How to Begin Implement Hierarchical Routing in NS3

To begin implementing Hierarchical Routing using NS3, we’ll need to create a routing protocol in which network is splitted into clusters or regions, and nodes are interaction in and over the regions through cluster heads or regional gateways. This method is generally leveraged for enhancing the scalability and effectiveness within large networks like Wireless Sensor Networks (WSNs) or Mobile Ad-Hoc Networks (MANETs).

The below is procedure to implement the simple hierarchical routing in NS3:

Steps to Begin Implement Hierarchical Routing in NS3

Step 1: Understand Hierarchical Routing

1. Key Concepts:
   • Cluster Formation: Split the network to the clusters or regions including each cluster contains a leader like a cluster head.
   • Intra-Cluster Routing: Nodes are interacting in the cluster with the support of cluster head like a mediator as required.
   • Inter-Cluster Routing: Cluster heads are communicating with other gateways or cluster heads for transmitting the information among clusters.
2. Example Protocols:
   • ZRP (Zone Routing Protocol).
   • LEACH (Low Energy Adaptive Clustering Hierarchy).

Step 2: Set Up NS3 Environment

1. Create a Directory:
   • Make a new protocol directory in src/hierarchical-routing/.
2. Add Required Files:
   • hierarchical-routing-protocol.h: Integrate header file for protocol.
   • hierarchical-routing-protocol.cc: Execution file.
   • hierarchical-routing-helper.h and hierarchical-routing-helper.cc: It is helper classes.
3. Update Build System:
   • Fine-tune the wscript file with routing protocol.

Step 3: Design the Protocol

1. Define the Protocol Class

Create a protocol class to prolong the Ipv4RoutingProtocol for executing the hierarchical routing protocol.

Header File (hierarchical-routing-protocol.h)

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

#include “ns3/socket.h”

#include “ns3/timer.h”

#include <map>

class HierarchicalRoutingProtocol : public ns3::Ipv4RoutingProtocol {

public:

static ns3::TypeId GetTypeId (void);

HierarchicalRoutingProtocol ();

virtual ~HierarchicalRoutingProtocol ();

// Override 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);

// Hierarchical Routing Specific Methods

void FormClusters ();

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

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

private:

ns3::Ipv4Address m_selfAddress;

std::map<ns3::Ipv4Address, ns3::Ipv4Address> m_clusterHeads; // Node -> Cluster Head

std::map<ns3::Ipv4Address, std::vector<ns3::Ipv4Address>> m_clusters; // Cluster Head -> Cluster Members

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

ns3::Timer m_clusterFormationTimer;

};

2. Implement Core Functions

Cluster Formation

Make clusters periodically through selecting the cluster heads and allocating nodes to clusters.

void HierarchicalRoutingProtocol::FormClusters () {

// Example: Elect cluster heads based on node IDs

for (auto &node : m_clusterHeads) {

if (node.first.Get() % 5 == 0) { // Elect cluster heads

m_clusterHeads[node.first] = node.first; // Self is cluster head

} else {

m_clusterHeads[node.first] = FindNearestClusterHead(node.first); // Assign to nearest cluster head

}

}

// Schedule next cluster formation

m_clusterFormationTimer.Schedule(ns3::Seconds(10.0));

}

Intra-Cluster Communication

We will need to transmit the packets in a cluster.

void HierarchicalRoutingProtocol::HandleIntraClusterCommunication (ns3::Ptr<const ns3::Packet> packet) {

// Extract destination address from packet

ns3::Ipv4Address dest = …; // Extract destination from packet header

// Check if the destination is in the same cluster

if (m_clusterHeads[dest] == m_clusterHeads[m_selfAddress]) {

// Direct communication or via the cluster head

} else {

HandleInterClusterCommunication(packet); // Forward to inter-cluster routing

}

}

Inter-Cluster Communication

Transmit packets among the clusters through cluster heads or gateways.

void HierarchicalRoutingProtocol::HandleInterClusterCommunication (ns3::Ptr<const ns3::Packet> packet) {

// Find the next hop to the destination cluster

ns3::Ipv4Address nextHop = …; // Find next hop based on inter-cluster routing

// Forward the packet

}

Packet Forwarding

Utilize RouteOutput and RouteInput for packet routing.

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

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

const ns3::Ipv4Header &header,

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

ns3::Socket::SocketErrno &sockerr) {

// Use routing table to determine next hop

…

}

Step 4: Write a Helper Class

Enable the protocol set up within simulation scripts using NS3.

#include “hierarchical-routing-protocol.h”

class HierarchicalRoutingHelper {

public:

void Install (ns3::NodeContainer nodes) {

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

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

(*it)->AggregateObject(protocol);

}

}

};

Step 5: Write a Simulation Script

Example Simulation Script

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “hierarchical-routing-helper.h”

using namespace ns3;

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

NodeContainer nodes;

nodes.Create (10);

InternetStackHelper stack;

stack.Install (nodes);

HierarchicalRoutingHelper hrHelper;

hrHelper.Install (nodes);

PointToPointHelper p2p;

p2p.SetDeviceAttribute (“DataRate”, StringValue (“10Mbps”));

p2p.SetChannelAttribute (“Delay”, StringValue (“2ms”));

p2p.Install (nodes.Get(0), nodes.Get(1));

p2p.Install (nodes.Get(1), nodes.Get(2));

// Add additional connections as needed

Ipv4AddressHelper address;

address.SetBase (“10.1.1.0”, “255.255.255.0”);

address.Assign (p2p.Install (nodes.Get (0), nodes.Get (1)));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 6: Compile and Run

1. Build:

./waf configure

./waf build

1. Run Simulation:

./waf –run your-script

Step 7: Analyze Results

1. Use Tracing:
   • Make use of PcapHelper or AsciiTraceHelper to seizure and examine the traffic flow.
2. Evaluate Metrics:
   • Estimate the performance parameters such as Packet Delivery Ratio (PDR), throughput, latency, and power utilization.

Step 8: Extend Protocol

1. Dynamic Cluster Formation:
   • Execute the mobility-aware clustering or energy-efficient cluster head selection for dynamically prolonging the cluster formation.
2. Inter-Cluster Optimization:
   • For inter-cluster routing, we can utilize the Dijkstra’s algorithms.

As illustrated above, we executed the simple outline, sample coding framework and implementation of Hierarchical Routing in NS3 simulation tool. Additional insights relevant to this topic, we will be made available.