实验2：Open vSwitch虚拟交换机实践

实验基础要求
a) /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；

b) /home/用户名/学号/lab2/目录下开启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

进阶要求

#!/usr/bin/env python

from mininet.net import Mininet
from mininet.node import Node
from mininet.link import TCLink
from mininet.log import  setLogLevel, info
 
def myNet():
    "Create network from scratch using Open vSwitch."
 
    info( "*** Creating nodes\n" )
    s1 = Node( 's1', inNamespace=False )
    s2 = Node( 's2', inNamespace=False )
    h1 = Node( 'h1' )
    h2 = Node( 'h2' )
    h3 = Node( 'h3' )
    h4 = Node( 'h4' )
 
    info( "*** Creating links\n" )
    linkopts1=dict(bw=100, delay='1ms', loss=0)
    linkopts2=dict(bw=1, delay='100ms', loss=0)
    TCLink( h1, s1, **linkopts1)
    TCLink( h2, s1, **linkopts1)
    TCLink( h3, s2, **linkopts1)
    TCLink( h4, s2, **linkopts1)
    TCLink( s1, s2, **linkopts2)
    
 
    info( "*** Configuring hosts\n" )
    h1.setIP( '192.168.123.1/24' )
    h2.setIP( '192.168.123.2/24' )
    h3.setIP( '192.168.123.3/24' )
    h4.setIP( '192.168.123.4/24' )
    info( str( h1 ) + '\n' )
    info( str( h2 ) + '\n' )
    info( str( h3 ) + '\n' )
    info( str( h4 ) + '\n' )
       
    info( "*** Starting network using Open vSwitch\n" )
    s1.cmd( 'ovs-vsctl del-br dp1' )
    s1.cmd( 'ovs-vsctl add-br dp1' )
    s2.cmd( 'ovs-vsctl del-br dp2' )
    s2.cmd( 'ovs-vsctl add-br dp2' )
 
    for intf in s1.intfs.values():
        intf
        s1.cmd('ovs-vsctl add-port dp1 %s' % intf)
 
    for intf in s2.intfs.values():
        intf
        s2.cmd('ovs-vsctl add-port dp2 %s' % intf)
   
    s1.cmd('ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3' )
    s1.cmd('ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3' )
    s1.cmd('ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:1' )
    s1.cmd('ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output:2' )

    s2.cmd('ovs-ofctl -O OpenFlow13 add-flow dp2 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3' )
    s2.cmd('ovs-ofctl -O OpenFlow13 add-flow dp2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3' )
    s2.cmd('ovs-ofctl -O OpenFlow13 add-flow dp2 priority=1,dl_vlan=0,actions=pop_vlan,output:1' )
    s2.cmd('ovs-ofctl -O OpenFlow13 add-flow dp2 priority=1,dl_vlan=1,actions=pop_vlan,output:2' )

    info( "*** Running test\n" )
    h1.cmdPrint( 'ping -c 3 ' + h2.IP() )
    h1.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h1.cmdPrint( 'ping -c 3 ' + h4.IP() )
    h2.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h2.cmdPrint( 'ping -c 3 ' + h4.IP() )
    h3.cmdPrint( 'ping -c 3 ' + h4.IP() )
 
    info( "*** Stopping network\n" )
    s1.cmd( 'ovs-vsctl del-br dp1' )
    s1.deleteIntfs()
    s2.cmd( 'ovs-vsctl del-br dp2' )
    s2.deleteIntfs()
    info( '\n' )
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)\n' )
    Mininet.init()
    myNet()

个人总结
个人感想:
在这次实验中我学习使用Open vSwitch进行基本操作，通过命令行终端使用OVS命令操作Open vSwitch交换机，管理流表，以及通过Mininet的Python代码运行OVS命令，控制网络拓扑中的Open vSwitch交换机。本次实验还算顺利，并没有出现很多的错误，但是过程中也出现了小错误，在进行通过命令行终端输入“ovs-ofctl”命令，直接在s1和s2上添加流表，划分出所要求的VLAN中，遇到“s1 is not a brigde or scoket”的情况，这时候需要在当前页面新建一个Terminal页面，重新运行即可。再者在抓包时，没有数据出现的情况，此时只要重新pingall即可。对于进阶要求中的代码部分，用了较多的时间，不过最后幸好还是做出来了，下次继续努力！