Add Group Tests, including TestGroupAdd, TestGroupMod, TestGroupAndFlow, TestGroupForwarding, and TransparentVlanTest
diff --git a/olt-topo.py b/olt-topo.py
new file mode 100755
index 0000000..438a59f
--- /dev/null
+++ b/olt-topo.py
@@ -0,0 +1,34 @@
+#!/usr/bin/python
+
+from mininet.topo import Topo
+from mininet.node import RemoteController
+from mininet.net import Mininet
+from mininet.util import irange
+from mininet.cli import CLI
+from mininet.log import setLogLevel
+
+class OltTopo( Topo ):
+    "Single switch with OLT port 129 and configurable number of ONU ports"
+
+    def build( self, k=1, **_opts ):
+        "k: number of onu"
+        self.k = k
+        switch = self.addSwitch( 's1' )
+        for h in irange( 1, k ):
+            host = self.addHost( 'h%s' % h, inNamespace=False )
+            self.addLink( host, switch )
+
+        olt_port = self.addHost( 'h129', inNamespace=False )
+        self.addLink( olt_port, switch, port2=129 )
+
+if __name__ == '__main__':
+    setLogLevel('debug')
+    topo = OltTopo()
+
+    net = Mininet( topo=topo, controller=RemoteController )
+
+    net.start()
+
+    CLI( net )
+
+    net.stop()