How to Implement Network Layer in OMNeT++

To implement the network layer in OMNeT++ requires to involve numerous stages, containing set up the simulation setting, defining network components, and creating the network layer itself.

The following step-by-step process is help to implement Network Layer in OMNeT++:

Step-by-Step Implementations:

1. Set up the OMNeT++ Environment

• Install OMNeT++: Make sure OMNeT++ is installed on the system. We can download it from the OMNeT++
• Create a New Project: Start OMNeT++, make a new project, and set up the essential folders for the simulation like src for source code, ned for network description files.

2. Define Network Components

• Create NED Files: Describe the structure of the network using NED (Network Description) files. It includes specifying modules and their connections.

Example NED File:

network SimpleNetwork

{

submodules:

node1: Node;

node2: Node;

connections:

node1.out –> node2.in;

node2.out –> node1.in;

}

3. Develop the Network Layer Module

• Create the Network Layer C++ Class: State a new C++ class for the network layer. It will manage the network layer’s functionalities, like packet forwarding, routing, etc.

Example Network Layer Class:

#include <omnetpp.h>

#include “Packet_m.h”

using namespace omnetpp;

class NetworkLayer : public cSimpleModule

{

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

};

Define_Module(NetworkLayer);

void NetworkLayer::initialize()

{

// Initialization code

}

void NetworkLayer::handleMessage(cMessage *msg)

{

// Handle incoming packets

if (Packet *pkt = dynamic_cast<Packet *>(msg)) {

// Perform network layer functions like routing, forwarding, etc.

// For simplicity, just forward to next layer

send(pkt, “out”);

}

}

4. Integrate the Network Layer into the Nodes

• Extend Node Definition: Change the NED file for the nodes to contain the network layer.

Example Node Definition:

simple Node

{

gates:

input in;

output out;

submodules:

netLayer: NetworkLayer;

appLayer: ApplicationLayer;

connections:

in –> netLayer.in;

netLayer.out –> appLayer.in;

appLayer.out –> netLayer.in;

netLayer.out –> out;

}

5. Configure the Simulation

• Omnetpp.ini File: Configure simulation parameters in the omnetpp.ini file. Denote simulation time, network topology, etc.

Example omnetpp.ini File:

[General]

network = SimpleNetwork

sim-time-limit = 100s

6. Run the Simulation

• Compile and Execute: Build the project and run the simulation. OMNeT++ will implement the defined network scenario, utilizing the network layer implementation.

7. Analyse Results

• Visualize and Analyse: To visualize the network’s behaviour and analyse the results by using  OMNeT++’s graphical tools.

8. Advanced Features (Optional)

• Routing Algorithms: Implement specific routing algorithms in the network layer like Dijkstra, AODV.
• Packet Processing: Increase packet inspection and modification logic, like header manipulation.
• Protocol Stack Integration: Add the network layer with other layers like transport, application.

In this paper, we provided how to define network components, develop network layer module, some examples, and advanced features to execute Network Layer in OMNeT++. We share more simulation ideas  about Network Layer as per your needs.