Configuration

The support for quality of service is available from linux kernel versions 2.1.90. However, the support is more comprehensive in the more recent kernels. This document is written with reference to the kernel version 2.2.1. This kernel also has support for differentiated services in the form of a patch, that can be downloaded from ftp://lrcftp.epfl.ch/pub/linux/diffserv/patches/ds-3.patch.gz. This patch needs to be applied in order to exercise all the QoS features supported in linux. The latest linux kernels can be downloaded from http://www.kernelnotes.org/.

1.

Apply the diff-serv patch to the linux-2.2.1 source tree.

2.

Do a 'make xconfig' or 'make menuconfig' or 'make make config' in the /usr/src/linux directory.

3.

Set the EXPERIMENTAL_OPTIONS to 'y'.

4.

Under networking options, say 'y' to the following kernel options: Kernel/User netlink socket, Routing messages,TCP/IP networking and QoS and/or fair queueing. After turning on the QoS and/or fair queuing option, enable the CBQ, CSZ, PRIO, RED, SFQ, TEQL, TBF, GRED, DS_MARK, 'tcindex' classifier, Packer Classifier API, U32 classifiers and routing table based classifier.

5.

Do a 'make dep; make clean; make bzilo'

6.

Reboot the linux box using the new kernel image.

Having discussed the configuration of the QoS support in linux, let us now discuss the details involved in the implementation of these features. The location of all the kernel related files referred to in the rest of this document are specified with respect to the /usr/src/linux directory.