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）修改代码为
#!/usr/bin/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" )
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\n" )
linkopts0=dict(bw=100, delay=‘1ms‘, loss=0)
linkopts1=dict(bw=1, delay=‘100ms‘, loss=0)
linkopts2=dict(bw=10, delay=‘50ms‘, loss=0)
TCLink( switch0, switch1, **linkopts0)
TCLink( h0, switch0, **linkopts1)
TCLink( h2, switch1, **linkopts1)
TCLink( h1, switch0, **linkopts2)
TCLink( h3, switch1, **linkopts2)
info( "*** Configuring hosts\n" )
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 ) + ‘\n‘ )
info( str( h1 ) + ‘\n‘ )
info( str( h2 ) + ‘\n‘ )
info( str( h3 ) + ‘\n‘ )
info( "*** Starting network using Open vSwitch\n" )
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 )
print switch0.cmd(r‘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(r‘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(r‘sudo ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1‘ )
print switch0.cmd(r‘sudo ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=1,actions=pop_vlan,output:2‘ )
print switch1.cmd(r‘ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3‘ )
print switch1.cmd(r‘ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3‘ )
print switch1.cmd(r‘ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:1‘ )
print switch1.cmd(r‘ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output:2‘ )
#switch0.cmd(‘tcpdump -i s0-eth0 -U -w aaa &‘)
#h0.cmd(‘tcpdump -i h0-eth0 -U -w aaa &‘)
info( "*** Running test\n" )
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() )
#h1.cmdPrint(‘iperf -s -p 12345 -u &‘)
#h0.cmdPrint(‘iperf -c ‘ + h1.IP() +‘ -u -b 10m -p 12345 -t 10 -i 1‘)
info( "*** Stopping network\n" )
switch0.cmd( ‘ovs-vsctl del-br dp0‘ )
switch0.deleteIntfs()
switch1.cmd( ‘ovs-vsctl del-br dp1‘ )
switch1.deleteIntfs()
info( ‘\n‘ )
if __name__ == ‘__main__‘:
setLogLevel( ‘info‘ )
info( ‘*** Scratch network demo (kernel datapath)\n‘ )
Mininet.init()
myNet()