Internet DRAFT - draft-ietf-rtcweb-qos
draft-ietf-rtcweb-qos
Network Working Group S. Dhesikan
Internet-Draft Cisco
Intended status: Standards Track D. Druta, Ed.
Expires: April 15, 2013 ATT
P. Jones
J. Polk
Cisco
October 15, 2012
DSCP and other packet markings for RTCWeb QoS
draft-ietf-rtcweb-qos-00
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 defines the
recommended DSCP values for browsers to use for various classes of
traffic.
This draft is a very early and far from done. It is meant to provide
the structure for the idea of how to do this but much discussion is
needed about the details.
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 April 15, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Relation to Other Standards . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. DSCP Mappings . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. QCI Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. WiFI Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 5
8. W3C API Implications . . . . . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
12. Appendix: Code Hints . . . . . . . . . . . . . . . . . . . . . 7
13. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
DiffServ 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, marking too many audio and/or video flows for a given
network's capacity 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. If the congested link is the broadband uplink in a Cable or DSL
scenario, often residential routers/NAT support preferential
treatment based on DSCP.
2. If the congested link is a local WiFi network, marking may help.
3. 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 a
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
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a non-normative summary of them and provides the context of how they
relate into the RTCWeb context. It also specified the requirements
for the W3C 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
TODO - add the boiler plate
4. Inputs
The first input is the type of the media. The browser provides this
input as it knows if the media is audio, video, or data. In this
specification, both interactive and streaming media is included.
They are treated in different categories as their QoS requirements
are slightly different. The second input is the relative treatment
of the stream within that session. Many applications have multiple
video streams and often some are more important than others.
JavaScript applications can tell the browser whether a particular
media stream is high, medium, or low importance to the application.
5. DSCP Mappings
Below is a table of DSCP markings for each application type RTCWeb
is interested in. These DSCPs for each application type listed are a
reasonable default set of code point values, and currently not
mandatory for every usage. For example, some networks may have a
policy in place to have Interactive Video use the EF DSCP.
+-----------------------+-----------+-----------+-----------+
| Application 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
[Editor's Note: the application type is currently inconsistent with
similar applications defined in [6]. Further
discussion is likely needed to resolve this.]
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6. QCI Mapping
+-----------------------+-----+--------+------+
| Application Type | Low | Medium | High |
+-----------------------+-----+--------+------+
| Audio | 1 | 1 | 1 |
| Interactive Video | 2 | 2 | 2 |
| Non-Interactive Video | 8 | 6 | 4 |
| Data | 9 | 9 | 3 |
+-----------------------+-----+--------+------+
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 Signalling |
| 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
+-----------------------+-----+--------+------+
| | 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
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+-------+----+------------------+---------------------+-------------+
| Value | | Traffic Type | Access Category | Designation |
| | | | (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 |
+-------+----+------------------+---------------------+-------------+
Table 5
8. W3C API Implications
To work with this proposal, the W3C specification would need to
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.
[Editor's Note: the idea of bundling applications/media needs to be
further explored.]
9. Security Considerations
TODO - discuss implications of what browser can set and what
JavaScript can set
10. IANA Considerations
This specification does not require any actions from IANA.
11. 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.
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12. Appendix: Code Hints
On windows setting the source interface works but BSD, OSX, Linux use
weak end-system model and will route out different interface if that
looks like a better route. (TODO - Can someone verify this with
specific versions?)
In windows you might be able to tell something about priority of an
interface for ICE purposes with WlanQueryInterface or GetIfTable.
The specific mechanisms required to set DSCP code points depend on
the application platform.
In windows, setting the DSCP is not easy. See Knowledge Base Article
KB248611. TODO - add more information about what can be done for
windows.
For most unix variants, the following program can set DSCP.
TODO - make this work in V6. For v6 have a look at IPv6_TCLASS or
better the tclass part of sin6_flowid for IPv6
TODO - Can someone test and report back results of program in iOS,
Android, Linux, OSX, BSD.
Example test program:
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#define MSG "Hello, World!"
int
main(void) {
int sock = -1;
struct sockaddr *local_addr = NULL;
struct sockaddr_in sockin, host;
int tos = 0x60; /* CS3 */
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socklen_t socksiz = 0;
char *buffer = NULL;
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
fprintf(stderr,"Error: %s\n", strerror(errno));
exit(-1);
}
memset(&sockin, 0, sizeof(sockin));
sockin.sin_family = PF_INET;
sockin.sin_addr.s_addr = inet_addr("11.1.1.1");
socksiz = sizeof(sockin);
local_addr = (struct sockaddr *) &sockin;
/* Set ToS/DSCP */
if (setsockopt(sock, IPPROTO_IP, IP_TOS, &tos,
sizeof(tos)) < 0) {
fprintf(stderr,"Error setting TOS: %s\n", strerror(errno));
}
/* Bind to a specific local address */
if (bind(sock, local_addr, socksiz) < 0) {
fprintf(stderr,"Error binding to socket: %s\n", strerror(errno));
close(sock); sock=-1;
exit(-1);
}
buffer = (char *) malloc(strlen(MSG) + 1);
if ( buffer == NULL ) {
fprintf(stderr,"Error allocating memory: %s\n", strerror(errno));
close( sock ); sock=-1;
exit(-1);
}
strlcpy(buffer, MSG, strlen(MSG) + 1);
memset(&host, 0, sizeof(host));
host.sin_family = PF_INET;
host.sin_addr.s_addr = inet_addr("10.1.1.1");
host.sin_port = htons(12345);
if (sendto(sock, buffer, strlen(buffer), 0,
(struct sockaddr *) &host, sizeof(host)) < 0) {
fprintf(stderr,"Error sending message: %s\n", strerror(errno));
close(sock); sock=-1;
free(buffer); buffer=NULL;
exit(-1);
}
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free(buffer); buffer=NULL;
close(sock); sock=-1;
return 0;
}
13. Normative References
[1] Babiarz, J., Chan, K., and F. Baker, "Configuration Guidelines
for DiffServ Service Classes", RFC 4594, August 2006.
[2] 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.
[3] 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.
[4] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, "Assured
Forwarding PHB Group", RFC 2597, June 1999.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[6] Polk, J., Dhesikan, S., "The Session Description Protocol (SDP)
'trafficclass' Attribute", "work in progress", July 2012
Authors' Addresses
Subha Dhesikan
Cisco
Email: sdhesika@cisco.com
Dan Druta (editor)
ATT
Email: dd5826@att.com
Paul Jones
Cisco
Email: paulej@packetizer.com
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James Polk
Cisco
Email: jmpolk@cisco.com
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