How to Begin Implement Optimal Routing in NS3

To begin the Optimal Routing in NS-3 has contains the model a routing protocol which calculate a routes according to well-defined the optimality principle like as minimum path, minimal delay, maximum bandwidth or energy effectiveness. This can be realized through executing a centralized or distributed procedure, reliant on this environment.

Here’s how you can begin implementing Optimal Routing in NS-3:

Steps to Begin Implement Optimal Routing in NS3

Step 1: Understand Optimal Routing

1. Key Concepts:
   • Optimality Criterion: Routes are selected according to the detailed performance of parameter metric:
     • Shortest Path: Reducing the hop count.
     • Minimal Delay: Selecting the paths through the minimum delay.
     • Maximum Bandwidth: Prioritizing the high-bandwidth connections.
     • Energy Efficiency: Reducing the energy usage in wireless networks.
   • Typically has includes the procedures such as:
     • Dijkstra’s Algorithm used the shortest path.
     • Bellman-Ford Algorithm like as distributed shortest path.
2. Use Cases:
   • High-performance networks in which congestion is routed terms on real-time Environments.
   • Wireless sensor networks for energy-efficient transmission.

Step 2: Set Up NS-3

1. Install NS-3:

git clone https://gitlab.com/nsnam/ns-3-dev.git

cd ns-3-dev

./ns3 configure –enable-examples –enable-tests

./ns3 build

1. Verify Installation: Validate by a basic script:

./ns3 run examples/tutorial/first

Step 3: Plan the Protocol Design

1. Core Components:
   • Network Graph Representation: Use adjacency lists or matrices for design the network.
   • Optimality Algorithm: Apply the procedures are Dijkstra, Bellman-Ford, or a custom algorithm.
   • Routing Table: Register the optimal routes for every destination.
2. Workflow:
   • Determine the network topology at initialization.
   • Calculate the optimal routes according to their selected metric.
   • Forward packets using the computed routing table.

Step 4: Implement Optimal Routing

Step 4.1: Define the Protocol Class

Encompass the Ipv4RoutingProtocol class:

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

#include <map>

#include <vector>

#include <limits>

using namespace ns3;

class OptimalRouting : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

OptimalRouting();

virtual ~OptimalRouting();

virtual Ptr<Ipv4Route> RouteOutput(Ptr<Packet> packet, const Ipv4Header &header,

Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) override;

virtual bool RouteInput(Ptr<const Packet> packet, 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 BuildRoutingTable();

private:

void DiscoverTopology();

void ComputeOptimalRoutes(Ipv4Address source);

std::map<Ipv4Address, std::map<Ipv4Address, uint32_t>> m_topology; // Adjacency list

std::map<Ipv4Address, std::pair<Ipv4Address, uint32_t>> m_routingTable; // Destination -> (NextHop, Cost)

};

Step 4.2: Implement Core Functions

• Topology Discovery: Populate the adjacency list by the network topology.

void OptimalRouting::DiscoverTopology() {

m_topology.clear();

for (uint32_t i = 0; i < GetNode()->GetNDevices(); ++i) {

Ptr<NetDevice> device = GetNode()->GetDevice(i);

Ipv4Address address = GetNode()->GetObject<Ipv4>()->GetAddress(i, 0).GetLocal();

for (uint32_t j = 0; j < GetNode()->GetNDevices(); ++j) {

if (i != j) {

Ptr<NetDevice> neighborDevice = GetNode()->GetDevice(j);

Ipv4Address neighborAddress = GetNode()->GetObject<Ipv4>()->GetAddress(j, 0).GetLocal();

uint32_t cost = 1; // Assign a uniform or metric-based cost

m_topology[address][neighborAddress] = cost;

}

}

}

}

• Optimal Route Computation (Dijkstra’s Algorithm): Calculate the optimal routes according to their performance of metric.

void OptimalRouting::ComputeOptimalRoutes(Ipv4Address source) {

std::map<Ipv4Address, uint32_t> distances;

std::map<Ipv4Address, Ipv4Address> previous;

std::vector<Ipv4Address> nodes;

for (const auto &node : m_topology) {

distances[node.first] = std::numeric_limits<uint32_t>::max();

previous[node.first] = Ipv4Address();

nodes.push_back(node.first);

}

distances[source] = 0;

while (!nodes.empty()) {

auto minNode = std::min_element(nodes.begin(), nodes.end(),

[&](const Ipv4Address &a, const Ipv4Address &b) {

return distances[a] < distances[b];

});

Ipv4Address current = *minNode;

nodes.erase(minNode);

for (const auto &neighbor : m_topology[current]) {

uint32_t alt = distances[current] + neighbor.second;

if (alt < distances[neighbor.first]) {

distances[neighbor.first] = alt;

previous[neighbor.first] = current;

}

}

}

m_routingTable.clear();

for (const auto &node : distances) {

if (node.second != std::numeric_limits<uint32_t>::max() && node.first != source) {

Ipv4Address nextHop = node.first;

while (previous[nextHop] != source) {

nextHop = previous[nextHop];

}

m_routingTable[node.first] = {nextHop, node.second};

}

}

}

• Build Routing Table: Associate the network topology detection for calculate the optimal route.

void OptimalRouting::BuildRoutingTable() {

DiscoverTopology();

Ipv4Address localAddress = GetNode()->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal();

ComputeOptimalRoutes(localAddress);

}

• Packet Forwarding: Sending their packets using the calculated routing table.

Ptr<Ipv4Route> OptimalRouting::RouteOutput(Ptr<Packet> packet, const Ipv4Header &header,

Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) {

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

auto it = m_routingTable.find(header.GetDestination());

if (it != m_routingTable.end()) {

route->SetDestination(header.GetDestination());

route->SetGateway(it->second.first); // Next hop

route->SetOutputDevice(oif);

}

return route;

}

bool OptimalRouting::RouteInput(Ptr<const Packet> packet, const Ipv4Header &header,

Ptr<const NetDevice> idev, UnicastForwardCallback ucb,

MulticastForwardCallback mcb, LocalDeliverCallback lcb,

ErrorCallback ecb) {

if (header.GetDestination() == GetNode()->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal()) {

lcb(packet, header, idev); // Deliver locally

return true;

}

auto it = m_routingTable.find(header.GetDestination());

if (it != m_routingTable.end()) {

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

route->SetDestination(header.GetDestination());

route->SetGateway(it->second.first); // Next hop

ucb(route, packet, header);

return true;

}

return false;

}

Step 5: Register the Protocol

Store the protocol by NS-3:

TypeId OptimalRouting::GetTypeId(void) {

static TypeId tid = TypeId(“ns3::OptimalRouting”)

.SetParent<Ipv4RoutingProtocol>()

.SetGroupName(“Internet”)

.AddConstructor<OptimalRouting>();

return tid;

}

Step 6: Integrate into a Simulation

1. Simulation Script Example:

#include “ns3/internet-stack-helper.h”

#include “ns3/optimal-routing.h”

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

NodeContainer nodes;

nodes.Create(4);

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)));

InternetStackHelper stack;

Ptr<OptimalRouting> optimalRouting = CreateObject<OptimalRouting>();

optimalRouting->BuildRoutingTable();

stack.SetRoutingHelper(optimalRouting);

stack.Install(nodes);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 7: Test and Debug

1. Enable Logging:

export NS_LOG=”OptimalRouting=level_all|prefix_time”

./ns3 run my-simulation

1. Verify Results:
   • Test the entries for optimal routing table.
   • Verify the packet forwarding accuracy.

Step 8: Extend and Optimize

1. Enhancements:
   • It helps for increase the dynamic metrics for sample bandwidth or delay.
   • Execute the multi-metric optimization for routing decisions.
2. Performance Testing:
   • Estimate the performance in large-scale networks.
   • Validate the scalability and convergence duration.

Here’s we provide, how you can replicate the basic optimal routing in ns3 simulation environment that leveraging one of the routing protocols or by configuring the network for optimal path selection. We will another manual to address your enquiries about this project.