simple_hub_controller.py

from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3

class Hub(app_manager.RyuApp):
    OFP_VERSIONS = [ ofproto_v1_3.OFP_VERSION ]

    @set_ev_cls(ofp_event.EventOFPSwitchFeatures , CONFIG_DISPATCHER)
    def switch_features_handler(self , ev):
        dp = ev.msg.datapath
        ofproto = dp.ofproto
        ofp_parser = dp.ofproto_parser

        match = ofp_parser.OFPMatch()
        actions = [ 
            ofp_parser.OFPActionOutput(
                ofproto.OFPP_CONTROLLER, 
                ofproto.OFPCML_NO_BUFFER
            ) 
        ]
        ins = [ 
            ofp_parser.OFPInstructionActions(
                ofproto.OFPIT_APPLY_ACTIONS, 
                actions
            ) 
        ]

        out = ofp_parser.OFPFlowMod(datapath=dp, match=match, instructions=ins)
        dp.send_msg(out)

    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        dp = msg.datapath
        ofp = dp.ofproto
        ofp_parser = dp.ofproto_parser

        actions = [ ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD) ]

        data = None
        if msg.buffer_id == ofp.OFP_NO_BUFFER:
             data = msg.data

        out = ofp_parser.OFPPacketOut(
            datapath=dp, buffer_id=msg.buffer_id, 
            in_port=msg.match['in_port'],
            actions=actions, data = data)
        dp.send_msg(out)