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Configuring a LAN

By default, IPMininet uses ~ipmininet.ipswitch.IPSwitch to create regular switches (not Openflow switches) and hubs. The switches use the Spanning Tree Protocol by default to break the loops. The hubs are switches that do not maintain a MAC address table and always broadcast any received frame on all its interfaces.

Here is an example of a LAN with a few switches and one hub.

lan

from ipmininet.iptopo import IPTopo

class MyTopology(IPTopo):

def build(self, args,*kwargs):

# Switches s1 = self.addSwitch("s1") s2 = self.addSwitch("s2") s3 = self.addSwitch("s3") s4 = self.addSwitch("s4")

# Hub hub1 = self.addHub("hub1")

# Links self.addLink(s1, s2) self.addLink(s1, hub1) self.addLink(hub1, s3) self.addLink(hub1, s4)

super(MyTopology, self).build(args,*kwargs)

The Spanning Tree Protocol can be configured by changing the `stp_cost` on the links (or directly on each interface). The default cost is 1.

stp

from ipmininet.iptopo import IPTopo

class MyTopology(IPTopo):

def build(self, args,*kwargs):

# Switches s1 = self.addSwitch("s1") s2 = self.addSwitch("s2") s3 = self.addSwitch("s3") s4 = self.addSwitch("s4")

# Hub hub1 = self.addHub("hub1")

# Links self.addLink(s1, s2, stp_cost=2) # Cost changed for both interfaces self.addLink(s1, hub1) ls3 = self.addLink(hub1, s3) ls3[s3].addParams(stp_cost=2) # Cost changed on a single interface self.addLink(hub1, s4)

super(MyTopology, self).build(args,*kwargs)

In the Spanning Tree Protocol, each switch has a priority. The lowest priority switch becomes the root of the spanning tree. By default, switches declared first have a lower priority number. You can manually set this value when you create the switch.

stp

from ipmininet.iptopo import IPTopo

class MyTopology(IPTopo):

def build(self, args,*kwargs):

# Switches with manually set STP priority s1 = self.addSwitch("s1", prio=1) s2 = self.addSwitch("s2", prio=2) s3 = self.addSwitch("s3", prio=3) s4 = self.addSwitch("s4", prio=4)

# Hub hub1 = self.addHub("hub1")

# Links self.addLink(s1, s2, stp_cost=2) # Cost changed for both interfaces self.addLink(s1, hub1) ls3 = self.addLink(hub1, s3) ls3[s3].addParams(stp_cost=2) # Cost changed on a single interface self.addLink(hub1, s4)

super(MyTopology, self).build(args,*kwargs)

from ipmininet.clean import cleanup cleanup(level='warning')

try:

MyTopology

except NameError:

MyTopology = None

if MyTopology is not None:

from ipmininet.ipnet import IPNet net = IPNet(topo=MyTopology()) net.start()

try:

net

except NameError:

net = None

if net is not None:

net.stop()