利用Python脚本完成一个Fat-tree型的拓扑

利用Python脚本完成如下图所示的一个Fat-tree型的拓扑（交换机和主机名需与图中一致，即s1h8）

• 参考资料
  
  
• 修改代码如下：

from mininet.topo import Topo

from mininet.net import Mininet

from mininet.node import RemoteController,CPULimitedHost

from mininet.link import TCLink

from mininet.util import dumpNodeConnections

class MyTopo( Topo ):

    "Simple topology example."

    def __init__( self ):

        "Create custom topo."

        # Initialize topology

        Topo.__init__( self )

        L1 = 2

        L2 = L1 * 2

        s = []

        # add core ovs

        for i in range( L1 ):

                sw = self.addSwitch( 's{}'.format( i + 1 ) )

                s.append( sw )

        # add aggregation ovs

        for i in range( L2 ):

                sw = self.addSwitch( 's{}'.format( i + L1 + 1 ) )

                s.append( sw )

        # add links between core and aggregation/edge ovs

        for i in range( L1 ):

		sw1 = s[i]

                for j in range( L2 ):

			sw2 = s[L1 + j]

			self.addLink( sw2, sw1 )

        #add hosts and its links with aggregation/edge ovs

        count = 1

        for sw1 in s[L1::1]:

                for i in range(2):

                	host = self.addHost( 'h{}'.format( count ) )

                	self.addLink( sw1, host )

                	count += 1

topos = { 'mytopo': ( lambda: MyTopo() ) }