How to Begin Implement Distance Vector Routing in NS3

To execute Distance Vector Routing utilising NS3 which requires replicating a routing protocol in which nodes are swap data regarding its distance to every other node within the network. The protocol normally functions with Bellman-Ford algorithm for determining the shortest routes.

Here, we can guide you through step-by-step process to execute the Distance Vector Routing in NS3:

Steps to Begin Implement Distance Vector Routing in NS3

Step 1: Understand Distance Vector Routing Basics

1. Core Principles:
   • Every single node sustains a routing table including distances (metrics) to all identified destinations.
   • Nodes swap routing tables periodically including its neighbors.
   • Compute the shortest path with Bellman-Ford algorithm.
2. Routing Table Format:
   • Destination: The victim node or network.
   • Next Hop: The next node within the path.
   • Cost/Metric: The distance or cost to the end node.
3. Key Actions:
   • Periodic Updates: Distribute the routing tables at ordered intervals.
   • Triggered Updates: Deliver the changes immediately based on the identifying topology changes such as link failure.

Step 2: Set Up NS3

1. Install NS3:

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: Confirm the installation using an example simulation script:

./ns3 run examples/tutorial/first

Step 3: Plan the Protocol Architecture

1. Key Components:
   • Routing Table: It saves distances to destinations.
   • Periodic Updates: Periodically transmits the routing tables.
   • Bellman-Ford Logic: Modernize routing tables according to the neighbors’ data.
2. Implementation Scope:
   • Replicate the simple Distance Vector Routing for a static or actively modifying topology.
   • Address packet forwarding depends on the routing tables.

Step 4: Implement Distance Vector Routing

Step 4.1: Define the Protocol Class

Create the protocol class by prolonging the Ipv4RoutingProtocol class:

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

#include “ns3/node.h”

#include “ns3/socket.h”

using namespace ns3;

class DistanceVectorRouting : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

DistanceVectorRouting();

virtual ~DistanceVectorRouting();

// Overrides for routing protocol

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;

virtual void NotifyInterfaceUp(uint32_t interface) override;

virtual void NotifyInterfaceDown(uint32_t interface) override;

private:

void UpdateRoutingTable();

void SendPeriodicUpdates();

void ReceiveUpdate(Ptr<Socket> socket);

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

Ptr<Socket> m_socket;

};

Step 4.2: Implement Core Functions

• Routing Table Management: Sustain a routing table for every known destination.

void DistanceVectorRouting::UpdateRoutingTable() {

// Bellman-Ford logic to update routing table

for (const auto &entry : m_neighbors) {

for (const auto &neighborEntry : entry.second.routingTable) {

uint32_t newCost = entry.second.cost + neighborEntry.second.cost;

if (newCost < m_routingTable[neighborEntry.first].second) {

m_routingTable[neighborEntry.first] = {entry.first, newCost};

}

}

}

}

• Periodic Updates: Transmit routing tables periodically to the neighbors.

void DistanceVectorRouting::SendPeriodicUpdates() {

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

// Serialize routing table into packet

for (const auto &entry : m_routingTable) {

// Add routing table entries to the packet

}

for (const auto &neighbor : m_neighbors) {

m_socket->SendTo(packet, 0, InetSocketAddress(neighbor.first, 520));

}

Simulator::Schedule(Seconds(10.0), &DistanceVectorRouting::SendPeriodicUpdates, this);

}

• Handle Received Updates: According to the neighbors’ advertisements modernizing the routing table.

void DistanceVectorRouting::ReceiveUpdate(Ptr<Socket> socket) {

Ptr<Packet> packet = socket->Recv();

// Deserialize packet and update routing table

UpdateRoutingTable();

}

• Packet Forwarding: Transmit packets with the support of routing table.

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

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

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

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

auto entry = m_routingTable[header.GetDestination()];

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

route->SetOutputDevice(oif);

return route;

}

bool DistanceVectorRouting::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);

return true;

}

auto entry = m_routingTable[header.GetDestination()];

if (entry.first.IsBroadcast()) {

return false;

}

ucb(Create<Ipv4Route>(entry.first), packet, header);

return true;

}

Step 5: Integrate the Protocol

Step 5.1: Register the Protocol

Record the protocol using NS3:

TypeId DistanceVectorRouting::GetTypeId(void) {

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

.SetParent<Ipv4RoutingProtocol>()

.SetGroupName(“Internet”)

.AddConstructor<DistanceVectorRouting>();

return tid;

}

Step 5.2: Add to Nodes

Add the protocol to a simulation script for nodes:

#include “ns3/internet-stack-helper.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<DistanceVectorRouting> dvRouting = CreateObject<DistanceVectorRouting>();

stack.SetRoutingHelper(dvRouting);

stack.Install(nodes);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 6: Test and Debug

1. Enable Logging: For debugging, we can leverage the NS3’s logging system:

export NS_LOG=”DistanceVectorRouting=level_all|prefix_time”

./ns3 run my-simulation

1. Validate Results:
   • Confirm routing table convergence.
   • Examine the packet delivery and path selection leveraging FlowMonitor.

Step 7: Extend and Optimize

1. Enhancements:
   • Execute the divided horizon for avoiding routing loops.
   • Integrate support for link failure detection and activated updates.
2. Performance Optimization:
   • Experiment the scalability within larger topologies.
   • Minimize overhead by way of enhancing the update frequency periodically.

We had executed successfully an extensive implementation technique for executing and analysing the Distance Vector Routing applying by NS3 environment. If additional data is needed, we will ready to provide it too.