How to Implement link state routing in ns3

To implement Link State Routing in ns3, we have to follow several steps which is similar to the Distance Vector Routing implementation. Below are the complete steps to setup and simulate Link State Routing in ns3.

Steps for implementation

• Include necessary libraries :
• In your script, include the necessary libraries.

 

• Define network topology :
• For your network topology, create the nodes and links.
• Install Internet Stack :
• On your nodes, install the internet stack.
• Configure LSR Routing Protocol :
• Configure the LSR routing protocol for your nodes..
• Set Up Applications :
• To generate traffic and test the routing, install applications.
• Run the Simulation :
• Define the simulation parameters and run it.

Example implementation in C++

Here is a complete example on implementing a basic LSR routing in ns3:

Include libraries :

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

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

#include “ns3/applications-module.h”

#include “ns3/ipv4-global-routing-helper.h”

#include “ns3/link-state-routing-helper.h” // Ensure you have this or similar header if using custom implementation

Define Network Topology :

using namespace ns3;

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

CommandLine cmd;

cmd.Parse(argc, argv);

NodeContainer nodes;

nodes.Create(4);

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“5Mbps”));

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

NetDeviceContainer devices;

devices = pointToPoint.Install(nodes.Get(0), nodes.Get(1));

devices = pointToPoint.Install(nodes.Get(1), nodes.Get(2));

devices = pointToPoint.Install(nodes.Get(2), nodes.Get(3));

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces;

interfaces = address.Assign(devices);

 

Configure Link State Routing :

// Assuming you have a link state routing implementation

LinkStateRoutingHelper linkStateRouting;

Ipv4ListRoutingHelper list;

list.Add(linkStateRouting, 0);

InternetStackHelper stack;

stack.SetRoutingHelper(list);

stack.Install(nodes);

Set Up Applications :

uint16_t port = 9;

UdpEchoServerHelper server(port);

ApplicationContainer apps = server.Install(nodes.Get(3));

apps.Start(Seconds(1.0));

apps.Stop(Seconds(10.0));

UdpEchoClientHelper client(interfaces.GetAddress(3), port);

client.SetAttribute(“MaxPackets”, UintegerValue(1));

client.SetAttribute(“Interval”, TimeValue(Seconds(1.0)));

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

apps = client.Install(nodes.Get(0));

apps.Start(Seconds(2.0));

apps.Stop(Seconds(10.0));

Run the Simulation :

Simulator::Run();

Simulator::Destroy();

return 0;

}

Implementing a Custom Link State Routing Protocol

As ns3 does not have a built-in support for Link State Routing protocol, you have to implement one. Here is a implementation :

1. Create a New Routing Protocol Class :

Derive your class from Ipv4RoutingProtocol.

class LinkStateRoutingProtocol : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

LinkStateRoutingProtocol();

virtual ~LinkStateRoutingProtocol();

// Inherited methods from Ipv4RoutingProtocol

Ptr<Ipv4Route> RouteOutput(Ptr<Packet> p, const Ipv4Header &header, Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) override;

bool RouteInput(Ptr<const Packet> p, const Ipv4Header &header, Ptr<const NetDevice> idev, UnicastForwardCallback ucb, MulticastForwardCallback mcb, LocalDeliverCallback lcb, ErrorCallback ecb) override;

void NotifyInterfaceUp(uint32_t interface) override;

void NotifyInterfaceDown(uint32_t interface) override;

void NotifyAddAddress(uint32_t interface, Ipv4InterfaceAddress address) override;

void NotifyRemoveAddress(uint32_t interface, Ipv4InterfaceAddress address) override;

void SetIpv4(Ptr<Ipv4> ipv4) override;

private:

void SendLinkStateAdvertisement();

void ReceiveLinkStateAdvertisement(Ptr<Socket> socket);

void UpdateRoutingTable();

// Data structures for routing table and LSA management

// …

Ptr<Ipv4> m_ipv4;

std::map<Ipv4Address, Ptr<Socket>> m_socketMap;

// …

};

2. Implement Link State Advertisements (LSA): Implement the methods for sending, receiving, and processing LSAs.

void LinkStateRoutingProtocol::SendLinkStateAdvertisement() {

// Create and send LSA packets

}

void LinkStateRoutingProtocol::ReceiveLinkStateAdvertisement(Ptr<Socket> socket) {

// Process received LSA packets and update routing table

}

void LinkStateRoutingProtocol::UpdateRoutingTable() {

// Compute shortest paths using Dijkstra’s algorithm

}

1. Integrate with ns3: Integrate your protocol into ns3 by modifying the InternetStackHelper to include your custom protocol.

Running the Code :

Save your script to a file, for example, link-state-routing.cc and compile the script using the ns3 build system

./waf configure –enable-examples

./waf build

./waf –run scratch/link-state-routing

Overall, we had learned on implementing Link State Routing (LSR) in ns3 by simulating Link State Routing using ns3 features. Also, we provide more project information on Link State Routing (LSR) with best programming results.