How to disable ipv6 in Mininet

disable_ipv6_example.py

#!/usr/bin/python

from mininet.topo import Topo
from mininet.net import Mininet
from mininet.node import CPULimitedHost, Controller, RemoteController, OVSSwitch, Ryu
from mininet.link import TCLink
from mininet.util import dumpNodeConnections
from mininet.log import setLogLevel
from mininet.cli import CLI
from functools import partial

from parse_topology import CustomTopo

class CustomMininetTopo(Topo):
    "Single switch connected to n hosts."
    def build(self):
        topo_dict = CustomTopo('topo.txt')
        routers = topo_dict.get_routers()
        links = topo_dict.get_links()
        self.host_id = 1
        print routers
        for name, router in routers.items():
            switch = self.addSwitch(router['dpid'])
            # Each host gets 50%/n of system CPU
            # host = self.addHost('h%d' % self.host_id , cpu=.5/n)
            host = self.addHost('h%d' % self.host_id)
            self.host_id += 1
            # 10 Mbps, 5ms delay, 10% loss, 1000 packet queue
            self.addLink(host, switch, bw=100 )
               # bw=10, delay='5ms', loss=10, max_queue_size=1000, use_htb=True)
        for link in links:
            # print link['x'], link['y'], link['kbps'], link['OSPF']
            self.addLink(link['x'], link['y'], bw=link['kbps']/10000)


def perfTest():
    "Create network and run simple performance test"
    topo = CustomMininetTopo()
    OVSSwitch13 = partial( OVSSwitch, protocols='OpenFlow13' )
    # ryu_controller = Ryu('ryu_c1', 'my_controller.py')
    net = Mininet(topo=topo,switch=OVSSwitch13,
                    ## Run controller manually
                    controller=RemoteController('c0', ip='127.0.0.1'),
                    ## Run controller Automatically
                    # controller=ryu_controller,
                    autoSetMacs = True,
                    autoStaticArp = True,
                    host=CPULimitedHost, link=TCLink)

    for h in net.hosts:
        print "disable ipv6"
        h.cmd("sysctl -w net.ipv6.conf.all.disable_ipv6=1")
        h.cmd("sysctl -w net.ipv6.conf.default.disable_ipv6=1")
        h.cmd("sysctl -w net.ipv6.conf.lo.disable_ipv6=1")

    for sw in net.switches:
        print "disable ipv6"
        sw.cmd("sysctl -w net.ipv6.conf.all.disable_ipv6=1")
        sw.cmd("sysctl -w net.ipv6.conf.default.disable_ipv6=1")
        sw.cmd("sysctl -w net.ipv6.conf.lo.disable_ipv6=1")

    net.start()
    print "Dumping host connections"
    dumpNodeConnections(net.hosts)
    CLI(net)
    net.stop()

if __name__ == '__main__':
    setLogLevel('info')
    perfTest()