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How to Implement Hybrid Topology in ns3

To implement a hybrid topology in ns3, we want to make sure that the topology has flexibility and robustness. For this we have to combine different network topologies (such as star, ring, mesh, and tree) into a single network, this provides the flexibility and robustness to the network design.

The given below steps will guide on how to implement the hybrid topology in ns3.

Steps to Implement a Hybrid Topology in ns3

  1. Set Up the ns3 Environment:
    • Make sure ns3 is installed and properly configured.
  2. Create the Nodes:
    • Create a set of nodes to represent different parts of the hybrid network.
  3. Set Up the Point-to-Point Channels:
    • Use point-to-point helpers to connect nodes in different topologies.
  4. Install Network Stack:
    • Install the internet stack on all nodes.
  5. Assign IP Addresses:
    • Assign IP addresses to the nodes connected to the point-to-point links.
  6. Set Up Applications:
    • Install applications to generate traffic and demonstrate communication between nodes.

Example Code

Here is an example given to set up a simple hybrid topology in ns3 that combines a star, ring, and tree topology:

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/applications-module.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“HybridTopologyExample”);

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes

NodeContainer starNodes;

starNodes.Create (5); // Create 5 nodes for the star

NodeContainer ringNodes;

ringNodes.Create (4); // Create 4 nodes for the ring

NodeContainer treeNodes;

treeNodes.Create (7); // Create 7 nodes for the tree (1 root, 2 intermediate, 4 leaves)

// Create point-to-point links

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“100Mbps”));

pointToPoint.SetChannelAttribute (“Delay”, TimeValue (NanoSeconds (6560)));

NetDeviceContainer devices;

InternetStackHelper stack;

stack.Install (starNodes);

stack.Install (ringNodes);

stack.Install (treeNodes);

 

Ipv4AddressHelper address;

int subnet = 1;

// Star Topology: Connect starNodes[0] (hub) to other star nodes

for (uint32_t i = 1; i < starNodes.GetN (); ++i)

{

NetDeviceContainer link = pointToPoint.Install (NodeContainer (starNodes.Get (0), starNodes.Get (i)));

devices.Add (link);

std::ostringstream subnetStream;

subnetStream << “10.1.” << subnet++ << “.0”;

address.SetBase (subnetStream.str ().c_str (), “255.255.255.0”);

address.Assign (link);

}

// Ring Topology: Connect ring nodes in a loop

for (uint32_t i = 0; i < ringNodes.GetN (); ++i)

{

NetDeviceContainer link;

if (i == ringNodes.GetN () – 1)

{

// Connect the last node to the first node to complete the ring

link = pointToPoint.Install (NodeContainer (ringNodes.Get (i), ringNodes.Get (0)));

}

else

{

// Connect the current node to the next node

link = pointToPoint.Install (NodeContainer (ringNodes.Get (i), ringNodes.Get (i + 1)));

}

devices.Add (link);

std::ostringstream subnetStream;

subnetStream << “10.1.” << subnet++ << “.0”;

address.SetBase (subnetStream.str ().c_str (), “255.255.255.0”);

address.Assign (link);

}

// Tree Topology: Connect tree nodes in a hierarchical manner

auto connectNodes = [&](uint32_t parent, uint32_t child, uint32_t subnet) {

NetDeviceContainer link = pointToPoint.Install (NodeContainer (treeNodes.Get (parent), treeNodes.Get (child)));

devices.Add (link);

std::ostringstream subnetStream;

subnetStream << “10.1.” << subnet << “.0”;

address.SetBase (subnetStream.str ().c_str (), “255.255.255.0”);

address.Assign (link);

};

// Root node to intermediate nodes

connectNodes(0, 1, subnet++);

connectNodes(0, 2, subnet++);

// Intermediate nodes to leaf nodes

connectNodes(1, 3, subnet++);

connectNodes(1, 4, subnet++);

connectNodes(2, 5, subnet++);

connectNodes(2, 6, subnet++);

// Enable routing

Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

// Create a UDP server on one of the star nodes

UdpServerHelper udpServer (9);

ApplicationContainer serverApp = udpServer.Install (starNodes.Get (1));

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

// Create a UDP client on one of the ring nodes

UdpClientHelper udpClient (Ipv4Address (“10.1.1.2”), 9); // Assuming starNodes[1]’s IP is 10.1.1.2

udpClient.SetAttribute (“MaxPackets”, UintegerValue (320));

udpClient.SetAttribute (“Interval”, TimeValue (MilliSeconds (50)));

udpClient.SetAttribute (“PacketSize”, UintegerValue (1024));

ApplicationContainer clientApp = udpClient.Install (ringNodes.Get (0));

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

// Enable packet capture

pointToPoint.EnablePcapAll (“hybrid-topology”);

// Enable logging

LogComponentEnable (“UdpClient”, LOG_LEVEL_INFO);

LogComponentEnable (“UdpServer”, LOG_LEVEL_INFO);

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Explanation

  1. Setup: Setting up a hybrid topology that combines star, ring, and tree structures with nodes connected by point-to-point links.
  2. Point-to-Point Links: Point-to-point links are created to connect nodes in different topologies. The data rate and delay are configured for the links.
  3. Network Stack: The internet stack is installed on all nodes.
  4. IP Addresses: IP addresses are assigned to the nodes connected to the point-to-point links.
  5. Applications: A UDP server is installed on one of the star nodes, and a UDP client is installed on one of the ring nodes to generate traffic and demonstrate communication.
  6. Packet Capture: Packet capture is enabled for the point-to-point links to observe network traffic.
  7. Logging: Logging is enabled for the UDP client and server applications to provide detailed output during the simulation.

Running the Simulation

Compile and run the simulation using the following commands in ns3 environment:

./waf configure

./waf build

./waf –run hybrid-topology-example

Replace hybrid-topology-example with the actual name of the script file.

Finally, the hybrid topology is implemented in ns3 by combining the star, ring, mesh, and tree topology for flexibility and robustness using point-to-point helpers to connect nodes in different topologies.

Diverse network topologies will be merged, and we furnish you with top-notch coding support based on your concept.