auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
    address 1.1.1.1
    netmask 255.255.255.0
    gateway 1.1.1.254
    dns-nameservers 8.8.4.4 8.8.8.8

auto br1
iface br1 inet manual
    bridge_ports eth1
    bridge_fd 0
    bridge_hello 2
    bridge_maxage 12
    bridge_stp off

auto br2
iface br2 inet manual
    bridge_ports eth2
    bridge_fd 0
    bridge_hello 2
    bridge_maxage 12
    bridge_stp off

<interface type='bridge'>
  <mac address='52:54:00:aa:aa:aa'/>
  <source bridge='br1'/>
  <target dev='vnet1'/>
  <model type='virtio'/>
  <alias name='net0'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>

<interface type='bridge'>
  <mac address='52:54:00:ba:ba:ba'/>
  <source bridge='br2'/>
  <target dev='vnet2'/>
  <model type='virtio'/>
  <alias name='net0'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>