def _generate_device_zone(self, short_port_id):
        try:
            zone = self._find_open_zone()
        except n_exc.CTZoneExhaustedError:
            # Free some zones and try again, repeat failure will not be caught
            self._free_zones_from_removed_ports()
            zone = self._find_open_zone()

        self._device_zone_map[short_port_id] = zone
        LOG.debug("Assigned CT zone %(z)s to port %(dev)s.",
                  {'z': zone, 'dev': short_port_id})
        return self._device_zone_map[short_port_id]
Generates a unique conntrack zone for the passed in ID.
dataset/ETHPy150Open openstack/neutron/neutron/agent/linux/iptables_firewall.py/IptablesFirewallDriver._generate_device_zone