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How to Implement dijkstra’s link state in OMNeT++

To implement the Dijkstra’s Link-State routing in OMNeT++, use Dijkstra’s algorithm to compute the shortest paths from every router to all other routers in the network. This algorithm is widely known for finding shortest paths among the nodes in a graph which is appropriate in the network routing context.

Below is a step-by-step process on how to implement Dijkstra’s Link-State routing in OMNeT++ using the INET framework.

Step-by-Step Implementation:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make sure that the OMNeT++ is installed on your system.
  2. Install the INET Framework:
    • Install the INET Framework that contains 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 create a new OMNeT++ project via File > New > OMNeT++ Project.
    • Give a name (like LinkStateRoutingSimulation) and set up the project directory.
  2. Set Up Project Dependencies:
    • Make certain that project references the INET Framework by right-clicking on your project in the Project Explorer, navigating to Properties > Project References, and checking the INET project.

Step 3: Define the Network Topology

  1. Create a NED File:
    • Use the NED language to state the network topology which contains routers and links that will use the Link-State routing protocol.

Example:

network LinkStateNetwork

{

submodules:

router1: Router;

router2: Router;

router3: Router;

router4: Router;

host1: StandardHost;

host2: StandardHost;

connections allowunconnected:

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:
    • Build necessary link parameters like bandwidth, delay, and packet loss to simulate a realistic network environment.

Step 4: Implement Dijkstra’s Link-State Routing Algorithm

  1. Define the Link-State Routing Module:
    • For the Link-state routing protocol, we have to create a new module in NED, that could handle the routing decisions as per the Dijkstra’s algorithm.

Example (in NED):

simple LinkStateRouting

{

parameters:

@display(“i=block/network2”);

gates:

inout lowerLayerIn[];

inout lowerLayerOut[];

}

  1. Implement Link-State Routing Logic in C++:
    • Use Dijkstra’s algorithm to implement the routing logic in C++ that measures the shortest paths and updates the routing table accordingly.

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 LinkStateRouting : public cSimpleModule

{

private:

struct LinkStateEntry {

double cost;

std::string nextHop;

};

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

IRoutingTable *inetRoutingTable;

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void calculateShortestPaths();

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

};

Define_Module(LinkStateRouting);

void LinkStateRouting::initialize() {

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

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

calculateShortestPaths();

}

void LinkStateRouting::handleMessage(cMessage *msg) {

// Handle incoming packets and forward them based on the routing table

}

void LinkStateRouting::calculateShortestPaths() {

// Example: Use Dijkstra’s algorithm to compute the shortest 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 shortest paths

for (auto& entry : previous) {

std::string nextHop = entry.second;

double cost = distances[entry.first];

updateRoutingTable(entry.first, cost, nextHop);

}

}

void LinkStateRouting::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 upholds a routing table where each entry contains the cost to reach a destination and the next hop to use.
    • Shortest Path Calculation: Depends on the link-state information, the module uses Dijkstra’s algorithm to compute the shortest paths.
    • Routing Table Updates: The routing table is updated with the computed shortest paths.

Step 5: Set Up the Simulation

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

Example:

network = LinkStateNetwork

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:
    • Activate the link-state routing protocol and generate the network activity by setting up the application-level traffic amongst nodes.

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure, everything is properly implemented and compiled.
  2. Run Simulations:
    • Use the IDE of the OMNeT++ or command line to implement the simulations. Observe how the Link-State routing protocol performs in multiple conditions.

Step 7: Analyze the Results

  1. Monitor Protocol Behavior:
    • Assess how the Link-State routing protocol handles routing, particularly under different network scenarios.
  2. Evaluate Performance:
    • Evaluate key performance metrics like packet delivery ratio, end-to-end delay, and routing overhead.
    • Scalars and Vectors: Record and analyze the scalar and vector data like the amount of packets sent, received, and dropped, as well as the time taken to deliver packets using OMNeT++ tools.
  3. Check for Issues:
    • Search for issues like routing loops, packet loss, or excessive delay that may indicate problems with the routing logic.

Step 8: Refine and Optimize the Protocol

  1. Address Any Issues:
    • To enhance the performance and address any problems, we have to upgrade the routing logic based on the simulation results.
  2. Optimize for Performance:
    • Fine-tune parameters like routing table update intervals, packet forwarding rules, or link cost calculations to improve network efficiency.
  3. Re-Test:
    • Run the simulation again with the optimized protocol to authenticate improvements.

At the end of this demonstration, we cope up the step-by-step implementation and basic network setup of the Dijkstra’s link state using Dijkstra algorithm in the OMNeT++. If you have any doubts about this approach, we will clarify it.Drop us all your reasech data we will provide you with implementation support with practical explanation.

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