实验2：Open vSwitch虚拟交换机实践

一、基本实验

（1）执行ovs-vsctl show命令、以及p0和p1连通性测试的执行结果截图

（2）开启Mininet CLI并执行pingall命令的截图、上述目录下查看OVS流表的命令结果截图，wireshark抓包截图

二、拓展实验

代码和执行结果截图

#!/usr/bin/env python

from mininet.net import Mininet
from mininet.node import Controller, RemoteController, OVSController
from mininet.node import CPULimitedHost, Host, Node
from mininet.node import OVSKernelSwitch, UserSwitch
from mininet.node import IVSSwitch
from mininet.cli import CLI
from mininet.log import setLogLevel, info
from mininet.link import TCLink, Intf
from subprocess import call

def myNetwork():

  net = Mininet( topo=None,
                 build=False,
                 ipBase='10.0.0.0/8')

  info( '*** Adding controller\n' )
  c0=net.addController(name='c0',
                    controller=Controller,
                    protocol='tcp',
                    port=6633)

  info( '*** Add switches\n')
  s1 = net.addSwitch('s1', cls=OVSKernelSwitch)
  s2 = net.addSwitch('s2', cls=OVSKernelSwitch)

  info( '*** Add hosts\n')
  h1 = net.addHost('h1', cls=Host, ip='192.168.1.1', defaultRoute=None)
  h2 = net.addHost('h2', cls=Host, ip='192.168.1.2', defaultRoute=None)
  h3 = net.addHost('h3', cls=Host, ip='192.168.1.3', defaultRoute=None)
  h4 = net.addHost('h4', cls=Host, ip='192.168.1.4', defaultRoute=None)
  
  info( '*** Add links\n')
  net.addLink(h1, s1,1,1)
  net.addLink(h2, s1,1,2)
  net.addLink(s1, s2,3,3)
  net.addLink(s2, h4,2,1)
  net.addLink(s2, h3,1,1)
  
  info( '*** Starting network\n')
  net.build()
  info( '*** Starting controllers\n')
  for controller in net.controllers:
      controller.start()

  info( '*** Starting switches\n')
  net.get('s1').start([c0])
  net.get('s2').start([c0])

  info( '*** Post configure switches and hosts\n')
  #add ovsml
  s1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3')
  s1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3')
  s1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=0,actions=pop_vlan,output:1')
  s1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=1,actions=pop_vlan,output:2')
  s2.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3')
  s2.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3')
  s2.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:1')
  s2.cmd(r'ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=1,actions=pop_vlan,output:2')



  CLI(net)
  net.stop()
if __name__ == '__main__':
  setLogLevel( 'info' )
  myNetwork()

三、实验总结

在本次实验中，设置p0端口号时设置错误，尝试用正确命令覆盖重新设置时，发现仍然无法ping通，后删除该端口重新配置后，可实现ping通。wireshark要在pingall命令执行前，对s1的eth3进行抓包，才能抓到带有vlan标签的icmp报文。本次实验的命令比较长，同时要注意命令要在同一行输入。在进阶实验中，只需在该拓扑可视化生成的python文件中添加ovs命令即可，执行此python文件时会自动执行下发流表的操作。本次实验整体难度适中，所用到的命令的长度较长，需要注意输入格式，同时注意命令的每一个位置所对应的属性