How to Begin Implement Dynamic Routing in NS3

To start executing Dynamic Routing in NS3, we can model a routing protocol which modifies the routes within real time according to the altering network conditions like topology modifications, traffic congestion, or link quality. Dynamic routing is specifically related in networks including the mobility or high variability like Mobile Ad-Hoc Networks (MANETs) or dynamic IoT deployments.

Below is simplest approach to get started with Dynamic Routing in NS3:

Steps to Begin Implement Dynamic Routing in NS3

Step 1: Understand Dynamic Routing

1. Core Features:
   • Route Adaptation: Dynamically adapt the routing tables since modify the network conditions.
   • Topology Awareness: Constantly observe the network topology or parameters like delay, throughput, and packet loss.
   • Fault Tolerance: Redirect packets in the event of node/link failures.
2. Common Protocols:
   • AODV (Ad-hoc On-demand Distance Vector)
   • OLSR (Optimized Link State Routing)
3. Design Focus:
   • Lightweight control message overhead.
   • Scalability to large networks.
   • Real-time route modifications.

Step 2: Set Up NS3 Environment

1. Create a New Directory:
   • Make a directory under src/, for the protocol like src/dynamic-routing/.
2. Add Required Files:
   • dynamic-routing-protocol.h: Describe the protocol class.
   • dynamic-routing-protocol.cc: It supports to execute the protocol logic.
   • dynamic-routing-helper.h and dynamic-routing-helper.cc: for simulation scripts, it offer helper classes.
3. Update Build System:
   • Fine-tune the wscript in src/ with the protocol.

Step 3: Design the Protocol

1. Define the Protocol Class

Make a protocol class to prolong the Ipv4RoutingProtocol class for dynamic routing.

Header File (dynamic-routing-protocol.h)

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

#include “ns3/socket.h”

#include “ns3/timer.h”

#include <map>

class DynamicRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

DynamicRoutingProtocol ();

virtual ~DynamicRoutingProtocol ();

// Override 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);

// Dynamic Routing Specific Methods

void DiscoverRoutes ();

void UpdateRoutingTable ();

void HandleTopologyChange ();

private:

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

ns3::Ipv4Address m_selfAddress;

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

ns3::Timer m_discoveryTimer; // Timer for route discovery

};

2. Implement Core Functions

Route Discovery

Propagate the route discovery messages and manage the responses.

void DynamicRoutingProtocol::DiscoverRoutes () {

// Broadcast route discovery message

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

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

// Reschedule discovery

m_discoveryTimer.Schedule(ns3::Seconds(5.0));

}

Update Routing Table

According to the received updates or topology modification, we need to modernize the routing table dynamically.

void DynamicRoutingProtocol::UpdateRoutingTable () {

// Example: Update routing table based on latest metrics

for (auto &entry : m_routingTable) {

// Update route to entry.first based on metric

}

}

Handle Topology Changes

Respond to topology modification like link failures or new links.

void DynamicRoutingProtocol::HandleTopologyChange () {

// Example: Recompute routes when a topology change is detected

UpdateRoutingTable ();

}

Packet Forwarding

For dynamic routing, we can utilise RouteOutput and RouteInput.

ns3::Ptr<ns3::Ipv4Route> DynamicRoutingProtocol::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 4: Write a Helper Class

Make easier the protocol integration into simulation scripts uisng helper class.

#include “dynamic-routing-protocol.h”

class DynamicRoutingHelper {

public:

void Install (ns3::NodeContainer nodes) {

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

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

(*it)->AggregateObject(protocol);

}

}

};

Step 5: Write a Simulation Script

Example Simulation Script

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “dynamic-routing-helper.h”

using namespace ns3;

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

NodeContainer nodes;

nodes.Create (5);

InternetStackHelper stack;

stack.Install (nodes);

DynamicRoutingHelper dynamicHelper;

dynamicHelper.Install (nodes);

PointToPointHelper p2p;

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

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

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

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

// Additional links as needed

Ipv4AddressHelper address;

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

address.Assign (p2p.Install (nodes.Get (0), nodes.Get (1)));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 6: Compile and Run

1. Build the Protocol:

./waf configure

./waf build

1. Run the Simulation:

./waf –run your-script

Step 7: Analyze and Extend

1. Analyze Results:
   • Seizure parameters such as throughput, delay, and packet loss utilising FlowMonitor and PcapHelper.
2. Enhance Protocol:
   • Integrate the support to utilize ns3::MobilityHelper for mobility.
   • Enhance for certain parameters like energy efficiency or QoS.

In this guide, implementation and analysis process for Dynamic Routing were conducted using NS3 with an innovative approach, and a detailed explanation regarding this project will be provided in the next manual.