# /*

#  * This program is free software; you can redistribute it and/or modify

#  * it under the terms of the GNU General Public License version 2 as

#  * published by the Free Software Foundation

#  *

#  * This program is distributed in the hope that it will be useful,

#  * but WITHOUT ANY WARRANTY; without even the implied warranty of

#  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

#  * GNU General Public License for more details.

#  *

#  * You should have received a copy of the GNU General Public License

#  * along with this program; if not, write to the Free Software

#  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#  */

# Network topology

#

#        n0     n1  

#        |      | 

#       ----------

#       | Switch |

#       ----------

#        |      | 

#        n2     n3  

#

#

# - CBR/UDP flows from n0 to n1 and from n3 to n0

# - DropTail queues 

# - Tracing of queues and packet receptions to file "csma-bridge.tr"

import ns3

def main(argv):

    #

    # Make the random number generators generate reproducible results.

    #

    ns3.RandomVariable.UseGlobalSeed(1, 1, 2, 3, 5, 8)

    #

    # Allow the user to override any of the defaults and the above Bind() at

    # run-time, via command-line arguments

    #

    cmd = ns3.CommandLine()

    cmd.Parse(argv)

    #

    # Explicitly create the nodes required by the topology(shown above).

    #

    print "Create nodes."

    terminals = ns3.NodeContainer()

    terminals.Create(4)

    csmaSwitch = ns3.NodeContainer()

    csmaSwitch.Create(1)

    print "Build Topology"

    csma = ns3.CsmaHelper()

    csma.SetChannelAttribute("DataRate", ns3.DataRateValue(ns3.DataRate(5000000)))

    csma.SetChannelAttribute("Delay", ns3.TimeValue(ns3.MilliSeconds(2)))

    # Create the csma links, from each terminal to the switch

    terminalDevices = ns3.NetDeviceContainer()

    switchDevices = ns3.NetDeviceContainer()

    for i in range(4):

        link = csma.Install(ns3.NodeContainer(ns3.NodeContainer(terminals.Get(i)), csmaSwitch))

        terminalDevices.Add(link.Get(0))

        switchDevices.Add(link.Get(1))

    # Create the bridge netdevice, which will do the packet switching

    switchNode = csmaSwitch.Get(0)

    bridgeDevice = ns3.BridgeNetDevice()

    switchNode.AddDevice(bridgeDevice)

    for portIter in range(switchDevices.GetN()):

        bridgeDevice.AddBridgePort(switchDevices.Get(portIter))

    # Add internet stack to the terminals

    internet = ns3.InternetStackHelper()

    internet.Install(terminals)

    # We've got the "hardware" in place.  Now we need to add IP addresses.

    #

    print "Assign IP Addresses."

    ipv4 = ns3.Ipv4AddressHelper()

    ipv4.SetBase(ns3.Ipv4Address("10.1.1.0"), ns3.Ipv4Mask("255.255.255.0"))

    ipv4.Assign(terminalDevices)

    #

    # Create an OnOff application to send UDP datagrams from node zero to node 1.

    #

    print "Create Applications."

    port = 9   # Discard port(RFC 863)

    onoff = ns3.OnOffHelper("ns3::UdpSocketFactory", 

                            ns3.Address(ns3.InetSocketAddress(ns3.Ipv4Address("10.1.1.2"), port)))

    onoff.SetAttribute("OnTime", ns3.RandomVariableValue(ns3.ConstantVariable(1)))

    onoff.SetAttribute("OffTime", ns3.RandomVariableValue(ns3.ConstantVariable(0)))

    app = onoff.Install(ns3.NodeContainer(terminals.Get(0)))

    # Start the application

    app.Start(ns3.Seconds(1.0))

    app.Stop(ns3.Seconds(10.0))

    # Create an optional packet sink to receive these packets

    sink = ns3.PacketSinkHelper("ns3::UdpSocketFactory",

                                ns3.Address(ns3.InetSocketAddress(ns3.Ipv4Address.GetAny(), port)))

    sink.Install(ns3.NodeContainer(terminals.Get(1)))

    # 

    # Create a similar flow from n3 to n0, starting at time 1.1 seconds

    #

    onoff.SetAttribute("Remote", 

                       ns3.AddressValue(ns3.InetSocketAddress(ns3.Ipv4Address("10.1.1.1"), port)))

    app2 = onoff.Install(ns3.NodeContainer(terminals.Get(3)))

    sink.Install(ns3.NodeContainer(terminals.Get(0)))

    app2.Start(ns3.Seconds(1.1))

    app2.Stop(ns3.Seconds(10.0))

    #

    # Configure tracing of all enqueue, dequeue, and NetDevice receive events.

    # Trace output will be sent to the file "csma-bridge.tr"

    #

    #print "Configure Tracing."

    #std.ofstream ascii

    #ascii.open("csma-bridge.tr")

    #CsmaHelper.EnableAsciiAll(ascii)

    #

    # Also configure some tcpdump traces; each interface will be traced.

    # The output files will be named:

    #     csma-bridge.pcap-<nodeId>-<interfaceId>

    # and can be read by the "tcpdump -r" command(use "-tt" option to

    # display timestamps correctly)

    #

    ns3.CsmaHelper.EnablePcapAll("csma-bridge")

    #

    # Now, do the actual simulation.

    #

    print "Run Simulation."

    ns3.Simulator.Run()

    ns3.Simulator.Destroy()

    print "Done."

if __name__ == '__main__':

    import sys

    main(sys.argv)