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How to implement least cost routing in OMNeT++

To implement least-cost routing in OMNeT++ contains to making a network for each node routes data packets minimizes a certain cost metrices like delay, hop count, or bandwidth based on the way. It can be succeed using Dijkstra’s algorithm, which help to find the shortest path based on the defined cost metric.

Given below procedure is help to implement least-cost routing in OMNeT++ using the INET framework.

Step-by-Step Implementations:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make sure OMNeT++ is installed on the system.
  2. Install the INET Framework:
    • Download and install the INET Framework, which offers numerous networking protocols and models. INET can be downloaded from the INET GitHub repository.

Step 2: Create a New OMNeT++ Project

  1. Create the Project:
    • Open OMNeT++ and form a new OMNeT++ project through File > New > OMNeT++ Project.
    • Name the project like LeastCostRoutingSimulation and set up the project directory.
  2. Set Up Project Dependencies:
    • Make certain the project references the INET Framework by right-clicking on the project in the Project Explorer, navigating to Properties > Project References, and verifying the INET project.

Step 3: Define the Network Topology

  1. Create a NED File:
    • Describe the network topology using the NED language. This topology will include nodes like routers, hosts that will use least-cost routing.

Example:

network LeastCostNetwork

{

submodules:

router1: Router;

router2: Router;

router3: Router;

router4: Router;

host1: StandardHost;

host2: StandardHost;

connections:

router1.ethg++ <–> Eth10Mbps <–> router2.ethg++;

router2.ethg++ <–> Eth10Mbps <–> router3.ethg++;

router3.ethg++ <–> Eth10Mbps <–> router4.ethg++;

router1.ethg++ <–> Eth10Mbps <–> host1.ethg++;

router4.ethg++ <–> Eth10Mbps <–> host2.ethg++;

}

  1. Configure Network Parameters:
    • Set up essential link parameters like delay, bandwidth, and packet loss to mimic a realistic network setting.

Step 4: Implement the Least-Cost Routing Algorithm

  1. Define the Routing Module:
  • Make a new module in NED for the least-cost routing protocol. Based on the least-cost path calculation the module will handle routing decisions.

Example (in NED):

simple LeastCostRouting

{

parameters:

@display(“i=block/network2”);

gates:

inout lowerLayerIn[];

inout lowerLayerOut[];

}

  1. Implement Least-Cost Routing Logic in C++:
    • Implement the routing logic in C++ using Dijkstra’s algorithm or a similar approach, considering the chosen cost metric like hop count, delay, or bandwidth that calculates the least-cost paths.

Example (C++ implementation):

#include <map>

#include <queue>

#include “inet/common/INETDefs.h”

#include “inet/networklayer/contract/IRoutingTable.h”

#include “inet/networklayer/ipv4/IPv4RoutingTable.h”

class LeastCostRouting : public cSimpleModule

{

private:

struct Link {

double cost;

std::string nextHop;

};

std::map<std::string, Link> routingTable;  // Destination -> (Cost, Next Hop)

IRoutingTable *inetRoutingTable;

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void calculateLeastCostPaths();

void updateRoutingTable(const std::string& destination, double cost, const std::string& nextHop);

};

Define_Module(LeastCostRouting);

void LeastCostRouting::initialize() {

inetRoutingTable = getModuleFromPar<IRoutingTable>(par(“routingTableModule”), this);

// Initialize the routing table with some example data (could be dynamic)

calculateLeastCostPaths();

}

void LeastCostRouting::handleMessage(cMessage *msg) {

// Handle incoming packets and route them based on the current routing table

// Example: forward the packet to the next hop with the least cost

}

void LeastCostRouting::calculateLeastCostPaths() {

// Example: Use Dijkstra’s algorithm to compute the least-cost paths

std::map<std::string, double> distances;  // Node -> Cost

std::map<std::string, std::string> previous;  // Node -> Previous Node in Path

// Initialize distances to infinity, except for the source node

std::string source = “router1”;  // Example source node

distances[source] = 0;

// Priority queue to process nodes based on the least cost

auto compare = [&](const std::string& left, const std::string& right) {

return distances[left] > distances[right];

};

std::priority_queue<std::string, std::vector<std::string>, decltype(compare)> pq(compare);

pq.push(source);

while (!pq.empty()) {

std::string currentNode = pq.top();

pq.pop();

// For each neighbor of the current node, calculate the cost

for (auto& neighbor : routingTable) {

double newCost = distances[currentNode] + neighbor.second.cost;

if (newCost < distances[neighbor.first]) {

distances[neighbor.first] = newCost;

previous[neighbor.first] = currentNode;

pq.push(neighbor.first);

}

}

}

// Update the routing table with the calculated least-cost paths

for (auto& entry : previous) {

std::string nextHop = entry.second;

double cost = distances[entry.first];

updateRoutingTable(entry.first, cost, nextHop);

}

}

void LeastCostRouting::updateRoutingTable(const std::string& destination, double cost, const std::string& nextHop) {

routingTable[destination] = {cost, nextHop};

EV << “Updated route to ” << destination << ” via ” << nextHop << ” with cost ” << cost << endl;

}

    • Routing Table: The module preserves a routing table where each entry contains the cost to reach a destination and the next hop to use.
    • Least-Cost Calculation: Using Dijkstra’s algorithm to calculate the least-cost paths based on the chosen metric.
    • Routing Table Updates: With the calculated least-cost paths the routing table is updated.

Step 5: Set Up the Simulation

  1. Configure the Simulation in omnetpp.ini:
  • Set up the simulation parameters, like traffic patterns, network settings, and simulation time.

Example:

[General]

network = LeastCostNetwork

sim-time-limit = 100s

**.scalar-recording = true

**.vector-recording = true

# Application traffic configuration (if needed)

*.host1.numApps = 1

*.host1.app[0].typename = “UdpBasicApp”

*.host1.app[0].destAddress = “host2”

*.host1.app[0].destPort = 5000

*.host1.app[0].messageLength = 1024B

*.host1.app[0].sendInterval = uniform(1s, 2s)

  1. Traffic Configuration:
    • Set up application-level traffic among the nodes to generate network activity, triggering the least-cost routing decisions.

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure everything is correctly implemented and compiled.
  2. Run Simulations:
    • Perform the simulations using OMNeT++’s IDE or command line. Observe the behaviour of the least-cost routing protocol, particularly how routes are established and packets are forwarded based on the minimum cost.

Step 7: Analyse the Results

  1. Monitor Routing Effectiveness:
    • Assess how effectively the network uses the least-cost paths, make sure that data is routed usefully.
  2. Evaluate Protocol Performance:
    • Analyse key performance metrics like network utilization, route optimality, and end-to-end delay.
    • Scalars and Vectors: To record and analyse scalar and vector data like such as the number of routing updates, the total number of hops, and the time taken to reach destinations by using OMNeT++.
  3. Check for Issues:
    • Check for issues like suboptimal routing paths or instability, which may indicate problems with the least-cost routing algorithm.

Step 8: Refine and Optimize the Protocol

  1. Address Any Issues:
    • If the protocol displays problems, the least-cost calculation algorithm to improve performance or consider refining the cost metrics.
  2. Optimize for Performance:
    • Modify parameters like update intervals or link cost estimations to develop network efficiency.
  3. Re-Test:
    • Validate improvement to the simulation again with the optimized protocol.

We have concluded that further data about that to implement least cost routing using the procedure like to execute this logic in C++, define network topology, optimize the protocol in OMNeT++. We are providing the extra details to implement the Least Cost Routing in other tools. Get  our experts implementation guidance on  least cost routing in OMNeT++  for your research work.

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