Merge pull request #174 from pantuza/master

Dynamic Network with Remote Controller example; Extended LinearTopo

examples/README

@@ -118,3 +118,8 @@ This example attempts to create a 1024-host network, and then runs the
 CLI on it. It may run into scalability limits, depending on available
 memory and sysctl configuration (see INSTALL.)
 
+dynamicnet.py:
+
+This example builds a network based on command line arguments and uses 
+a remote controller. It is a good option to use with POX controller and
+develop Software Defined Networks. 

examples/dynamicnet.py

+#!/usr/bin/python
+
+"""
+    This script builds a network using mininet for using with
+a remote controller like POX.
+
+    The script receives from command line two arguments. The number
+of Switches and the number of Hosts per Switch. Then, it will build
+the network topology based on this arguments.
+
+    First of all, it build a topology and add the Switches to the network.
+After that, add the same number of Hosts for each Switch added. Lastly
+it make links between each switch.
+
+@author: Gustavo Pantuza
+@since: 18.07.2013
+
+"""
+
+from optparse import OptionParser
+
+from mininet.topo import LinearTopo
+from mininet.log import setLogLevel
+from mininet.net import Mininet
+from mininet.cli import CLI
+from mininet.node import RemoteController
+
+def main():
+    # Defines the log level
+    setLogLevel('info')
+
+    # parses command line arguments
+    parser = OptionParser()
+    parser.add_option('-H', dest='hosts', default=5,
+                      help='Number of hosts per switch')
+    parser.add_option('-S', dest='switches', default=2,
+                      help='Number of switches')
+    (options, args) = parser.parse_args()
+
+    # Build network topology (see mininet/topo.py)
+    topo = LinearTopo(int(options.switches), int(options.hosts))
+
+    # Creates the Network using a remote controller
+    net = Mininet(topo,
+                  controller=lambda a: RemoteController(a, ip='127.0.0.1'))
+
+    # Starts the network
+    net.start()
+    # Run the mininet client
+    CLI(net)
+    # Stop the network
+    net.stop()
+
+if __name__ == "__main__":
+    main()

mininet/topo.py

@@ -236,23 +236,30 @@ def __init__(self, k=2, **opts):
                          port1=0, port2=(k - h + 1))
 
 class LinearTopo(Topo):
-    "Linear topology of k switches, with one host per switch."
+    "Linear topology of k switches, with n hosts per switch."
 
-    def __init__(self, k=2, **opts):
+    def __init__(self, k=2, n=1, **opts):
         """Init.
-           k: number of switches (and hosts)
+           k: number of switches
+           n: number of hosts per switch
            hconf: host configuration options
            lconf: link configuration options"""
 
         super(LinearTopo, self).__init__(**opts)
 
         self.k = k
+        self.n = n
 
         lastSwitch = None
         for i in irange(1, k):
-            host = self.addHost('h%s' % i)
+            # Add switch
             switch = self.addSwitch('s%s' % i)
-            self.addLink( host, switch)
+            # Add hosts to switch
+            for j in irange(1, n):
+              hostNum = (i-1)*n + j
+              host = self.addHost('h%s' % hostNum)
+              self.addLink(host, switch)
+            # Connect switch to previous
             if lastSwitch:
-                self.addLink( switch, lastSwitch)
+                self.addLink(switch, lastSwitch)
             lastSwitch = switch