Move router class to its own file

.gitignore

@@ -1 +1,2 @@
 logs/
+*.pyc

router.py

@@ -0,0 +1,27 @@
+from mininet.node import Switch, Node
+
+
+class Router(Switch):
+    """Defines a new router that is inside a network namespace so that the
+    individual routing entries don't collide.
+
+    """
+
+    ID = 0
+
+    def __init__(self, name, **kwargs):
+
+        kwargs['inNamespace'] = True
+        Switch.__init__(self, name, **kwargs)
+
+        Router.ID += 1
+        self.switch_id = Router.ID
+
+    def start(self, controllers):
+        pass
+
+    def defaultIntf(self):
+        if hasattr(self, "controlIntf") and self.controlIntf:
+            return self.controlIntf
+
+        return Node.defaultIntf(self)

two-nodes/net.py

@@ -1,64 +1,41 @@
 #!/usr/bin/env python
 
+import os
+import sys
+
 from mininet.topo import Topo
 from mininet.net import Mininet
 from mininet.cli import CLI
-from mininet.node import Switch, Node
 
-import os
-
-class Router(Switch):
-    """Defines a new router that is inside a network namespace so that the
-    individual routing entries don't collide.
-    """
-    ID = 0
-    def __init__(self, name, **kwargs):
-        kwargs['inNamespace'] = True
-        Switch.__init__(self, name, **kwargs)
-        Router.ID += 1
-        self.switch_id = Router.ID
-
-    @staticmethod
-    def setup():
-        return
-
-    def defaultIntf( self ):
-        if hasattr(self, "controlIntf") and self.controlIntf:
-            return self.controlIntf
-        else:
-            return Node.defaultIntf(self)
-
-    def start(self, controllers):
-        pass
-
-    def stop(self):
-        self.deleteIntfs()
+sys.path.append(os.path.join(
+    os.path.dirname(os.path.realpath(__file__)),
+    '..'))
+from router import Router
 
 
 class NetTopo(Topo):
     """The network topology.
     """
+
     def __init__(self):
         # Add default members to class.
-        super(NetTopo, self ).__init__()
+        super(NetTopo, self).__init__()
 
         # The topology has one router per AS
-	routers = [
-            self.addSwitch('R1'),
-            self.addSwitch('R2'),
-        ]
-        hosts = []
+        r_1 = self.addSwitch('R1')
+        r_2 = self.addSwitch('R2')
 
         # Setup the links as follows:
         #
         # R1 --- R2
         #
-        self.addLink('R1', 'R2')
-
-        return
+        self.addLink(r_1, r_2)
 
 
-def main():
+def scenario():
+    """Start the network scenario.
+    """
+
     os.system("rm -f /tmp/R*.log /tmp/R*.pid logs/*")
     os.system("mn -c >/dev/null 2>&1")
     os.system("killall -9 zebra > /dev/null 2>&1")
@@ -71,7 +48,12 @@ def main():
         router.waitOutput()
 
         # Start Zebra (routing table daemon)
-        router.cmd("/usr/lib/frr/zebra -f conf/zebra-%s.conf -d -i /tmp/zebra-%s.pid > logs/%s-zebra-stdout 2>&1" % (router.name, router.name, router.name))
+        router.cmd("/usr/lib/frr/zebra"
+                   " -f conf/zebra-%s.conf"
+                   " -d"
+                   " -i /tmp/zebra-%s.pid"
+                   " > logs/%s-zebra-stdout 2>&1"
+                   % (router.name, router.name, router.name))
         router.waitOutput()
 
         # Delete spare loopback address for convenience
@@ -84,4 +66,4 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    scenario()