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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (December 14, 2013) is 3785 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 4594 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Dhesikan 3 Internet-Draft Cisco 4 Intended status: Standards Track D. Druta, Ed. 5 Expires: June 17, 2014 ATT 6 P. Jones 7 J. Polk 8 Cisco 9 December 14, 2013 11 DSCP and other packet markings for RTCWeb QoS 12 draft-dhesikan-tsvwg-rtcweb-qos-03 14 Abstract 16 Many networks, such as service provider and enterprise networks, can 17 provide per packet treatments based on Differentiated Services Code 18 Points (DSCP) on a per hop basis. This document provides the 19 recommended DSCP values for browsers to use for various classes of 20 traffic. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on June 17, 2014. 39 Copyright Notice 41 Copyright (c) 2013 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Relation to Other Standards . . . . . . . . . . . . . . . . . 3 58 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 4. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 5. DSCP Mappings . . . . . . . . . . . . . . . . . . . . . . . . 4 61 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 62 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 8. Downward References . . . . . . . . . . . . . . . . . . . . . 5 64 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 65 10. Document History . . . . . . . . . . . . . . . . . . . . . . 5 66 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 67 11.1. Normative References . . . . . . . . . . . . . . . . . . 5 68 11.2. Informative References . . . . . . . . . . . . . . . . . 5 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 71 1. Introduction 73 Differentiated Services Code Points (DSCP)[RFC2474] style packet 74 marking can help provide QoS in some environments. There are many 75 use cases where such marking does not help, but it seldom makes 76 things worse if packets are marked appropriately. In other words, if 77 too many packets, say all audio or all audio and video, are marked 78 for a given network condition then it can prevent desirable results. 79 Either too much other traffic will be starved, or there is not enough 80 capacity for the preferentially marked packets (i.e., audio and/or 81 video). 83 This draft proposes how a browser and other VoIP applications can 84 mark packets. This draft does not contradict or redefine any advice 85 from previous IETF RFCs but simply provides a simple set of 86 recommendations for implementers based on the previous RFCs. 88 There are some environments where priority markings frequently help. 89 These include: 91 1. Private networks (Wide Area). 93 2. If the congested link is the broadband uplink in a Cable or DSL 94 scenario, often residential routers/NAT support preferential 95 treatment based on DSCP. 97 3. If the congested link is a local WiFi network, marking may help. 99 Traditionally DSCP values have been thought of as being site 100 specific, with each site selecting its own code points for each QoS 101 level. However in the RTCWeb use cases, the browsers need to set 102 them to something when there is no site specific information. This 103 document describes a reasonable default set of DSCP code point values 104 drawn from existing RFCs and common usage. These code points are 105 solely defaults. Future drafts may define mechanisms for site 106 specific mappings to override the values provided in this draft. 108 This draft defines some inputs that the browser can look at to 109 determine how to set the various packet markings and defines the 110 mapping from abstract QoS policies (data type, priority level) to 111 those packet markings. 113 2. Relation to Other Standards 115 This specification does not change or override the advice in any 116 other standards about setting packet markings. It simply provides a 117 summary of them and provides the context of how they relate into the 118 RTCWeb context. In some cases, such as DSCP where the normative RFC 119 leaves open multiple options to choose from, this clarifies which 120 choice should be used in the RTCWeb context. This document also 121 specifies the inputs that are needed by browser to provide to the 122 media engine. 124 3. Terminology 126 The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" 127 in this document are to be interpreted as described in [RFC2119]. 129 4. Inputs 131 The following are the inputs that the browser provides to the media 132 engine: 134 o Data Type: The browser provides this input as it knows if the flow 135 is audio, interactive video with or without audio, non-interactive 136 video with or without audio, or data. 137 o Priority: Another input is the relative treatment of the stream 138 within that data type. Many applications have multiple video 139 flows and often some are more important than others. Likewise, in 140 a videoconference where the audio and video streams of the 141 conference is of the same data type, the audio stream may be more 142 important than the video stream. JavaScript applications can tell 143 the browser whether a particular media flow is high, medium, low 144 or very low importance to the application. 146 Multiplexing behaviour of multiple media streams onto a single 147 5-tuple is covered in draft-ietf-mmusic-sdp-mux-attributes and is not 148 in the scope for this document. 150 5. DSCP Mappings 152 Below is a table of DSCP markings for each data type of interest to 153 RTCWeb. These DSCPs for each data type listed are a reasonable 154 default set of code point values taken from [RFC4594]. A web browser 155 SHOULD use these values to mark the appropriate media packets. More 156 information on EF can be found in [RFC3246]. More information on AF 157 can be found in [RFC2597]. 159 +------------------------+-------+------+-------------+-------------+ 160 | Data Type | Very | Low | Medium | High | 161 | | Low | | | | 162 +------------------------+-------+------+-------------+-------------+ 163 | Audio | CS1 | BE | EF (46) | EF (46) | 164 | | (8) | (0) | | | 165 | | | | | | 166 | Interactive Video with | CS1 | BE | AF42, AF43 | AF41, AF42 | 167 | or without audio | (8) | (0) | (36, 38) | (34, 36) | 168 | | | | | | 169 | Non-Interactive Video | CS1 | BE | AF32, AF33 | AF31, AF32 | 170 | with or without audio | (8) | (0) | (28, 30) | (26, 28) | 171 | | | | | | 172 | Data | CS1 | BE | AF1x (10, | AF2x (18, | 173 | | (8) | (0) | 12, 14) | 20, 22) | 174 +------------------------+-------+------+-------------+-------------+ 176 Table 1 178 The combination of priority input and multiple precedence levels 179 within a data class provides flexibility for an implementation in 180 deciding the importance of the stream and packets within a stream. 181 For example, if I frames are more important than the P frames then 182 the I frames can be marked with a DSCP with the lower drop 183 precedence. 185 6. Security Considerations 187 This draft does not add any additional security implication other 188 than the normal application use of DSCP. For security implications 189 on use of DSCP, please refer to Section 6 of RFC 4594 . Please also 190 see work-in-progress draft draft-ietf-rtcweb-security-04 as an 191 additional reference. 193 7. IANA Considerations 195 This specification does not require any actions from IANA. 197 8. Downward References 199 This specification contains a downwards reference to [RFC4594] 200 however the parts of that RFC used by this specification are 201 sufficiently stable for this downward reference. 203 9. Acknowledgements 205 Cullen Jennings was one of the authors of this text in the original 206 individual submission but was unceremoniously kicked off by the 207 chairs when it became a WG version. Thanks for hints on code to do 208 this from Paolo Severini, Jim Hasselbrook, Joe Marcus, and Erik 209 Nordmark. 211 10. Document History 213 Note to RFC Editor: Please remove this section. 215 This document was originally an individual submission in RTCWeb WG. 216 The RTCWeb working group selected it to be become a WG document. 217 Later the transport ADs requested that this be moved to the TSVWG WG 218 as that seemed to be a better match. This document is now being 219 submitted as individual submission to the TSVWG with the hope that WG 220 will select it as a WG draft and move it forward to an RFC. 222 11. References 224 11.1. Normative References 226 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 227 Requirement Levels", BCP 14, RFC 2119, March 1997. 229 [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration 230 Guidelines for DiffServ Service Classes", RFC 4594, August 231 2006. 233 11.2. Informative References 235 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 236 "Definition of the Differentiated Services Field (DS 237 Field) in the IPv4 and IPv6 Headers", RFC 2474, December 238 1998. 240 [RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, 241 "Assured Forwarding PHB Group", RFC 2597, June 1999. 243 [RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec, 244 J., Courtney, W., Davari, S., Firoiu, V., and D. 245 Stiliadis, "An Expedited Forwarding PHB (Per-Hop 246 Behavior)", RFC 3246, March 2002. 248 Authors' Addresses 250 Subha Dhesikan 251 Cisco 253 Email: sdhesika@cisco.com 255 Dan Druta (editor) 256 ATT 258 Email: dd5826@att.com 260 Paul Jones 261 Cisco 263 Email: paulej@packetizer.com 265 James Polk 266 Cisco 268 Email: jmpolk@cisco.com