Passing a Custom Switch class to Mininet topology

Question

This is a topology file for a popular network simulator called mininet

I have created a class MultiSwitch() below which I want to be passed to my Topology class to be used as the default switch is there a way to do that? I am not very proficient in Python

from mininet.topo import Topo
from mininet.node import OVSSwitch, Controller, RemoteController

# Two "external" controllers 
c0 = RemoteController( 'c1', ip='192.168.81.132')
c1 = RemoteController( 'c2', ip='192.168.81.130')

cmap = { 's1': c0, 's2': c0, 's3': c1,'s4':c1 }

class MultiSwitch( OVSSwitch ):
    def start( self, controllers ):
        return OVSSwitch.start( self, [ cmap[ self.name ] ] )

class OnosTopo( Topo ):

    "Simple topology example."
    def __init__( self ):

        "Create custom topo."
        # Initialize topology

        Topo.__init__( self )

        # Add hosts and switches
        h1 =  [ self.addHost( 'h1')]
        h2 =  [ self.addHost( 'h2')]
        h3 =  [ self.addHost( 'h3')]
        h4 =  [ self.addHost( 'h4')]

    s1 = [ self.addSwitch( 's1', dpid="0000000000000201")]
    s2 = [ self.addSwitch( 's2', dpid="0000000000000202")]
    s3 = [ self.addSwitch( 's3', dpid="0000000000000203")]
    s4 = [ self.addSwitch( 's4', dpid="0000000000000204")]

    #host to switch links
    self.addLink('s1','h1')
    self.addLink('s2','h2')
    self.addLink('s3','h3')
    self.addLink('s4','h4')


    #switch to swtich links
    self.addLink('s1','s2')
    self.addLink('s3','s4')

topos = { 'onostopo': ( lambda: OnosTopo() ) }

Answer 1

the mininet.topo.py defines a method called as add_switch(),may be you can try over-writting the add_switch() method with a custom add_switch() which adds your custom switch in your custom topology, so whenever you run your topology, the add_switch() method would create the custom switch .