克隆一个ryu虚拟机（1号） ，得到2号ryu虚拟机
开启1，2号ryu控制器：进入ryu/ryu/app目录，然后启动相应模块：sudo ryu-manager --verbose simple_switch_13.py ofctl_rest.py rest_topology.py
mininet虚拟机中，在桌面上自定义一个topo文件，如：sudo gedit 1.py
1.py的内容：
#!/usr/bin/python from mininet.net import Mininet from mininet.node import Controller, RemoteController from mininet.cli import CLI from mininet.log import setLogLevel, info def myNet(): #c0 c0_IP=‘192.168.231.131‘ #c1 c1_IP=‘192.168.231.133‘ net = Mininet( topo=None, build=False) # Create nodes h1 = net.addHost( ‘h1‘, mac=‘01:00:00:00:01:00‘, ip=‘192.168.0.1/24‘ ) h2 = net.addHost( ‘h2‘, mac=‘01:00:00:00:02:00‘, ip=‘192.168.0.2/24‘ ) # Create switches s1 = net.addSwitch( ‘s1‘, listenPort=6634, mac=‘00:00:00:00:00:01‘ ) s2 = net.addSwitch( ‘s2‘, listenPort=6634, mac=‘00:00:00:00:00:02‘ ) print "*** Creating links" net.addLink(h1, s1, ) net.addLink(h2, s2, ) net.addLink(s1, s2, ) # Add Controllers c0_ctrl = net.addController( ‘c0‘, controller=RemoteController, ip=c0_IP, port=6653) c1_ctrl = net.addController( ‘c1‘, controller=RemoteController, ip=c1_IP, port=6653) net.build() # Connect each switch to a different controller s1.start( [c0_ctrl] ) s2.start( [c1_ctrl] ) s1.cmdPrint(‘ovs-vsctl show‘) CLI( net ) net.stop() if __name__ == ‘__main__‘: setLogLevel( ‘info‘ ) myNet()
在终端运行该文件：sudo python 1.py
可以发现：交换机 s1的master控制器为1号ryu控制器，s2的master控制器为2号ryu控制器。
如果想进行控制器角色转换，比如s1的master控制器设置为2号ryu控制器，使用命令：
sudo ovs-vsctl set-controller s1 tcp:192.168.231.133:6653
此时再次查看sudo ovs-vsctl show，发现角色转变成功。