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How to Implement Irregular Topology in OMNeT++

To implement an irregular topology in OMNeT++, the nodes should be linked in an arbitrary and non-uniform manner in the created network. It should not have a fixed pattern or structure like those in the regular topologies (like mesh, ring, star). In irregular topologies, nodes can be added over time and connections are made depends on the different factors like availability, cost or geographical constraints. Follow the offered steps below to implement the irregular topology:

Step-by-Step Implementation:

  1. Set Up OMNeT++ and INET Framework
  • Make certain OMNeT++ and INET framework is properly installed and configured. To simulate the multiple network topologies as well as irregular ones, we can use the essential modules which are provided by the INET framework.
  1. Define the Irregular Topology in a NED File
  • State the network topology by creating a .ned file. Based on the specific criteria or randomness, the node’s connection are manually stated in an irregular topology.

Example: An Irregular Topology with 6 Nodes

package irregularTopologyExample;

import inet.node.inet.StandardHost;

network IrregularTopology

{

parameters:

int numNodes = default(6);  // Number of nodes in the irregular topology

submodules:

node[numNodes]: StandardHost {

parameters:

@display(“p=100+150*cos(pi/2+i*2*pi/numNodes),100+150*sin(pi/2+i*2*pi/numNodes)”);

}

connections allowunconnected:

// Define irregular connections between nodes

node[0].ethg++ <–> EtherChannel <–> node[1].ethg++;

node[0].ethg++ <–> EtherChannel <–> node[2].ethg++;

node[1].ethg++ <–> EtherChannel <–> node[3].ethg++;

node[2].ethg++ <–> EtherChannel <–> node[4].ethg++;

node[3].ethg++ <–> EtherChannel <–> node[5].ethg++;

node[4].ethg++ <–> EtherChannel <–> node[5].ethg++;

}

  • Irregular Connections: The connections amongst nodes are defined manually, permitting for an irregular and non-uniform topology.
  • Nodes: Every node can signify a host, router, or any network device.
  1. Configure the Nodes in OMNeT++ INI File
  • Configure the properties of the nodes like IP addresses, routing, and the applications they will run in the omnetpp.ini file.

Example:

network = irregularTopologyExample.IrregularTopology

# Configure IP addresses for the nodes

*.node[*].ipv4.arp.typename = “GlobalArp”

*.node[*].eth[0].ipv4.address = “10.0.0.x”

*.node[*].eth[0].ipv4.netmask = “255.255.255.0”

# Example application setup: node[0] communicates with node[5]

*.node[0].numApps = 1

*.node[0].app[0].typename = “UdpBasicApp”

*.node[0].app[0].destAddresses = “10.0.0.6”  # IP address of node[5]

*.node[0].app[0].destPort = 5000

*.node[0].app[0].messageLength = 1024B

*.node[0].app[0].sendInterval = 1s

*.node[5].numApps = 1

*.node[5].app[0].typename = “UdpSink”

*.node[5].app[0].localPort = 5000

  • IP Addressing: Allocate IP addresses to each node in the network.
  • Applications: Simulate network traffic by configuring applications on the nodes.
  1. Implement Routing Logic
  • Routing Protocols: In an irregular topology, routing may need to be handled by dynamic routing protocols like OSPF (Open Shortest Path First) or custom routing algorithms, based on the difficulty of the network.

Example: Enabling OSPF on all nodes

*.node[*].hasOspf = true

  • Custom Routing: If needed, to manage the irregular nature of the topology by executing custom routing logic, ensuring that packets are properly progressed through the network.
  1. Run the Simulation
  • After setting up the network topology and configuration, compile and run the simulation in OMNeT++. Monitor how traffic flows amongst nodes in the irregular topology, how routing is managed, and how the network performs.
  1. Analyze the Results
  • Visualize and analyze the network traffic, we have to use OMNeT++’s in-built tools. Examine how data is transmitted amongst nodes, how the routing protocols perform in the irregular topology, and how network performance differs with various traffic patterns.
  1. Enhancements and Variations
  • Dynamic Topology: Present dynamic changes to the topology by adding or removing nodes or links during the simulation, imitating real-world network changes.
  • Failure Scenarios: Study how the irregular topology manages interruptions and how resilient the network is to failures by simulating a node or link failures.
  • Traffic Analysis: Experiment with various traffic patterns to study how data flows over the irregular topology and how the network manages congestion.

Example Files

  1. IrregularTopology.ned: states the irregular topology.
  2. omnetpp.ini: Has configuration settings for the simulation.

In this demonstration, we aggregated the valuable information of the irregular topology and how to implement them using INET framework in the OMNeT++. For further references, we can provide the extra or related details to you. The team at omnet-manual.com provides expert guidance for implementing Irregular Topology in the OMNeT++ tool for your projects. Reach out to us to ensure you achieve the best simulation results.

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