SDN

# Ryu SDN 컨트롤러 - 간단한 L2 스위치 구현
# pip install ryu
from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, set_ev_cls
from ryu.ofproto import ofproto_v1_3
from ryu.lib.packet import packet, ethernet

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

    def __init__(self, *args, **kwargs):
        super(SimpleSwitch, self).__init__(*args, **kwargs)
        self.mac_to_port = {}  # MAC 주소 학습 테이블

    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser
        in_port = msg.match['in_port']

        pkt = packet.Packet(msg.data)
        eth = pkt.get_protocol(ethernet.ethernet)
        dst = eth.dst
        src = eth.src
        dpid = datapath.id

        # MAC 주소 학습
        self.mac_to_port.setdefault(dpid, {})
        self.mac_to_port[dpid][src] = in_port

        # 목적지 MAC이 학습되어 있으면 해당 포트로, 아니면 Flood
        if dst in self.mac_to_port[dpid]:
            out_port = self.mac_to_port[dpid][dst]
        else:
            out_port = ofproto.OFPP_FLOOD

        actions = [parser.OFPActionOutput(out_port)]

        # Flow Entry 추가 (MAC 학습된 경우)
        if out_port != ofproto.OFPP_FLOOD:
            match = parser.OFPMatch(in_port=in_port, eth_dst=dst)
            self.add_flow(datapath, 1, match, actions)

        # 패킷 전달
        out = parser.OFPPacketOut(
            datapath=datapath, buffer_id=msg.buffer_id,
            in_port=in_port, actions=actions, data=msg.data)
        datapath.send_msg(out)

    def add_flow(self, datapath, priority, match, actions):
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser
        inst = [parser.OFPInstructionActions(
            ofproto.OFPIT_APPLY_ACTIONS, actions)]
        mod = parser.OFPFlowMod(
            datapath=datapath, priority=priority,
            match=match, instructions=inst)
        datapath.send_msg(mod)

# 실행: ryu-manager simple_switch.py