How to Begin Implement a IGP Protocol in NS3

To execute an Interior Gateway Protocol (IGP) using ns3 that requires replicating a routing protocol which is intended for routing in a single autonomous system (AS). The two most general kinds of IGPs are OSPF (Open Shortest Path First) and RIP (Routing Information Protocol), however IS-IS can be executed in an advanced situation. While NS3 doesn’t directly offer unstandardized for executions in OSPF or IS-IS, but we need to replicate them with custom execution or by prolonging the ns3.

This guide will addresses executing the OSPF for simplicity leveraging IGP within ns3, by utilising ns3’s existing routing functionalities like RIP and manual set up, and integrating them using custom or external components as needed.

Steps to Begin Implement an IGP Protocol in NS3

1. Set Up ns3 Environment

1. Install ns3:
   • We can download and set up the new version of ns3 on the machine.
   • Make sure that the installation using a basic example script as ./waf –run hello-simulator.
2. Include the Required Modules:
   • We require internet module, and probably others are relying on the simulation type such as point-to-point, wifi to replicating the routing protocols.

2. Define Objectives for the IGP Simulation

Define the IGP simulation goals to replicate:

• OSPF routing: Mimic OSPF routing protocol for determining shortest paths actively in an AS.
• IS-IS routing: It is an alternative IGP protocol.
• Performance Metrics: Estimate how rapid routes meet and how OSPF manages teh link failures, or how it performs in heavy traffic.

3. Set Up Network Topology

1. Create Nodes:
   • Make a network topology which contains routers (nodes).

NodeContainer routers;

routers.Create(3); // Three routers in the network

1. Create Links:
   • Introduce connections among the routers using PointToPointHelper or WifiHelper.

PointToPointHelper p2p;

p2p.SetDeviceAttribute(“DataRate”, StringValue(“1Gbps”));

p2p.SetChannelAttribute(“Delay”, StringValue(“2ms”));

NetDeviceContainer routerLink1 = p2p.Install(routers.Get(0), routers.Get(1));

NetDeviceContainer routerLink2 = p2p.Install(routers.Get(1), routers.Get(2));

1. Add Hosts (Optional):
   • If we require hosts which are linked to routers then make and associate them.

NodeContainer hosts;

hosts.Create(2); // Two hosts in the network

1. Assign IP Addresses:
   • Allocate an IP addresses to set boundaries among routers and hosts.

InternetStackHelper internet;

internet.Install(routers);

internet.Install(hosts);

Ipv4AddressHelper ipv4;

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

Ipv4InterfaceContainer interfaces1 = ipv4.Assign(routerLink1);

ipv4.SetBase(“10.1.2.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces2 = ipv4.Assign(routerLink2);

4. Enable IGP (OSPF in This Case)

NS3 offers an OspfHelper class, which can be used to set up and allow OSPF routing for replicating the OSPF.

1. Configure OSPF:
   • For each router, we can configure OSPF routing protocol.

OspfHelper ospfRouting;

ospfRouting.Install(routers.Get(0));

ospfRouting.Install(routers.Get(1));

ospfRouting.Install(routers.Get(2));

1. Customize OSPF Parameters (Optional):
   • We will need to modify OSPF-specific metrics such as timers, area IDs, and so on.

ospfRouting.SetRouterID(routers.Get(0), Ipv4Address(“10.1.1.1”));

ospfRouting.SetAreaID(routers.Get(0), 0);

5. Install Applications

1. Generate Traffic:
   • Make traffic among the nodes, replicating typical data flow to apply UdpEchoClientHelper and UdpEchoServerHelper.

UdpEchoServerHelper echoServer(9);

ApplicationContainer serverApps = echoServer.Install(hosts.Get(1));

serverApps.Start(Seconds(1.0));

serverApps.Stop(Seconds(10.0));

UdpEchoClientHelper echoClient(interfaces2.GetAddress(1), 9);

echoClient.SetAttribute(“MaxPackets”, UintegerValue(10));

echoClient.SetAttribute(“Interval”, TimeValue(Seconds(1.0))); // Send every second

echoClient.SetAttribute(“PacketSize”, UintegerValue(1024));

ApplicationContainer clientApps = echoClient.Install(hosts.Get(0));

clientApps.Start(Seconds(2.0));

clientApps.Stop(Seconds(10.0));

1. Monitor Traffic:
   • Make use of FlowMonitor to seizure and examine the traffic flow.

FlowMonitorHelper flowmon;

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

6. Simulate Network Changes (Optional)

1. Link Failures:
   • Replicate link failures and then estimate how rapidly the OSPF protocol meets to determine the new paths.

Simulator::Schedule(Seconds(5.0), &PointToPointNetDevice::SetLinkDown, routerLink1.Get(1)->GetObject<PointToPointNetDevice>());

1. Restoring Links:
   • Reinstate a failed connection for monitoring the dynamic behavior of OSPF during retrieval.

Simulator::Schedule(Seconds(7.0), &PointToPointNetDevice::SetLinkUp, routerLink1.Get(1)->GetObject<PointToPointNetDevice>());

7. Run the Simulation

1. Start the Simulator:
   • Execute the simulation after configuring the nodes, links, and applications:

Simulator::Run();

Simulator::Destroy();

1. Monitor Results:
   • Debug and examine the routing behavior with NS_LOG.

NS_LOG_COMPONENT_DEFINE(“OspfRouting”);

8. Analyze and Visualize Results

1. FlowMonitor Analysis:
   • We want to leverage FlowMonitor for examining the performance parameters such as throughput, packet delivery ratio, and latency after the simulation.

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

1. Visualization with NetAnim:
   • Transfer the simulation data to envision the nodes communications and behavior of routing.

AnimationInterface anim(“ospf-simulation.xml”);

9. Extend and Optimize

1. Scaling the Network:
   • Integrate additional routers and hosts for replicating larger and more complex networks for scalability.
2. Simulating Different Topologies:
   • Experiment the performance of OSPF under various network topologies such as mesh, star, or fully connected topology.
3. Test Convergence:
   • After link failures, assess the behaviour of OSPF like route convergence time and traffic rerouting.
4. Implementing Other IGPs:
   • We will need to prolong the ns3 by means of executing other IGPs like IS-IS or EIGRP to apply same mechanisms.

Example Use Cases:

• Simulating Dynamic Routing in Data Centers: Experiment how OSPF adjusts to changes within the network.
• Network Performance Testing: In large networks, we can estimate the routing convergence and scalability.
• Educational Simulations: Explain the behaviour of OSPF within classroom situations.

By using the above techniques, we had completed the implementation of IGP Protocol with the help of NS3 environment. We provided basic approach with sample coding, sample use cases and extensions for this project. If you want extra details regarding this process we will offered it.