from pox.core import core

from pox.lib.addresses import EthAddr

import pox.openflow.libopenflow$\_01$ as of

class Switch:

def $\_\_$init$\_\_($self$,$ connection, switch$\_$id$)$:

self.connection $=$ connection

self.macToPort $=\{\}$

self.switch$\_$id $=$ switch$\_$id

connection.addListeners$($self$)$

def $\_$handle$\_$PacketIn$($self$,$ event$)$:

in$\_$port $=$ event.port

packet $=$ event.parsed

eth $=$ packet.find$("$ethernet$")$

self.macToPort$[$eth$.$src$]=$ in$\_$port

if eth.dst in self.macToPort:

out$\_$port $=$ self.macToPort$[$eth$.$dst$]$

else:

out$\_$port $=$ of$.$OFPP$\_$FLOOD

if out$\_$port $!=$ of$.$OFPP$\_$FLOOD:

msg $=$ of$.$ofp$\_$flow$\_$mod$()$

msg$.$match $=$ of$.$ofp$\_$match$()$

msg$.$match.dl$\_$dst $=$ eth.dst

msg$.$match.in$\_$port $=$ event.port

msg$.$idle$\_$timeout $=10$

msg$.$hard$\_$timeout $=30$

msg$.$actions.append$($of$.$ofp$\_$action$\_$output$($port$=$out$\_$port$))$

self.connection.send$($msg$)$

else:

msg $=$ of$.$ofp$\_$packet$\_$out$()$

msg$.$actions.append$($of$.$ofp$\_$action$\_$output$($port$=$out$\_$port$))$

msg$.$data $=$ event.ofp

self.connection.send$($msg$)$

def $\_$handle$\_$ConnectionUp$($event$)$:

switch$\_$id $=$ event.connection$).$dpid # Extracting switch ID

Switch$($event$.$connection, switch$\_$id$)$

def launch$()$:

core.openflow.addListenerByName$("$ConnectionUp$",\_$handle$\_$ConnectionUp$)$ How to update this application of SDN controller as a switch in a mininet emulator for a tree topology with $2$ levels and each swich connected to $4$ hosts i$.$e$.$ mn $--$topo,$2,4$ so that i am able to transfer packets to hosts connected to different switches through controller