'Setup ancillary bridges - for example br-ex.'

def setup_ancillary_bridges(self, integ_br, tun_br):

    ovs = ovs_lib.BaseOVS()
    ovs_bridges = set(ovs.get_bridges())
    ovs_bridges.remove(integ_br)
    if self.enable_tunneling:
        ovs_bridges.remove(tun_br)
    br_names = [self.phys_brs[physical_network].br_name for physical_network in self.phys_brs]
    ovs_bridges.difference_update(br_names)
    br_names = []
    for bridge in ovs_bridges:
        bridge_id = ovs.get_bridge_external_bridge_id(bridge)
        if (bridge_id != bridge):
            br_names.append(bridge)
    ovs_bridges.difference_update(br_names)
    ancillary_bridges = []
    for bridge in ovs_bridges:
        br = ovs_lib.OVSBridge(bridge)
        LOG.info(_LI('Adding    %s    to    list    of    bridges.'), bridge)
        ancillary_bridges.append(br)
    return ancillary_bridges
