1.浏览RYU官网学习RYU控制器的安装和RYU开发入门教程，提交你对于教程代码的理解，包括但不限于：

• 描述官方教程实现了一个什么样的交换机功能？

  答：官方教程实现了一个将接收到的数据包发送到所有端口的交换机功能

• 控制器设定交换机支持什么版本的OpenFlow？

  答：控制器设定交换机支持OpenFlow 1.0

• 控制器设定了交换机如何处理数据包？

  答：'''@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)'''

  答：当Ryu收到OpenFlow交换机送来的packet_in消息时调用新增方法packet_in_handler，set_ev_cls的第一个参数也声明了

2.根据官方教程和提供的示例代码（SimpleSwitch.py），将具有自学习功能的交换机代码（SelfLearning.py）补充完整

• 代码链接

  如下是补充完整代码：

  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

  from ryu.lib.mac import haddr_to_bin
  from ryu.lib.packet import packet
  from ryu.lib.packet import ethernet
  from ryu.lib.packet import ether_types
  from ryu.lib.packet import ipv4

  class SimpleSwitch(app_manager.RyuApp):
  # TODO define OpenFlow 1.0 version for the switch
  # add your code here
  OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

  def __init__(self, *args, **kwargs):
      super(SimpleSwitch, self).__init__(*args, **kwargs)
      self.mac_to_port = {}
  
  def add_flow(self, datapath, in_port, dst, src, actions):
      ofproto = datapath.ofproto
  match = datapath.ofproto_parser.OFPMatch(
      in_port=in_port,
      dl_dst=haddr_to_bin(dst), dl_src=haddr_to_bin(src))
  
  mod = datapath.ofproto_parser.OFPFlowMod(
      datapath=datapath, match=match, cookie=0,
      command=ofproto.OFPFC_ADD, idle_timeout=0, hard_timeout=0,
      priority=ofproto.OFP_DEFAULT_PRIORITY,
      flags=ofproto.OFPFF_SEND_FLOW_REM, actions=actions)
  # TODO send modified message out
  # add your code here
  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
  pkt = packet.Packet(msg.data)
  eth = pkt.get_protocol(ethernet.ethernet)
  
  if eth.ethertype == ether_types.ETH_TYPE_LLDP:
      # ignore lldp packet
      return
  if eth.ethertype == ether_types.ETH_TYPE_IPV6:
      # ignore ipv6 packet
      return       
  
  dst = eth.dst
  src = eth.src
  dpid = datapath.id
  self.mac_to_port.setdefault(dpid, {})
  
  self.logger.info("packet in DPID:%s MAC_SRC:%s MAC_DST:%s IN_PORT:%s", dpid, src, dst, msg.in_port)
  
  # learn a mac address to avoid FLOOD next time.
  self.mac_to_port[dpid][src] = msg.in_port
  
  if dst in self.mac_to_port[dpid]:
      out_port = self.mac_to_port[dpid][dst]
  else:
      out_port = ofproto.OFPP_FLOOD
  
  # TODO define the action for output
  # add your code here
  actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]
  
  # install a flow to avoid packet_in next time
  if out_port != ofproto.OFPP_FLOOD:
      self.logger.info("add flow s:DPID:%s Match:[ MAC_SRC:%s MAC_DST:%s IN_PORT:%s ], Action:[OUT_PUT:%s] ", dpid, src, dst, msg.in_port, out_port)
      self.add_flow(datapath, msg.in_port, dst, src, actions)
  
  data = None
  if msg.buffer_id == ofproto.OFP_NO_BUFFER:
      data = msg.data
  
  # TODO define the OpenFlow Packet Out
  # add your code here
  out = datapath.ofproto_parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port,  actions=actions, data=data)
  datapath.send_msg(out)
  print ("PACKET_OUT...")</code></pre></li>

#!/usr/bin/python
#Creating Inernet Topo

from mininet.topo import Topo

class MyTopo(Topo):

    def __init__(self):

        # initilaize topology
        Topo.__init__(self)

        # add hosts and switches
        h1 = self.addHost('h1')
        h2 = self.addHost('h2')

        s1 = self.addSwitch('s1')

        # add links
        self.addLink(h1, s1, 1, 1)
        self.addLink(h2, s1, 1, 2)

topos = {'mytopo': (lambda: MyTopo())}

ryu-manager SelfLearning.py

感觉这次实验除了Ryu难装其他还是很轻松的，这个实验很有意思，代码要看好久才能懂得一点···希望自己加油吧！