def slot_enable_nio(self, slot_number, port_number):
        """
        Enables a slot NIO binding.

        :param slot_number: slot number
        :param port_number: port number
        """

        is_running = yield from self.is_running()
        if is_running:  # running router
            yield from self._hypervisor.send('vm slot_enable_nio "{name}" {slot_number} {port_number}'.format(name=self._name,
                                                                                                              slot_number=slot_number,
                                                                                                              port_number=port_number))

            log.info('Router "{name}" [{id}]: NIO enabled on port {slot_number}/{port_number}'.format(name=self._name,
                                                                                                      id=self._id,
                                                                                                      slot_number=slot_number,
                                                                                                      port_number=port_number))
Enables a slot NIO binding.

        :param slot_number: slot number
        :param port_number: port number