实验原理
在SDN环境中，控制器可以通过对交换机下发流表操作来控制交换机的转发行为。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。
实验内容
一台交换机两台主机，实现从1端口进入的数据流转发到2端口，从2端口进入的数据流转发到1端口
mininet脚本代码如下：
1 from mininet.net import Mininet 2 from mininet.node import Node 3 from mininet.link import Link 4 from mininet.log import setLogLevel, info 5 from mininet.util import quietRun 6 ??7 from time import sleep 8 ??9 def scratchNet( cname=‘controller‘, cargs=‘-v ptcp:‘ ):10 ????"Create network from scratch using Open vSwitch."11 ?12 ????info( "*** Creating nodes\n" )13 ????controller = Node( ‘c0‘, inNamespace=False )14 ????switch0 = Node( ‘s0‘, inNamespace=False )15 ????h0 = Node( ‘h0‘ )16 ????h1 = Node( ‘h1‘ )17 ?18 ????info( "*** Creating links\n" )19 ????Link( h0, switch0 )20 ????Link( h1, switch0 )21 ?22 ????info( "*** Configuring hosts\n" )23 ????h0.setIP( ‘192.168.123.1/24‘ )24 ????h1.setIP( ‘192.168.123.2/24‘ )25 ????info( str( h0 ) + ‘\n‘ )26 ????info( str( h1 ) + ‘\n‘ )27 ?28 ????info( "*** Starting network using Open vSwitch\n" )29 ????controller.cmd( cname + ‘ ‘ + cargs + ‘&‘ )30 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )31 ????switch0.cmd( ‘ovs-vsctl add-br dp0‘ )32 ?33 ????for intf in switch0.intfs.values():34 ????????print (intf)35 ????????print (switch0.cmd( ‘ovs-vsctl add-port dp0 %s‘ % intf ))36 ????switch0.cmd( ‘ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633‘ )37 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"‘ )38 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"‘ )39 ?40 ????info( ‘*** Waiting for switch to connect to controller‘ )41 ????while ‘is_connected‘ not in quietRun( ‘ovs-vsctl show‘ ):42 ????????sleep( 1 )43 ????????info( ‘.‘ )44 ????info( ‘\n‘ )45 ?46 ????info( "*** Running test\n" )47 ????h0.cmdPrint( ‘ping -c6 ‘ + h1.IP() )48 ????h1.cmdPrint( ‘ping -c6 ‘ + h0.IP() )49 ?50 ????info( "*** Stopping network\n" )51 ????controller.cmd( ‘kill %‘ + cname )52 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )53 ????switch0.deleteIntfs()54 ????info( ‘\n‘ )55 ?56 if __name__ == ‘__main__‘:57 ????setLogLevel( ‘info‘ )58 ????info( ‘*** Scratch network demo (kernel datapath)\n‘ )59 ????Mininet.init()60 ????scratchNet()
其实，源码中的也可以不用连接controller，直接就可以使用“ovs-vsctl”命令控制控制器。也就是代码中的 switch0.cmd( ‘ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633‘ )其实不是那么必要。
两台交换机两台主机，主机0连接交换机0，主机1连接交换机1，交换机0连接交换机1，数据转发端口要求同脚本1
mininet代码如下：
1 from mininet.net import Mininet 2 from mininet.node import Node 3 from mininet.link import Link 4 from mininet.log import setLogLevel, info 5 from mininet.util import quietRun 6 ??7 from time import sleep 8 ??9 def scratchNet( cname=‘controller‘, cargs=‘-v ptcp:‘ ):10 ????"Create network from scratch using Open vSwitch."11 ?12 ????info( "*** Creating nodes\n" )13 ????controller = Node( ‘c0‘, inNamespace=False )14 ????switch0 = Node( ‘s0‘, inNamespace=False )15 ????switch1 = Node( ‘s1‘, inNamespace=False )16 ????h0 = Node( ‘h0‘ )17 ????h1 = Node( ‘h1‘ )18 ?19 ????info( "*** Creating links\n" )20 ????Link( h0, switch0 )21 ????Link( h1, switch1 )22 ????Link( switch0, switch1 )23 ?24 ????info( "*** Configuring hosts\n" )25 ????h0.setIP( ‘192.168.123.1/24‘ )26 ????h1.setIP( ‘192.168.123.2/24‘ )27 ????info( str( h0 ) + ‘\n‘ )28 ????info( str( h1 ) + ‘\n‘ )29 ?30 ????info( "*** Starting network using Open vSwitch\n" )31 ????controller.cmd( cname + ‘ ‘ + cargs + ‘&‘ )32 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )33 ????switch0.cmd( ‘ovs-vsctl add-br dp0‘ )34 ????switch1.cmd( ‘ovs-vsctl del-br dp1‘ )35 ????switch1.cmd( ‘ovs-vsctl add-br dp1‘ )36 ?37 ?38 ????for intf in switch0.intfs.values():39 ????????print (intf)40 ????????print (switch0.cmd( ‘ovs-vsctl add-port dp0 %s‘ % intf ))41 ?42 ????for intf in switch1.intfs.values():43 ????????print (intf)44 ????????print (switch1.cmd( ‘ovs-vsctl add-port dp1 %s‘ % intf ))45 ?46 ????switch0.cmd( ‘ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633‘ )47 ????switch1.cmd( ‘ovs-vsctl set-controller dp1 tcp:127.0.0.1:6633‘ )48 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"‘ )49 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"‘ )50 ????switch1.cmd( ‘ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"‘ )51 ????switch1.cmd( ‘ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"‘ )52 ?53 ?54 ????info( ‘*** Waiting for switch to connect to controller‘ )55 ????while ‘is_connected‘ not in quietRun( ‘ovs-vsctl show‘ ):56 ????????sleep( 1 )57 ????????info( ‘.‘ )58 ????info( ‘\n‘ )59 ????print (switch0.cmd( ‘ovs-ofctl show dp0‘ ))60 ????print (switch1.cmd( ‘ovs-ofctl show dp1‘ ))61 ?62 ?63 ????info( "*** Running test\n" )64 ????h0.cmdPrint( ‘ping -c3 ‘ + h1.IP() )65 ????h1.cmdPrint( ‘ping -c3 ‘ + h0.IP() )66 ?67 ????info( "*** Stopping network\n" )68 ????controller.cmd( ‘kill %‘ + cname )69 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )70 ????switch0.deleteIntfs()71 ????switch1.cmd( ‘ovs-vsctl del-br dp1‘ )72 ????switch1.deleteIntfs()73 ????info( ‘\n‘ )74 ?75 if __name__ == ‘__main__‘:76 ????setLogLevel( ‘info‘ )77 ????info( ‘*** Scratch network demo (kernel datapath)\n‘ )78 ????Mininet.init()79 ????scratchNet()
在脚本2的基础上设置带宽、延迟以及丢包率
mininet代码如下：
1 from mininet.net import Mininet 2 from mininet.node import Node 3 from mininet.link import TCLink 4 from mininet.log import setLogLevel, info 5 from mininet.util import quietRun 6 ??7 from time import sleep 8 ??9 def scratchNet( cname=‘controller‘, cargs=‘-v ptcp:‘ ):10 ????"Create network from scratch using Open vSwitch."11 ?12 ????info( "*** Creating nodes\n" )13 ????controller = Node( ‘c0‘, inNamespace=False )14 ????switch0 = Node( ‘s0‘, inNamespace=False )15 ????switch1 = Node( ‘s1‘, inNamespace=False )16 ????h0 = Node( ‘h0‘ )17 ????h1 = Node( ‘h1‘ )18 ?19 ????info( "*** Creating links\n" )20 ?21 ????linkopts0=dict(bw=10)22 ????linkopts1=dict(bw=10, delay=‘5ms‘, loss=10)23 ????TCLink( h0, switch0,**linkopts0)24 ????TCLink( h1, switch1,**linkopts0)25 ????TCLink( switch0, switch1,**linkopts1)26 ?27 ?28 ????info( "*** Configuring hosts\n" )29 ????h0.setIP( ‘192.168.123.1/24‘ )30 ????h1.setIP( ‘192.168.123.2/24‘ )31 ????info( str( h0 ) + ‘\n‘ )32 ????info( str( h1 ) + ‘\n‘ )33 ?34 ????info( "*** Starting network using Open vSwitch\n" )35 ????controller.cmd( cname + ‘ ‘ + cargs + ‘&‘ )36 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )37 ????switch0.cmd( ‘ovs-vsctl add-br dp0‘ )38 ????switch1.cmd( ‘ovs-vsctl del-br dp1‘ )39 ????switch1.cmd( ‘ovs-vsctl add-br dp1‘ )40 ?41 ?42 ????for intf in switch0.intfs.values():43 ????????print (intf)44 ????????print (switch0.cmd( ‘ovs-vsctl add-port dp0 %s‘ % intf ))45 ?46 ????for intf in switch1.intfs.values():47 ????????print (intf)48 ????????print (switch1.cmd( ‘ovs-vsctl add-port dp1 %s‘ % intf ))49 ?50 ????switch0.cmd( ‘ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633‘ )51 ????switch1.cmd( ‘ovs-vsctl set-controller dp1 tcp:127.0.0.1:6633‘ )52 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"‘ )53 ????switch0.cmd( ‘ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"‘ )54 ????switch1.cmd( ‘ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"‘ )55 ????switch1.cmd( ‘ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"‘ )56 ?57 ?58 ????info( ‘*** Waiting for switch to connect to controller‘ )59 ????while ‘is_connected‘ not in quietRun( ‘ovs-vsctl show‘ ):60 ????????sleep( 1 )61 ????????info( ‘.‘ )62 ????info( ‘\n‘ )63 ????print (switch0.cmd( ‘ovs-ofctl show dp0‘ ))64 ????print (switch1.cmd( ‘ovs-ofctl show dp1‘ ))65 ?66 ?67 ????info( "*** Running test\n" )68 ????h0.cmdPrint( ‘ping -c3 ‘ + h1.IP() )69 ????h1.cmdPrint( ‘ping -c3 ‘ + h0.IP() )70 ?71 ????info( "*** Stopping network\n" )72 ????controller.cmd( ‘kill %‘ + cname )73 ????switch0.cmd( ‘ovs-vsctl del-br dp0‘ )74 ????switch0.deleteIntfs()75 ????switch1.cmd( ‘ovs-vsctl del-br dp1‘ )76 ????switch1.deleteIntfs()77 ????info( ‘\n‘ )78 ?79 if __name__ == ‘__main__‘:80 ????setLogLevel( ‘info‘ )81 ????info( ‘*** Scratch network demo (kernel datapath)\n‘ )82 ????Mininet.init()83 ????scratchNet()
Mininet实验 脚本实现控制交换机行为
原文地址：https://www.cnblogs.com/pullself/p/10225343.html