customTopo.py

from mininet.topo import Topo
from mininet.node import Node
from mininet.net import Mininet
from mininet.cli import CLI
from mininet.link import TCIntf
from enum import Enum


class NodeRoles(Enum):
  ROUTER = 'Router'
  SWITCH = 'Switch'
  HOST = 'Host'


class Router(Node):

  def config(self, **params):
    super(Router, self).config(**params)
    self.cmd('sysctl net.ipv4.ip_forward=1')
    self.waitOutput()

  def terminate(self):
    self.cmd('sysctl net.ipv4.ip_forward=0')
    self.waitOutput()
    super(Router, self).terminate()

  def print_routing_table(self):
    print(self.name + ' - Routing Table')
    print(self.cmd('ip route'))


class CustomTopo(Topo):

  __LINK_BANDWIDTH = 1

  def __init__(self):
      Topo.__init__(self)

  def build(self):

    r1 = self.addNode('r1', cls=Router, ip=None,
                      role=NodeRoles.ROUTER.value)

    s1 = self.addSwitch('s1', role=NodeRoles.SWITCH.value)
    s2 = self.addSwitch('s2', role=NodeRoles.SWITCH.value)

    h11 = self.addHost('h11', ip='10.0.1.11/24',
                       # inNamespace=False,
                       defaultRoute='via 10.0.1.254',
                       role=NodeRoles.HOST.value)
    h12 = self.addHost('h12', ip='10.0.1.12/24',
                       defaultRoute='via 10.0.1.254',
                       role=NodeRoles.HOST.value)

    h21 = self.addHost('h21', ip='10.0.2.21/24',
                       defaultRoute='via 10.0.2.254',
                       role=NodeRoles.HOST.value)
    h22 = self.addHost('h22', ip='10.0.2.22/24',
                       defaultRoute='via 10.0.2.254',
                       role=NodeRoles.HOST.value)

    for node1, node2 in [(h11, s1), (h12, s1), (h21, s2), (h22, s2)]:
      self.addLink(node1, node2,
                   cls1=TCIntf, cls2=TCIntf,
                   intfName1=node1 + '-' + node2,
                   intfName2=node2 + '-' + node1,
                   params1={'bw': self.__LINK_BANDWIDTH},
                   params2={'bw': self.__LINK_BANDWIDTH})

    self.addLink(r1, s1,
                 cls1=TCIntf, cls2=TCIntf,
                 intfName1=r1 + '-' + s1,
                 intfName2=s1 + '-' + r1,
                 params1={'ip': '10.0.1.254/24', 'bw': self.__LINK_BANDWIDTH},
                 params2={'bw': self.__LINK_BANDWIDTH})

    self.addLink(r1, s2,
                 cls1=TCIntf, cls2=TCIntf,
                 intfName1=r1 + '-' + s2,
                 intfName2=s2 + '-' + r1,
                 params1={'ip': '10.0.2.254/24', 'bw': self.__LINK_BANDWIDTH},
                 params2={'bw': self.__LINK_BANDWIDTH})


def run():
  topo = CustomTopo()
  net = Mininet(topo=topo)
  net.start()

  for node in net.topo.nodes():
    print(net[node].params['role'])
  net['r1'].print_routing_table()

  CLI(net)
  net.stop()


if __name__ == '__main__':
  run()