Add controlnet.py example.

examples/README

@@ -28,6 +28,11 @@ This example creates a network with multiple controllers by
 creating an empty network, adding nodes to it, and manually
 starting the switches.
 
+controlnet.py:
+
+This examples shows how you can model the control network as well
+as the data network, by actually creating two Mininet objects.
+
 cpu.py:
 
 This example tests iperf bandwidth for varying CPU limits.

examples/controlnet.py

@@ -0,0 +1,117 @@
+#!/usr/bin/python
+
+"""
+controlnet.py: Mininet with a custom control network
+
+We create two Mininet() networks, a control network
+and a data network, running four DataControllers on the
+control network to control the data network.
+
+Since we're using UserSwitch on the data network,
+it should correctly fail over to a backup controller.
+
+We also hack/subclass the CLI slightly so it can talk to
+both the control and data networks.
+"""
+
+from mininet.net import Mininet
+from mininet.node import Controller, UserSwitch
+from mininet.cli import CLI
+from mininet.topo import Topo
+from mininet.topolib import TreeTopo
+from mininet.log import setLogLevel, info
+
+# Some minor hacks
+
+class DataController( Controller ):
+    """Data Network Controller.
+       patched to avoid checkListening error"""
+    def checkListening( self ):
+        "Ignore spurious error"
+        pass
+
+
+class CLI2( CLI ):
+    "CLI that can talk to two networks"
+    
+    def __init__( self, *args, **kwargs ):
+        "cnet: second network"
+        self.cnet = kwargs.pop( 'cnet' )
+        CLI.__init__( self, *args, **kwargs )
+
+    def updateVars( self ):
+        "Update variables to include cnet"
+        cnet = self.cnet
+        nodes2 = cnet.controllers + cnet.switches + cnet.hosts
+        self.nodelist += nodes2
+        for node in nodes2:
+            self.nodemap[ node.name ] = node
+        self.locals[ 'cnet' ] = cnet
+        self.locals.update( self.nodemap )
+    
+    def cmdloop( self, *args, **kwargs ):
+        "Patch to add cnet if needed"
+        if 'cnet' not in self.locals:
+            self.updateVars()
+        CLI.cmdloop( self, *args, **kwargs )
+
+
+# A real control network!
+
+class ControlNetwork( Topo ):
+    "Control Network Topology"
+    def __init__( self, n, dataController=DataController, **kwargs ):
+        """n: number of data network controller nodes
+           dataController: class for data network controllers"""
+        Topo.__init__( self, **kwargs )
+        # Connect everything to a single switch
+        cs0 = self.addSwitch( 'cs0' )
+        # Add hosts which will serve as data network controllers
+        for i in range( 0, n ):
+            c = self.addHost( 'c%s' % i, cls=dataController,
+                              inNamespace=True )
+            self.addLink( c, cs0 )
+        # Connect switch to root namespace so that data network
+        # switches will be able to talk to us
+        root = self.addHost( 'root', inNamespace=False )
+        self.addLink( root, cs0 )
+
+
+# Make it Happen!!
+
+setLogLevel( 'info' )
+
+info( '* Creating Control Network\n' )
+ctopo = ControlNetwork( n=4, dataController=DataController )
+cnet = Mininet( topo=ctopo, ipBase='192.168.123.0/24', build=False )
+info( '* Adding Control Network Controller\n')
+cnet.addController( 'cc0' )
+info( '* Starting Control Network\n')
+cnet.build()
+cnet.start()
+dataControllers = cnet.hosts[ : -1 ]  # ignore 'root' node
+
+info( '* Creating Data Network\n' )
+topo = TreeTopo( depth=2, fanout=2 )
+# UserSwitch so we can easily test failover
+net = Mininet( topo=topo, switch=UserSwitch, build=False )
+info( '* Adding Controllers to Data Network\n' )
+net.controllers = dataControllers
+net.build()
+info( '* Starting Data Network\n')
+net.start()
+
+CLI2( net, cnet=cnet )
+
+info( '* Stopping Data Network\n' )
+net.stop()
+
+info( '* Stopping Control Network\n' )
+net.hosts = []  # Avoid stopping controllers twice
+cnet.stop()
+
+
+
+
+
+