Merge remote-tracking branch 'origin/master'

+#!/usr/bin/env python
+
+''' file: custom/optical.py '''
+
+from mininet.topo import Topo
+from mininet.net import Mininet
+from mininet.cli import CLI
+from mininet.log import setLogLevel, info
+from mininet.util import irange
+
+class OpticalTopo( Topo ):
+
+    def build( self, n=3, tapStart=3 ):
+
+        # Add hosts and switches
+        hosts = []
+        switches = []
+        for i in irange( 1, n ):
+            h = self.addHost( 'h%d' % i )
+            s = self.addSwitch( 's%d' % i )
+            self.addLink( h, s )
+            hosts.append( h )
+            switches.append( s )
+
+        # Add optical tap interfaces
+        tapNum = tapStart
+        for sw in switches:
+            self.addLink( sw, sw, intfName1='%s-eth0' % sw, intfName2='tap%d' % tapNum )
+            tapNum += 1
+
+# if you use, sudo mn --custom custom/optical.py, then register the topo:
+#sudo mn --custom optical-topo.py --topo optical,5
+topos = { 'optical': OpticalTopo }
+
+def installStaticFlows( net ):
+    for swName in [ 's1', 's2', 's3', 's4', 's5', 's6' ]:
+      info( 'Adding flows to %s...' % swName )
+      sw = net[ swName ]
+      sw.dpctl( 'add-flow', 'in_port=1,actions=output=2' )
+      sw.dpctl( 'add-flow', 'in_port=2,actions=output=1' )
+      info( sw.dpctl( 'dump-flows' ) )
+
+def run():
+    net = Mininet( topo=OpticalTopo() )
+    net.start()
+    #installStaticFlows( net )
+    CLI( net )
+    net.stop()
+
+# if the script is run directly (sudo custom/optical.py):
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    run()