How to Begin Implement Data Link Layer in NS3

To implement a Data Link Layer (DLL) in NS-3 environment has built a custom component which replicates the functionality of this layer in a network stack. The Data Link Layer typically manages the framing, finding the error, medium access control (MAC), and consistent delivery devices.

Here’s a step-by-step guide to help you implement the Data Link Layer in NS-3:

Steps to Begin Implement Data Link Layer in NS3

Step 1: Understand the Data Link Layer

1. Key Features:
   • Framing: Packets in frames for Encapsulation.
   • Error Detection: It allows the data integrity using devices such as checksums or CRC.
   • Medium Access Control (MAC): Organizes are assigning the physical medium for sample CSMA, TDMA.
   • Flow Control: Avoid the data overflow through managing frame communication.
   • Logical Link Control (LLC): It delivers the error correction and flow control.
2. Applications:
   • Further link-layer network technologies or replicate the Ethernet, Wi-Fi.
   • Validate the custom MAC protocols.
   • It increases the consistency or communication stack for QoS.

Step 2: Set Up NS-3 Environment

1. Create a Protocol Directory:
   • Generate a directory below src/, e.g., src/data-link-layer/.
2. Add Necessary Files:
   • data-link-layer.h: The Data Link Layer for Header file.
   • data-link-layer.cc: It execute the file.
   • data-link-layer-helper.h and data-link-layer-helper.cc: Helper classes.
3. Update Build System:
   • Alter the wscript in src/ to contain the different Data Link Layer component.

Step 3: Design the Data Link Layer

Define the DLL Class

Make a custom class for the Data Link Layer, management the frame for encapsulation, error finding, and MAC functionalities.

Header File (data-link-layer.h)

#include “ns3/net-device.h”

#include “ns3/packet.h”

#include “ns3/ptr.h”

#include <queue>

class DataLinkLayer : public ns3::Object {

public:

static ns3::TypeId GetTypeId (void);

DataLinkLayer ();

virtual ~DataLinkLayer ();

void SetDevice (ns3::Ptr<ns3::NetDevice> device);

void Send (ns3::Ptr<ns3::Packet> packet);

void Receive (ns3::Ptr<ns3::Packet> packet);

private:

void AddErrorDetection (ns3::Ptr<ns3::Packet> packet);

bool CheckErrorDetection (ns3::Ptr<ns3::Packet> packet);

ns3::Ptr<ns3::NetDevice> m_device; // Network device interface

std::queue<ns3::Ptr<ns3::Packet>> m_frameQueue; // Frame queue for transmission

};

Implement Core Functions

Set Device

Compare the Data Link Layer through a detailed network device.

void DataLinkLayer::SetDevice (ns3::Ptr<ns3::NetDevice> device) {

m_device = device;

}

Send Frames

Encapsulate a packet in a frame and improve the error findings.

void DataLinkLayer::Send (ns3::Ptr<ns3::Packet> packet) {

AddErrorDetection(packet);

m_frameQueue.push(packet);

// Simulate frame transmission

if (!m_frameQueue.empty()) {

ns3::Ptr<ns3::Packet> frame = m_frameQueue.front();

m_frameQueue.pop();

m_device->Send(frame, ns3::Mac48Address::GetBroadcast(), 0x0800);

}

}

Receive Frames

Receive frames, verify for errors, and pass the upper layer.

void DataLinkLayer::Receive (ns3::Ptr<ns3::Packet> packet) {

if (CheckErrorDetection(packet)) {

// Remove error detection bits and deliver to the upper layer

// …

} else {

NS_LOG_WARN(“Frame dropped due to error detection failure”);

}

}

Add Error Detection

Execute a simple checksum or CRC for finding the error.

void DataLinkLayer::AddErrorDetection (ns3::Ptr<ns3::Packet> packet) {

uint16_t checksum = CalculateChecksum(packet); // Implement CalculateChecksum

packet->AddTrailer(ns3::PacketTrailer(checksum));

}

Check Error Detection

Authorize the received frame for reliability.

bool DataLinkLayer::CheckErrorDetection (ns3::Ptr<ns3::Packet> packet) {

uint16_t receivedChecksum;

// Extract trailer to retrieve checksum

// …

return receivedChecksum == CalculateChecksum(packet);

}

Step 4: Write a Helper Class

Build a helper class for facilitate incorporate for replication of simulation scripts.

#include “data-link-layer.h”

class DataLinkLayerHelper {

public:

void Install (ns3::NodeContainer nodes, ns3::NetDeviceContainer devices) {

for (size_t i = 0; i < nodes.GetN(); ++i) {

ns3::Ptr<DataLinkLayer> dll = ns3::CreateObject<DataLinkLayer>();

dll->SetDevice(devices.Get(i));

nodes.Get(i)->AggregateObject(dll);

}

}

};

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 “data-link-layer-helper.h”

using namespace ns3;

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

NodeContainer nodes;

nodes.Create(2);

PointToPointHelper p2p;

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

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

NetDeviceContainer devices = p2p.Install(nodes);

DataLinkLayerHelper dllHelper;

dllHelper.Install(nodes, devices);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 6: Compile and Run

1. Build the Protocol:

./waf configure

./waf build

1. Run the Simulation:

./waf –run your-script

Step 7: Analyze and Extend

1. Tracing:
   • Use AsciiTraceHelper or PcapHelper for track the frames and errors.
2. Enhancements:
   • Execute the detailed for MAC protocol for sample CSMA, TDMA.
   • Improve the flow control help for ARQ devices.
   • Encompass the protocol for performance of metrices for estimation in larger network topologies.

Complete, we had implemented the Data link layer that makes new classes and executed by its DLL characteristic in ns3 tool. Please refer to the supplementary manual for any project-related inquiries.