code: def _create_response(self, datapath, port, req):
          
          src = datapath.ports[port].hw_addr
          res_ether = ethernet.ethernet(
              slow.SLOW_PROTOCOL_MULTICAST, src, ether.ETH_TYPE_SLOW)
          res_lacp = self._create_lacp(datapath, port, req)
          res_pkt = packet.Packet()
          res_pkt.add_protocol(res_ether)
          res_pkt.add_protocol(res_lacp)
          res_pkt.serialize()
          return res_pkt
docs: create a packet including LACP.