How to Begin Implement Distance Routing in NS3

To implement Distance routing in NS3, it normally denote to execute a Distance Vector Routing Protocol such as RIP utilizing NS3. This encompasses to make a protocol in which nodes are interchanging routing data with its neighbors and leverage the distance (cost) parameters for determining the shortest paths to every destination.

Below is a sequential mechanism on how to execute Distance Vector Routing in NS3:

Steps to Begin Implement Distance Routing in NS3

Step 1: Understand Distance Vector Routing

1. Key Concepts:
   • Every single node sustains a routing table including:
     • Destination: Target node.
     • Next Hop: Intermediate node for attaining the destination.
     • Cost: The metric to the destination for the path.
   • Nodes swap routing tables periodically including its neighbors.
   • The routing table is modernized according to the Bellman-Ford mechanism: d(u,v)=min⁡w∈neighbors(u){c(u,w)+d(w,v)}d(u, v) = \min_{w \in neighbors(u)} \{c(u, w) + d(w, v)\}d(u,v)=w∈neighbors(u)min​{c(u,w)+d(w,v)} where:
     • d(u,v)d(u, v)d(u,v): Cost from uuu to vvv.
     • d(w,v)d(w, v)d(w,v): Cost from www to vvv.
     • c(u,w)c(u, w)c(u,w): Cost from uuu to neighbor www.
2. Characteristics:
   • It makes simpler to execute.
   • Susceptible to the count-to-infinity challenges like loops.

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: Execute a sample simulation scripts to confirm the set up:

./ns3 run examples/tutorial/first

Step 3: Plan the Protocol Design

1. Core Components:
   • Routing Table: Links destinations to next hops and costs.
   • Periodic Updates: Periodically interchanges routing tables including neighbors.
   • Route Computation: Modernizes the routing table with received updates.
2. Implementation Workflow:
   • Set the routing table including direct neighbors.
   • Swap routing data periodically with neighbors.
   • According to the Bellman-Ford mechanism, bring up to date routing table.

Step 4: Implement Distance Routing

Step 4.1: Define the Protocol Class

Describe the protocol class to prolong the Ipv4RoutingProtocol class:

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

#include “ns3/socket.h”

#include <map>

using namespace ns3;

class DistanceRouting : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

DistanceRouting();

virtual ~DistanceRouting();

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:

void InitializeRoutingTable();

void SendRoutingUpdates();

void ReceiveRoutingUpdates(Ptr<Socket> socket);

void UpdateRoutingTable(Ipv4Address neighbor, const std::map<Ipv4Address, uint32_t> &neighborTable);

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

Ptr<Socket> m_socket;

};

Step 4.2: Implement Core Functions

• Initialize the Routing Table: Inhabit the routing table including direct neighbors.

void DistanceRouting::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, 0}; // Cost to itself is 0

}

}

• Send Routing Updates: Transmit routing updates periodically to the neighbors.

void DistanceRouting::SendRoutingUpdates() {

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

for (const auto &entry : m_routingTable) {

// Serialize routing table entries into packet

}

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

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

m_socket->SendTo(packet, 0, InetSocketAddress(Ipv4Address(“255.255.255.255”), 520));

}

Simulator::Schedule(Seconds(10.0), &DistanceRouting::SendRoutingUpdates, this);

}

• Update the Routing Table: Modernize the routing table to leverage Bellman-Ford depends on the received updates.

void DistanceRouting::UpdateRoutingTable(Ipv4Address neighbor,

const std::map<Ipv4Address, uint32_t> &neighborTable) {

for (const auto &entry : neighborTable) {

Ipv4Address dest = entry.first;

uint32_t costToDest = entry.second;

uint32_t newCost = m_routingTable[neighbor].second + costToDest;

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

m_routingTable[dest] = {neighbor, newCost};

}

}

}

• Packet Forwarding: According to the routing table, transmit the packets.

Ptr<Ipv4Route> DistanceRouting::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); // Use next hop from routing table

route->SetOutputDevice(oif);

}

return route;

}

bool DistanceRouting::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); // Use next hop from routing table

ucb(route, packet, header);

return true;

}

return false;

}

Step 5: Register the Protocol

1. Register with NS3: Add the protocol with the TypeId system of NS3.

TypeId DistanceRouting::GetTypeId(void) {

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

.SetParent<Ipv4RoutingProtocol>()

.SetGroupName(“Internet”)

.AddConstructor<DistanceRouting>();

return tid;

}

Step 6: Integrate into a Simulation

1. Simulation Script Example:

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

#include “ns3/distance-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<DistanceRouting> distanceRouting = CreateObject<DistanceRouting>();

stack.SetRoutingHelper(distanceRouting);

stack.Install(nodes);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 7: Test and Debug

1. Enable Logging:

export NS_LOG=”DistanceRouting=level_all|prefix_time”

./ns3 run my-simulation

1. Validate:
   • Confirm the updates of routing table.
   • Observe packet forwarding and route selection.

Step 8: Extend and Optimize

1. Enhancements:
   • Execute the divided horizon for avoiding loops.
   • Integrate dynamic performance indicators such as delay or bandwidth.
2. Performance Testing:
   • Experiment the performance within large-scale networks.
   • Probe scalability and convergence time.

We had demonstrated a collection of implementation steps to execute and extend the Distance Routing via NS3 platform. We can explore this subject further and offer complete information upon request.