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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (January 20, 2014) is 3739 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: July 24, 2014 ATT 6 P. Jones 7 J. Polk 8 Cisco 9 January 20, 2014 11 DSCP and other packet markings for RTCWeb QoS 12 draft-dhesikan-tsvwg-rtcweb-qos-04 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 July 24, 2014. 39 Copyright Notice 41 Copyright (c) 2014 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 . . . . . . . . . . . . . . . . . . . 5 62 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 8. Downward References . . . . . . . . . . . . . . . . . . . . . 5 64 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 65 10. Document History . . . . . . . . . . . . . . . . . . . . . . 5 66 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 67 11.1. Normative References . . . . . . . . . . . . . . . . . . 6 68 11.2. Informative References . . . . . . . . . . . . . . . . . 6 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 The DSCP value set by the endpoint is not always trusted by the 125 network. Therefore, the DSCP value may be remarked to any other 126 DSCp, even to best effort at the network edge through policy. The 127 mitigation for such action is through an authorization mechanism. 128 Such authorization mechanism is outside the scope of this document. 130 3. Terminology 132 The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" 133 in this document are to be interpreted as described in [RFC2119]. 135 4. Inputs 137 The following are the inputs that the browser provides to the media 138 engine: 140 o Data Type: The browser provides this input as it knows if the flow 141 is audio, interactive video with or without audio, non-interactive 142 video with or without audio, or data. 143 o Priority: Another input is the relative treatment of the stream 144 within that data type. Many applications have multiple video 145 flows and often some are more important than others. Likewise, in 146 a videoconference where the audio and video streams of the 147 conference is of the same data type, the audio stream may be more 148 important than the video stream. JavaScript applications can tell 149 the browser whether a particular media flow is high, medium, low 150 or very low importance to the application. 152 Multiplexing behaviour of multiple media streams onto a single 153 5-tuple is covered in draft-ietf-mmusic-sdp-mux-attributes and is not 154 in the scope for this document. 156 5. DSCP Mappings 158 Below is a table of DSCP markings for each data type of interest to 159 RTCWeb. These DSCPs for each data type listed are a reasonable 160 default set of code point values taken from [RFC4594]. A web browser 161 SHOULD use these values to mark the appropriate media packets. More 162 information on EF can be found in [RFC3246]. More information on AF 163 can be found in [RFC2597]. 165 +------------------------+-------+------+-------------+-------------+ 166 | Data Type | Very | Low | Medium | High | 167 | | Low | | | | 168 +------------------------+-------+------+-------------+-------------+ 169 | Audio | CS1 | BE | EF (46) | EF (46) | 170 | | (8) | (0) | | | 171 | | | | | | 172 | Interactive Video with | CS1 | BE | AF42, AF43 | AF41, AF42 | 173 | or without audio | (8) | (0) | (36, 38) | (34, 36) | 174 | | | | | | 175 | Non-Interactive Video | CS1 | BE | AF32, AF33 | AF31, AF32 | 176 | with or without audio | (8) | (0) | (28, 30) | (26, 28) | 177 | | | | | | 178 | Data | CS1 | BE | AF1x (10, | AF2x (18, | 179 | | (8) | (0) | 12, 14) | 20, 22) | 180 +------------------------+-------+------+-------------+-------------+ 182 Table 1 184 The combination of priority input and multiple precedence levels 185 within a data class provides flexibility for an implementation in 186 deciding the importance of the stream and packets within a stream. 187 For example, if I frames are more important than the P frames then 188 the I frames can be marked with a DSCP with the lower drop 189 precedence. 191 If a packet enters a QoS domain that has no support for the above 192 defined Data Types/Application classes, then the network node at the 193 edge SHOULD map the DSCP value to one used by supported classes. 194 Here are a couple of examples: 196 o If a QoS domain supports only one video class, then the packets 197 from the two video classes SHOULD be remarked to use the same 198 DSCP, either AF4 or AF3 whichever is supported. 199 o If a QoS domain supports a single class for all voice and video 200 traffic, then the packets from all the video and voice classes 201 SHOULD be combined and remarked to the single supported DSCP. 203 Subsequently, if the packet enters a QoS domain that supports a 204 larger number of Data types/Application (service) classes, there is 205 not sufficient information in the packet to restore the original 206 markings. Mechanisms for restoring such original DSCP is outside the 207 scope of this document. 209 6. Security Considerations 211 This draft does not add any additional security implication other 212 than the normal application use of DSCP. For security implications 213 on use of DSCP, please refer to Section 6 of RFC 4594 . Please also 214 see work-in-progress draft draft-ietf-rtcweb-security-04 as an 215 additional reference. 217 7. IANA Considerations 219 This specification does not require any actions from IANA. 221 8. Downward References 223 This specification contains a downwards reference to [RFC4594] 224 however the parts of that RFC used by this specification are 225 sufficiently stable for this downward reference. 227 9. Acknowledgements 229 Cullen Jennings was one of the authors of this text in the original 230 individual submission but was unceremoniously kicked off by the 231 chairs when it became a WG version. Thanks for hints on code to do 232 this from Paolo Severini, Jim Hasselbrook, Joe Marcus, and Erik 233 Nordmark. 235 10. Document History 237 Note to RFC Editor: Please remove this section. 239 This document was originally an individual submission in RTCWeb WG. 240 The RTCWeb working group selected it to be become a WG document. 242 Later the transport ADs requested that this be moved to the TSVWG WG 243 as that seemed to be a better match. This document is now being 244 submitted as individual submission to the TSVWG with the hope that WG 245 will select it as a WG draft and move it forward to an RFC. 247 11. References 249 11.1. Normative References 251 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 252 Requirement Levels", BCP 14, RFC 2119, March 1997. 254 [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration 255 Guidelines for DiffServ Service Classes", RFC 4594, August 256 2006. 258 11.2. Informative References 260 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 261 "Definition of the Differentiated Services Field (DS 262 Field) in the IPv4 and IPv6 Headers", RFC 2474, December 263 1998. 265 [RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, 266 "Assured Forwarding PHB Group", RFC 2597, June 1999. 268 [RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec, 269 J., Courtney, W., Davari, S., Firoiu, V., and D. 270 Stiliadis, "An Expedited Forwarding PHB (Per-Hop 271 Behavior)", RFC 3246, March 2002. 273 Authors' Addresses 275 Subha Dhesikan 276 Cisco 278 Email: sdhesika@cisco.com 280 Dan Druta (editor) 281 ATT 283 Email: dd5826@att.com 284 Paul Jones 285 Cisco 287 Email: paulej@packetizer.com 289 James Polk 290 Cisco 292 Email: jmpolk@cisco.com