How to Start OSPF Algorithm Projects Using NS3

To start an OSPF (Open Shortest Path First) algorithm project using NS3, we need to replicate or execute the OSPF protocol that is generally utilized link-state routing protocol. Although NS3 doesn’t support a built-in OSPF execution then we can make a custom execution or replicate the OSPF behaviour to utilise their routing framework.

Below is a sequential approach on how to start and execute the OSPF Algorithm Projects in NS3:

Steps to Start OSPF Algorithm Projects in NS3

  1. Understand OSPF

Key Features of OSPF:

  1. Link-State Routing:
    • Routers swap the link state advertisements (LSAs) including neighbors.
    • Each router constructs a map of the network topology.
  2. Shortest Path First (SPF) Algorithm:
    • OSPF try to determine the shortest path using Dijkstra’s algorithm.
  3. Area-Based Hierarchy:
    • For scalability, splits the networks to areas.
    • Area 0 (backbone area) associate to every other area.

Goals:

  • We mimic or execute the behaviour of OSPF like:
    • LSA generation and flooding.
    • SPF computation.
    • Dynamic route recalculations for topology changes.
  1. Set Up NS3

Install NS3:

  • Go to nsnam.org to download and install NS3.
  • Confirm installation:

./waf –run scratch/test-example

Required Modules:

  • internet: It supports for or IP and routing framework.
  • point-to-point, wifi, or csma: For replicating network topologies.
  1. Plan Your OSPF Simulation

Define Objectives:

  • To replicate a custom OSPF execution.
  • Experiment the response of routing protocol to topology modifications.

Example Topology:

  • Mimic a network including several areas:

Area 1: Node A ↔ Node B ↔ Node C

Area 0: Node B ↔ Node D ↔ Node E

Area 2: Node E ↔ Node F ↔ Node G

Metrics to Measure:

  • Convergence Time: Estimate the duration for routes after topology modifications.
  • Routing Overhead: We want to estimate the volume of LSA traffic.
  • Path Accuracy: Confirm shortest paths are utilised.
  • Throughput and Latency: We compute the performance of data delivery.
  1. Implement OSPF in NS3

Option 1: Custom OSPF Implementation

We need to enhance a custom OSPF protocol by prolonging the Ipv4RoutingProtocol class.

Option 2: Simulate OSPF Behavior

In NS3, utilize the dynamic routing capabilities to replicate the OSPF-like behavior.

4.1 Custom OSPF Implementation

Step 1: Define an OSPF Protocol Class

  • We can prolong the Ipv4RoutingProtocol class.
  • Override approaches for:
    • LSA generation and flooding.
    • SPF computation to utilise Dijkstra’s algorithm.
    • Routing table updates.

Example Code:

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

using namespace ns3;

class OspfRoutingProtocol : public Ipv4RoutingProtocol {

public:

OspfRoutingProtocol();

virtual ~OspfRoutingProtocol();

void GenerateLsa();

void FloodLsa();

void ComputeShortestPath();

private:

std::map<uint32_t, uint32_t> m_linkStateDatabase; // Node ID -> Cost

std::map<uint32_t, uint32_t> m_routingTable;      // Destination -> Next Hop

};

OspfRoutingProtocol::OspfRoutingProtocol() {}

OspfRoutingProtocol::~OspfRoutingProtocol() {}

void OspfRoutingProtocol::GenerateLsa() {

// Simulate LSA generation

}

void OspfRoutingProtocol::FloodLsa() {

// Simulate LSA flooding to neighbors

}

void OspfRoutingProtocol::ComputeShortestPath() {

// Implement Dijkstra’s algorithm to compute shortest paths

// Update routing table

}

Step 2: Integrate OSPF Protocol in Simulation

  • Swap the default NS3 routing protocol including the execution of OSPF.

Example Main Simulation Script:

int main(int argc, char *argv[]) {

NodeContainer nodes;

nodes.Create(6);

PointToPointHelper p2p;

p2p.SetDeviceAttribute(“DataRate”, StringValue(“10Mbps”));

p2p.SetChannelAttribute(“Delay”, StringValue(“5ms”));

NetDeviceContainer devices;

devices.Add(p2p.Install(nodes.Get(0), nodes.Get(1)));

devices.Add(p2p.Install(nodes.Get(1), nodes.Get(2)));

devices.Add(p2p.Install(nodes.Get(1), nodes.Get(3)));

devices.Add(p2p.Install(nodes.Get(3), nodes.Get(4)));

devices.Add(p2p.Install(nodes.Get(4), nodes.Get(5)));

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper ipv4;

ipv4.SetBase(“10.1.1.0”, “255.255.255.0”);

ipv4.Assign(devices);

Ptr<OspfRoutingProtocol> ospf = CreateObject<OspfRoutingProtocol>();

nodes.Get(0)->AggregateObject(ospf);

Simulator::Run();

Simulator::Destroy();

return 0;

}

4.2 Simulate OSPF-Like Behavior

Use OLSR (Optimized Link State Routing Protocol)

OLSR executes the link-state principles in NS3 and it can utilise as per initial point, replicating the OSPF-like behavior.

#include “ns3/olsr-module.h”

OlsrHelper olsr;

InternetStackHelper stack;

stack.SetRoutingHelper(olsr);

stack.Install(nodes);

Add Traffic Sources

Mimic application traffic to experiment the routing behavior.

OnOffHelper onOffHelper(“ns3::UdpSocketFactory”, Address(InetSocketAddress(ipv4Addresses.GetAddress(1), 9)));

onOffHelper.SetAttribute(“DataRate”, StringValue(“500Kbps”));

onOffHelper.SetAttribute(“PacketSize”, UintegerValue(512));

ApplicationContainer app = onOffHelper.Install(nodes.Get(0));

app.Start(Seconds(1.0));

app.Stop(Seconds(10.0));

  1. Test and Debug
  • Enable Logging:

export NS_LOG=OspfRoutingProtocol=level_all:OlsrRoutingProtocol=level_all

./waf –run scratch/ospf-routing

  • Inspect Routing Tables: Confirm shortest paths are properly determined:

Ptr<Ipv4> ipv4 = nodes.Get(0)->GetObject<Ipv4>();

ipv4->GetRoutingProtocol()->Print(std::cout);

  • Capture Packets: Examine the routing and LSA packets within Wireshark to utilize PCAP tracing:

p2p.EnablePcapAll(“ospf”);

  1. Evaluate Performance

Metrics to Measure:

  • Convergence Time: Compute the duration for routing tables to stable.
  • Routing Overhead: Measure the volume of LSA traffic generated.
  • Path Accuracy: Confirm the proper shortest paths are utilized.
  • Packet Delivery Metrics: We need to estimate the performance metrics such as throughput, delay, packet loss.

Use FlowMonitor:

FlowMonitorHelper flowMonitor;

Ptr<FlowMonitor> monitor = flowMonitor.InstallAll();

monitor->SerializeToXmlFile(“ospf-performance.xml”, true, true);

  1. Advanced Features
  • Hierarchical OSPF:
    • We split the network to areas and then we execute the inter-area routing.
  • Dynamic Topologies:
    • Experiment the OSPF to utilize mobility models within dynamic environments.
  • Failure Recovery:
    • Mimic link or node failures, monitoring how OSPF retrieves.
  1. Document and Visualize
  • Document Implementation:
    • It offers protocol goals, techniques, and outcomes.
  • Visualize Results:
    • Envision the simulation to utilise NetAnim.
    • We want to graph the performance parameters to utilize tools such as Matplotlib or Gnuplot.

These projects cover step-by-step approach with sample coding to implement and simulate the OSPF Algorithm projects using NS3 tool. If you did like to want more details on this project we will be offered it.

Our developers are here to boost your project’s performance, so feel free to reach out for more guidance. If you’re kicking off an OSPF (Open Shortest Path First) algorithm project with NS3, you can count on the team at phdprojects.org to help you through every step. Take advantage of phdprojects.org  tailored support to achieve the best results and finish on time