How to Implement Routing Protocols Design in OMNeT++
To implement the routing protocols design in OMNeT++ has several steps to design and implement that has generate the custom modules that describe how network nodes explore and maintain routes, manage the packets, and respond to network changes. The below are the procedures to execute the simple routing protocol in OMNeT++, along with an example of a simple Distance Vector Routing Protocol.
Steps to Implement a Routing Protocol in OMNeT++
- Install OMNeT++ and INET Framework:
- Make sure that OMNeT++ and the INET framework are installed, as INET delivers a simple network models and tools that can be expanded for routing protocol design.
- Define Network Topology:
- Generate a network topology in a .ned file that contains the nodes to denote the devices in the network.
- Design the Routing Algorithm:
- Choose on the routing algorithm that we want to execute. This could be a Distance Vector protocol, Link State protocol, or any custom routing mechanism. State the data structures needed for routing tables, neighbour information, and route metrics.
- Implement the Routing Protocol in C++:
- Generate a novel C++ module in OMNeT++ to execute the routing protocol. This contains to state how nodes update their routing tables, how they forward packets, and how they react to network topology changes.
- Integrate the Routing Protocol with Network Nodes:
- Adjust the node models to contain the new routing protocol and this could contain to changing how nodes manage incoming packets and how they start route discoveries.
- Simulation Configuration:
- Setup the simulation using the .ini file and this contains to setting the parameters like the frequency of routing updates, packet transmission intervals, and node mobility.
- Run and Analyse the Simulation:
- Implement the simulation and execute the performance of the routing protocol. The performance metrics such as packet delivery ratio, average delay, and control overhead are usually used to evaluate protocol performance.
Example: Implementing a Simple Distance Vector Routing Protocol
- Network Definition in .ned File
network DVNetwork
{
submodules:
node1: DVNode {
@display(“p=100,200”);
}
node2: DVNode {
@display(“p=200,200”);
}
node3: DVNode {
@display(“p=300,200”);
}
node4: DVNode {
@display(“p=200,100”);
}
connections:
node1.radioModule <–> node2.radioModule;
node2.radioModule <–> node3.radioModule;
node2.radioModule <–> node4.radioModule;
node3.radioModule <–> node4.radioModule;
}
- Implement the Distance Vector Routing Protocol in C++
Generate a C++ class for the Distance Vector Routing Protocol.
#include <omnetpp.h>
#include <map>
using namespace omnetpp;
class DVRouting : public cSimpleModule
{
protected:
struct RoutingTableEntry {
int nextHop;
int distance;
};
std::map<int, RoutingTableEntry> routingTable; // Map: Destination -> Routing Table Entry
std::map<int, int> neighborTable; // Map: Neighbor -> Distance
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void updateRoutingTable(int source, int destination, int distance, int nextHop);
void sendRoutingUpdates();
void handlePacket(cPacket *packet);
public:
void forwardPacket(cPacket *packet);
};
Define_Module(DVRouting);
void DVRouting::initialize()
{
// Initialize the routing table with direct neighbors
for (int i = 0; i < gateSize(“out”); i++) {
cGate *outGate = gate(“out”, i);
int neighborId = outGate->getNextGate()->getOwnerModule()->getId();
int distance = outGate->getChannel()->par(“distance”).intValue();
neighborTable[neighborId] = distance;
routingTable[neighborId] = {neighborId, distance};
}
sendRoutingUpdates();
}
void DVRouting::handleMessage(cMessage *msg)
{
if (cPacket *packet = dynamic_cast<cPacket *>(msg)) {
handlePacket(packet);
} else {
delete msg; // Delete any other message
}
}
void DVRouting::updateRoutingTable(int source, int destination, int distance, int nextHop)
{
if (routingTable.find(destination) == routingTable.end() || routingTable[destination].distance > distance) {
routingTable[destination] = {nextHop, distance};
}
}
void DVRouting::sendRoutingUpdates()
{
// Create and send routing update packets to all neighbors
for (auto &neighbor : neighborTable) {
int neighborId = neighbor.first;
cPacket *updatePacket = new cPacket(“RoutingUpdate”);
updatePacket->addPar(“source”) = getParentModule()->getId();
for (auto &entry : routingTable) {
updatePacket->addPar(“destination”) = entry.first;
updatePacket->addPar(“distance”) = entry.second.distance;
}
send(updatePacket, “out”, neighborId);
}
scheduleAt(simTime() + 5, new cMessage(“sendRoutingUpdates”)); // Periodically send updates
}
void DVRouting::handlePacket(cPacket *packet)
{
int source = packet->par(“source”).intValue();
int destination = packet->par(“destination”).intValue();
int distance = packet->par(“distance”).intValue();
if (source != getParentModule()->getId()) {
int newDistance = distance + neighborTable[source];
updateRoutingTable(source, destination, newDistance, source);
}
forwardPacket(packet);
}
void DVRouting::forwardPacket(cPacket *packet)
{
int destination = packet->par(“destination”).intValue();
if (routingTable.find(destination) != routingTable.end()) {
send(packet, “out”, routingTable[destination].nextHop);
} else {
delete packet; // Drop the packet if no route is found
}
}
- Modify Node Modules to Use Distance Vector Routing
Expand the node definition to contains the DVRouting module.
simple DVNode
{
gates:
input radioIn;
output radioOut;
submodules:
radioModule: Radio {
@display(“p=50,50”);
}
routing: DVRouting {
@display(“p=100,100”);
}
connections:
radioIn –> routing.in;
routing.out –> radioOut;
}
- Configure the Simulation in .ini File
network = DVNetwork
sim-time-limit = 100s
**.radio.txPower = 1mW
**.routing.updateInterval = 5s # Time interval for sending routing updates
Running the Simulation
- Compile the C++ code and execute the simulation using OMNeT++.
- Monitor how the Distance Vector Routing protocol builds and updates routing tables, and how packets are forwarded based on these tables.
We had successfully executed the routing protocols design in OMNeT++ tool that has to generate a network topology then select the routing algorithm to execute the routing protocol to evaluate protocol performance. We intend to expand on how the routing protocols design is performed in other simulation settings.
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