draft-ietf-tsvwg-rtcweb-qos-02.txt   draft-ietf-tsvwg-rtcweb-qos-03.txt 
Network Working Group S. Dhesikan Network Working Group S. Dhesikan
Internet-Draft C. Jennings Internet-Draft C. Jennings
Intended status: Standards Track Cisco Intended status: Standards Track Cisco Systems
Expires: December 25, 2014 D. Druta, Ed. Expires: May 16, 2015 D. Druta, Ed.
ATT AT&T
P. Jones P. Jones
J. Polk J. Polk
Cisco Cisco Systems
June 23, 2014 November 12, 2014
DSCP and other packet markings for RTCWeb QoS DSCP and other packet markings for RTCWeb QoS
draft-ietf-tsvwg-rtcweb-qos-02 draft-ietf-tsvwg-rtcweb-qos-03
Abstract Abstract
Many networks, such as service provider and enterprise networks, can Many networks, such as service provider and enterprise networks, can
provide per packet treatments based on Differentiated Services Code provide treatment for individual packets based on Differentiated
Points (DSCP) on a per-hop basis. This document provides the Services Code Points (DSCP) on a per-hop basis. This document
recommended DSCP values for browsers to use for various classes of provides the recommended DSCP values for browsers to use for various
traffic. classes of traffic.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 25, 2014. This Internet-Draft will expire on May 16, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Relation to Other Standards . . . . . . . . . . . . . . . . . 3 2. Relation to Other Standards . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. DSCP Mappings . . . . . . . . . . . . . . . . . . . . . . . . 4 5. DSCP Mappings . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Downward References . . . . . . . . . . . . . . . . . . . . . 6 8. Downward References . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. Document History . . . . . . . . . . . . . . . . . . . . . . 6 10. Document History . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . 6 11.1. Normative References . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
Differentiated Services Code Points (DSCP)[RFC2474] style packet Differentiated Services Code Points (DSCP) [RFC2474] style packet
marking can help provide QoS in some environments. There are many marking can help provide QoS in some environments. There are many
use cases where such marking does not help, but it seldom makes use cases where such marking does not help, but it seldom makes
things worse if packets are marked appropriately. In other words, if things worse if packets are marked appropriately. In other words, if
too many packets, say all audio or all audio and video, are marked too many packets, say all audio or all audio and video, are marked
for a given network condition then it can prevent desirable results. for a given network condition then it can prevent desirable results.
Either too much other traffic will be starved, or there is not enough Either too much other traffic will be starved, or there is not enough
capacity for the preferentially marked packets (i.e., audio and/or capacity for the preferentially marked packets (i.e., audio and/or
video). video).
This draft proposes how WebRTC applications can mark packets. This This specification proposes how WebRTC applications can mark packets.
draft does not contradict or redefine any advice from previous IETF This specification does not contradict or redefine any advice from
RFCs but simply provides a simple set of recommendations for previous IETF RFCs but simply provides a simple set of
implementers based on the previous RFCs. recommendations for implementers based on the previous RFCs.
There are some environments where priority markings frequently help. There are some environments where priority markings frequently help.
These include: These include:
1. Private networks (Wide Area). 1. Private, wide-area networks.
2. Residential Networks: If the congested link is the broadband 2. Residential Networks. If the congested link is the broadband
uplink in a Cable or DSL scenario, often residential routers/NAT uplink in a cable or DSL scenario, often residential routers/NAT
support preferential treatment based on DSCP. support preferential treatment based on DSCP.
3. Wireless Networks: If the congested link is a local WiFi network, 3. Wireless Networks. If the congested link is a local wireless
marking may help. network, marking may help.
Traditionally DSCP values have been thought of as being site Traditionally DSCP values have been thought of as being site
specific, with each site selecting its own code points for each QoS specific, with each site selecting its own code points for each QoS
level. However in the RTCWeb use cases, the browsers need to set level. However in the RTCWeb use cases, the browsers need to set
them to something when there is no site specific information. them to something when there is no site specific information. In
Browsers, in this document is used synonmously with "interactive User this document, "browsers" is used synonmously with "interactive User
Agent" as defined in teh HTML specification, [W3C.WD-html-20110525]. Agent" as defined in the HTML specification, [W3C.WD-html-20110525].
This document describes a reasonable default set of DSCP code point This document describes a reasonable default set of DSCP code point
values drawn from existing RFCs and common usage. These code points values drawn from existing RFCs and common usage. These code points
are solely defaults. Future drafts may define mechanisms for site are solely defaults.
specific mappings to override the values provided in this draft.
This draft defines some inputs that the browser in an WebRTC This specification defines some inputs that the browser in an WebRTC
application can look at to determine how to set the various packet application can look at to determine how to set the various packet
markings and defines the mapping from abstract QoS policies (data markings and defines the mapping from abstract QoS policies (data
type, priority level) to those packet markings. type, priority level) to those packet markings.
2. Relation to Other Standards 2. Relation to Other Standards
This document exists as a complement to [I-D.ietf-dart-dscp-rtp],
which describes the interaction between DSCP and real-time
communications. It covers the implications of using various DSCP
values, particularly focusing on Real-time Transport Protocol (RTP)
[RFC3550] streams that are multiplexed onto a single transport-layer
flow.
This specification does not change or override the advice in any This specification does not change or override the advice in any
other standards about setting packet markings. It simply provides a other standards about setting packet markings. It simply provides a
summary of them and provides the context of how they relate in the summary of them and provides the context of how they relate in the
RTCWeb context. In some cases, such as DSCP where the normative RFC RTCWeb context. In some cases, such as DSCP where the normative RFC
leaves open multiple options from which to choose, this clarifies leaves open multiple options from which to choose, this clarifies
which choice should be used in the RTCWeb context. This document which choice should be used in the RTCWeb context. This document
also specifies the inputs that are needed by the browser to provide also specifies the inputs that are needed by the browser to provide
to the media engine. to the media engine.
The DSCP value set by the endpoint is not always trusted by the The DSCP value set by the endpoint is not always trusted by the
network. Therefore, the DSCP value may be remarked at the network network. Therefore, the DSCP value may be remarked at any place in
edge through policy to any other DSCP value, including best effort. the network for a variety of reasons to any other DSCP value,
The mitigation for such action is through an authorization mechanism. including default forwarding (DF) which provides basic best effort
Such authorization mechanism is outside the scope of this document. service. The mitigation for such action is through an authorization
mechanism. Such authorization mechanism is outside the scope of this
document.
3. Terminology 3. Terminology
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
in this document are to be interpreted as described in [RFC2119]. in this document are to be interpreted as described in [RFC2119].
4. Inputs 4. Inputs
The below uses the concept of a media flow, however these are The below uses the concept of a media flow, however this is usually
commonly not equivalent to a transport flow, i.e. as defined by a not equivalent to a transport flow, i.e. as defined by a 5-tuple
5-tuple (source address, destination address, source port, (source address, destination address, source port, destination port,
destination port, and protocol). Instead each media flow contains and protocol). Instead each media flow contains all the packets
all the packets associated with an independent media entity within associated with an independent media entity within one 5-tuple.
one 5-tuple. There may be multiple media flows within the same 5- There may be multiple media flows within the same 5- tuple. These
tuple. These media flows might consist of different media types and media flows might consist of different media types and have different
have different priorities. The following are the inputs that the priorities. The following are the inputs that the browser provides
browser provides to the media engine: to the media engine:
o Data Type: The browser provides this input as it knows if the flow o Data Type: The browser provides this input as it knows if the flow
is audio, interactive video with or without audio, non-interactive is audio, interactive video with or without audio, non-interactive
video with or without audio, or data. video with or without audio, or data.
o Priority: Another input is the relative treatment of the flow o Priority: Another input is the relative treatment of the flow
within that data type. Many applications have multiple media within that data type. Many applications have multiple media
flows of the same data type and often some are more important than flows of the same data type and often some are more important than
others. Likewise, in a video conference where the flows in the others. Likewise, in a video conference where the flows in the
conference is of the same data type but contains different media conference is of the same data type but contains different media
types, the flow for audio may be more important than the video types, the flow for audio may be more important than the video
flow. JavaScript applications can tell the browser whether a flow. JavaScript applications can tell the browser whether a
particular media flow is high, medium, low or very low importance particular media flow is high, medium, low or very low importance
to the application. to the application.
When it comes to data transmission, a media (data) flow is the SCTP
stream under a common congestion control (currently within the same
SCTP association).
[I-D.ietf-rtcweb-transports] defines in more detail what an [I-D.ietf-rtcweb-transports] defines in more detail what an
individual media flow is within the WebRTC context. individual media flow is within the WebRTC context.
5. DSCP Mappings 5. DSCP Mappings
Below is a table of DSCP markings for each data type of interest to Below is a table of DSCP markings for each data type of interest to
RTCWeb. These DSCP values for each data type listed are a reasonable RTCWeb. These DSCP values for each data type listed are a reasonable
default set of code point values taken from [RFC4594]. A web browser default set of code point values taken from [RFC4594]. A web browser
SHOULD use these values to mark the appropriate media packets. More SHOULD use these values to mark the appropriate media packets. More
information on EF can be found in [RFC3246]. More information on AF information on EF can be found in [RFC3246]. More information on AF
can be found in [RFC2597]. can be found in [RFC2597]. DF is default forwarding which provides
the basic best effort service. The mitigation for such action is
through an authorization mechanism. Such authorization mechanism is
outside the scope of this document.
+---------------------------+-------+------+------------+-----------+ +---------------------------+-------+------+------------+-----------+
| Data Type | Very | Low | Medium | High | | Data Type | Very | Low | Medium | High |
| | Low | | | | | | Low | | | |
+---------------------------+-------+------+------------+-----------+ +---------------------------+-------+------+------------+-----------+
| Audio | CS1 | BE | EF (46) | EF (46) | | Audio | CS1 | DF | EF (46) | EF (46) |
| | (8) | (0) | | | | | (8) | (0) | | |
| | | | | | | | | | | |
| Interactive Video with or | CS1 | BE | AF42, AF43 | AF41, | | Interactive Video with or | CS1 | DF | AF42, AF43 | AF41, |
| without audio | (8) | (0) | (36, 38) | AF42 (34, | | without audio | (8) | (0) | (36, 38) | AF42 (34, |
| | | | | 36) | | | | | | 36) |
| | | | | | | | | | | |
| Non-Interactive Video | CS1 | BE | AF32, AF33 | AF31, | | Non-Interactive Video | CS1 | DF | AF32, AF33 | AF31, |
| with or without audio | (8) | (0) | (28, 30) | AF32 (26, | | with or without audio | (8) | (0) | (28, 30) | AF32 (26, |
| | | | | 28) | | | | | | 28) |
| | | | | | | | | | | |
| Data | CS1 | BE | AF1x (10, | AF2x (18, | | Data | CS1 | DF | AF1x (10, | AF2x (18, |
| | (8) | (0) | 12, 14) | 20, 22) | | | (8) | (0) | 12, 14) | 20, 22) |
+---------------------------+-------+------+------------+-----------+ +---------------------------+-------+------+------------+-----------+
Table 1 Table 1
The columns "very low", "low", "Medium" and "high" are the priority The columns "very low", "low", "Medium" and "high" are the priority
levels. The browser SHOULD first select the data type of the media levels. This priority value signifies the relative priority of the
flow. Within the data type, the priority of the media flow SHOULD be media flow within the application and is provided to the browser to
selected. All packets within a media flow SHOULD have the same assist it in selecting the DSCP value. The browser SHOULD first
priority. In some cases, the selected cell may have multiple DSCP select the data type of the media flow. Within the data type, the
values, such as AF41 and AF42. These offer different drop priority of the media flow SHOULD be selected. All packets within a
precedences. One may select difference drop precedences for the media flow SHOULD have the same priority. In some cases, the
different packets in the media flow. Therefore, all packets in the selected cell may have multiple DSCP values, such as AF41 and AF42.
stream SHOULD be marked with the same priority but can have These offer different drop precedences. One may select difference
difference drop precedences. drop precedences for the different packets in the media flow.
Therefore, all packets in the stream SHOULD be marked with the same
priority but can have difference drop precedences.
The combination of data type and priority provides specificity and The combination of data type and priority provides specificity and
helps in selecting the right DSCP value for the media flow. In some helps in selecting the right DSCP value for the media flow. In some
cases, the different drop precedence values provides additional cases, the different drop precedence values provides additional
granularity in classifying packets within a media flow. For example, granularity in classifying packets within a media flow. For example,
in a video conference, the video media flow may be medium priority. in a video conference, the video media flow may be medium priority.
If so, either AF42 or AF43 may be selected. If the I frames in the 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 stream are more important than the P frames then the I frames can be
marked with AF42 and the P frames marked with AF43. marked with AF42 and the P frames marked with AF43.
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If a packet enters a QoS domain that has no support for the above If a packet enters a QoS domain that has no support for the above
defined Data Types/Application (service) classes, then the network defined Data Types/Application (service) classes, then the network
node at the edge will remark the DSCP value based on policies. node at the edge will remark the DSCP value based on policies.
Subsequently, if the packet enters a QoS domain that supports a Subsequently, if the packet enters a QoS domain that supports a
larger number of Data types/Application (service) classes, there may larger number of Data types/Application (service) classes, there may
not be sufficient information in the packet to restore the original not be sufficient information in the packet to restore the original
markings. Mechanisms for restoring such original DSCP is outside the markings. Mechanisms for restoring such original DSCP is outside the
scope of this document. scope of this document.
6. Security Considerations 6. Security Considerations
This draft does not add any additional security implication other
than the normal application use of DSCP. For security implications This specification does not add any additional security implication
on use of DSCP, please refer to Section 6 of RFC 4594. Please also other than the normal application use of DSCP. For security
see work-in-progress draft draft-ietf-rtcweb-security-04 as an implications on use of DSCP, please refer to Section 6 of RFC 4594.
additional reference. Please also see [I-D.ietf-rtcweb-security] as an additional
reference.
7. IANA Considerations 7. IANA Considerations
This specification does not require any actions from IANA. This specification does not require any actions from IANA.
8. Downward References 8. Downward References
This specification contains a downwards reference to [RFC4594] This specification contains a downwards reference to [RFC4594].
however the parts of that RFC used by this specification are However, the parts of that RFC used by this specification are
sufficiently stable for this downward reference. sufficiently stable for this downward reference.
9. Acknowledgements 9. Acknowledgements
Thanks To David Black, Magnus Westerland, Paolo Severini, Jim Thanks To David Black, Magnus Westerland, Paolo Severini, Jim
Hasselbrook, Joe Marcus, and Erik Nordmark for their help. Hasselbrook, Joe Marcus, and Erik Nordmark for their help.
10. Document History 10. Document History
Note to RFC Editor: Please remove this section. Note to RFC Editor: Please remove this section.
skipping to change at page 6, line 40 skipping to change at page 7, line 9
The RTCWeb working group selected it to be become a WG document. 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 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 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 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. will select it as a WG draft and move it forward to an RFC.
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-dart-dscp-rtp]
Black, D. and P. Jones, "Differentiated Services
(DiffServ) and Real-time Communication", draft-ietf-dart-
dscp-rtp-10 (work in progress), November 2014.
[I-D.ietf-rtcweb-security]
Rescorla, E., "Security Considerations for WebRTC", draft-
ietf-rtcweb-security-07 (work in progress), July 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration
Guidelines for DiffServ Service Classes", RFC 4594, August Guidelines for DiffServ Service Classes", RFC 4594, August
2006. 2006.
11.2. Informative References 11.2. Informative References
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
skipping to change at page 7, line 20 skipping to change at page 7, line 40
1998. 1998.
[RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, [RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, June 1999. "Assured Forwarding PHB Group", RFC 2597, June 1999.
[RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec, [RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec,
J., Courtney, W., Davari, S., Firoiu, V., and D. J., Courtney, W., Davari, S., Firoiu, V., and D.
Stiliadis, "An Expedited Forwarding PHB (Per-Hop Stiliadis, "An Expedited Forwarding PHB (Per-Hop
Behavior)", RFC 3246, March 2002. Behavior)", RFC 3246, March 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
Authors' Addresses Authors' Addresses
Subha Dhesikan Subha Dhesikan
Cisco Cisco Systems
Email: sdhesika@cisco.com Email: sdhesika@cisco.com
Cullen Jennings Cullen Jennings
Cisco Cisco Systems
Email: fluffy@cisco.com Email: fluffy@cisco.com
Dan Druta (editor) Dan Druta (editor)
ATT AT&T
Email: dd5826@att.com Email: dd5826@att.com
Paul Jones Paul E. Jones
Cisco Cisco Systems
Email: paulej@packetizer.com Email: paulej@packetizer.com
James Polk James Polk
Cisco Cisco Systems
Email: jmpolk@cisco.com Email: jmpolk@cisco.com
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