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Versions: (draft-ietf-rtcweb-qos) 00 01 02 03 04 05 06 07 draft-ietf-tsvwg-rtcweb-qos

Network Working Group                                        S. Dhesikan
Internet-Draft                                                     Cisco
Intended status: Standards Track                           D. Druta, Ed.
Expires: January 15, 2014                                            ATT
                                                                P. Jones
                                                                 J. Polk
                                                                   Cisco
                                                           July 14, 2013


             DSCP and other packet markings for RTCWeb QoS
                   draft-dhesikan-tsvwg-rtcweb-qos-02

Abstract

   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.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 15, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Relation to Other Standards . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Inputs  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  DSCP Mappings . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  QCI Mapping . . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  WiFI Mapping  . . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  W3C API Implications  . . . . . . . . . . . . . . . . . . . .   6
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   11. Downward References . . . . . . . . . . . . . . . . . . . . .   6
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   13. Document History  . . . . . . . . . . . . . . . . . . . . . .   6
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     14.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     14.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Differentiated Services Code Points (DSCP)[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,
   when attempting to avoid congestion by marking certain traffic flows,
   say all audio or all audio and video, causes the marking of too many
   audio and/or video flows for a given network's capacity, 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).

   This draft proposes how a browser and other VoIP 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 implementors based on the previous RFCs.

   There are some environments where priority markings frequently help.
   These include:

   1.  Private networks (Wide Area).




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   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.

   3.  If the congested link is a local WiFi network, marking may help.

   4.  In some cellular style deployments, markings may help in cases
   where the network does not remove them.

   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.

   This draft defines some inputs that the browser can look at to
   determine how to set the various packet markings and defines the
   mapping from abstract QoS policies (media type, priority level) to
   those packet markings.

2.  Relation to Other Standards

   This specification does not change or override the advice in any
   other standards about setting packet markings.  It simply provides a
   non-normative summary of them and provides the context of how they
   relate into the RTCWeb context.  This document also specifies the
   requirements for the W3C WebRTC API to understand what it needs to
   control, and how the control splits between things the JavaScript
   application running in the browser can control and things the browser
   needs to control.  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.

3.  Terminology

   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
   in this document are to be interpreted as described in [RFC2119].

4.  Inputs

   The following are the inputs that the browser provides to the media
   engine:

   o  Type of flow: The browser provides this input as it knows if the
      flow is audio, video, or data.  In this specification, both



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      interactive and streaming media are included.  They are treated in
      different categories as their QoS requirements are slightly
      different.  If the type of flow is multiplexed content, then the
      input is a list of the type of flows that are multiplexed within
      the single stream.
   o  Session Context: This input provides the session context for the
      type of flow.  For example, the type of flow may be audio.  The
      flow may be part of a VoIP session or an audio/video session.
      Such session context information helps the media engine and the
      underlying network to make decisions on how to treat the audio
      flow which may differ based on the entire session to which the
      flow belongs.  The browser should know this information.
   o  Relative priority: Another input is the relative treatment of the
      stream within that session.  Many applications have multiple video
      flows and often some are more important than others.  JavaScript
      applications can tell the browser whether a particular media flow
      is high, medium, or low importance to the application.

5.  DSCP Mappings

   Below is a table of DSCP markings for each media type RTCWeb is
   interested in.  These DSCPs for each media type listed are a
   reasonable default set of code point values taken from [RFC4594].  A
   web browser SHOULD use these values to mark the appropriate media
   packets.  More information on EF can be found in [RFC3246].  More
   information on AF can be found in [RFC2597].

       +-----------------------+-----------+-----------+-----------+
       | Media Type            |    Low    |   Medium  |    High   |
       +-----------------------+-----------+-----------+-----------+
       | Audio                 |  46 (EF)  |  46 (EF)  |  46 (EF)  |
       | Interactive Video     | 38 (AF43) | 36 (AF42) | 34 (AF41) |
       | Non-Interactive Video | 26 (AF33) | 28 (AF32) | 30 (AF31) |
       | Data                  |  8 (CS1)  |   0 (BE)  | 10 (AF11) |
       +-----------------------+-----------+-----------+-----------+

                                  Table 1

6.  QCI Mapping

              +-----------------------+-----+--------+------+
              | Media Type            | Low | Medium | High |
              +-----------------------+-----+--------+------+
              | Audio                 |  1  |   1    |  1   |
              | Interactive Video     |  2  |   2    |  2   |
              | Non-Interactive Video |  8  |   6    |  4   |
              | Data                  |  9  |   9    |  3   |
              +-----------------------+-----+--------+------+



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                                  Table 2

   This corresponds to the mapping provided in TODO REF which are: QCI
   values (LTE)

   +---------+----------+-----+----------------------------------------+
   | Value   |          |     |                  Use                   |
   +---------+----------+-----+----------------------------------------+
   | 1       |   GBR    |  2  |           Interactive Voice            |
   | 2       |   GBR    |  4  |           Interactive Video            |
   | 3       |   GBR    |  5  |         Non-Interactive Video          |
   | 4       |   GBR    |  3  |            Real Time Gaming            |
   | 5       |  Non-BG  | R 1 |             IMS Signaling              |
   | 6       |  Non-BG  | R 7 |    interactive Voice, video, games     |
   | 7-9     |  Non-BG  | R 6 |    non interactive video / TCP web,    |
   |         |          |     |     email, / Platinum vs gold user     |
   +---------+----------+-----+----------------------------------------+

                                  Table 3

7.  WiFI Mapping

              +-----------------------+-----+--------+------+
              | Media Type            | Low | Medium | High |
              +-----------------------+-----+--------+------+
              | Audio                 |  6  |   6    |  6   |
              | Interactive Video     |  5  |   5    |  5   |
              | Non-Interactive Video |  4  |   4    |  4   |
              | Data                  |  1  |   0    |  3   |
              +-----------------------+-----+--------+------+

                                  Table 4

   This corresponds to the mappings from TODO REF of

   +---------+----+------------------+----------------+----------------+
   | Value   |    |   Traffic Type   |     Access     |  Designation   |
   |         |    |                  | Category (AC)  |                |
   +---------+----+------------------+----------------+----------------+
   | 1       | BK |    Background    |     AC_BK      |   Background   |
   | 2       | -  |     (spare)      |     AC_BK      |   Background   |
   | 0       | BE |   Best Effort    |     AC_BE      |  Best Effort   |
   | 3       | EE | Excellent Effort |     AC_BE      |  Best Effort   |
   | 4       | CL | Controlled Load  |     AC_VI      |     Video      |
   | 5       | VI |      Video       |     AC_VI      |     Video      |
   | 6       | VO |      Voice       |     AC_VO      |     Voice      |
   | 7       | NC | Network Control  |     AC_VO      |     Voice      |
   +---------+----+------------------+----------------+----------------+



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                                  Table 5

8.  W3C API Implications

   To work with this proposal, the W3C specification SHOULD provide a
   way to specify the importance of media and data streams.

   The W3C API SHOULD also provide a way for the application to find out
   the source and destination IP and ports of any flow as well as the
   DSCP value or other markings in use for that flow.  The JavaScript
   application can then communicate this to a web service that may
   install a particular policy for that flow.

   The W3C API SHOULD NOT provide a way for the JavaScript to
   arbitrarily set the marking to any value of the JavaScript choosing
   as this reduces the security provided by the browser knowing the
   media type.

9.  Security Considerations

   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.

10.  IANA Considerations

   This specification does not require any actions from IANA.

11.  Downward References

   This specification contains a downwards reference to [RFC4594]
   however the parts of that RFC used by this specificaiton are
   sufficiently stable for this donward reference.

12.  Acknowledgements

   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.

13.  Document History

   Note to RFC Editor: Please remove this section.




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   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.

14.  References

14.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4594]  Babiarz, J., Chan, K., and F. Baker, "Configuration
              Guidelines for DiffServ Service Classes", RFC 4594, August
              2006.

14.2.  Informative References

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474, December
              1998.

   [RFC2597]  Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
              "Assured Forwarding PHB Group", RFC 2597, June 1999.

   [RFC3246]  Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec,
              J., Courtney, W., Davari, S., Firoiu, V., and D.
              Stiliadis, "An Expedited Forwarding PHB (Per-Hop
              Behavior)", RFC 3246, March 2002.

Authors' Addresses

   Subha Dhesikan
   Cisco

   Email: sdhesika@cisco.com


   Dan Druta (editor)
   ATT

   Email: dd5826@att.com






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   Paul Jones
   Cisco

   Email: paulej@packetizer.com


   James Polk
   Cisco

   Email: jmpolk@cisco.com









































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