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How to implement path vector routing in OMNeT++

To implement the path vector routing in OMNeT++ has numerous steps. The term path vector routing is a protocol used in large networks especially across numerous autonomous systems (ASes) that mitigate the routing loops and make sure that the best path to each destination is selected. The Border Gateway Protocol (BGP) is a popular instance of a path vector routing protocol. In the below we deliver the complete procedures to implement the simple path vector routing protocol in OMNeT++;

Step-by-Step Implementation:

Step 1: Set Up OMNeT++ and INET Framework

  1. Install OMNeT++:
    • Make sure OMNeT++ is installed on system. We need download it from the OMNeT++
  2. Install the INET Framework:
    • Download and install the INET Framework, which offers different  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 generate a new OMNeT++ project through File > New > OMNeT++ Project.
    • Name project such as PathVectorRoutingSimulation and set up the project directory.
  2. Set Up Project Dependencies:
    • Make sure 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:
    • To state the network topology using the NED language. This topology will concludes the routers and hosts that will use the path vector routing protocol.

Example:

network PathVectorRoutingNetwork

{

submodules:

as1_router1: Router;

as2_router1: Router;

as3_router1: Router;

host1: StandardHost;

host2: StandardHost;

connections allowunconnected:

as1_router1.ethg++ <–> Eth10Gbps <–> as2_router1.ethg++;

as2_router1.ethg++ <–> Eth10Gbps <–> as3_router1.ethg++;

as1_router1.ethg++ <–> Eth1Gbps <–> host1.ethg++;

as3_router1.ethg++ <–> Eth1Gbps <–> host2.ethg++;

}

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

Step 4: Implement the Path Vector Routing Protocol

  1. Define the Path Vector Routing Module:
    • Generate a new module in NED for the path vector routing protocol. This module will manage the transmission of path vectors among routers, update routing tables, and choose the best paths based on the received vectors.

Example (in NED):

simple PathVectorRouting

{

parameters:

@display(“i=block/router”);

gates:

inout lowerLayerIn[];

inout lowerLayerOut[];

}

  1. Implement Path Vector Routing Logic in C++:
    • To execute the routing logic in C++ that manages the advertisement and reception of path vectors, updating the routing table respectively.

Example (C++ implementation):

#include <map>

#include <vector>

#include “inet/common/INETDefs.h”

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

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

#include “inet/networklayer/ipv4/IPv4Route.h”

class PathVectorRouting : public cSimpleModule

{

private:

struct PathVectorEntry {

std::string prefix;

std::string nextHop;

std::vector<int> asPath;  // AS Path

};

std::map<std::string, PathVectorEntry> pathVectorTable;  // Prefix -> PathVectorEntry

IRoutingTable *inetRoutingTable;

cMessage *updateMsg;

simtime_t updateInterval;

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void sendUpdateMessages();

void processUpdateMessage(cMessage *msg);

void selectBestPath(const std::string& prefix);

};

Define_Module(PathVectorRouting);

void PathVectorRouting::initialize() {

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

updateInterval = par(“updateInterval”);

updateMsg = new cMessage(“PathVectorUpdate”);

scheduleAt(simTime() + updateInterval, updateMsg);

// Initialize the Path Vector table (e.g., with directly connected networks)

// This might involve setting up initial paths based on the network topology

}

void PathVectorRouting::handleMessage(cMessage *msg) {

if (msg == updateMsg) {

sendUpdateMessages();

scheduleAt(simTime() + updateInterval, updateMsg);

} else {

processUpdateMessage(msg);

}

}

void PathVectorRouting::sendUpdateMessages() {

// Create and send path vector update messages to neighbors

for (int i = 0; i < gateSize(“lowerLayerOut”); i++) {

cPacket *updatePacket = new cPacket(“PathVectorUpdate”);

// Add path vector data to the update packet

send(updatePacket, “lowerLayerOut”, i);

}

}

void PathVectorRouting::processUpdateMessage(cMessage *msg) {

// Process incoming path vector update messages from neighbors

// Extract routing information and update the path vector table

cPacket *packet = check_and_cast<cPacket *>(msg);

// Assume the packet contains path vector data

// Update the path vector table with the received data

delete packet;  // Don’t forget to delete the message

}

void PathVectorRouting::selectBestPath(const std::string& prefix) {

// Implement best path selection based on the AS path length

// The selected path is then installed in the routing table

auto it = pathVectorTable.find(prefix);

if (it != pathVectorTable.end()) {

PathVectorEntry bestPath = it->second;

// Update the local routing table with the best route

Ipv4Route *route = new Ipv4Route();

route->setDestination(Ipv4Address(prefix.c_str()));

route->setNetmask(Ipv4Address::ALLONES_ADDRESS);

route->setGateway(Ipv4Address(bestPath.nextHop.c_str()));

route->setSourceType(IPv4Route::BGP);

inetRoutingTable->addRoute(route);

}

}

    • Path Vector Table: The path vector table stores routes received from neighbours that has the prefix, next hop, and AS path.
    • Session Management: To manage the advertisement and reception of path vectors with neighbours, updating the table accordingly.
    • Best Path Selection: Implement logic to choose the best path based on conditions like AS path length and next-hop reachability.

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 = PathVectorRoutingNetwork

sim-time-limit = 200s

**.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)

# Path vector routing parameters

**.pathVectorRouting.updateInterval = 30s

  1. Traffic Configuration:
    • Set up application-level traffic among hosts to generate network activity, triggering path vector updates and routing decisions.

Step 6: Run the Simulation

  1. Compile the Project:
    • Make sure everything is correctly implemented and compiled.
  2. Run Simulations:
    • Implement the simulations using OMNeT++’s IDE or command line. Monitor how the path vector routing protocol performs under numerous conditions.

Step 7: Analyze the Results

  1. Monitor Path Vector Behavior:
    • To assess how path vectors are advertised, received, and processed by routers in the network.
  2. Evaluate Performance:
    • Measure key performance metrics like convergence time, routing stability, and packet delivery ratio.
    • Scalars and Vectors: Use OMNeT++ tools to record and measure scalar and vector data, like the number of routes exchanged, convergence times, and packet delivery statistics.
  3. Check for Issues:
    • Consider the challenges like routing loops, route flapping, or slow convergence that may shows the difficulties with the path vector implementation.

Step 8: Refine and Optimize the Protocol

  1. Address Any Issues:
    • Refine the path vector routing logic based on the simulation outcomes to enhance performance and address any issues.
  2. Optimize for Performance:
    • Fine-tune parameters such as update intervals, path selection criteria, or route advertisement policies to optimize network efficiency.

In this setup we learn and understand how the path vector routing will prevent the loops and make the best path in the network. If you need more information regarding the path vector routing we will support and provide that too. Relating to the Border Gateway Protocol (BGP), we are dedicated to assisting you with your projects. We encourage you to connect with omnet-manual.com for simulation and configuration outcomes pertaining to path vector routing within the OMNeT++ tool for your initiatives. Additionally, we provide you with the latest project concepts along with performance analysis support in this domain.

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