How to Implement Grid Topology in ns3

To implement a grid topology in ns3, we need to create a network in which the nodes are aligned to a specific coordinates that are organized in a structured manner to form a grid pattern. The following steps will guide on how to implement Grid Topology in ns3.

Step-by-step to implement Grid Topology in ns3

Step 1: Install ns3

Make sure ns3 is installed on the system

Step 2: Create a New Simulation Script

Create a new C++ or Python script for your simulation. For this example, we will use C++.

Step 3: Include Necessary Headers

In your script, include the necessary ns3 headers:

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/applications-module.h”

#include “ns3/mobility-module.h”

#include “ns3/wifi-module.h”

Step 4: Set Up the Grid Topology

You can use the GridPositionAllocator class to set up a grid topology. Here is an example of setting up a 3×3 grid:

using namespace ns3;

 

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

{

// Set up default values for the simulation.

double distance = 50.0; // Distance between nodes

// Create nodes

NodeContainer nodes;

nodes.Create (9); // Create 9 nodes for a 3×3 grid

// Configure mobility model

MobilityHelper mobility;

mobility.SetPositionAllocator (“ns3::GridPositionAllocator”,

“MinX”, DoubleValue (0.0),

“MinY”, DoubleValue (0.0),

“DeltaX”, DoubleValue (distance),

“DeltaY”, DoubleValue (distance),

“GridWidth”, UintegerValue (3),

“LayoutType”, StringValue (“RowFirst”));

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

mobility.Install (nodes);

// Set up the internet stack

InternetStackHelper internet;

internet.Install (nodes);

// Assign IP addresses

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign (devices);

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

uint16_t port = 9; // Port number for applications

// Create an OnOff application to send UDP datagrams

OnOffHelper onoff (“ns3::UdpSocketFactory”, Address (InetSocketAddress (interfaces.GetAddress (1), port)));

onoff.SetConstantRate (DataRate (“500kb/s”));

ApplicationContainer apps = onoff.Install (nodes.Get (0));

apps.Start (Seconds (1.0));

apps.Stop (Seconds (10.0));

// Create a packet sink to receive these packets

PacketSinkHelper sink (“ns3::UdpSocketFactory”, Address (InetSocketAddress (Ipv4Address::GetAny (), port)));

apps = sink.Install (nodes.Get (1));

apps.Start (Seconds (0.0));

apps.Stop (Seconds (10.0));

// Run simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 5: Build and Run the Simulation

1. Save the script as grid-topology.cc.
2. Build the script using waf:

./waf configure –enable-examples

./waf build

1. Run the simulation:

./waf –run scratch/grid-topology

Explanation of the Script

• Node Creation: Creates 9 nodes to form a 3×3 grid.
• Position Allocator: Configures the GridPositionAllocator to place nodes in a grid with specified distances between them.
• Mobility Model: Sets the mobility model to ConstantPositionMobilityModel to keep nodes static.
• Internet Stack: Installs the internet stack on all nodes.
• IP Addressing: Assigns IP addresses to the nodes.
• Applications: Sets up a UDP echo server and client to demonstrate communication between nodes.

Finally, we all get to know how to implement Grid topology in ns3 and we have used C++ script for the simulation process and USP applications for the communication between the nodes.

Share the specifics of your parameters so we can help you to analyze your networking performance on a Grid topology.