如何连接主机？

如何解决如何连接主机？

我正在用mininet开发一个项目的拓扑网络，该拓扑开始运行，但是当我尝试对主机进行ping操作或执行iperf操作时，说在所选主机之间不存在连接。我已经尝试查看汇总错误，但没有成功

 from mininet.net import Mininet
from mininet.node import Controller,OVSSwitch
from mininet.cli import CLI
from mininet.log import setLogLevel

def multiControllerNet():



    net = Mininet( controller=Controller,switch=OVSSwitch )

    print
    c1 = net.addController( 'c1',port=6633 )
    c2 = net.addController( 'c2',port=6634 )

    print
    s1 = net.addSwitch( 's1' )
    s2 = net.addSwitch( 's2' )
    s3 = net.addSwitch( 's3' )
    s4 = net.addSwitch( 's4' )
    s5 = net.addSwitch( 's5' )
    s6 = net.addSwitch( 's6' )
    s7 = net.addSwitch( 's7' )
    s8 = net.addSwitch( 's8' )

    print
   # hosts1 = [ net.addHost( 'h%d' % n ) for n in (1,2,3,4) ]
    h1 = net.addHost( 'h1' )
    h2 = net.addHost( 'h2' )
    h3 = net.addHost( 'h3' )
    h4 = net.addHost( 'h4' )

    print
    #for h in hosts1:
    net.addLink( s5,h1 )
    net.addLink( s6,h2 )
    net.addLink( s7,h3 )
    net.addLink( s8,h4 )
    net.addLink( s1,s5 )
    net.addLink( s2,s5 )
    net.addLink( s3,s5 )
    net.addLink( s4,s5 )
    net.addLink( s1,s6 )
    net.addLink( s2,s6 )
    net.addLink( s3,s6 )
    net.addLink( s4,s6 )
    net.addLink( s1,s7 )
    net.addLink( s2,s7 )
    net.addLink( s3,s7 )
    net.addLink( s4,s7 )
    net.addLink( s1,s8 )
    net.addLink( s2,s8 )
    net.addLink( s3,s8 )
    net.addLink( s4,s8 )

# net.addLink( s1,s2 )
 #   net.addLink( s2,s3 )
  #  net.addLink( s3,s4 )

    print
    net.build()
    c1.start()
    c2.start()
    s1.start( [ c1,c2 ] )
    s2.start( [ c1,c2 ] )
    s3.start( [ c2,c1 ] )
    s4.start( [ c2,c1 ] )
    s5.start( [ c2,c1 ] )
    s6.start( [ c2,c1 ] )
    s7.start( [ c2,c1 ] )
    s8.start( [ c2,c1 ] )
    net.start()

    print
    CLI( net )

    print
    net.stop()

if __name__ == '__main__':

这是我开发和使用的代码，如果有人帮助我，我不会在主机之间建立连接。