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

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、实验要求

学习 ovsSingleBr.py 和 ovsMultiBr.py，中实现一个 VLAN。
上述代码将 h0 和 h2 划分在 VLAN 0 中，h1 和 h3 划分在 VLAN 1 中，由于拓扑没有控制器，并且初始化时删除了交换机中的所有流表，因此除非下发流表，否则主机之间网络无法连通。请尝试修改代码，利用 ovs 命令直接下发 VLAN 设置的流表项，最终测试 h0 和 h2 互通，h1 和 h3 互通，其余主机均不通，结果如下图。OVS 实现 VLAN 可参考博客：https://www.cnblogs.com/fjlinww/p/11791846.html

三、实验代码

`#!/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" )
TCLink( h0, switch0)
TCLink( h1, switch0)
TCLink( h2, switch1)
TCLink( h3, switch1)
TCLink( switch0, switch1)

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( "*** 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'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1' )
print switch0.cmd(r'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' )

info( "*** Running test\n" )
h0.cmdPrint( 'ping -c 3 ' + h1.IP() )
h0.cmdPrint( 'ping -c 3 ' + h2.IP() )
h0.cmdPrint( 'ping -c 3 ' + h3.IP() )
h1.cmdPrint( 'ping -c 3 ' + h2.IP() )
h1.cmdPrint( 'ping -c 3 ' + h3.IP() )
h2.cmdPrint( 'ping -c 3 ' + h3.IP() )

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()`