br-vlan interface with a veth pluged into it.

gistfile1.txt

auto br-vlan
iface br-vlan inet static
    bridge_stp off
    bridge_waitport 0
    bridge_fd 0
    address 172.29.248.100
    netmask 255.255.252.0
    # Create veth pair, don't bomb if already exists
    pre-up ip link add br-vlan-veth type veth peer name eth12 || true
    # Set both ends UP
    pre-up ip link set br-vlan-veth up
    pre-up ip link set eth12 up
    # Delete veth pair on DOWN
    post-down ip link del br-vlan-veth || true
    bridge_ports br-vlan-veth