How to Begin Implement Network Hubs in NS3

To implement network hubs in ns-3, we can replicate the simple hub-based network in which a hub performs as the central devices linked are several nodes. In ns-3, hubs are not natively executed, as it primarily concentrate on switches and routers. However, we can replicate the hub through generate and distribute the medium or propagation conditions in which packets are forwarding the hub are communicated to linked the all devices.

Here’s how to implement a hub-like functionality in ns-3:

Steps to Begin Implement Network Hubs in NS3

1. Understand Network Hubs

• Hub Behavior:
  • A hub stimulates the incoming packets for all linked the other nodes.
  • It functions for the physical layer like as Layer 1.
• In ns3, hubs can be stimulated using a Broadcast Channel or custom scripts.

2. Set up ns-3

• Assure the ns-3 is installed and functional:

./waf configure –build-profile=debug –enable-examples –enable-tests

./waf build

• Validate the installation:

./waf –run hello-simulator

3. Choose an Approach

• Broadcast Channel: Simulates a shared medium like Ethernet hubs.
• Custom Node Implementation: It stimulates the hub functionality through sending the packets for linked the nodes.

4. Implement a Hub with a Broadcast Channel

Use the CsmaHelper (Carrier Sense Multiple Access) for build distributes the channel.

Example: Hub Simulation

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/csma-module.h”

#include “ns3/internet-module.h”

#include “ns3/applications-module.h”

using namespace ns3;

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

{

Time::SetResolution(Time::NS);

// Create nodes

NodeContainer nodes;

nodes.Create(4); // 1 Hub + 3 End Devices

// Create a CSMA channel (shared medium)

CsmaHelper csma;

csma.SetChannelAttribute(“DataRate”, StringValue(“100Mbps”));

csma.SetChannelAttribute(“Delay”, TimeValue(NanoSeconds(10)));

// Install devices and connect to the shared channel

NetDeviceContainer devices;

devices = csma.Install(nodes);

// Install Internet stack

InternetStackHelper stack;

stack.Install(nodes);

// Assign IP addresses

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign(devices);

// Set up a UDP echo server on node 3

uint16_t port = 9;

UdpEchoServerHelper echoServer(port);

ApplicationContainer serverApps = echoServer.Install(nodes.Get(3));

serverApps.Start(Seconds(1.0));

serverApps.Stop(Seconds(10.0));

// Set up a UDP echo client on node 0

UdpEchoClientHelper echoClient(interfaces.GetAddress(3), port);

echoClient.SetAttribute(“MaxPackets”, UintegerValue(5));

echoClient.SetAttribute(“Interval”, TimeValue(Seconds(1.0)));

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

ApplicationContainer clientApps = echoClient.Install(nodes.Get(0));

clientApps.Start(Seconds(2.0));

clientApps.Stop(Seconds(10.0));

// Enable packet tracing

csma.EnablePcap(“hub”, devices, true);

// Run simulation

Simulator::Run();

Simulator::Destroy();

return 0;

}

5. Analyze Hub Behavior

• All packets are forward the hub nodes are propagate for all other nodes in the network.
• Use the trace for validates this behavior such as CsmaHelper pcap.

6. Enhance the Hub Implementation

• Traffic Monitoring: Record the incoming and outgoing packets for the hub.
• Packet Filtering: Executes the basic filter for the hub to conditionally forwarding the packets.
• Custom Packet Forwarding: Write a callback for stimulates the advanced hub behaviors.

Example: Custom Packet Forwarding

void HubPacketForward(Ptr<Packet> packet, Ptr<NetDevice> device, Ptr<NetDevice> sender)

{

NS_LOG_UNCOND(“Hub received a packet at: ” << Simulator::Now().GetSeconds() << “s”);

// Forward packet to all devices except the sender

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

{

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

if (otherDevice != sender)

{

otherDevice->Send(packet->Copy(), otherDevice->GetBroadcast(), 0);

}

}

}

7. Run and Test

• Compile and executes the script:

./waf –run scratch/hub-simulation

• Examine the outcomes for using logs or pcap files for validate which the packets all nodes are broadcasted.

In this manual, we clearly explained the concepts about how to simulate and install the environment for Network Hubs projects in ns3 tool and also we offered the simulation procedures, sample snippets and the extension for this project with the project ideas. If you want to know more details feel free to ask!