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?

实现将接收到的数据包发送到所有端口

控制器设定交换机支持什么版本的OpenFlow?

OpenFlow 1.0

控制器设定了交换机如何处理数据包?

当Ryu收到OpenFlow交换机送来的packet_in消息时调用,set_ev_cls的第一个参数也声明了。
set_ev_cls的第二个参数MAIN_DISPATCHER意味着当Ryu和交换机握手过程(即hello, features request/reply, Set Config等)完毕,才会调用packet_in_handler。
之后定义packet_in消息数据结构,交换机datapath,OpenFlow协议和解析过程;
定义发给交换机packet_out的动作,要求交换机将数据包泛洪广播;定义Ryu向交换机发送的packet_out内容,最后发送消息。
至此,一个能够接收packet和转发packet的交换机完成了(接收packet,广播packet)。
ev.msg是表示packet_in数据结构的对象。
msg.dp是代表数据路径(开关)的对象。
dp.ofproto和dp.ofproto_parser是代表Ryu和交换机协商的OpenFlow协议的对象。

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

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 SelfLearning(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(SelfLearning, 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...")

3.在mininet创建一个最简拓扑,并连接RYU控制器

python脚本:

from mininet.topo import Topo
 
class Mytopo(Topo):
	
    def __init__(self):

        Topo.__init__(self)

        sw=self.addSwitch('s1')

        count=1

        for i in range(2):

            host = self.addHost('h{}'.format(count))

            self.addLink(host,sw,1,count)

            count = count + 1

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

4.验证自学习交换机的功能,提交分析过程和验证结果

在mininet中查看此时s1的流表

开启具有SelfLearning功能的控制器

进行h1对h2的ping操作

控制器中显示出预期信息

此时再次查看s1的流表

5.写下你的实验体会

ryu安装的时候一直出错,安装了好久。由于之前没学过python,看python脚本的时候有些吃力。
posted @ 2019-12-04 13:37  大口吃肉  阅读(224)  评论(0编辑  收藏  举报