How to Implement Logical Topology in OMNeT++

To implement the logical topology in OMNeT++ requires a network in which the logic connections amongst nodes are stated independently of the physical connections by creating it. Logic topologies signify how data flows amongst devices that will differ from the physical layout. For instance, in physical bus topology, the logical topology can be a ring or star based on how the network protocols routing traffic. In below, we provided the implementation details of Logical topology:

Step-by-Step Implementation:

1. Set Up OMNeT++ and INET Framework

• Make certain that you have OMNeT++ and INET framework installed and properly configured. Simulate the different network topologies as well as logical network by using the modules offered by INET framework.

2. Define the Physical Topology in a NED File

• First, we have to state the underlying physical network topology. This could be any physical arrangement of nodes like a bus, ring, or star.

Example:

package logicalTopologyExample;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

network PhysicalNetwork

{

parameters:

int numNodes = default(6);  // Number of nodes in the physical network

submodules:

router[numNodes]: Router {

parameters:

@display(“p=200+300*cos(pi/2+i*2*pi/numNodes),200+300*sin(pi/2+i*2*pi/numNodes)”);

}

node[numNodes]: StandardHost {

parameters:

@display(“p=400+300*cos(pi/2+i*2*pi/numNodes),400+300*sin(pi/2+i*2*pi/numNodes)”);

}

connections allowunconnected:

// Connect each node to its corresponding router

for i=0..numNodes-1 {

node[i].ethg++ <–> Eth10G <–> router[i].ethg++;

}

// Create a physical backbone by connecting routers

for i=0..numNodes-2 {

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

}

router[numNodes-1].ethg++ <–> Eth10G <–> router[0].ethg++;

}

• In this example:
  • In the physical network, Router signifies the routers.
  • StandardHost represents the end devices connected to the network.
  • The physical topology links each node to a router, with routers forming a ring topology.

3. Define the Logical Topology in the Same or Another NED File

• Now, on the top of physical topology, we have to state the logical connections. This logical network describes how data flows amongst nodes, which may not directly map to the physical connections.

Example:

network LogicalTopology extends PhysicalNetwork

{

connections:

// Logical connections between nodes (can represent a logical star, ring, etc.)

node[0].pppg++ <–> Ppp <–> node[3].pppg++;

node[1].pppg++ <–> Ppp <–> node[4].pppg++;

node[2].pppg++ <–> Ppp <–> node[5].pppg++;

node[0].pppg++ <–> Ppp <–> node[5].pppg++;

}

• In this example:
  • By adding logical connections amongst nodes which don’t essentially correspond to the physical connections, we can extend the physicalnetwork using LogicalTopology.
  • These logical connections signify how data is logically directed amongst nodes, independent of the underlying physical layout.

4. Configure the Nodes in OMNeT++ INI File

• In the omnetpp.ini file, configure the properties of the nodes as well as IP addresses, routing, and the applications they will run.

Example:

network = logicalTopologyExample.LogicalTopology

# Configure IP addresses

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

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

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

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

# Example application setup: node[0] communicates with node[3] via logical connection

*.node[0].numApps = 1

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

*.node[0].app[0].destAddresses = “10.0.0.4”  # IP address of node[3]

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

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

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

*.node[3].numApps = 1

*.node[3].app[0].typename = “UdpSink”

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

• In this example:
  • node[0] is configured to send UDP packets to node[3] via the logical connection.
  • node[3] is configured to receive and process the packets.

5. Configure Routing Protocols

• We might need to configure routing protocol to handle how data is forwarded amongst nodes based on the difficulty of the logical topology.

Example:

*.router[*].hasOspf = true

*.node[*].hasOspf = true

• This configuration enables OSPF on all routers and nodes, permiting dynamic routing through both the physical and logical networks.

6. Run the Simulation

• After setting up the network topology and configuration, compile and run the simulation in OMNeT++. Depends on the logical connections, we can see the nodes communicating irrespective of the physical layout.

7. Analyze the Results

• Use OMNeT++’s built-in tools to visualize and analyze the network traffic. Examine how data is transferred over the logical network, how the logical and physical layers interact, and how the network manages traffic.

8. Enhancements and Variations

• Dynamic Logical Topologies: Depends on the network conditions or application requirements, we have to build a mechanisms that has a logical topology can change dynamically.
• Overlay Networks: Logical topologies can also represent overlay networks where additional services or features are provided on top of the physical infrastructure.
• Application-Specific Logical Topologies: Create logical topologies tailored to certain applications like multicast trees or virtual circuits.

Example Files

1. PhysicalNetwork.ned: Describes the underlying physical network.
2. LogicalTopology.ned: Extends the physical network with logical connections.
3. omnetpp.ini: Has configuration settings for the simulation.
   

At the end, we were completely aware of when to implement the Logical topology with the help of Physical Topology in the OMNeT++ through this demonstration.

We continuously monitor the latest developments in Logical Topology within the OMNeT++ tool, ensuring that you receive the most relevant project topics. Rely on us for high-quality simulation concepts and successful project execution outcomes