（一）、基础要求

1. /home/用户名/学号/lab2/目录下执行ovs-vsctl show命令、以及p0和p1连通性测试的执行结果截图

2./home/用户名/学号/lab2/目录下开启Mininet CLI

(a)执行pingall命令的截图

(b)上述目录下查看OVS流表的命令结果截图

(c)wireshark抓包截图

（二）、进阶要求

阅读SDNLAB实验使用Mininet，编写Python代码，生成（一）中的SDN拓扑，并在代码中直接使用OVS命令，做到可以直接运行Python程序完成和（一）相同的VLAN划分。

代码部分

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')
    s1 = net.addSwitch('s1', cls=OVSKernelSwitch)
    s2 = net.addSwitch('s2', 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)
    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 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')
 
 
    CLI(net)
    net.stop()
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    myNetwork()

执行结果部分

个人总结

本次实验总体不难，容易理解。但自己不熟悉mininet和wireshark的使用，导致实验中出现奇怪的问题，花了点时间解决。通过本次实验，能在命令行终端使用OVS命令操作Open vSwitch交换机、管理流表，也能够通过Mininet的Python代码运行OVS命令，控制网络拓扑中的Open vSwitch交换机。

实验过程中遇到的问题和解决方法：

• 交换机命名ovs-switch032002618，报错“could not add network device ovs-switch to ofproto (invalid argument) see ovs-vswitchd log for details.”，不影响ping通，但想要不报错的话把switch去了就行
• 没注意看PDF文档，没看到添加流表的代码，因此白费时间在网上查原理和命令，希望之后实验自己能稍微耐心点看文档
• Mininet CLI开起来之后，需要新开一个终端来添加流表