实验2：Open vSwitch虚拟交换机实践

（一）基本要求
1.ovs-vsctl基础操作实践：创建OVS交换机。

2.在创建的交换机上增加端口p0和p1

3.创建虚拟网络空间ns0

4.创建虚拟网络空间ns1

5.最后测试p0和p1的连通性

（二）Mininet搭建的SDN拓扑

自定义拓扑

运行拓扑

划分VLAN

3.下发流表与查看

4.主机连通性要求

（三）进阶要求

#!/usr/bin/python

from mininet.node import CPULimitedHost, Host, Node
from mininet.node import OVSKernelSwitch, UserSwitch
from mininet.net import Mininet
from mininet.node import Controller, RemoteController, OVSController
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 myNet():
 
    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 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)
    h3 = net.addHost('h3', cls=Host, ip='10.0.0.3', defaultRoute=None)
    h4 = net.addHost('h4', cls=Host, ip='10.0.0.4', defaultRoute=None)
    
    info( '*** Add switches\n')
    s1 = net.addSwitch('s1', cls=OVSKernelSwitch)
    s2 = net.addSwitch('s2', cls=OVSKernelSwitch)
 
    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('s1').start([c0])
    net.get('s2').start([c0])
 
    info( '*** Post configure switches and hosts\n')
    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')
 
    info( "*** Running test\n" )
    h1.cmdPrint( 'ping -c 3 ' + h4.IP() )
    h1.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h2.cmdPrint( 'ping -c 3 ' + h4.IP() )
    h2.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h3.cmdPrint( 'ping -c 3 ' + h2.IP() )
    h3.cmdPrint( 'ping -c 3 ' + h1.IP() )
    h4.cmdPrint( 'ping -c 3 ' + h2.IP() )
    h4.cmdPrint( 'ping -c 3 ' + h1.IP() )

    CLI(net)
    net.stop()
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)\n' )
    Mininet.init()
    myNet()

（四）心得
本次实验我遇到了两个问题。第一，在没下发流表的时候就去pingall导致pingall的结果错误；第二，不在pingall的时候抓包，导致抓包没有结果。在解决完这两个问题之后这次的实验就能完整完成了。