Merge pull request #229 from mininet/devel/mobility-example

A simple mobility API and example

examples/README.md

@@ -65,6 +65,11 @@ that uses Linux IP forwarding.
 
 This example demonstrates creating a network via a graphical editor.
 
+#### mobility.py
+
+This example demonstrates detaching an interface from one switch and
+attaching it another as a basic way to move a host around a network.
+
 #### multiping.py:
 
 This example demonstrates one method for

examples/mobility.py

@@ -0,0 +1,136 @@
+#!/usr/bin/python
+
+"""
+Simple example of Mobility with Mininet
+(aka enough rope to hang yourself.)
+
+We move a host from s1 to s2, s2 to s3, and then back to s1.
+
+Gotchas:
+
+The reference controller doesn't support mobility, so we need to
+manually flush the switch flow tables!
+
+Good luck!
+
+to-do:
+
+- think about wifi/hub behavior
+- think about clearing last hop - why doesn't that work?
+"""
+
+from mininet.net import Mininet
+from mininet.node import OVSSwitch
+from mininet.topo import LinearTopo
+from mininet.util import quietRun
+from mininet.log import output, warn
+
+from random import randint
+from re import findall
+
+
+class MobilitySwitch( OVSSwitch ):
+    "Switch that can reattach and rename interfaces"
+
+    def delIntf( self, intf ):
+        "Remove (and detach) an interface"
+        port = self.ports[ intf ]
+        del self.ports[ intf ]
+        del self.intfs[ port ]
+        del self.nameToIntf[ intf.name ]
+
+    def addIntf( self, intf, rename=False, **kwargs ):
+        "Add (and reparent) an interface"
+        OVSSwitch.addIntf( self, intf, **kwargs )
+        intf.node = self
+        if rename:
+            self.renameIntf( intf )
+
+    def attach( self, intf ):
+        "Attach an interface and set its port"
+        port = self.ports[ intf ]
+        if port:
+            if self.isOldOVS():
+                self.cmd( 'ovs-vsctl add-port', self, intf )
+            else:
+                self.cmd( 'ovs-vsctl add-port', self, intf,
+                          '-- set Interface', intf,
+                          'ofport_request=%s' % port )
+            self.validatePort( intf )
+
+    def validatePort( self, intf ):
+        "Validate intf's OF port number"
+        ofport = int( self.cmd( 'ovs-vsctl get Interface', intf,
+                              'ofport' ) )
+        if ofport != self.ports[ intf ]:
+            warn( 'WARNING: ofport for', intf, 'is actually', ofport,
+                  '\n' )
+
+    def renameIntf( self, intf, newname='' ):
+        "Rename an interface (to its canonical name)"
+        intf.ifconfig( 'down' )
+        if not newname:
+            newname = '%s-eth%d' % ( self.name, self.ports[ intf ] )
+        intf.cmd( 'ip link set', intf, 'name', newname )
+        del self.nameToIntf[ intf.name ]
+        intf.name = newname
+        self.nameToIntf[ intf.name ] = intf
+        intf.ifconfig( 'up' )
+
+    def moveIntf( self, intf, switch, port=None, rename=True ):
+        "Move one of our interfaces to another switch"
+        self.detach( intf )
+        self.delIntf( intf )
+        switch.addIntf( intf, port=port, rename=rename )
+        switch.attach( intf )
+
+
+def printConnections( switches ):
+    "Compactly print connected nodes to each switch"
+    for sw in switches:
+        output( '%s: ' % sw )
+        for intf in sw.intfList():
+            link = intf.link
+            if link:
+                intf1, intf2 = link.intf1, link.intf2
+                remote = intf1 if intf1.node != sw else intf2
+                output( '%s(%s) ' % ( remote.node, sw.ports[ intf ] ) )
+        output( '\n' )
+
+
+def moveHost( host, oldSwitch, newSwitch, newPort=None ):
+    "Move a host from old switch to new switch"
+    hintf, sintf = host.connectionsTo( oldSwitch )[ 0 ]
+    oldSwitch.moveIntf( sintf, newSwitch, port=newPort )
+    return hintf, sintf
+
+
+def mobilityTest():
+    "A simple test of mobility"
+    print '* Simple mobility test'
+    net = Mininet( topo=LinearTopo( 3 ), switch=MobilitySwitch )
+    print '* Starting network:'
+    net.start()
+    printConnections( net.switches )
+    print '* Testing network'
+    net.pingAll()
+    print '* Identifying switch interface for h1'
+    h1, old = net.get( 'h1', 's1' )
+    for s in 2, 3, 1:
+        new = net[ 's%d' % s ]
+        port = randint( 10, 20 )
+        print '* Moving', h1, 'from', old, 'to', new, 'port', port
+        hintf, sintf = moveHost( h1, old, new, newPort=port )
+        print '*', hintf, 'is now connected to', sintf
+        print '* Clearing out old flows'
+        for sw in net.switches:
+            sw.dpctl( 'del-flows' )
+        print '* New network:'
+        printConnections( net.switches )
+        print '* Testing connectivity:'
+        net.pingAll()
+        old = new
+    net.stop()
+
+if __name__ == '__main__':
+    mobilityTest()

examples/test/test_mobility.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+"""
+Test for mobility.py
+"""
+
+import unittest
+from subprocess import check_output
+
+class testMobility( unittest.TestCase ):
+
+    def testMobility( self ):
+        "Run the example and verify its 4 ping results"
+        cmd = 'python -m mininet.examples.mobility 2>&1'
+        grep = ' | grep -c " 0% dropped" '
+        result = check_output( cmd + grep, shell=True )
+        assert int( result ) == 4
+
+if __name__ == '__main__':
+    unittest.main()