// - Node n4 listens for the data 

#include "ns3/core-module.h"

#include "ns3/helper-module.h"

#include "ns3/simulator-module.h"

  //

  // Users may find it convenient to turn on explicit debugging

  // for selected modules; the below lines suggest how to do this

  //

  // LogComponentEnable ("CsmaMulticastExample", LOG_LEVEL_INFO);

  //

  // Set up default values for the simulation.  

  //

  // Select Ethernet II-style encapsulation (no LLC/Snap header)

  Config::SetDefault ("ns3::CsmaNetDevice::EncapsulationMode", String ("IpArp"));  

  // Allow the user to override any of the defaults at

  // run-time, via command-line arguments

  NS_LOG_INFO ("Create nodes.");

  NodeContainer c;

  c.Create (5);

  // We will later want two subcontainers of these nodes, for the two LANs

  NodeContainer c0 = NodeContainer (c.Get (0), c.Get (1), c.Get (2));

  NodeContainer c1 = NodeContainer (c.Get (2), c.Get (3), c.Get (4));

  NS_LOG_INFO ("Build Topology.");

  CsmaHelper csma;

  csma.SetChannelParameter ("BitRate", DataRate (5000000));

  csma.SetChannelParameter ("Delay", MilliSeconds (2));

  // We will use these NetDevice containers later, for IP addressing

  NetDeviceContainer nd0 = csma.Build (c0);  // First LAN

  NetDeviceContainer nd1 = csma.Build (c1);  // Second LAN

  NS_LOG_INFO ("Add IP Stack.");

  InternetStackHelper internet;

  internet.Build (c0);

  internet.Build (c1);

  NS_LOG_INFO ("Assign IP Addresses.");

  Ipv4AddressHelper ipv4Addr;

  ipv4Addr.SetBase ("10.1.1.0", "255.255.255.0");

  ipv4Addr.Allocate (nd0);

  ipv4Addr.SetBase ("10.1.2.0", "255.255.255.0");

  ipv4Addr.Allocate (nd1);

  //

  // Now we can configure multicasting.  As described above, the multicast 

  // source is at node zero, which we assigned the IP address of 10.1.1.1 

  // earlier.  We need to define a multicast group to send packets to.  This

  // can be any multicast address from 224.0.0.0 through 239.255.255.255

  // (avoiding the reserved routing protocol addresses).  

  //

  // Now, we will set up multicast routing.  We need to do three things:

  // 1) Configure a (static) multicast route on node n2

  // 2) Set up a default multicast route on the sender n0 

  // 3) Have node n4 join the multicast group

  // We have a helper that can help us with static multicast

  StaticMulticastRouteHelper multicast;

  // 1) Configure a (static) multicast route on node n2 (multicastRouter)

  Ptr<Node> multicastRouter = c.Get (2);  // The node in question

  Ptr<NetDevice> inputIf = nd0.Get (2);  // The input NetDevice

  NetDeviceContainer outputDevices;  // A container of output NetDevices

  outputDevices.Add (nd1.Get (0));  // (we only need one NetDevice here)

  multicast.AddMulticastRoute (multicastRouter, multicastSource, 

    multicastGroup, inputIf, outputDevices);

  // 2) Set up a default multicast route on the sender n0 

  Ptr<Node> sender = c.Get (0);

  Ptr<NetDevice> senderIf = nd0.Get(0);

  multicast.SetDefaultMulticastRoute (sender, senderIf);

  // 3) Have node n4 join the multicast group

  Ptr<Node> receiver = c.Get (4);

  multicast.JoinMulticastGroup (receiver, multicastSource, multicastGroup);

  //

  // Create an OnOff application to send UDP datagrams from node zero to the

  // multicast group (node four will be listening).

  //

  uint16_t multicastPort = 9;   // Discard port (RFC 863)

  OnOffHelper onoff;

  onoff.SetUdpRemote (multicastGroup, multicastPort);

  onoff.SetAppAttribute ("OnTime", ConstantVariable (1));

  onoff.SetAppAttribute ("OffTime", ConstantVariable (0));

  onoff.SetAppAttribute ("DataRate", DataRate ("255b/s"));

  onoff.SetAppAttribute ("PacketSize", Uinteger (128));

  ApplicationContainer srcC = onoff.Build (c0.Get (0));

  //

  // Tell the application when to start and stop.

  //

  srcC.Start(Seconds(1.));

  srcC.Stop (Seconds(10.));

  PacketSinkHelper sink;

  sink.SetupUdp (Ipv4Address::GetAny(), multicastPort);

  ApplicationContainer sinkC = sink.Build (c1.Get (2)); // Node n4 

  sinkC.Start (Seconds (1.0));

  sinkC.Stop (Seconds (10.0));

  //

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

  // Trace output will be sent to the file "csma-multicast.tr"

  //

  //

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

  // The output files will be named:

  //     csma-multicast.pcap-<nodeId>-<interfaceId>

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

  // display timestamps correctly)

  //

  //

  // Now, do the actual simulation.

  //