How to Begin Implement Routing Information Protocol in NS3

To begin the Routing Information Protocol (RIP) is a distance-vector routing protocol which uses the hop count as a routing metric. Nodes are modify the routing tables has periodically by neighbors for generate and handle the routes. Here’s how you can begin implementing RIP in NS-3:

Steps to Begin Implement Routing Information Protocol in NS3

Step 1: Understand RIP

1. Key Concepts:
   • Hop Count Metric: RIP uses the number of hops as the metric. The maximum hop count is 15, and 16 indicates “infinity” (unreachable).
   • Periodic Updates: Nodes broadcast their routing tables periodically.
   • Split Horizon: Avoid the routing loops through not commercial for route back in a node from known.
2. RIP Characteristics:
   • It a basic executes.
   • Finding the scalability because of maximum hop count of 15.

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: Execute a basic example script:

./ns3 run examples/tutorial/first

Step 3: Plan the RIP Protocol Design

1. Core Components:
   • Routing Table: Handle the destination, next hop, and hop count.
   • Periodic Updates: Modify the routing tables by neighbors at regular intervals.
   • Update Processing: Bring up-to-date routes according to their received routing tables.
2. Workflow:
   • Start the routing table by direct neighbors.
   • Periodically has propagated the routing table for neighbors.
   • Bring up-to-date the routing table according to their received bring up-to-date using the Bellman-Ford procedure.

Step 4: Implement RIP

Step 4.1: Define the Protocol Class

Cover the Ipv4RoutingProtocol class:

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

#include “ns3/socket.h”

#include <map>

#include <set>

using namespace ns3;

class RipRouting : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

RipRouting();

virtual ~RipRouting();

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;

private:

struct RoutingEntry {

Ipv4Address destination;

Ipv4Address nextHop;

uint32_t hopCount;

Time lastUpdate;

};

std::map<Ipv4Address, RoutingEntry> m_routingTable; // Routing table

std::set<Ipv4Address> m_neighbors;                 // List of neighbors

void InitializeRoutingTable();

void SendRoutingUpdates();

void ReceiveRoutingUpdates(Ptr<Packet> packet, Ipv4Address source);

void UpdateRoutingTable(Ipv4Address source, const std::map<Ipv4Address, RoutingEntry> &neighborTable);

};

Step 4.2: Implement Core Functions

• Initialize Routing Table: Populate the routing table by direct neighbors.

void RipRouting::InitializeRoutingTable() {

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

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

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

m_routingTable[address] = {address, address, 0, Simulator::Now()}; // Cost to self is 0

m_neighbors.insert(address);

}

}

• Send Routing Updates: Periodically propagate the routing table for neighbors.

void RipRouting::SendRoutingUpdates() {

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

for (const auto &entry : m_routingTable) {

// Serialize routing table entries into the packet

}

for (const auto &neighbor : m_neighbors) {

Ptr<Socket> socket = Socket::CreateSocket(GetNode(), UdpSocketFactory::GetTypeId());

socket->SendTo(packet, 0, InetSocketAddress(neighbor, 520)); // RIP uses port 520

}

Simulator::Schedule(Seconds(30.0), &RipRouting::SendRoutingUpdates, this); // Update every 30 seconds

}

• Receive Routing Updates: Develop for received routing bring up-to-date from neighbors.

void RipRouting::ReceiveRoutingUpdates(Ptr<Packet> packet, Ipv4Address source) {

std::map<Ipv4Address, RoutingEntry> neighborTable;

// Deserialize the packet into neighborTable

UpdateRoutingTable(source, neighborTable);

}

• Update Routing Table: Bring up-to-date routes according to their received bring up-to-date using the Bellman-Ford procedures.

void RipRouting::UpdateRoutingTable(Ipv4Address source, const std::map<Ipv4Address, RoutingEntry> &neighborTable) {

for (const auto &entry : neighborTable) {

Ipv4Address dest = entry.first;

uint32_t newCost = entry.second.hopCount + 1;

if (newCost > 15) {

// Drop unreachable routes

m_routingTable.erase(dest);

continue;

}

if (m_routingTable.find(dest) == m_routingTable.end() || newCost < m_routingTable[dest].hopCount) {

m_routingTable[dest] = {dest, source, newCost, Simulator::Now()};

}

}

}

• Packet Forwarding: Use the routing table for packet sending.

Ptr<Ipv4Route> RipRouting::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() && it->second.hopCount <= 15) {

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

route->SetGateway(it->second.nextHop);

route->SetOutputDevice(oif);

return route;

}

sockerr = Socket::ERROR_NOROUTETOHOST;

return nullptr;

}

Step 5: Register the Protocol

Store the protocol by the TypeId system:

TypeId RipRouting::GetTypeId(void) {

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

.SetParent<Ipv4RoutingProtocol>()

.SetGroupName(“Internet”)

.AddConstructor<RipRouting>();

return tid;

}

Step 6: Integrate into a Simulation

1. Simulation Script Example:

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

#include “ns3/rip-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<RipRouting> ripRouting = CreateObject<RipRouting>();

stack.SetRoutingHelper(ripRouting);

stack.Install(nodes);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 7: Test and Debug

1. Enable Logging: Use NS-3’s logging system:

export NS_LOG=”RipRouting=level_all|prefix_time”

./ns3 run my-simulation

1. Verify Results:
   • Test the routing table bring up-to-date.
   • Verify the packet delivery.

Step 8: xtend and Optimize

1. Enhancements:
   • Apply the divided horizon and hold-down duration for enhanced loop prevention.
   • Enhance the route aging for delete the stale routes.
2. Performance Testing:
   • Validate the protocol on various network topologies.
   • Estimate the convergence time and scalability.

We validate and shows how the Routing Information Protocol will generate the network then executes the Routing Information Protocol in the routing modify that used in ns3 tool. If you have concerns or queries, they will be addressed in a separate manual.