Simulation of persistent vs. non-persistent CSMA in a 15-node wired LAN and compare channel utilization.

                                                Computer Networks Digital Assignment

Topic:

Simulate persistent vs. non-persistent CSMA in a 15-node wired LAN and compare channel utilization.

Code:

// csma-persistent.cc
#include "ns3/core-module.h"
#include "ns3/network-module.h"
#include "ns3/csma-module.h"
#include "ns3/internet-module.h"
#include "ns3/applications-module.h"
#include "ns3/netanim-module.h"
#include "ns3/flow-monitor-module.h"
using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("CsmaSimulation");
int main (int argc, char *argv[])
{
bool persistent = true; // change to false for non-persistent
CommandLine cmd;
cmd.AddValue ("persistent", "Enable persistent CSMA", persistent);
cmd.Parse (argc, argv);

NodeContainer nodes;
nodes.Create (15);
CsmaHelper csma;
csma.SetChannelAttribute ("DataRate", StringValue ("100Mbps"));
csma.SetChannelAttribute ("Delay", TimeValue (NanoSeconds (6560)));

NetDeviceContainer devices = csma.Install (nodes);
InternetStackHelper stack;
stack.Install (nodes);
Ipv4AddressHelper address;
address.SetBase ("10.1.1.0", "255.255.255.0");
Ipv4InterfaceContainer interfaces = address.Assign (devices);
uint16_t port = 9;

// Server on node 0
UdpServerHelper server (port);
ApplicationContainer serverApp = server.Install (nodes.Get (0));
serverApp.Start (Seconds (1.0));
serverApp.Stop (Seconds (20.0));

// Clients on remaining nodes
for (int i = 1; i < 15; i++)
{
UdpClientHelper client (interfaces.GetAddress (0), port);
client.SetAttribute ("MaxPackets", UintegerValue (1000));
client.SetAttribute ("Interval",
TimeValue (persistent ? Seconds (0.01) : Seconds (0.05))); // key difference
client.SetAttribute ("PacketSize", UintegerValue (1024));
ApplicationContainer clientApp = client.Install (nodes.Get (i));
clientApp.Start (Seconds (2.0 + i * 0.1));
clientApp.Stop (Seconds (20.0));
}

// Enable tracing
csma.EnablePcapAll ("csma");
// NetAnim
std::string mode = persistent ? "persistent" : "nonpersistent";
// NetAnim file
AnimationInterface anim ("csma-" + mode + ".xml");
// PCAP trace file
csma.EnablePcapAll ("csma-" + mode);
Simulator::Stop (Seconds (20.0));

FlowMonitorHelper flowmon;
Ptr<FlowMonitor> monitor = flowmon.InstallAll();
Simulator::Run ();
monitor->CheckForLostPackets();

Ptr<Ipv4FlowClassifier> classifier = DynamicCast<Ipv4FlowClassifier>(flowmon.GetClassifier());
std::map<FlowId, FlowMonitor::FlowStats> stats = monitor->GetFlowStats();

for (auto &flow : stats)
{
std::cout << "Flow ID: " << flow.first << std::endl;
std::cout << "Tx Packets: " << flow.second.txPackets << std::endl;
std::cout << "Rx Packets: " << flow.second.rxPackets << std::endl;
std::cout << "Throughput: " << flow.second.rxBytes * 8.0 /(flow.second.timeLastRxPacket.GetSeconds() -
flow.second.timeFirstTxPacket.GetSeconds()) / 1024 << " Kbps\n";
}
Simulator::Destroy ();
return 0;
}

Commands to run the code:

1.    Create a file in the scratch and type code in it and name it csma-persistent with extension .cc .

2.    To run code in persistent mode.

./ns3  run "scratch/csma-persistent --persistent=1"

3.    To run code in non-persistent mode:

 ./ns3  run "scratch/csma-persistent --persistent=0"

4.    Files created named:

For Persistent:

csma-persistent.xml

 

csma-persistent-*.pcap

For Non Persistent   csma-nonpersistent.xml   csma-nonpersistent-*.pcap

Output: For non-persistent:

For Persistent:

Graph: