text: """Custom topology example
  
  Two directly connected switches plus a host for each switch:
  
     host --- switch --- switch --- host
  
  Adding the 'topos' dict with a key/value pair to generate our newly defined
  topology enables one to pass in '--topo=mytopo' from the command line.
  """
  
  from mininet.topo import Topo
  
  class MyTopo( Topo ):
  	"Simple topology example."
  
  	def __init__( self ):
  		"Create custom topo."
  
  		# Initialize topology
  		Topo.__init__( self )
  
  		# Add hosts and switches
  		sHost1 = self.addHost( 'h1' )
  		sHost2 = self.addHost( 'h2' )
  		sHost3 = self.addHost( 'h3' )
  		sHost4 = self.addHost( 'h4' )
  
  		cSwitch = self.addSwitch( 's1' )
  
  
  
  		# Add links
  		self.addLink( sHost1, cSwitch )
  		self.addLink( sHost2, cSwitch )
  		self.addLink( sHost3, cSwitch )
  		self.addLink( sHost4, cSwitch )
  
  
  topos = { 'mytopo': ( lambda: MyTopo() ) }
  
  
  #sudo mn --custom topo-LAB02.py --topo mytopo --test pingall
  