adding vlanhost.py

examples/vlanhost.py

+"""
+vlanhost.py: Host subclass that uses a VLAN tag for the default interface.
+
+Dependencies:
+    This class depends on the "vlan" package
+    $ sudo apt-get install vlan
+
+Usage (example uses VLAN ID=1000):
+    From the command line:
+        sudo mn --custom vlanhost.py --host vlan,vlan=1000
+
+    From a script (see exampleUsage function below):
+        from functools import partial
+        from vlanhost import VLANHost
+
+        ....
+
+        host = partial( VLANHost, vlan=1000 )
+        net = Mininet( host=host, ... )
+
+    Directly running this script:
+        sudo python vlanhost.py 1000
+
+"""
+
+from mininet.node import Host
+
+class VLANHost( Host ):
+
+   def config( self, vlan=100, **params ):
+        """Configure VLANHost according to (optional) parameters:
+           vlan: VLAN ID for default interface"""
+
+        r = super( Host, self ).config( **params )
+
+        intf = self.defaultIntf()
+        # remove IP from default, "physical" interface
+        self.cmd( 'ifconfig %s inet 0' % intf )
+        # create VLAN interface 
+        self.cmd( 'vconfig add %s %d' % ( intf, vlan ) )
+        # assign the host's IP to the VLAN interface
+        self.cmd( 'ifconfig %s.%d inet %s' % ( intf, vlan, params['ip'] ) )
+        # update the intf name and host's intf map
+        newName = '%s.%d' % ( intf, vlan )
+        # update the (Mininet) interface to refer to VLAN interface name
+        intf.name = newName
+        # add VLAN interface to host's name to intf map
+        self.nameToIntf[ newName ] = intf
+
+        return r
+
+hosts = { 'vlan': VLANHost }
+
+
+def exampleUsage( vlan ):
+    """Simple example of how VLANHost can be used in a script"""
+    # This is where the magic happens...
+    host = partial( VLANHost, vlan=vlan )
+    # vlan (type: int): VLAN ID to be used by all hosts
+
+    # Start a basic network using our VLANHost
+    topo = SingleSwitchTopo( k=2 )
+    net = Mininet( host=host, topo=topo )
+    net.start()
+    CLI( net )
+    net.stop()
+
+if __name__ == '__main__':
+    import sys
+    from functools import partial
+
+    from mininet.net import Mininet
+    from mininet.cli import CLI
+    from mininet.topo import SingleSwitchTopo
+
+    try:
+        vlan = int( sys.argv[ 1 ] )
+    except Exception:
+        print 'Usage: vlanhost.py <vlan id>\n'
+        print 'Using VLAN ID=100...'
+        vlan = 100
+
+    exampleUsage( vlan )