I'm new to mininet, I want to see the network topology using opendaylight(carbon) controller. I have tried command:

```
sudo mn --topo linear,3 --mac \
    --controller=remote,ip=10.109.253.152,port=6633 \
    --switch ovs,protocols=OpenFlow13,stp=1

```

And the opendaylight can successfully show the whole topology. And Then, I want to show the same result by using python code solely. However, it doesn't work.

```
#!/usr/bin/python

from mininet.net import Mininet
from mininet.node import RemoteController, OVSSwitch
from mininet.log import info, setLogLevel
from mininet.cli import CLI

def RemoteCon():
    net = Mininet(controller=RemoteController, switch=OVSSwitch)

    c1 = net.addController('c1', ip='10.109.253.152',port=6633)
    h1 = net.addHost('h1')
    h2 = net.addHost('h2')
    s1 = net.addSwitch('s1')
    net.addLink(s1, h1)
    net.addLink(s1, h2)

    net.build()
    net.start()

    CLI(net)

    net.stop()

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

```

Oh, by the way, does the switches have default forwarding functionality? Sometimes, I have hosts and switch connected to each other and hosts can ping each other while running above code, h1 cannot ping h2 and vice versa.

Thanks in advance.