enter a flow entry for the packet from the slave i/f
        with idle_timeout. for OpenFlow ver1.2 and ver1.3.

def _add_flow_v1_2(self, src, port, timeout, datapath):
        """enter a flow entry for the packet from the slave i/f
        with idle_timeout. for OpenFlow ver1.2 and ver1.3."""
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        match = parser.OFPMatch(
            in_port=port, eth_src=src, eth_type=ether.ETH_TYPE_SLOW)
        actions = [parser.OFPActionOutput(
            ofproto.OFPP_CONTROLLER, ofproto.OFPCML_MAX)]
        inst = [parser.OFPInstructionActions(
            ofproto.OFPIT_APPLY_ACTIONS, actions)]
        mod = parser.OFPFlowMod(
            datapath=datapath, command=ofproto.OFPFC_ADD,
            idle_timeout=timeout, priority=65535,
            flags=ofproto.OFPFF_SEND_FLOW_REM, match=match,
            instructions=inst)
        datapath.send_msg(mod)