Xen domUs with two NICs

/etc/xen/scripts/my-network-bridge

Start the second bridge (xenbr1 on eth1)

#!/bin/sh
# start bridges on both eth0 and eth1

XENDIR="/etc/xen/scripts" 

$XENDIR/network-bridge "$@" netdev=eth0 bridge=xenbr0 vifnum=0
$XENDIR/network-bridge "$@" netdev=eth1 bridge=xenbr1 vifnum=1

/etc/xen/xend-config.sxp

Replace:

(network-script network-bridge)

with

(network-script my-network-bridge)

/etc/xen/{domU}-config.sxp

Add the entry for the second NIC and bind it to xenbr1 bridge

...
dhcp ="off" 
vif = [ 'mac=00:10:10:10:02:##IP##,bridge=xenbr0', 'mac=00:10:10:03:02:##IP##,bridge=xenbr1' ]
...

Inside the domUs

/etc/network/interfaces – add the second interface

...

auto eth1
iface eth1 inet static
        address ...
        netmask ...
        network ...
        broadcast ...