def set_qinq_port(self, port_number, outer_vlan, ethertype):
        """
        Sets the specified port as a trunk (QinQ) port.

        :param port_number: allocated port number
        :param outer_vlan: outer VLAN (transport VLAN) for this QinQ port
        """

        if port_number not in self._nios:
            raise DynamipsError("Port {} is not allocated".format(port_number))

        nio = self._nios[port_number]
        if ethertype != "0x8100" and parse_version(self.hypervisor.version) < parse_version('0.2.16'):
            raise DynamipsError("Dynamips version required is >= 0.2.16 to change the default QinQ Ethernet type, detected version is {}".format(self.hypervisor.version))

        yield from self._hypervisor.send('ethsw set_qinq_port "{name}" {nio} {outer_vlan} {ethertype}'.format(name=self._name,
                                                                                                              nio=nio,
                                                                                                              outer_vlan=outer_vlan,
                                                                                                              ethertype=ethertype if ethertype != "0x8100" else ""))

        log.info('Ethernet switch "{name}" [{id}]: port {port} set as a QinQ ({ethertype}) port with outer VLAN {vlan_id}'.format(name=self._name,
                                                                                                                                  id=self._id,
                                                                                                                                  port=port_number,
                                                                                                                                  vlan_id=outer_vlan,
                                                                                                                                  ethertype=ethertype))
        self._mappings[port_number] = ("qinq", outer_vlan, ethertype)
Sets the specified port as a trunk (QinQ) port.

        :param port_number: allocated port number
        :param outer_vlan: outer VLAN (transport VLAN) for this QinQ port