Exception: Error creating interface pair (s2-eth5,s3-eth1): RTNETLINK answers: File exists

Hi, I’m using mininet I created a topology using miniedit and generated a script (minitopo.py)
and i’m getting this error when executing the script

Traceback (most recent call last):
  File "minitopo1.py", line 70, in <module>
    myNetwork()
  File "minitopo1.py", line 49, in myNetwork
    net.addLink(s2, s3)
  File "/home/mininet/mininet/mininet/net.py", line 364, in addLink
    link = cls( node1, node2, **options )
  File "/home/mininet/mininet/mininet/link.py", line 424, in __init__
    node1, node2, deleteIntfs=False )
  File "/home/mininet/mininet/mininet/link.py", line 468, in makeIntfPair
    deleteIntfs=deleteIntfs )
  File "/home/mininet/mininet/mininet/util.py", line 194, in makeIntfPair
    ( intf1, intf2, cmdOutput ) )
Exception: Error creating interface pair (s2-eth5,s3-eth1): RTNETLINK answers: File exists

I’ve tried to use it without the remote controller, and had the same problem , there’s something wrong in creating the links between (s2,s3) and (s4,s3)

here’s the script (minitopo.py) ,

#!/usr/bin/python

from mininet.net import Mininet
from mininet.node import Controller, RemoteController, OVSController
from mininet.node import CPULimitedHost, Host, Node
from mininet.node import OVSKernelSwitch, UserSwitch
from mininet.node import IVSSwitch
from mininet.cli import CLI
from mininet.log import setLogLevel, info
from mininet.link import TCLink, Intf
from subprocess import call

def myNetwork():

    net = Mininet( topo=None,
                   build=False,
                   ipBase='10.0.0.0/8')

    info( '*** Adding controller\n' )
    c1=net.addController(name='c1',
                      controller=Controller,
                      protocol='tcp',
                      port=6633)

    info( '*** Add switches\n')
    s2 = net.addSwitch('s2', cls=OVSKernelSwitch)
    s4 = net.addSwitch('s4', cls=OVSKernelSwitch)
    s3 = net.addSwitch('s3', cls=OVSKernelSwitch)

    info( '*** Add hosts\n')
    h7 = net.addHost('h7', cls=Host, ip='10.0.0.7', defaultRoute=None)
    h2 = net.addHost('h2', cls=Host, ip='10.0.0.2', defaultRoute=None)
    h3 = net.addHost('h3', cls=Host, ip='10.0.0.3', defaultRoute=None)
    h4 = net.addHost('h4', cls=Host, ip='10.0.0.4', defaultRoute=None)
    h6 = net.addHost('h6', cls=Host, ip='10.0.0.6', defaultRoute=None)
    h5 = net.addHost('h5', cls=Host, ip='10.0.0.5', defaultRoute=None)
    h8 = net.addHost('h8', cls=Host, ip='10.0.0.8', defaultRoute=None)
    h1 = net.addHost('h1', cls=Host, ip='10.0.0.1', defaultRoute=None)

    info( '*** Add links\n')
    net.addLink(s2, h4)
    net.addLink(s2, h3)
    net.addLink(s2, h2)
    net.addLink(s2, h1)
    net.addLink(s4, h5)
    net.addLink(s4, h6)
    net.addLink(s4, h7)
    net.addLink(s4, h8)
    net.addLink(s2, s3)
    net.addLink(s3, s4)

    info( '*** Starting network\n')
    net.build()
    info( '*** Starting controllers\n')
    for controller in net.controllers:
        controller.start()

    info( '*** Starting switches\n')
    net.get('s2').start([])
    net.get('s4').start([])
    net.get('s3').start([c1])

    info( '*** Post configure switches and hosts\n')

    CLI(net)
    net.stop()

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

could you please telle me what’s wrong ?

[hwchiu]

Can you use “sudo mn -c” to clean your env and try again ?

[mishi-a]

Remove the Previous topology by using sudo mn -c