+# !/usr/bin/python
+
+# usage: sudo mn --controller=remote,ip=<controller_ip> --switch=ovsk,protocols=OpenFlow13 --custom <path to customtopo.py> --topo ring ...
+
+from mininet.topo import Topo
+
+
+def add_hosts_to_switch(self, switch, hosts, start_host_suffix):
+ host_suffix = start_host_suffix
+ for _ in range(hosts):
+ host = self.addHost("h%s" % host_suffix)
+ self.addLink(switch, host)
+ host_suffix += 1
+
+
+class RingTopo(Topo):
+ def __init__(self, switches=3, hosts_per_switch=1, **opts):
+ Topo.__init__(self, **opts)
+ host_suffix = 1
+ switch = self.addSwitch('s%s' % 1)
+ first_switch = switch
+ for i in range(1, switches):
+ # add hosts to switch
+ add_hosts_to_switch(self, switch, hosts_per_switch, host_suffix)
+ host_suffix += hosts_per_switch
+
+ new_switch = self.addSwitch('s%s' % (i + 1))
+ self.addLink(new_switch, switch)
+ switch = new_switch
+
+ add_hosts_to_switch(self, switch, hosts_per_switch, host_suffix)
+ self.addLink(switch, first_switch)
+
+
+class MeshTopo(Topo):
+ def __init__(self, switches=3, hosts_per_switch=1, **opts):
+ Topo.__init__(self, **opts)
+ created_switches = []
+ host_suffix = 1
+ for i in range(switches):
+ new_switch = self.addSwitch('s%s' % (i + 1))
+
+ # add hosts to new switch
+ add_hosts_to_switch(self, new_switch, hosts_per_switch, host_suffix)
+ host_suffix += hosts_per_switch
+
+ for switch in created_switches:
+ self.addLink(new_switch, switch)
+
+ created_switches.append(new_switch)
+
+
+topos = {'ring': RingTopo,
+ 'mesh': MeshTopo}