simple_switch.py

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

class L2Switch(app_manager.OSKenApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(L2Switch, self).__init__(*args, **kwargs)
    
    def add_flow(self, datapath, priority, match, actions):
        dp = datapath
        ofp = dp.ofproto
        parser = dp.ofproto_parser

        inst = [parser.OFPInstructionActions(ofp.OFPIT_APPLY_ACTIONS, actions)]
        mod = parser.OFPFlowMod(datapath=dp, priority=priority, match=match, instructions=inst)
        dp.send_msg(mod)
 
	# add default flow table which sends packets to the controller
    @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
    def switch_features_handler(self, ev):
        msg = ev.msg
        dp = msg.datapath
        ofp = dp.ofproto
        parser = dp.ofproto_parser

        match = parser.OFPMatch()
        actions = [parser.OFPActionOutput(ofp.OFPP_CONTROLLER, ofp.OFPCML_NO_BUFFER)]
        self.add_flow(dp, 0, match, actions)

	# handle packet_in message
    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        dp = msg.datapath
        ofp = dp.ofproto
        parser = dp.ofproto_parser

        actions = [parser.OFPActionOutput(ofp.OFPP_FLOOD)]
        out = parser.OFPPacketOut(
            datapath=dp, buffer_id=msg.buffer_id, in_port=msg.match['in_port'],actions=actions, data=msg.data)
        dp.send_msg(out)