How to Begin Implement Link State Routing in NS3

To begin a Link State Routing (LSR) in NS3 tool contains the pattern a proactive routing protocol in which nodes is periodically altercation link-state information by neighbor for generate a comprehensive network topology plan. Using this plan, every node has measured the minimum paths for all other nodes using algorithms such as Dijkstra’s.

Here’s a step-by-step guide to implementing Link State Routing in NS-3:

Steps to Begin Implement Link State Routing in NS3

Step 1: Understand Link State Routing

1. Core Concepts:
   • Link State Advertisements (LSAs): Nodes are propagating the LSAs encompassing the data about their neighbor and metrices for connection.
   • Topology Database: Nodes are managing the global view of network through aggregating LSAs.
   • Shortest Path Calculation: The procedures are used like Dijkstra’s for calculate the routes for all nodes.
2. Protocol Requirements:
   • Interrupted the LSA generation and distribution.
   • Keep a database for link-state.
   • Routing table calculation terms of the database.

Step 2: Familiarize Yourself with NS-3

1. Existing Protocols:
   • Investigate the src/olsr/ as OLSR (Optimized Link State Routing) is equal to LSR.
   • Evaluation the Ipv4RoutingProtocol base class that delivers an interface for custom routing protocols.
2. Tracing and Metrics:
   • Use the files metrices for FlowMonitor, AsciiTraceHelper, and PcapHelper to tracing and validating the outcomes.

Step 3: Set Up NS-3 Development Environment

1. Create a Directory:
   • Build a directory for the protocol, for sample src/lsr/.
2. Add Required Files:
   • lsr-routing-protocol.h: Header file intended for LSR.
   • lsr-routing-protocol.cc: Is a execution file.
   • lsr-helper.h and lsr-helper.cc: Helper classes to illustrate the incorporate.
3. Update Build System:
   • Change the wscript in src/ to contain the protocol directory.

Step 4: Design LSR Protocol

1. Define the LSR Class

Encompass the Ipv4RoutingProtocol for LSR functionality.

Header File (lsr-routing-protocol.h)

#include “ns3/ipv4-routing-protocol.h”

#include “ns3/ipv4-address.h”

#include “ns3/socket.h”

#include “ns3/timer.h”

class LsrRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

LsrRoutingProtocol ();

virtual ~LsrRoutingProtocol ();

// Ipv4RoutingProtocol methods

virtual ns3::Ptr<ns3::Ipv4Route> RouteOutput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<ns3::NetDevice> oif,

ns3::Socket::SocketErrno &sockerr);

virtual bool RouteInput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<const ns3::NetDevice> idev,

ns3::UnicastForwardCallback ucb,

ns3::MulticastForwardCallback mcb,

ns3::LocalDeliverCallback lcb,

ns3::ErrorCallback ecb);

// LSR-specific methods

void GenerateLsa ();

void ProcessLsa (ns3::Ptr<const ns3::Packet> packet);

void UpdateRoutingTable ();

private:

ns3::Ptr<ns3::Socket> m_socket;

ns3::Ipv4Address m_selfAddress;

std::map<ns3::Ipv4Address, std::map<ns3::Ipv4Address, uint32_t>> m_topologyDatabase; // Link-state database

std::map<ns3::Ipv4Address, ns3::Ipv4Address> m_routingTable; // Destination -> Next hop

ns3::Timer m_lsaTimer; // Timer for periodic LSA generation

};

2. Implement Core Functions

LSA Generation and Dissemination

Periodically broadcast LSAs containing neighbor information and connection metrics.

void LsrRoutingProtocol::GenerateLsa () {

// Create LSA packet

ns3::Ptr<ns3::Packet> packet = ns3::Create<ns3::Packet> ();

// Serialize topology information into the packet

// …

// Broadcast LSA

m_socket->SendTo (packet, 0, ns3::InetSocketAddress (ns3::Ipv4Address::GetBroadcast (), 9999));

m_lsaTimer.Schedule (ns3::Seconds (5)); // Reschedule for periodic updates

}

Process Incoming LSAs

Bring up-to-date the topology database by received LSA information.

void LsrRoutingProtocol::ProcessLsa (ns3::Ptr<const ns3::Packet> packet) {

// Deserialize packet to extract LSA information

// …

// Update the topology database

m_topologyDatabase[sender][neighbor] = metric;

// Recompute routing table

UpdateRoutingTable ();

}

Routing Table Calculation

Use Dijkstra’s procedure for calculate the minimum paths according to their topology database.

void LsrRoutingProtocol::UpdateRoutingTable () {

// Implement Dijkstra’s algorithm

// Populate m_routingTable with shortest paths

}

Packet Forwarding

Manage the routing for packets using the calculated routing table.

ns3::Ptr<ns3::Ipv4Route> LsrRoutingProtocol::RouteOutput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<ns3::NetDevice> oif,

ns3::Socket::SocketErrno &sockerr) {

ns3::Ptr<ns3::Ipv4Route> route = ns3::Create<ns3::Ipv4Route> ();

if (m_routingTable.count(header.GetDestination ())) {

route->SetGateway (m_routingTable[header.GetDestination ()]);

} else {

sockerr = ns3::Socket::ERROR_NOROUTETOHOST;

return nullptr;

}

return route;

}

Step 5: Write a Helper Class

Clarify the configure a LSR for replication scripts.

#include “lsr-routing-protocol.h”

class LsrHelper {

public:

void Install (ns3::NodeContainer nodes) {

for (auto it = nodes.Begin(); it != nodes.End(); ++it) {

ns3::Ptr<LsrRoutingProtocol> protocol = ns3::CreateObject<LsrRoutingProtocol>();

(*it)->AggregateObject(protocol);

}

}

};

Step 6: Write a Simulation Script

Example Simulation Script

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “lsr-helper.h”

using namespace ns3;

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

NodeContainer nodes;

nodes.Create (5);

InternetStackHelper stack;

stack.Install (nodes);

LsrHelper lsrHelper;

lsrHelper.Install (nodes);

// Configure point-to-point links

PointToPointHelper p2p;

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

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

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

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

devices.Add (p2p.Install (nodes.Get (2), nodes.Get (3)));

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

Ipv4AddressHelper address;

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

address.Assign (devices);

// Set up traffic

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApps = echoServer.Install (nodes.Get (4));

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (10.0));

UdpEchoClientHelper echoClient (Ipv4Address (“10.1.1.4”), 9);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (100));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (0.1)));

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

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

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 7: Compile and Test

1. Build the Protocol:

./waf configure

./waf build

1. Run Simulation:

./waf –run your-script

Step 8: Analyze Results

1. Use Tracing Tools:
   • Allow the PcapHelper or AsciiTraceHelper for specific packet investigation.
2. Evaluate Metrics:
   • The performance of parameter metrices such as throughput, latency, and packet delivery ratio.

Step 9: Extend and Validate

1. Add Features:
   • Encourage for mobility and dynamic connection bring up-to-date.
   • Further parameter metrices for routing decisions for instance bandwidth, delay.
2. Test Scalability:
   • Verify the performance by larger topologies and different congestion loads.

For each of these projects, we can utilize the NS3 to replicate a network with different node configurations, traffic models, and mobility scenarios to evaluate the effectiveness of Dijkstra’s algorithm in changing conditions. Additional specific details regarding the dijikstra algorithms based examples will be provided if required.