How to Calculate Network Hubs in ns3

To calculate network hubs in ns3, we need to simulate it using CSMA (Carrier Sense Multiple Access) devices, that multiple nodes in a bus topology. To calculate the performance of network hubs, we have to set up a network with CSMA devices and measure the performance metrics such as throughput, latency, and packet loss. Here is complete guide to achieve this.

Steps for calculating Network Hubs

1. Set up the simulation :

• Make sure that ns3 is installed in the computer. If not, install it and include necessary modules.

2. Define Network Topology:

• create the network topology by incorporating CSMA devices representing the hubs.

3. Configure CSMA Devices:

• To enable traffic forwarding between subnets, Configure routing protocols on the gateway nodes.

4. Configure Applications:

• On the nodes, setup applications to generate and receive traffic.

5. Monitor Performance Metrics:

• To monitor performance metrics such as throughput, latency, and packet loss, use trace sources or callbacks.

6. Analyze Hub Performance:

• To evaluate the network hub’s performance, calculate and log the performance metrics.

Example code

Here is an example to set up a basic simulation to calculate the performance of network hubs in ns3 using CSMA devices.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/csma-module.h”

#include “ns3/applications-module.h”

#include “ns3/flow-monitor-module.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“NetworkHubExample”);

void CalculateHubPerformance (Ptr<FlowMonitor> flowMonitor, FlowMonitorHelper &flowHelper)

{

Ptr<Ipv4FlowClassifier> classifier = DynamicCast<Ipv4FlowClassifier> (flowHelper.GetClassifier ());

std::map<FlowId, FlowMonitor::FlowStats> stats = flowMonitor->GetFlowStats ();

double totalThroughput = 0.0;

double totalLatency = 0.0;

uint32_t totalPackets = 0;

uint32_t lostPackets = 0;

for (auto it = stats.begin (); it != stats.end (); ++it)

{

Ipv4FlowClassifier::FiveTuple t = classifier->FindFlow (it->first);

double throughput = it->second.rxBytes * 8.0 / (it->second.timeLastRxPacket.GetSeconds () – it->second.timeFirstTxPacket.GetSeconds ()) / 1024; // kbps

double latency = it->second.delaySum.GetSeconds () / it->second.rxPackets * 1000; // ms

uint32_t packets = it->second.rxPackets + it->second.lostPackets;

totalThroughput += throughput;

totalLatency += latency;

totalPackets += packets;

lostPackets += it->second.lostPackets;

}

double averageLatency = totalPackets > 0 ? totalLatency / stats.size () : 0;

double packetLoss = totalPackets > 0 ? (static_cast<double> (lostPackets) / totalPackets) * 100 : 0;

NS_LOG_UNCOND (“Total Throughput: ” << totalThroughput << ” kbps”);

NS_LOG_UNCOND (“Average Latency: ” << averageLatency << ” ms”);

NS_LOG_UNCOND (“Packet Loss: ” << packetLoss << ” %”);

}

int main (int argc, char *argv[])

{

CommandLine cmd;

cmd.Parse (argc, argv);

Time::SetResolution (Time::NS);

NodeContainer nodes;

nodes.Create (6);

CsmaHelper csma;

csma.SetChannelAttribute (“DataRate”, StringValue (“100Mbps”));

csma.SetChannelAttribute (“Delay”, TimeValue (NanoSeconds (6560)));

NetDeviceContainer devices;

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);

// Create a UDP server on node 5

UdpServerHelper server (9);

ApplicationContainer serverApp = server.Install (nodes.Get (5));

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

// Create UDP clients on nodes 0 to 4

for (uint32_t i = 0; i < 5; ++i)

{

UdpClientHelper client (interfaces.GetAddress (5), 9);

client.SetAttribute (“MaxPackets”, UintegerValue (320));

client.SetAttribute (“Interval”, TimeValue (MilliSeconds (10)));

client.SetAttribute (“PacketSize”, UintegerValue (1024));

ApplicationContainer clientApp = client.Install (nodes.Get (i));

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

}

FlowMonitorHelper flowHelper;

Ptr<FlowMonitor> flowMonitor = flowHelper.InstallAll ();

Simulator::Stop (Seconds (11.0));

Simulator::Run ();

CalculateHubPerformance (flowMonitor, flowHelper);

Simulator::Destroy ();

return 0;

}

Explanation

1. Setup:

Created six nodes and in a simple CSMA-based network.

1. CSMA Configuration:

To simulate a hub-like environment, CSMA channels and devices are configured.

1. Applications:

On node 5, a UDP server is installed, and a UDP client is installed on node 0 to 4 to generate traffic.

1. Flow Monitor:

To gather performance metrics like throughput, latency, and packet loss, the FlowMonitor is used.

1. CalculateHubPerformance Function:

This function calculates the total throughput, average latency, and packet loss, and logs these metrics to evaluate the performance of the network hub.

Running the Simulation

Compile and run the simulation using the following commands :

./waf configure

./waf build

./waf –run your-script-name

Replace your-script-name with the actual name of your script file.

Overall, we had a performance analysis on calculating network hub in ns3 by simulating CSMA devices, which connect multiple nodes in a bus topology. Also, we provide a detailed explanation on Network Hub.Networking comparison analysis are carried out for your projects so share with us all your parameter details we will guide you with best results on Calculating Network Hubs in ns3simulation.