实验 4：Open vSwitch 实验——Mininet 中使用 OVS 命令

一、实验目的

Mininet 安装之后，会连带安装 Open vSwitch，可以直接通过 Python 脚本调用Open vSwitch 命令，从而直接控制 Open vSwitch，通过实验了解调用控制的方法。

二、实验任务

在本实验中，使用 Mininet 基于 Python 的脚本，调用“ovs-vsctl”命令直接控制Open vSwitch。使用默认的交换机泛洪规则，设置更高的优先级规则进行预先定义 IP 报文的转发。在多个交换机中通过设置不同 TOS 值的数据包将通过不同的方式到达目的地址，验证主机间的连通性及到达目的地址的时间。

三、实验步骤

1. 实验环境

安装了 Ubuntu 18.04.5 Desktop amd64 的虚拟机

2. 实验过程

（1）实验拓扑图

（2）实验代码

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
" )

    switch0 = Node( 's0', inNamespace=False )

    switch1 = Node( 's1', inNamespace=False )


    h0 = Node( 'h0' )

    h1 = Node( 'h1' )

    h2 = Node( 'h2' )

    h3 = Node( 'h3' )

 

    info( "*** Creating links
" )

    linkopts0=dict(bw=100, delay='1ms', loss=0)
    linkopts1=dict(bw=1,delay='100ms',loss=0)

    TCLink( h0, switch0, **linkopts0)

    #TCLink( switch0, switch1, **linkopts0)

    TCLink( h1, switch0, **linkopts0)

    TCLink( h2, switch1, **linkopts0)

    TCLink( h3, switch1, **linkopts0)

    TCLink( switch0, switch1, **linkopts1)

 

    info( "*** Configuring hosts
" )

    h0.setIP( '192.168.123.1/24' )

    h1.setIP( '192.168.123.2/24' )
    
    h2.setIP( '192.168.123.3/24' )

    h3.setIP( '192.168.123.4/24' )

    info( str( h0 ) + '
' )

    info( str( h1 ) + '
' )

       

    info( "*** Starting network using Open vSwitch
" )

    switch0.cmd( 'ovs-vsctl del-br dp0' )

    switch0.cmd( 'ovs-vsctl add-br dp0' )

    switch1.cmd( 'ovs-vsctl del-br dp1' )

    switch1.cmd( 'ovs-vsctl add-br dp1' )
 

    for intf in switch0.intfs.values():

        print(intf)

        print(switch0.cmd( 'ovs-vsctl add-port dp0 %s' % intf ))

 

    for intf in switch1.intfs.values():

        print(intf)

        print(switch1.cmd( 'ovs-vsctl add-port dp1 %s' % intf ))

    info( " ** ovs-ofctl
 ")

    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:3'))
    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13  add-flow dp0 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:3'))
    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13  add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1'))
    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=1,actions=pop_vlan,output:2'))

    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:3'))
    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:3'))
    print(switch0.cmd( 'ovs-ofctl -O OpenFlow13  add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:1'))
    print(switch0.cmd( 'ovs-ofctl  -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output:2'))


    h0.cmdPrint( 'ping -Q 0x10 -c 3 ' + h1.IP() )

    h0.cmdPrint( 'ping -Q 0x20 -c 3 ' + h2.IP() )

    h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )

    h1.cmdPrint( 'ping -Q 0x40 -c 3 ' + h2.IP())

    h1.cmdPrint( 'ping -Q 0x50 -c 3 ' + h3.IP())

    h2.cmdPrint( 'ping -Q 0x60 -c 3 ' + h3.IP())


 

    info( "*** Stopping network
" )

    switch0.cmd( 'ovs-vsctl del-br dp0' )

    switch0.deleteIntfs()

    switch1.cmd( 'ovs-vsctl del-br dp1' )

    switch1.deleteIntfs()



    info( '
' )

 

if __name__ == '__main__':

    setLogLevel( 'info' )

    info( '*** Scratch network demo (kernel datapath)
' )

    Mininet.init()

    myNet()

（3）运行结果