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How to Implement Hybrid Topology in OMNeT++

To implement the hybrid topology in OMNeT++ requires to involve combining various kinds of network topologies like ring, star, mesh or tree topologies to make an extra complex and multipurpose network. This topology are usually used in real-world networks to leverage the benefits of many topologies while mitigating their individual drawbacks. Here’s how to implement a hybrid topology in OMNeT++ using the INET framework:

Step-by-Step Implementations:

  1. Set up OMNeT++ and INET Framework
  • Make sure that OMNeT++ and the INET framework are installed and correctly configured. The INET framework offers the required modules for mimicking numerous network topologies and protocols.
  1. Define the Hybrid Topology in a NED File
  • Make a .ned file to define the network topology. In this topology, we can combine various network topologies, like star, ring, mesh, and tree.

Example: Combining a Star and a Ring Topology

package hybridTopologyExample;

import inet.node.inet.StandardHost;

import inet.node.inet.Router;

network HybridTopology

{

parameters:

int numStarNodes = default(3);  // Number of nodes in the star topology

int numRingNodes = default(4);  // Number of nodes in the ring topology

submodules:

centralNode: Router {

parameters:

@display(“p=400,200”);

}

starNode[numStarNodes]: StandardHost {

parameters:

@display(“p=200+200*i,100”);

}

ringNode[numRingNodes]: StandardHost {

parameters:  @display(“p=100+300*cos(pi/2+i*2*pi/numRingNodes),300+300*sin(pi/2+i*2*pi/numRingNodes)”);

}

connections allowunconnected:

for i=0..numStarNodes-1 {

starNode[i].ethg++ <–> Eth10G <–> centralNode.ethg++;

}

for i=0..numRingNodes-2 {

ringNode[i].ethg++ <–> Eth10G <–> ringNode[i+1].ethg++;

}

ringNode[numRingNodes-1].ethg++ <–> Eth10G <–> ringNode[0].ethg++;  // Close the ring

centralNode.ethg++ <–> Eth10G <–> ringNode[0].ethg++;  // Connect star to ring

}

  • In this example:
    • The centralNode connects to numerous starNode devices in a star topology.
    • The ringNode devices make a ring topology.
    • The star topology is linked to the ring topology by connecting the central node of the star to one of the ring nodes.
  1. Configure the Nodes in OMNeT++ INI File
  • In the omnetpp.ini file, configure the properties of the nodes. We can identify IP addresses, routing protocols, applications running on the nodes, and other related parameters.

Example:

[General]

network = hybridTopologyExample.HybridTopology

# Configure IP addresses and routing (assuming IPv4)

*.centralNode.ipv4.arp.typename = “GlobalArp”

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

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

# Example application setup: one star node sends data to a ring node

*.starNode[0].numApps = 1

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

*.starNode[0].app[0].destAddresses = “10.0.0.4”  # IP address of a ring node

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

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

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

*.ringNode[3].numApps = 1

*.ringNode[3].app[0].typename = “UdpSink”

*.ringNode[3].app[0].localPort = 5000

  • In this example:
    • starNode[0] is configured to send UDP packets to ringNode[3].
    • The hybrid topology connects the star and ring topologies, permitting communication between them.
  1. Configure Routing Protocols
  • Depending on the difficulty of the hybrid topology, we might want to configure routing protocols to manage how data is forwarded through the network. For example, we can allow OSPF (Open Shortest Path First) or other suitable protocol.

Example:

*.centralNode.hasOspf = true

*.starNode[*].hasOspf = true

*.ringNode[*].hasOspf = true

  • This configuration permits OSPF on all nodes, allowing dynamic routing across the hybrid network.
  1. Run the Simulation
  • Compile and run the simulation in OMNeT++ after setting up the network topology and configuration. We should see nodes related in both star and ring topologies, with data being routed among various parts of the network.
  1. Analyze the Results
  • To visualize and consider the network traffic using OMNeT++’s built-in tools. Observe how data flows among the various topologies, how routing protocols handle traffic, and the total performance of the hybrid network.
  1. Enhancements and Variations
  • Multiple Topologies: Join extra than two topologies like add a mesh or tree section to make a more complex hybrid network.
  • Performance Analysis: Calculate the performance of the network in terms of throughput, latency, and load balancing under various traffic conditions.
  • Fault Tolerance: Mimic failures in numerous portions of the hybrid topology and watch how the network adapts to maintain communication.

Example Files

  1. HybridTopology.ned: Describes the hybrid topology.
  2. omnetpp.ini: Encompasses configuration settings for the simulation.

In this paper, we had shown hybrid topology that includes various types of topologies and to execute their process in OMNeT++. We will offers further details about Hybrid Topology in other tools. We are always updated in the loop with the latest concepts on Hybrid Topology in the OMNeT++ tool, so you can count on us for the best project topics!

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