实验2：Open vSwitch虚拟交换机实践

基础作业

a) 执行 ovs-vsctl show 命令、测试 p0 和 p1 的连通性

b）开启 Mininet CLI 并执行 pingall、查看 OVS 流表的命令、wireshark 抓包

进阶作业

代码部分

#!/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,
                      ip='127.0.0.1',
                      protocol='OpenFlow13',
                      port=6653)

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

    info( '*** Add hosts\n')
    h1 = net.addHost('h1', cls=Host, ip='10.0.0.1', defaultRoute=None)
    h2 = net.addHost('h2', cls=Host, ip='10.0.0.2', defaultRoute=None)
    h4 = net.addHost('h4', cls=Host, ip='10.0.0.4', defaultRoute=None)
    h3 = net.addHost('h3', cls=Host, ip='10.0.0.3', defaultRoute=None)

    info( '*** Add links\n')
    net.addLink(h1, s1, 1, 1)
    net.addLink(h2, s1, 1, 2)
    net.addLink(h3, s2, 1, 1)
    net.addLink(h4, s2, 1, 2)
    net.addLink(s1, s2, 3, 3)

    info( '*** Starting network\n')
    net.build()
    info( '*** Starting controllers\n')
    for controller in net.controllers:
        controller.start()

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

    info( '*** Post configure switches and hosts\n')

    # add flow table to switches and divide VLAN
    s1.cmd('sudo 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('sudo 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('sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=0,actions=pop_vlan,output:1')
    s1.cmd('sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=1,actions=pop_vlan,output:2')

    s2.cmd('sudo 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('sudo 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('sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:1')
    s2.cmd('sudo 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()

执行结果

个人总结

这次实验总体上难度不大，按部就班就基本上没什么问题，但更重要的是理解VLAN背后的技术。通过对广播域的切割来避免广播风暴，同时提高了网络设计的自由度。
通过本次实验，掌握了对 Open vSwitch 的基本操作，并且能够通过命令行终端使用 OVS 命令操作 Open vSwitch 交换机，管理流表，更进一步能够通过 Mininet 的Python 代码运行 OVS 命令，控制网络拓扑中的 Open vSwitch 交换机。
软件定义网络还有很多东西需要去实际操作，去实践，还有待进一步的学习。