• Debian Etch Linux distribution
• Xen
• Bridge Utils
• VLAN tools

apt-get install linux-image-2.6.18-5-xen-686 \
xen-hypervisor-3.0.3-1-i386-pae \
xen-utils-3.0.3-1 xen-tools \
vlan bridge-utils libc6-xen

KERNEL=="eth*", SYSFS{address}=="00:1a:a0:1c:3f:ae", NAME="eth0", DRIVERS=="?*"
KERNEL=="eth*", SYSFS{address}=="00:1a:a0:1c:3f:ac", NAME="eth1", DRIVERS=="?*"

Then create a symbolic link in the udev rules.d directory to the newly created file so udev uses it.

ln -s /etc/udev/netinterfaces.rules /etc/udev/rules.d/z10_netinterfaces.rules

Also, although it's possible to set network options using Xen's tools, i prefer to do it manually since it allows me to specify multiple vlans to a single interface in a rather easy way, without having to fiddle around Xen's configuration files. \\First we need to disable Xen's options to auto-configure the network parameters. Edit /etc/xen/xend-config.sxp and comment the line

#(network-script network-dummy)

Usually i reserve one of the interfaces for management and the other one to bridge over to the VM's with the appropriate VLAN settings. In this example my management interface, eth0, will have the IP 10.1.1.20 and i'm assigning VLAN's 2 and 3 to the bridged interface, which will be eth1.

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0 eth1

auto eth0 eth1 xenbr32 xenbr37

# Management interface
iface eth0 inet static
        address 10.1.1.20
        netmask 255.255.255.0
        network 10.1.1.0
        broadcast 10.1.1.255
        gateway 10.1.1.254
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 10.1.1.1
        dns-search domain.com

# Bridged interface
iface eth1 inet manual
        up ifconfig eth1 up

iface xenbr2 inet manual
        up vconfig add eth1 2
        up ifconfig eth1.2 up
        up brctl addbr xenbr2
        up ifconfig xenbr2 up
        up brctl addif xenbr2 eth1.2
        down brctl delif xenbr2 eth1.2
        down vconfig rem eth1.2
        down ifconfig xenbr2 down
        down brctl delbr xenbr2

iface xenbr3 inet manual
        up vconfig add eth1 3
        up ifconfig eth1.3 up
        up brctl addbr xenbr3
        up ifconfig xenbr3 up
        up brctl addif xenbr3 eth1.3
        down brctl delif xenbr3 eth1.3
        down vconfig rem eth1.3
        down ifconfig xenb3 down
        down brctl delbr xenbr3

Reboot and start creating VM's.

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