How to Implement Star Bus Hybrid Topology in ns3

To implement a star-bus topology, we need to create nodes which is connected in a star configuration, with one of the star’s central nodes connected to bus topology.

Below are the steps to implement this in ns3.

Steps for implementation

Step 1: Install ns-3

Make sure that ns3 is installed in the computer. If not, install it.

Step 2: Create a New Simulation Script

For your simulation, create a new C++ script.

Step 3: Include Necessary Headers

include the necessary ns3 headers in your script.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/csma-module.h”

#include “ns3/mobility-module.h”

#include “ns3/applications-module.h”

Step 4: Set Up the Star-Bus Hybrid Topology

Below is an example to set up a star-bus topology with one star and a bus.

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“StarBusHybridTopology”);

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

{

// Configure command line parameters

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes

NodeContainer starCentralNode;

starCentralNode.Create (1); // Create the central node for the star topology

NodeContainer starNodes;

starNodes.Create (4); // Create 4 nodes for the star topology

NodeContainer busNodes;

busNodes.Create (4); // Create 4 nodes for the bus topology

// Set up point-to-point links for the star topology

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“1Gbps”));

pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));

NetDeviceContainer starDevices;

for (uint32_t i = 0; i < starNodes.GetN (); ++i)

{

NodeContainer pair (starCentralNode.Get (0), starNodes.Get (i));

NetDeviceContainer devicePair = pointToPoint.Install (pair);

starDevices.Add (devicePair);

}

// Set up CSMA links for the bus topology

CsmaHelper csma;

csma.SetChannelAttribute (“DataRate”, StringValue (“1Gbps”));

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

NetDeviceContainer busDevices = csma.Install (busNodes);

// Connect the central node of the star topology to the bus

NodeContainer busStarLink (starCentralNode.Get (0), busNodes.Get (0));

NetDeviceContainer busStarDevices = pointToPoint.Install (busStarLink);

// Install the internet stack

InternetStackHelper stack;

stack.Install (starCentralNode);

stack.Install (starNodes);

stack.Install (busNodes);

// Assign IP addresses to the star devices

Ipv4AddressHelper address;

address.SetBase (“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer starInterfaces = address.Assign (starDevices);

// Assign IP addresses to the bus devices

address.SetBase (“10.1.2.0”, “255.255.255.0”);

Ipv4InterfaceContainer busInterfaces = address.Assign (busDevices);

// Assign IP addresses to the bus-star link

address.SetBase (“10.1.3.0”, “255.255.255.0”);

Ipv4InterfaceContainer busStarInterfaces = address.Assign (busStarDevices);

// Set up mobility model (optional)

MobilityHelper mobility;

Ptr<ListPositionAllocator> positionAlloc = CreateObject<ListPositionAllocator> ();

positionAlloc->Add (Vector (50.0, 50.0, 0.0)); // Star central node position

positionAlloc->Add (Vector (100.0, 50.0, 0.0)); // Star node 1 position

positionAlloc->Add (Vector (50.0, 100.0, 0.0)); // Star node 2 position

positionAlloc->Add (Vector (0.0, 50.0, 0.0)); // Star node 3 position

positionAlloc->Add (Vector (50.0, 0.0, 0.0)); // Star node 4 position

positionAlloc->Add (Vector (200.0, 50.0, 0.0)); // Bus node 1 position

positionAlloc->Add (Vector (250.0, 50.0, 0.0)); // Bus node 2 position

positionAlloc->Add (Vector (300.0, 50.0, 0.0)); // Bus node 3 position

positionAlloc->Add (Vector (350.0, 50.0, 0.0)); // Bus node 4 position

mobility.SetPositionAllocator (positionAlloc);

mobility.SetMobilityModel (“ns3::ConstantPositionMobilityModel”);

mobility.Install (starCentralNode);

mobility.Install (starNodes);

mobility.Install (busNodes);

// Set up applications (e.g., UDP echo server and client)

uint16_t port = 9; // Port number for applications

// Install UDP Echo Server on the central node of the star topology

UdpEchoServerHelper echoServer (port);

ApplicationContainer serverApps = echoServer.Install (starCentralNode.Get (0));

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (10.0));

// Install UDP Echo Clients on star nodes to communicate with the central node

for (uint32_t i = 0; i < starNodes.GetN (); ++i)

{

UdpEchoClientHelper echoClient (starInterfaces.GetAddress (0), port);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (1));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));

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

ApplicationContainer clientApps = echoClient.Install (starNodes.Get (i));

clientApps.Start (Seconds (2.0 + i)); // Stagger start times

clientApps.Stop (Seconds (10.0));

}

// Install UDP Echo Clients on bus nodes to communicate with the central node

for (uint32_t i = 1; i < busNodes.GetN (); ++i)

{

UdpEchoClientHelper echoClient (busStarInterfaces.GetAddress (1), port);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (1));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));

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

ApplicationContainer clientApps = echoClient.Install (busNodes.Get (i));

clientApps.Start (Seconds (2.0 + i + starNodes.GetN ())); // Stagger start times

clientApps.Stop (Seconds (10.0));

}

// Run simulation

Simulator::Stop (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 5: Build and Run the Simulation

Save the script as star-bus-hybrid-topology.cc and build the script using waf, then run the simulation.

./waf configure –enable-examples

./waf build

./waf –run scratch/ star-bus-hybrid -topology

Explanation of the script

• Node Creation: For star topology’s central node, the star nodes, and the bus nodes, creates several nodes.
• Point-to-Point Links: To form the star topology and to connect the central node to the bus topology, configured point-to-point links.
• CSMA links: To connect the bus nodes, configured CSMA links.
• Internet Stack: On all nodes, installs the internet stack.
• IP Addressing: To star devices, bus devices, and the link connecting the star central node to the bus, assigns IP addresses.
• Mobility Model: Sets the position of nodes using ListPositionAllocator and ConstantPositionMobilityModel. This is an optional step.
• Applications: On central node of the star topology, sets up a UDP echo server and a UDP echo client on star and bus nodes to demonstrate communication.

On the whole, we had a performance analysis on the implementation on star-bus hybrid topology by creating nodes connected in a star configuration, with one of the star’s central nodes connected to a bus topology.

Even after reading it if you find hard in Implementing Star Bus Hybrid Topology in ns3 then reach us out at ns3simulation.com our developers will give you good outcome.