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 Dhesikan, et al. Expires January 15, 2014 [Page 1] Internet-Draft RTCWeb QoS July 2013 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). Dhesikan, et al. Expires January 15, 2014 [Page 2] Internet-Draft RTCWeb QoS July 2013 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 Dhesikan, et al. Expires January 15, 2014 [Page 3] Internet-Draft RTCWeb QoS July 2013 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 | +-----------------------+-----+--------+------+ Dhesikan, et al. Expires January 15, 2014 [Page 4] Internet-Draft RTCWeb QoS July 2013 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 | +---------+----+------------------+----------------+----------------+ Dhesikan, et al. Expires January 15, 2014 [Page 5] Internet-Draft RTCWeb QoS July 2013 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. Dhesikan, et al. Expires January 15, 2014 [Page 6] Internet-Draft RTCWeb QoS July 2013 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 Dhesikan, et al. Expires January 15, 2014 [Page 7] Internet-Draft RTCWeb QoS July 2013 Paul Jones Cisco Email: paulej@packetizer.com James Polk Cisco Email: jmpolk@cisco.com Dhesikan, et al. Expires January 15, 2014 [Page 8]