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。
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。
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()
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()
