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How to Implement Open shortest path First routing in OMNeT++

To Implement shortest path routing in OMNeT++ has encompasses to generate the network model where the routers or nodes can use the techniques such as Dijkstra’s algorithm to regulate the shortest path to all other nodes in the network. This procedure will walk you to help to implement the shortest path routing in OMNeT++ using the INET framework.

Step-by-Step Implementation:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make sure OMNeT++ is installed on system. We need to download it from the OMNeT++
  2. Install the INET Framework:
    • Download and install the INET Framework, which offers a rich set of network models and protocols. INET can be downloaded from the INET GitHub repository.

Step 2: Create a New OMNeT++ Project

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

Step 3: Define the Network Topology

  1. Create a NED File:
    • Describe network topology using the NED language. The topology should contains the routers or hosts that will run the shortest path routing algorithm.

Example:

network ShortestPathNetwork

{

submodules:

router1: Router;

router2: Router;

router3: Router;

router4: Router;

connections:

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

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

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

router4.ethg++ <–> Eth10Mbps <–> router1.ethg++;

}

  1. Configure Network Parameters:
    • Set up the necessary link performance metrics like bandwidth, delay, and packet loss to mimic a realistic network environment.

Step 4: Implement the Shortest Path Routing Algorithm

  1. Define the Routing Module:
    • Generate a new module in NED for the Shortest Path Routing. This module will be responsible for computing the shortest paths and updating the routing tables.

Example (in NED):

simple ShortestPathRouting

{

parameters:

@display(“i=block/network2”);

gates:

inout lowerLayerIn;

inout lowerLayerOut;

}

  1. Implement Dijkstra’s Algorithm in C++:
    • To execute the Shortest Path Routing logic in a C++ class. This will contains to maintaining a graph of the network, simulated the Dijkstra’s algorithm to estimate the shortest paths, and updating the routing table respectively.

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 ShortestPathRouting : public cSimpleModule

{

private:

std::map<std::string, std::map<std::string, int>> graph;  // Node -> (Neighbor -> Cost)

IRoutingTable *routingTable;

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void calculateShortestPaths();

void updateRoutingTable(const std::map<std::string, std::string>& nextHop);

};

Define_Module(ShortestPathRouting);

void ShortestPathRouting::initialize() {

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

// Build the graph from the network topology

// This could be dynamically constructed based on received link state advertisements

graph[“router1”][“router2”] = 1;

graph[“router2”][“router3”] = 1;

graph[“router3”][“router4”] = 1;

graph[“router4”][“router1”] = 1;

// Calculate the shortest paths

calculateShortestPaths();

}

void ShortestPathRouting::handleMessage(cMessage *msg) {

// Handle incoming packets, if necessary

}

void ShortestPathRouting::calculateShortestPaths() {

std::map<std::string, int> distances;

std::map<std::string, std::string> previous;

std::map<std::string, std::string> nextHop;

std::string source = “router1”;  // The source node could be dynamically set

// Initialize distances

for (auto &node : graph) {

distances[node.first] = INT_MAX;

previous[node.first] = “”;

}

distances[source] = 0;

auto cmp = [&distances](std::string left, std::string right) {

return distances[left] > distances[right];

};

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

pq.push(source);

while (!pq.empty()) {

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

pq.pop();

for (auto &neighbor : graph[current]) {

int alt = distances[current] + neighbor.second;

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

distances[neighbor.first] = alt;

previous[neighbor.first] = current;

pq.push(neighbor.first);

}

}

}

// Determine the next hop for each destination

for (auto &dest : distances) {

std::string hop = dest.first;

while (previous[hop] != source && previous[hop] != “”) {

hop = previous[hop];

}

if (hop != source) {

nextHop[dest.first] = hop;

}

}

// Update the routing table with the computed next hops

updateRoutingTable(nextHop);

}

void ShortestPathRouting::updateRoutingTable(const std::map<std::string, std::string>& nextHop) {

// Clear the current routing table

routingTable->clear();

// Add routes based on the computed next hops

for (auto &route : nextHop) {

IPv4Route *newRoute = new IPv4Route();

newRoute->setDestination(Ipv4Address::resolve(route.first.c_str()));

newRoute->setGateway(Ipv4Address::resolve(route.second.c_str()));

newRoute->setNetmask(Ipv4Address::ALLONES_ADDRESS);

newRoute->setInterface(routingTable->getInterfaceByName(“eth0”));

newRoute->setSourceType(IPv4Route::MANUAL);

routingTable->addRoute(newRoute);

}

}

    • Graph Representation: The network topology is denotes as a graph where nodes are routers and edges are links with associated costs.
    • Dijkstra’s Algorithm: Use Dijkstra’s algorithm to estimate the shortest paths from the source node to all other nodes.
    • Routing Table Update: Update the routing table based on the outcomes of the shortest path computation.

Step 5: Set Up the Simulation

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

Example:

network = ShortestPathNetwork

sim-time-limit = 100s

# Enable scalar and vector recording for analysis

**.scalar-recording = true

**.vector-recording = true

# Application traffic configuration (if needed)

*.router1.numApps = 1

*.router1.app[0].typename = “UdpBasicApp”

*.router1.app[0].destAddress = “router4”

*.router1.app[0].destPort = 5000

*.router1.app[0].messageLength = 1024B

*.router1.app[0].sendInterval = uniform(1s, 2s)

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

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure everything is properly applied and compiled.
  2. Run Simulations:
    • Execute the simulations using OMNeT++’s IDE or command line. Observe the performance of the routing protocol, particularly how the shortest paths are intended and modernized.

Step 7: Analyze the Results

  1. Monitor Convergence Time:
    • Asses the time it takes for the routing tables in all routers to stabilize.
  2. Evaluate Protocol Performance:
    • Measure key performance metrics like route optimality, update overhead, and network utilization.
    • Scalars and Vectors: Use OMNeT++ tools to record and measure scalar and vector data. This can contain tracking the number of routing updates, the total number of hops, and the time taken to reach destinations.
  3. Check for Issues:
    • Look for issues that have routing loops or instability, especially under dynamic network conditions.

Step 8: Refine and Optimize the Protocol

  1. Address Any Bugs or Inefficiencies:
    • If the protocol exhibits issues then, consider executing the improvements such as more efficient path recalculation or optimized data structures for managing the graph.
  2. Optimize for Performance:
    • Fine-tune parameters like update intervals or damping mechanisms to optimize performance under numerous network conditions.
  3. Re-Test:
    • Run the simulation again with the optimized protocol to test the enhancements.

In this page, we clearly showed the performance analysis of shortest path routing by using the dijkstra techniques that applied in the OMNeT++ tool using the INET framework. Additional specifics details were intended to provide in further simulation setup. We handle your projects on all routers or nodes. For simulation and configuration results using Open Shortest Path First routing in the OMNeT++ tool, check out omnet-manual.com. We also provide you with the latest project ideas and comparison analysis to help you in this field.