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How to Implement centralized routing in OMNeT++

To implement the centralized routing in OMNeT++, we need to create a network in which their routing decisions are made by central controller instead of specific nodes. It is usually used in Software-Defined Networking (SDN), where a centralized controller has a global view of the network and can enhance routing paths accordingly.

In the following , we provided the step-by-step approach to implement it:

Step-by-Step Implementation:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make certain that you have OMNeT++ installed on your computer.
  2. Install the INET Framework:
    • Download and install the INET Framework, which offers multiple 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.
    • Name your project (example: CentralizedRoutingSimulation) and set up the project directory.
  2. Set Up Project Dependencies:
    • Make sure the project references the INET Framework by right-clicking on 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:
    • State the network topology with the help of NED language. This topology will have routers, hosts, and a central controller.

Example:

network CentralizedRoutingNetwork

{

submodules:

controller: StandardHost {

@display(“p=100,100”);

}

router1: Router {

@display(“p=200,200”);

}

router2: Router {

@display(“p=300,200”);

}

router3: Router {

@display(“p=400,200”);

}

host1: StandardHost {

@display(“p=150,300”);

}

host2: StandardHost {

@display(“p=450,300”);

}

connections allowunconnected:

controller.ethg++ <–> Eth100Mbps <–> router1.ethg++;

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

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

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

router3.ethg++ <–> Eth10Mbps <–> host2.ethg++;

}

  1. Configure Network Parameters:
    • Simulate the realistic network environment by set up necessary link parameters which includes bandwidth, delay, and packet loss to simulate a realistic network environment.

Step 4: Implement the Centralized Routing Protocol

  1. Define the Centralized Controller Module:
    • To manage the routing decisions, we have to generate a new module in NED for the centralized controller.

sample (in NED):

simple CentralController

{

parameters:

@display(“i=block/control”);

gates:

inout controlIn[];

inout controlOut[];

}

  1. Implement the Centralized Controller Logic in C++:
    • Generating the logic in C++ that permits the central controller to aggregate network information, compute optimal paths, and distribute routing information to routers.

Example (C++ implementation):

#include <map>

#include “inet/common/INETDefs.h”

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

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

class CentralController : public cSimpleModule

{

private:

std::map<std::string, std::string> routingTable;  // Destination -> Next Hop

std::vector<cModule*> routers;  // List of routers in the network

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void collectNetworkInformation();

void calculateOptimalPaths();

void distributeRoutingInformation();

};

Define_Module(CentralController);

void CentralController::initialize() {

// Collect information about all routers in the network

collectNetworkInformation();

// Calculate optimal routing paths

calculateOptimalPaths();

// Distribute routing information to all routers

distributeRoutingInformation();

}

void CentralController::handleMessage(cMessage *msg) {

// Handle incoming messages, if any

}

void CentralController::collectNetworkInformation() {

// Example: Discover all routers in the network

for (cModule::SubmoduleIterator it(getParentModule()); !it.end(); ++it) {

cModule *mod = *it;

if (strcmp(mod->getName(), “Router”) == 0) {

routers.push_back(mod);

}

}

EV << “Discovered ” << routers.size() << ” routers in the network.” << endl;

}

void CentralController::calculateOptimalPaths() {

// Example: Simple logic to set up static routes

for (auto router : routers) {

// Set up routing paths from each router to other routers or hosts

// In a real implementation, you would run an algorithm like Dijkstra here

routingTable[“host2”] = “router3”;  // Example: Route to host2 via router3

routingTable[“host1”] = “router1”;  // Example: Route to host1 via router1

}

}

void CentralController::distributeRoutingInformation() {

for (auto router : routers) {

IRoutingTable *routingTableModule = check_and_cast<IRoutingTable *>(router->getSubmodule(“routingTable”));

for (const auto &entry : routingTable) {

// Create and add routing table entries for each router

IPv4Route *route = new IPv4Route();

route->setDestination(Ipv4Address(entry.first.c_str()));

route->setNetmask(Ipv4Address::ALLONES_ADDRESS);

route->setGateway(Ipv4Address(entry.second.c_str()));

route->setSourceType(IPv4Route::MANUAL);

routingTableModule->addRoute(route);

}

EV << “Distributed routing information to ” << router->getFullName() << endl;

}

}

    • Routing Table: The central controller manage a routing table mapping destinations to next hops.
    • Network Information Collection: The controller requires information related to the network like available routers and links.
    • Path Calculation: The controller estimate optimal paths using a routing algorithm (e.g., Dijkstra) and updates the routing tables of individual routers.
    • Routing Information Distribution: The controller distributes the estimate routing paths to all routers.

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 = CentralizedRoutingNetwork

sim-time-limit = 100s

**.scalar-recording = true

**.vector-recording = true

# Application traffic configuration

*.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 amongst hosts to spawn network activity, activating the centralized routing protocol.

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure that everything is properly executed and compiled.
  2. Run Simulations:
    • Use IDE in the OMNeT++ or command line to implement the simulations. Keep an eye on how the centralized routing protocol performs in different conditions.

Step 7: Analyze the Results

  1. Monitor Protocol Behavior:
    • Assess how the centralized routing protocol manages the routing, especially under diverse network scenarios.
  2. Evaluate Performance:
    • Analyze key performance metrics like packet delivery ratio, end-to-end delay, and routing overhead.
    • Scalars and Vectors: Use OMNeT++ tools to record and analyze scalar and vector data includes the total of packets sent, received, and dropped, as well as the time taken to deliver packets.
  3. Check for Issues:
    • Look for issues like routing loops, packet loss, or excessive delay that may specify problems with the centralized routing logic.

Step 8: Refine and Optimize the Protocol

  1. Address Any Issues:
    • Refine the routing logic based on the simulation results to optimize performance and address any problems.
  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 enhanced protocol to authenticate progresses.

In this approach, we successfully provided the guide to implement a simple centralized routing protocol in OMNeT++ using the INET framework. If you need any details regarding this process, we can provide it. So approach omnet-manual.com for best implementation and simulation results.

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