'Generates a unique conntrack zone for the passed in ID.'

def _generate_device_zone(self, short_device_id):

    try:
        zone = self._find_open_zone()
    except n_exc.CTZoneExhaustedError:
        self._free_zones_from_removed_ports()
        zone = self._find_open_zone()
    self._device_zone_map[short_device_id] = zone
    LOG.debug('Assigned    CT    zone    %(z)s    to    device    %(dev)s.', {'z': zone, 'dev': short_device_id})
    return self._device_zone_map[short_device_id]
