基本要求

• 搭建下图所示SDN拓扑，协议使用Open Flow 1.0，并连接Ryu控制器
  
• 建立拓扑
  
• 连接RYU控制器
  
• L2Switch.py
  from ryu.base import app_manager
  from ryu.controller import ofp_event
  from ryu.controller.handler import MAIN_DISPATCHER
  from ryu.controller.handler import set_ev_cls
  from ryu.ofproto import ofproto_v1_0

class L2Switch(app_manager.RyuApp):
OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

def __init__(self, *args, **kwargs):
    super(L2Switch, self).__init__(*args, **kwargs)

@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.in_port,
        actions=actions, data = data)
    dp.send_msg(out)

• 运行L2Switch
  
  
• h1 ping h2
  
  
  
• h1 ping h3
  
  
  
• 分析L2Switch和POX的Hub模块有何不同
• Hub和L2Switch模块都是洪泛转发，但L2Switch模块下发的流表无法查看，而Hub模块下发的流表可以查看
• L032002404.py
  from ryu.base import app_manager
  from ryu.ofproto import ofproto_v1_3
  from ryu.controller import ofp_event
  from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
  from ryu.controller.handler import set_ev_cls

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

def __init__(self, *args, **kwargs):
    super(hub, self).__init__(*args, **kwargs)

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

    # install flow table-miss flow entry
    match = ofp_parser.OFPMatch()
    actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_CONTROLLER, ofproto.OFPCML_NO_BUFFER)]
    # 1\OUTPUT PORT, 2\BUFF IN SWITCH?
    self.add_flow(datapath, 0, match, actions)

def add_flow(self, datapath, priority, match, actions):
    # 1\ datapath for the switch, 2\priority for flow entry, 3\match field, 4\action for packet
    ofproto = datapath.ofproto
    ofp_parser = datapath.ofproto_parser
    # install flow
    inst = [ofp_parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS, actions)]
    mod = ofp_parser.OFPFlowMod(datapath=datapath, priority=priority, match=match, instructions=inst)
    datapath.send_msg(mod)

@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def packet_in_handler(self, ev):
    msg = ev.msg
    datapath = msg.datapath
    ofproto = datapath.ofproto
    ofp_parser = datapath.ofproto_parser
    in_port = msg.match['in_port']  # get in port of the packet

    # add a flow entry for the packet
    match = ofp_parser.OFPMatch()
    actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_FLOOD)]
    self.add_flow(datapath, 1, match, actions)

    # to output the current packet. for install rules only output later packets
    out = ofp_parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=in_port, actions=actions)
    # buffer id: locate the buffered packet
    datapath.send_msg(out)

• 查看流表
  
  

实验总结

本次实验的难度相较于之前的几次实验要有所提升，本次实验中运用RYU控制器，这使得我熟悉了这一控制器的安装方法及其基础使用方法，同时对于在前几次实验中学习到的知识也有了新的体会，在本次实验的过程中，许多操作还不够熟练，还需多多熟悉掌握，望下次实验能够有所进步