mininet模拟dhcp请求的topo

import os
from mininet.net import Mininet
from mininet.node import Controller, RemoteController
from mininet.cli import CLI
from mininet.link import Intf
from mininet.log import setLogLevel, info
def ():
    c0 = RemoteController( 'c0', ip='10.190.23.112', port=6653 )  
    net = Mininet( topo=None, build=False)
    info( '*** Adding controllern' )
    net.addController(c0)
    info( '*** Add switchesn')
    s1 = net.addSwitch('s1')
    info( '*** Add hostsn')
    h1 = net.addHost('h1', ip='0.0.0.0')
    h2 = net.addHost('h2', ip='0.0.0.0')
    info( '*** Add linksn')
    net.addLink(h1, s1)
    net.addLink(h2, s1)
    info( '*** Starting networkn')
    net.start()
    os.popen('ovs-vsctl add-port s1 eth0')       
    h1.cmdPrint('dhclient '+h1.defaultIntf().name)      
    h2.cmdPrint('dhclient '+h2.defaultIntf().name)      
    CLI(net)
    net.stop()
if __name__ == '__main__':
    setLogLevel( 'info' )
    ToRealnet()