How to simulate Network Routing in OMNeT++

To implement network routing in OMNeT++ has encompasses to generates a network where nodes enthusiastically regulate the best paths to forward packets based on a selected routing protocol. This will walk you via the setting up a simple network routing simulation in OMNeT++ using the INET framework.

Steps-by-Steps Implementation:

Set Up OMNeT++ Environment:

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

Define the Network Topology:

Describe a network topology with multiple nodes like hosts, routers where we will execute routing. We can use a basic network with three or more nodes interconnected by point-to-point links.

Example NED File (SimpleNetwork.ned):

package mynetwork;

import inet.node.inet.Router;

import inet.node.inet.StandardHost;

import inet.node.ethernet.EthernetSwitch;

import inet.networklayer.configurator.ipv4.IPv4NetworkConfigurator;

import inet.node.ethernet.EthernetSwitch;

network SimpleNetwork

{

submodules:

host1: StandardHost {

@display(“p=100,100”);

}

host2: StandardHost {

@display(“p=300,100”);

}

router1: Router {

@display(“p=200,200”);

}

router2: Router {

@display(“p=400,200”);

}

configurator: IPv4NetworkConfigurator {

@display(“p=300,50”);

}

connections:

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

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

router2.ethg++ <–> ethernetLine <–> host2.ethg++;

}

This sample describes a basic network with two hosts (host1 and host2) and two routers (router1 and router2). The IPv4NetworkConfigurator automatically allocates IP addresses and sets up routing tables.

Configure Routing Protocol:

The INET framework delivers numerous routing protocols like RIP, OSPF, and AODV, that can be configured in the omnetpp.ini file.

Example Configuration (omnetpp.ini):

network = SimpleNetwork

**.ipv4Routing.tableSize = 100

**.router1.ipv4.routingProtocol = “^RIPRouting”

**.router2.ipv4.routingProtocol = “^RIPRouting”

**.configurator.config = xml(config.xml)

Here, RIPRouting is particular as the routing protocol for both routers. We can replace this with OSPFv2, AODV, or other supported protocols depending on needs.

Create Configuration XML (optional):

If we want to describe more particular routing settings, we can generate an XML file for the IPv4NetworkConfigurator.

Example Configuration XML (config.xml):

<?xml version=”1.0″?>

</interfaces>

</routing>

</config>

This file particularly interfaces configurations and static routes. The configurator will use this to set up the network.

Simulate Network Traffic:

We need to emulate traffic to track the routing behaviour. This can be completed by sending packets from host1 to host2 and observing how they are routed via the network.

Example Traffic Generator (TrafficGenerator.ned):

package mynetwork;

import inet.applications.udpapp.UDPBasicApp;

import inet.applications.udpapp.UDPSink;

simple TrafficGenerator extends UDPBasicApp

{

}

network SimpleNetwork

{

submodules:

host1: StandardHost {

@display(“p=100,100”);

}

host2: StandardHost {

@display(“p=300,100”);

applications: <udpsink>

}

router1: Router {

@display(“p=200,200”);

}

router2: Router {

@display(“p=400,200”);

}

configurator: IPv4NetworkConfigurator {

@display(“p=300,50”);

}

generator: TrafficGenerator {

@display(“p=50,50”);

localAddress = “host1”;

destAddresses = “host2”;

startTime = 1s;

stopTime = 10s;

}

connections:

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

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

router2.ethg++ <–> ethernetLine <–> host2.ethg++;

}

This setup creates UDP traffic from host1 to host2 and permits to observe how the routers manage the packets.

Run the Simulation:

Compile and run the simulation using OMNeT++.
Observe the routing behaviour: Use OMNeT++’s built-in tools to visualize the packet flow and routing decisions.
Analyse the results: Investigate routing tables, packet delivery times, and path selection to appreciate how the network routes packets.

Analyse and Extend the Routing:

Routing Metrics: Evaluate the parameters such as hop count, route convergence time, and packet delivery ratio.
Dynamic Routing: Execute dynamic routing protocols such as AODV, which acclimatises to network changes in real-time.
Scalability Testing: Extend the network with more nodes and validate how the routing protocol scales.
Custom Routing Protocol: If we want to execute a custom routing protocol, we can generate a new module in C++ and incoporates it with the INET framework.

Example of Routing Table in a Router:

To see the routing table in a router, we can examine the router’s module in OMNeT++ during or after the simulation:

cModule *router = getModuleByPath(“SimpleNetwork.router1”);

Ipv4RoutingTable *rt = check_and_cast<Ipv4RoutingTable*>(router->getSubmodule(“ipv4.routingTable”));

rt->printRoutingTable();

Further Exploration:

Implementing OSPF: Replace RIPRouting with OSPFv2 in the omnetpp.ini and configure OSPF parameters.
Implementing AODV for Ad-Hoc Networks: Use AODV in wireless networks to study ad-hoc routing.
Experiment with Failover: To emulate link failures and monitor how the routing protocol reacts.

We had successfully executed the network routing using the OMNeT++ tool that provides the best path for transmission. We plan to deliver more details regarding the network routing performance.

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