实验2:Open vSwitch虚拟交换机实践
一、实验目的
- 能够对Open vSwitch进行基本操作;
- 能够通过命令行终端使用OVS命令操作Open vSwitch交换机,管理流表;
- 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
二、实验环境
Ubuntu 20.04 Desktop amd64
三、实验要求
(一)基本要求
1. 在/home/用户名/学号/lab2/目录下执行ovs-vsctl show命令,并且要验证p0,p1的连通性。
2. /home/用户名/学号/lab2/目录下开启Mininet CLI并执行pingall命令的截图
3.查看OVS流表,并且使用wireshark进行抓包
(二)进阶实验
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。
代码如下
#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import Link
from mininet.log import setLogLevel, info
def myNet():
"Create network from scratch using Open vSwitch."
info( "*** Creating nodes\n" )
switch1 = Node( 's1', inNamespace=False )
switch2 = Node( 's2', inNamespace=False )
h1 = Node( 'h1' )
h2 = Node( 'h2' )
h3 = Node( 'h3' )
h4 = Node( 'h4' )
info( "*** Creating links\n" )
Link( h1, switch1)
Link( h2, switch1)
Link( h3, switch2)
Link( h4, switch2)
Link( switch1, switch2)
info( "*** Configuring hosts\n" )
h1.setIP( '192.168.123.1/24' )
h2.setIP( '192.168.124.1/24' )
h3.setIP( '192.168.123.2/24' )
h4.setIP( '192.168.124.2/24' )
info( "*** Starting network using Open vSwitch\n" )
switch1.cmd( 'ovs-vsctl del-br dp0' )
switch1.cmd( 'ovs-vsctl add-br dp0' )
switch2.cmd( 'ovs-vsctl del-br dp1' )
switch2.cmd( 'ovs-vsctl add-br dp1' )
for intf in switch1.intfs.values():
print (intf)
print (switch1.cmd( 'ovs-vsctl add-port dp0 %s' % intf ))
for intf in switch2.intfs.values():
print (intf)
print (switch2.cmd( 'ovs-vsctl add-port dp1 %s' % intf ))
# Note: controller and switch are in root namespace, and we
# can connect via loopback interface
#switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633' )
print (switch1.cmd(r'ovs-vsctl show'))
print (switch1.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 (switch1.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 (switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1'))
print (switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=1,actions=pop_vlan,output:2'))
print (switch2.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 (switch2.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 (switch2.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:1'))
print (switch2.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" )
h1.cmdPrint( 'ping -c 3 ' + h3.IP() )
h2.cmdPrint( 'ping -c 3 ' + h4.IP() )
h1.cmdPrint( 'ping -c 3 ' + h4.IP() )
h2.cmdPrint( 'ping -c 3 ' + h3.IP() )
#print switch0.cmd( 'ovs-ofctl show dp0' )
#print switch0.cmd( 'ovs-ofctl dump-tables dp0' )
#print switch0.cmd( 'ovs-ofctl dump-ports dp0' )
#print switch0.cmd( 'ovs-ofctl dump-flows dp0' )
#print switch0.cmd( 'ovs-ofctl dump-aggregate dp0' )
#print switch0.cmd( 'ovs-ofctl queue-stats dp0' )
info( "*** Stopping network\n" )
switch1.cmd( 'ovs-vsctl del-br dp0' )
switch1.deleteIntfs()
switch2.cmd( 'ovs-vsctl del-br dp1' )
switch2.deleteIntfs()
info( '\n' )
if __name__ == '__main__':
setLogLevel( 'info' )
info( '*** Scratch network demo (kernel datapath)\n' )
Mininet.init()
myNet()
运行结果
测试连通性
四、总结
- 本次实验学习了Open vSwitch虚拟交换机的相关知识与概念。实验中,通过ovs-vsctl、ovs-ofctl等指令实现OVS交换机的创建以及添加流表、划分VLAN等操作。
- 进行本次实验时,我认为比较重要的就是如果做错某一步需要重新进行实验时,需要将已经添加的交换机删除干净,可以使用PDF给出的命令,也可以使用sudo mn -c进行删除。
- 在进阶实验中,我利用了python代码调用了OVS代码,令我对于Open vSwitch以及Mininet有了进一步深入的了解,也令我对SDN相关的知识有了更加充实的储备。