Switching to VoIP

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Chapter 9: Quality of Service

in the stream flows from one core router to the next. DiffServ has several advanta-

geous qualities:

• As an IP-only solution, is usually managed with the same equipment used to

manage an IP WAN: routers

• Can run transparently alongside other QoS solutions—including 802.1p and

RSVP

• Is easy to set up on small- to mid-sized routed enterprise networks

• Can be optionally policy-based using COPS or LDAP

• Pushes QoS decisions to the edge of the network, resulting in less complexity

• Is compatible with IPv4 and IPv6

Project 9.1. Create a DiffServ Decision Point with Linux

What you need for this project:

• A Linux server capable of running the Netfilter firewall

• LAN

A Linux server that acts as a firewall or edge router can provide DiffServ policy

enforcement just as a Cisco router can. It can also perform some packet-manipula-

tion—say, to tag the priority of an 802.1p-tagged packet as it hits a locally con-

nected Ethernet segment. Red Hat Linux 9 and Red Hat Enterprise Linux have

DiffServ and 802.1p support precompiled. Other Linux kernels of Version 2.4 and

above can have support for DiffServ and 802.1p compiled, as long as the kernel in

question is compiled with these options enabled:

• Kernel/user netlink socket CONFIG_NETLINK

• Packet filtering CONFIG_NETFILTER ...