Internet Protocol - Quality of Service Page

This page reports the efforts made by ITTC  in IP QoS research. QoS provisioning in the internet using IP has been a topic of active research in the last few years. The efforts pursued by ITTC  in this area include a study of the various approaches suggested for QoS in IP based networks, implementation of some of these approaches and evaluations of the implementations.

Study Topics

Various approaches have been suggested for provisioning QoS in IP networks.  A study of these approaches in done is this report This report contains a number of links to related work on IP QoS.

Another report on the various approaches, with a comparison between integrated services and differentiated services, is done here .

Linux has support for QoS. A detailed study of Linux QoS Support was done. Thanks to Alexey Kuznetsov,  a Linux-QoS-HOWTO (.ps)(.pdf) (HTML) was prepared. This HOWTO describes in brief, the methods to set up various kinds of queues. The queues supported currently include Class Based Queues (CBQ), Token Bucket Flows (TBFs), priority queues, Random Early Drop (RED), DSMARK etc. Examples have been included in the HOWTO. Also we have prepared a short HOWTO (.ps )(.pdf) (HTML.) giving an overview of netlink sockets both from the implementation and usage point of view.

If you need a quick overview of the QoS support in Linux, take a look at this presentation. This has be updated to include the new diffserv support in Linux.

Implementations and Evaluations

ITTC has been working on a number of differentiated services related projects recently. If you need a quick overview of the work that has been done in ITTC in the area of IP QoS, click here  for a presentation that was made recently.

Linux DiffServ Testbed
We are trying to set up a linux diffserv testbed with a Bandwidth Broker component. This testbed would essentially have the capabilities that are expected in a fully capable diff-serv domain.  Here is a link to the presentation that was made on this recently.

Differentiated Services in Zebra
 Zebra  was modified to have differentiated services configuration capability. An interface to configure assured forwarding services on a linux box running zebra was provided. Suport for expedited forwarding is under way.  Send a mail to the project group.

The design and implementation of DiffSpec, a differentiated services tool that can be used by the administrator to configure diff-serv parameters in a linux router.

Bandwidth Broker
A preliminary BB has been implemented here in ITTC.  The BB concept, introduced by Van Jacobson, deals the resource management in a diff-serv internet. This group deals with intra-domain interactions between the BB, hosts and the routers in a diff-serv domain.  Send a mail to this project roup.

Socket API for QoS configuration
An API was developed to use the QoS support in Linux. The current QoS support does not have an API, that is, there is no way to associate a socket with a queuing discipline. Also, there is no possible means to create the queues from an application program.  Send a mail to the project group.

Performance Measurements
A diff serv testbed was set up using the linux QoS support. Assured Forwarding (AF) and Expedited Forwarding (EF) PHBs  were tested. The details of the tests and the results can be obtained by following these links.

Assured Forwarding testbed and Results
Expedited Forwarding testbed and Results

                                       Linux Diff-Serv Patches

The ds-2 patch.gz  patch adds the diff serv functionality to the linux kernel. Thanks to Werner Almesberger.
The iproute2.tar.gz package with the diffserv capabilities will help to set up differentiated services in Linux.

Some very interesting papers

Link Sharing and Resource Management Models for Packet Networks.
                          Sally Floyd and Van Jacobson.

A Two-bit Differentiated Services Architecture for the Internet
                   K Nichols, V. Jacobson & L.Zhang

Differential Services for internet and ATM
                      Rüdiger Geib

Some useful talks

Van Jacobson's talk on  Moving the Internet Beyond Best Effort ,  he discusses Bandwidth Brokers in this. He has also given a talk on differentiated services.

Lixia Zhang's talk on Resource Management and differentiated services.

Proffessor Torsten Braun's presentation on   presentation on diff-serv.

Differentiated Services Links

Werner Almesberger's Linux diff-serv page
The Official IETF page on diff-serv

Please send comments and questions to the webmaster .