How to Begin Implement Gateway Routing Protocol in NS3

To begin a Gateway Routing Protocol (GRP) utilising NS3 that have to create a routing protocol which handles the gateways to link various network domains like a MANET toward the internet or other fixed networks. It has effectively handling the gateway discovery, commercial, and routing packet traffic among the domains.

The given below are the detailed procedures on how to implement a Gateway Routing Protocol (GRP) in NS3:

Steps to Begin Implement Gateway Routing Protocol in NS3

Step 1: Understand the Protocol Requirements

1. Protocol Objectives:
   • Determine and sustain the gateway nodes within the network.
   • Effectively transmit the packets among MANET nodes and external networks such as internet.
   • It supports to manage the gateway chosen in the event of numerous gateways.
2. Core Features:
   • Gateway discovery and commercial.
   • Forwarding table management that contains gateway nodes.
   • To manage an inter-domain and intra-domain routing.

Step 2: Familiarize Yourself with NS3

1. Study Existing Routing Protocols:
   • AODV: src/aodv/
   • OLSR: src/olsr/
2. Understand NS3’s Ipv4RoutingProtocol:
   • The Ipv4RoutingProtocol base class offers the interface to execute routing protocols.
   • Study mechanisms such as RouteOutput() and RouteInput() for packet transmission.

Step 3: Set Up NS3 Development Environment

1. Create a New Protocol Directory:
   • Make a protocol directory under src/ like src/grp/.
2. Add Required Files:
   • grp-routing-protocol.h: Describe the structure of protocol and API.
   • grp-routing-protocol.cc: Execute the protocol logic.
   • grp-helper.h and grp-helper.cc: It offers helper classes for replication.
3. Update Build System:
   • Alter wscript in the src/ directory with new protocol.

Step 4: Design GRP Components

1. Define GRP Protocol Class

For executing GRP, we can prolong the Ipv4RoutingProtocol class.

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

#include “ns3/ipv4-address.h”

#include “ns3/timer.h”

#include “ns3/socket.h”

class GrpRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

GrpRoutingProtocol ();

virtual ~GrpRoutingProtocol ();

// 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);

// GRP-specific methods

void DiscoverGateways ();

void AdvertiseGateway ();

void HandleGatewayAdvertisement (ns3::Ptr<const ns3::Packet> packet);

private:

ns3::Ipv4Address m_gatewayAddress; // Address of the selected gateway

std::map<ns3::Ipv4Address, uint32_t> m_routingTable; // Destination -> Next hop

ns3::Timer m_gatewayDiscoveryTimer; // Timer for periodic discovery

};

2. Gateway Discovery

Execute gateways periodic discovery to leverage a timer.

void GrpRoutingProtocol::DiscoverGateways () {

// Broadcast a gateway discovery message

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

// Add custom header for gateway discovery if needed

BroadcastPacket(discoveryPacket);

}

void GrpRoutingProtocol::AdvertiseGateway () {

// Respond to discovery messages or periodically advertise gateway

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

// Add custom header for gateway advertisement

BroadcastPacket(advertisementPacket);

}

3. Routing Table Management

Modernize the routing table with discovered gateways.

void GrpRoutingProtocol::HandleGatewayAdvertisement (ns3::Ptr<const ns3::Packet> packet) {

// Extract gateway information from the packet

ns3::Ipv4Address gatewayAddress; // Extract from packet header

uint32_t metric;                 // Extract metric (e.g., hop count)

// Update the routing table with the gateway

m_routingTable[gatewayAddress] = metric;

}

4. Packet Forwarding

Apply RouteOutput() and RouteInput() for managing the packet forwarding.

ns3::Ptr<ns3::Ipv4Route> GrpRoutingProtocol::RouteOutput (

ns3::Ptr<const ns3::Packet> packet,

const ns3::Ipv4Header &header,

ns3::Ptr<ns3::NetDevice> oif,

ns3::Socket::SocketErrno &sockerr) {

// Determine if the packet should be routed to a gateway

ns3::Ipv4Route route;

if (m_routingTable.count(header.GetDestination())) {

route.SetGateway(m_routingTable[header.GetDestination()]);

} else {

sockerr = ns3::Socket::ERROR_NOROUTETOHOST;

return nullptr;

}

return route;

}

bool GrpRoutingProtocol::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) {

// Handle incoming packets and forward them to the gateway if necessary

return true;

}

Step 5: Write a Helper Class

Make a helper class to make simpler the GRP’s set up within simulation scripts.

#include “grp-routing-protocol.h”

class GrpHelper {

public:

void Install (ns3::NodeContainer nodes) {

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

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

(*it)->AggregateObject(protocol);

}

}

};

Step 6: Write a Simulation Script

Experiment the functionality of GRP to utilize a simulation script.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “grp-helper.h”

int main () {

ns3::NodeContainer nodes;

nodes.Create(5);

ns3::InternetStackHelper stack;

stack.Install(nodes);

GrpHelper grpHelper;

grpHelper.Install(nodes);

// Configure network topology and traffic sources

ns3::Simulator::Run();

ns3::Simulator::Destroy();

return 0;

}

Step 7: Compile and Run

1. Build the Protocol:

./waf configure

./waf build

1. Run the Simulation:

./waf –run your-script

Step 8: Validate and Extend

1. Validation:
   • Make use of NS3’s tracing tools like AsciiTraceHelper, PcapHelper to confirm the behaviour of GRP.
   • Verify if packets are transmitted via gateways properly.
2. Extensions:
   • Integrate the load balancing among numerous gateways.
   • For gateway selection, combine performance indicators such as bandwidth or delay.
   • Execute further gateway discovery approaches.

These projects provide a comprehensive exploration and implementation of Gateway Routing Protocol using NS3, covering its performance, GRP components, and functionality of GRP. We will also be offered further information related to these projects, if necessary.