Merge pull request #361 from mininet/devel/linuxrouter

Adding LinuxRouter to Examples

examples/README.md

@@ -56,6 +56,11 @@ This example shows how to use link and CPU limits.
 This example shows how to create a custom topology programatically
 by subclassing Topo, and how to run a series of tests on it.
 
+### linuxrouter.py:
+
+This example shows how to create and configure a router in Mininet
+that uses Linux IP forwarding.
+
 #### miniedit.py:
 
 This example demonstrates creating a network via a graphical editor.

examples/linuxrouter.py

+#!/usr/bin/python
+
+"""
+linuxrouter.py: Example network with Linux IP router
+ 
+This example converts a Node into a router using IP forwarding
+already built into Linux.
+
+The topology contains a router with three IP subnets:
+ - 192.168.1.0/24 (interface IP: 192.168.1.1)
+ - 172.16.0.0/12 (interface IP: 172.16.0.1)
+ - 10.0.0.0/8 (interface IP: 10.0.0.1)
+
+ It also contains three hosts, one in each subnet:
+ - h1 (IP: 192.168.1.100)
+ - h2 (IP: 172.16.0.100)
+ - h3 (IP: 10.0.0.100)
+
+ Routing entries can be added to the routing tables of the 
+ hosts or router using the "ip route add" or "route add" command.
+ See the man pages for more details.
+
+"""
+
+from mininet.topo import Topo
+from mininet.net import Mininet
+from mininet.node import Node
+from mininet.log import setLogLevel, info
+from mininet.cli import CLI
+from mininet.util import irange
+
+class LinuxRouter( Node ):
+    "A Node with IP forwarding enabled."
+
+    def config( self, **params ):
+        super( LinuxRouter, self).config( **params )
+        # Enable forwarding on the router
+        self.cmd( 'sysctl net.ipv4.ip_forward=1' )
+
+    def terminate( self ):
+        self.cmd( 'sysctl net.ipv4.ip_forward=0' )
+        super( LinuxRouter, self ).terminate()
+
+
+class NetworkTopo( Topo ):
+    "A simple topology of a router with three subnets (one host in each)."
+
+    def build( self, n=2, h=1, **opts ):
+        router = self.addNode( 'r0', cls=LinuxRouter, ip='192.168.1.1/24' )
+        h1 = self.addHost( 'h1', ip='192.168.1.100/24', defaultRoute='via 192.168.1.1' )
+        h2 = self.addHost( 'h2', ip='172.16.0.100/12', defaultRoute='via 172.16.0.1' )
+        h3 = self.addHost( 'h3', ip='10.0.0.100/8', defaultRoute='via 10.0.0.1' )
+        self.addLink( h1, router, intfName2='r0-eth1', params2={ 'ip' : '192.168.1.1/24' } )
+        self.addLink( h2, router, intfName2='r0-eth2', params2={ 'ip' : '172.16.0.1/12' } )
+        self.addLink( h3, router, intfName2='r0-eth3', params2={ 'ip' : '10.0.0.1/8' } )
+
+def run():
+    topo = NetworkTopo()
+    net = Mininet( topo=topo, controller=None ) # no controller needed
+    net.start()
+    info( '*** Routing Table on Router\n' )
+    print net[ 'r0' ].cmd( 'route' )
+    CLI( net )
+    net.stop()
+
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    run()

examples/test/test_linuxrouter.py

+#!/usr/bin/env python
+
+"""
+Test for linuxrouter.py
+"""
+
+import unittest
+import pexpect
+from mininet.util import quietRun
+
+class testLinuxRouter( unittest.TestCase ):
+
+    prompt = 'mininet>'
+
+    def testPingall( self ):
+        "Test connectivity between hosts"
+        p = pexpect.spawn( 'python -m mininet.examples.linuxrouter' )
+        p.expect( self.prompt )
+        p.sendline( 'pingall' )
+        p.expect ( '(\d+)% dropped' )
+        percent = int( p.match.group( 1 ) ) if p.match else -1
+        p.expect( self.prompt )
+        p.sendline( 'exit' )
+        p.wait()
+        self.assertEqual( percent, 0 )
+
+    def testRouterPing( self ):
+        "Test connectivity from h1 to router"
+        p = pexpect.spawn( 'python -m mininet.examples.linuxrouter' )
+        p.expect( self.prompt )
+        p.sendline( 'h1 ping -c 1 r0' )
+        p.expect ( '(\d+)% packet loss' )
+        percent = int( p.match.group( 1 ) ) if p.match else -1
+        p.expect( self.prompt )
+        p.sendline( 'exit' )
+        p.wait()
+        self.assertEqual( percent, 0 )
+
+    def testTTL( self ):
+        "Verify that the TTL is decremented"
+        p = pexpect.spawn( 'python -m mininet.examples.linuxrouter' )
+        p.expect( self.prompt )
+        p.sendline( 'h1 ping -c 1 h2' )
+        p.expect ( 'ttl=(\d+)' )
+        ttl = int( p.match.group( 1 ) ) if p.match else -1
+        p.expect( self.prompt )
+        p.sendline( 'exit' )
+        p.wait()
+        self.assertEqual( ttl, 63 ) # 64 - 1
+
+if __name__ == '__main__':
+    unittest.main()