>

          <date month="March" year="2002" />
        </front>

        <seriesInfo name="RFC" value="3246" />

        <format octets="33896"
                target="http://www.rfc-editor.org/rfc/rfc3246.txt" type="TXT" />
      </reference>

      <reference anchor="RFC2474">
        <front>
          <title abbrev="Differentiated Services Field">Definition of the
          Differentiated Services Field (DS Field) in the IPv4 and IPv6
          Headers</title>

          <author fullname="Kathleen Nichols" initials="K." surname="Nichols">
            <organization>Cisco Systems</organization>

            <address>
              <postal>
                <street>170 West Tasman Drive</street>

                <city>San Jose</city>

                <region>CA</region>

                <code>95134-1706</code>

                <country>USA</country>
              </postal>

              <phone>+1 408 525 4857</phone>

              <email>kmn@cisco.com</email>
            </address>
          </author>

          <author fullname="Steven Blake" initials="S." surname="Blake">
            <organization>Torrent Networking Technologies</organization>

            <address>
              <postal>
                <street>3000 Aerial Center</street>

                <city>Morrisville</city>

                <region>NC</region>

                <code>27560</code>

                <country>USA</country>
              </postal>

              <phone>+1 919 468 8466 x232</phone>

              <email>slblake@torrentnet.com</email>
            </address>
          </author>

          <author fullname="Fred Baker" initials="F." surname="Baker">
            <organization>Cisco Systems</organization>

            <address>
              <postal>
                <street>519 Lado Drive</street>

                <city>Santa Barbara</city>

                <region>CA</region>

                <code>93111</code>

                <country>USA</country>
              </postal>

              <phone>+1 408 526 4257</phone>

              <email>fred@cisco.com</email>
            </address>
          </author>

          <author fullname="David L. Black" initials="D.L." surname="Black">
            <organization>EMC Corporation</organization>

            <address>
              <postal>
                <street>35 Parkwood Drive</street>

                <city>Hopkinton</city>

                <region>MA</region>

                <code>01748</code>

                <country>USA</country>
              </postal>

              <phone>+1 508 435 1000 x76140</phone>

              <email>black_david@emc.com</email>
            </address>
          </author>

          <date month="December" year="1998" />

          <area>Internet</area>

          <keyword>internet protocol version 4</keyword>

          <keyword>IPv6</keyword>

          <keyword>IPv4</keyword>

          <keyword>internet protocol version 6</keyword>

          <keyword>type of service</keyword>
        </front>

        <seriesInfo name="RFC" value="2474" />

        <format octets="50576"
                target="http://www.rfc-editor.org/rfc/rfc2474.txt" type="TXT" />

        <format octets="67719"
                target="http://xml.resource.org/public/rfc/html/rfc2474.html"
                type="HTML" />

        <format octets="62259"
                target="http://xml.resource.org/public/rfc/xml/rfc2474.xml"
                type="XML" />
      </reference>

      <reference anchor="RFC2597">
        <front>
          <title>Assured Forwarding PHB Group</title>

          <author fullname="Juha Heinanen" initials="J." surname="Heinanen">
            <organization>Telia Finland</organization>

            <address>
              <postal>
                <street>Myyrmaentie 2</street>

                <city>Vantaa</city>

                <code>01600</code>

                <country>FI</country>
              </postal>

              <email>jh@telia.fi</email>
            </address>
          </author>

          <author fullname="Fred Baker" initials="F." surname="Baker">
            <organization>Cisco Systems</organization>

            <address>
              <postal>
                <street>519 Lado Drive</street>

                <city>Santa Barbara</city>

                <region>CA</region>

                <code>93111</code>

                <country>US</country>
              </postal>

              <email>fred@cisco.com</email>
            </address>
          </author>

          <author fullname="Walter Weiss" initials="W." surname="Weiss">
            <organization>Lucent Technologies</organization>

            <address>
              <postal>
                <street>300 Baker Avenue</street>

                <street>Suite 100</street>

                <city>Concord</city>

                <region>MA</region>

                <code>01742-2168</code>

                <country>US</country>
              </postal>

              <email>wweiss@lucent.com</email>
            </address>
          </author>

          <author fullname="J. Wroclawski" initials="J." surname="Wroclawski">
            <organization>MIT Laboratory for Computer Science</organization>

            <address>
              <postal>
                <street>545 Technology Square</street>

                <city>Cambridge</city>

                <region>MA</region>

                <code>02139</code>

                <country>US</country>
              </postal>

              <email>jtw@lcs.mit.edu</email>
            </address>
          </author>

          <date month="June" year="1999" />
        </front>

        <seriesInfo name="RFC" value="2597" />

        <format octets="24068"
                target="http://www.rfc-editor.org/rfc/rfc2597.txt" type="TXT" />
      </reference>

    </references>
  </back>
</rfc>