#

# * 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   n2   n3

#       |     |    |    |

#       =================

#              LAN

#

# - UDP flows from n0 to n1 and back

# - DropTail queues 

# - Tracing of queues and packet receptions to file "udp-echo.tr"

import ns3

def main(argv):

  #

  # 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)

  #

  # But since this is a realtime script, don't allow the user to mess with

  # that.

  #

  ns3.GlobalValue.Bind("SimulatorImplementationType", ns3.StringValue("ns3::RealtimeSimulatorImpl"))

  #

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

  #

  print "Create nodes."

  n = ns3.NodeContainer()

  n.Create(4)

  internet = ns3.InternetStackHelper()

  internet.Install(n)

  #

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

  #

  print ("Create channels.")

  csma = ns3.CsmaHelper()

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

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

  csma.SetDeviceAttribute("Mtu", ns3.UintegerValue(1400))

  d = csma.Install(n)

  #

  # 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"))

  i = ipv4.Assign(d)

  print ("Create Applications.")

  #

  # Create a UdpEchoServer application on node one.

  #

  port = 9  # well-known echo port number

  server = ns3.UdpEchoServerHelper(port)

  apps = server.Install(n.Get(1))

  apps.Start(ns3.Seconds(1.0))

  apps.Stop(ns3.Seconds(10.0))

  #

  # Create a UdpEchoClient application to send UDP datagrams from node zero to

  # node one.

  #

  packetSize = 1024

  maxPacketCount = 500

  interPacketInterval = ns3.Seconds(0.01)

  client = ns3.UdpEchoClientHelper(i.GetAddress (1), port)

  client.SetAttribute("MaxPackets", ns3.UintegerValue(maxPacketCount))

  client.SetAttribute("Interval", ns3.TimeValue(interPacketInterval))

  client.SetAttribute("PacketSize", ns3.UintegerValue(packetSize))

  apps = client.Install(n.Get(0))

  apps.Start(ns3.Seconds(2.0))

  apps.Stop(ns3.Seconds(10.0))

  ascii = ns3.AsciiTraceHelper()

  csma.EnableAsciiAll(ascii.CreateFileStream("realtime-udp-echo.tr"))

  csma.EnablePcapAll("realtime-udp-echo", False)

  #

  # Now, do the actual simulation.

  #

  print ("Run Simulation.")

  ns3.Simulator.Run()

  ns3.Simulator.Destroy()

  print ("Done.")

if __name__ == '__main__':

  import sys

  main(sys.argv)