apt-get install bridge-utils brctl addbr br 100 brctl addif br100 eth1
nano /etc/network/interfaces
auto lo iface lo inet loopback
auto eth0 iface eth0 inet static address 10.10.10.200 netmask 255.255.255.0 network 10.10.10.0 gateway 10.10.10.1
auto br100
iface br100 inet static
address 10.10.10.201
netmask 255.255.255.0
network 10.10.10.0
bridge_ports eth1