How to Implement Network Topology in OMNeT++

To implement network topology in OMNeT++ has needs to state the layout of nodes like hosts, routers, or switches and the connections among them. The topology can signify numerous network architectures such as star, mesh, ring, or custom layouts. Here, we can see the brief procedures on how to implement the network topology in OMNeT++.

Step-by-Step Implementation:

1. Set Up OMNeT++ Environment:

• Install OMNeT++: Make sure OMNeT++ is installed on system.
• Install INET Framework: Download and set up the INET framework that delivers the necessary models for networking components.

2. Create a Simple Network Topology:

Initiate by generating a simple network topology with a few nodes and connections.

Example 1: Star Topology

In a star topology, all nodes are interconnected to a central hub (or switch/router).

Example NED File (StarTopology.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network StarTopology

{

submodules:

centralRouter: Router {

@display(“p=200,200”);

}

host1: StandardHost {

@display(“p=100,100”);

}

host2: StandardHost {

@display(“p=300,100”);

}

host3: StandardHost {

@display(“p=100,300”);

}

host4: StandardHost {

@display(“p=300,300”);

}

connections:

host1.pppg++ <–> ethernetLine <–> centralRouter.pppg++;

host2.pppg++ <–> ethernetLine <–> centralRouter.pppg++;

host3.pppg++ <–> ethernetLine <–> centralRouter.pppg++;

host4.pppg++ <–> ethernetLine <–> centralRouter.pppg++;

}

This sample describes a basic star topology where four hosts are connected to a central router.

3. Create a Mesh Topology:

A mesh topology has nodes that are fully interconnected their implication is each node is connected to every other node.

Example NED File (MeshTopology.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network MeshTopology

{

submodules:

host1: StandardHost {

@display(“p=100,100”);

}

host2: StandardHost {

@display(“p=300,100”);

}

host3: StandardHost {

@display(“p=100,300”);

}

host4: StandardHost {

@display(“p=300,300”);

}

connections allowunconnected:

host1.pppg++ <–> ethernetLine <–> host2.pppg++;

host1.pppg++ <–> ethernetLine <–> host3.pppg++;

host1.pppg++ <–> ethernetLine <–> host4.pppg++;

host2.pppg++ <–> ethernetLine <–> host3.pppg++;

host2.pppg++ <–> ethernetLine <–> host4.pppg++;

host3.pppg++ <–> ethernetLine <–> host4.pppg++;

}

This sample generates a fully connected mesh topology with four hosts.

4. Create a Ring Topology:

In a ring topology, each node is linked to exactly two other nodes that forms a circular path.

Example NED File (RingTopology.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network RingTopology

{

submodules:

host1: StandardHost {

@display(“p=100,200”);

}

host2: StandardHost {

@display(“p=200,100”);

}

host3: StandardHost {

@display(“p=300,200”);

}

host4: StandardHost {

@display(“p=200,300”);

}

connections:

host1.pppg++ <–> ethernetLine <–> host2.pppg++;

host2.pppg++ <–> ethernetLine <–> host3.pppg++;

host3.pppg++ <–> ethernetLine <–> host4.pppg++;

host4.pppg++ <–> ethernetLine <–> host1.pppg++;

}

This sample forms a ring topology with four hosts.

5. Create a Custom Topology:

We need to generate any custom topology by manually stipulating the connections among nodes.

Example NED File (CustomTopology.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network CustomTopology

{

submodules:

router1: Router {

@display(“p=200,200”);

}

router2: Router {

@display(“p=400,200”);

}

host1: StandardHost {

@display(“p=100,100”);

}

host2: StandardHost {

@display(“p=300,100”);

}

host3: StandardHost {

@display(“p=500,100”);

}

host4: StandardHost {

@display(“p=300,300”);

}

connections:

host1.pppg++ <–> ethernetLine <–> router1.pppg++;

router1.pppg++ <–> ethernetLine <–> router2.pppg++;

host2.pppg++ <–> ethernetLine <–> router1.pppg++;

host3.pppg++ <–> ethernetLine <–> router2.pppg++;

host4.pppg++ <–> ethernetLine <–> router2.pppg++;

}

This custom topology connects two routers and four hosts in particular layout.

6. Simulate Network Traffic:

To track how the topology behaves under traffic, add traffic generators to the network.

Example Traffic Generator (TrafficGenerator.ned):

package mynetwork;

import inet.applications.udpapp.UDPBasicApp;

import inet.applications.udpapp.UDPSink;

network TrafficNetwork

{

submodules:

hostA: StandardHost {

@display(“p=100,100”);

applications: <udpbasicapp> {

localPort = 1234;

destAddresses = “hostB”;

destPort = 5678;

messageLength = 1000B;

sendInterval = 1s;

numPackets = 100;

}

}

hostB: StandardHost {

@display(“p=300,100”);

applications: <udpsink> {

localPort = 5678;

}

}

router: Router {

@display(“p=200,200”);

}

connections:

hostA.pppg++ <–> ethernetLine <–> router.pppg++;

router.pppg++ <–> ethernetLine <–> hostB.pppg++;

}

This example creates UDP traffic from hostA to hostB through a router.

7. Run the Simulation:

• Compile and run the simulation using OMNeT++.
• Monitor the behaviour of the network in the simulation environment.
• Use OMNeT++’s visualization tools to examine packet flows, delays, and other network characteristics.

8. Extend the Topology:

• Add more nodes and routers: Upsurge the complexity of the network by adding more devices.
• Implement different network protocols: validate how numerous protocols like TCP, UDP, OSPF, and RIP that perform in the topology.
• Measure performance metrics: Use OMNeT++ to evaluate latency, throughput, packet loss, etc., for numerous topologies.

9. Example of a Complex Topology:

Example NED File (ComplexTopology.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network ComplexTopology

{

submodules:

router1: Router {

@display(“p=100,200”);

}

router2: Router {

@display(“p=300,200”);

}

router3: Router {

@display(“p=500,200”);

}

host1: StandardHost {

@display(“p=50,100”);

}

host2: StandardHost {

@display(“p=150,100”);

}

host3: StandardHost {

@display(“p=350,100”);

}

host4: StandardHost {

@display(“p=550,100”);

}

host5: StandardHost {

@display(“p=650,100”);

}

connections:

host1.pppg++ <–> ethernetLine <–> router1.pppg++;

host2.pppg++ <–> ethernetLine <–> router1.pppg++;

router1.pppg++ <–> ethernetLine <–> router2.pppg++;

host3.pppg++ <–> ethernetLine <–> router2.pppg++;

router2.pppg++ <–> ethernetLine <–> router3.pppg++;

host4.pppg++ <–> ethernetLine <–> router3.pppg++;

host5.pppg++ <–> ethernetLine <–> router3.pppg++;

}

This instance generates a more complex network with three routers and five hosts, that demonstrating how to scale up the topology.

We had understood how to execute and verify the network topology among the various layouts that were implemented in OMNeT++ tool. We also deliver more information regarding the network topology performance in other simulation settings. Our developers  work on every aspect of network topology in the OMNeT++ tool; our services are customized. Let our developers take care of your network’s performance.