print "Create Applications."
    port = 9 
    onoff = ns.applications.OnOffHelper("ns3::UdpSocketFactory", 
                            ns.network.Address(ns.network.InetSocketAddress(ns.network.Ipv4Address("10.1.1.2"), port)))
    onoff.SetConstantRate (ns.network.DataRate ("500kb/s"))
    app = onoff.Install(ns.network.NodeContainer(terminals.Get(0)))
    # empieza la aplicacion
    app.Start(ns.core.Seconds(1.0))
    sink = ns.applications.PacketSinkHelper("ns3::UdpSocketFactory",
                                ns.network.Address(ns.network.InetSocketAddress(ns.network.Ipv4Address.GetAny(), port)))
    app = sink.Install(ns.network.NodeContainer(terminals.Get(1)))
    app.Start(ns.core.Seconds(0.0))