2019 SDN上机第5次作业

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?

• functionality that sends a received packet to all the ports将接收到的数据包发送到所有端口的功能

控制器设定交换机支持什么版本的OpenFlow？

• OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]设定交换机支持OpenFlow1.0

控制器设定了交换机如何处理数据包？

• actions = [ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD)] 将接收到的数据包发送到所有端口

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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

# TODO define OpenFlow 1.0 version for the switch
    OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

# TODO send modified message out
        datapath.send_msg(mod)

 # TODO define the action for output
        actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]

# TODO define the OpenFlow Packet Out
        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)

全部具有自学习功能的交换机代码（SelfLearning.py）如下

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


class SimpleSwitch(app_manager.RyuApp):
    # TODO define OpenFlow 1.0 version for the switch
    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
        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
        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
        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...")

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3.在mininet创建一个最简拓扑，并连接RYU控制器

• 用sudo mn --controller=remote,ip=127.0.0.1,port=6633创建只有一个交换机两个主机的简单Topo

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4.验证自学习交换机的功能，提交分析过程和验证结果

在链接Ryu控制器前

• 利用命令h1 ping h2可以在wireshark上看到 交换机端口s1-eh1是有收到ARP请求但是端口s1-eh2没有任何检测到任何包，这是因为初始时交换机s1的路由表为空且对收到的包不做任何处理
  
  

链接Ryu控制器后

• 再次利用命令h1 ping h2就可以在wireshark上检测到端口s1-eh2收到了ARP请求 ，这是因为Ryu控制器中设置将交换机收到的包进行广播
  

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5.写下你的实验体会

• 装Ryu控制器是真的麻烦
• python空格非法是真的坑