How to Begin Implement Presentation Layer in NS3

To begin the Presentation Layer in the OSI model negotiate the data translation, encode, compression, and preparation for application layer message. While the Presentation Layer is not explicitly designed the NS3 such as which typically concentrate on the lower layers, we can replicate the functionality through model a custom protocol module for challenges such as data encoding/decoding, or compression/decompression.

Here’s a step-by-step guide to implement a Presentation Layer in NS-3:

Steps to Begin Implement Presentation Layer in NS3

Step 1: Understand the Presentation Layer

1. Key Features:
   • Data Translation: Changes the data formats for instance JSON to binary, ASCII to EBCDIC.
   • Encryption/Decryption: Assure the secure data transfer.
   • Compression/Decompression: It decreases the data size for faster transmission.
2. Applications:
   • Replicate a secure message for sample SSL/TLS encryption.
   • Validate the performance for effects in a data compression.
   • Application-specific for applying the data formats.

Step 2: Set Up NS-3 Environment

1. Create a Protocol Directory:
   • Build a directory below src/, e.g., src/presentation-layer/.
2. Add Necessary Files:
   • presentation-layer.h: Header file for the Presentation Layer.
   • presentation-layer.cc: Execution of the file.
   • presentation-layer-helper.h and presentation-layer-helper.cc: Helper classes for replicate the incorporate.
3. Update Build System:
   • Alter the wscript in src/ has involves the presentation-layer component.

Step 3: Design the Presentation Layer

Define the Presentation Layer Class

Generate a class which offers the APIs for data transformation, encode, and compression.

Header File (presentation-layer.h)

#include “ns3/application.h”

#include “ns3/packet.h”

class PresentationLayer : public ns3::Object {

public:

static ns3::TypeId GetTypeId (void);

PresentationLayer ();

virtual ~PresentationLayer ();

void SetUpperLayer (ns3::Ptr<ns3::Application> app);

void SetLowerLayer (ns3::Ptr<ns3::Application> app);

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

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

private:

ns3::Ptr<ns3::Application> m_upperLayer; // Application Layer

ns3::Ptr<ns3::Application> m_lowerLayer; // Transport Layer

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

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

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

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

};

Implement Core Functions

Set Upper and Lower Layers

Launch the transmission among the Presentation Layer and adjacent layers.

void PresentationLayer::SetUpperLayer (ns3::Ptr<ns3::Application> app) {

m_upperLayer = app;

}

void PresentationLayer::SetLowerLayer (ns3::Ptr<ns3::Application> app) {

m_lowerLayer = app;

}

Send Data to Lower Layer

Change the data before transmitting the Transport Layer.

void PresentationLayer::SendToLower (ns3::Ptr<ns3::Packet> packet) {

Encrypt(packet);

Compress(packet);

m_lowerLayer->Send(packet);

}

Receive Data from Lower Layer

Redirect the transformations and pass the data for the Application Layer.

void PresentationLayer::ReceiveFromLower (ns3::Ptr<ns3::Packet> packet) {

Decompress(packet);

Decrypt(packet);

m_upperLayer->Receive(packet);

}

Encryption and Decryption

It replicate the basic encode and decode procedures.

void PresentationLayer::Encrypt (ns3::Ptr<ns3::Packet> packet) {

uint8_t *data = new uint8_t[packet->GetSize()];

packet->CopyData(data, packet->GetSize());

for (size_t i = 0; i < packet->GetSize(); ++i) {

data[i] ^= 0xAA; // Example XOR encryption

}

packet->RemoveAtEnd(packet->GetSize());

packet->AddAtEnd(ns3::Create<ns3::Packet>(data, packet->GetSize()));

delete[] data;

}

void PresentationLayer::Decrypt (ns3::Ptr<ns3::Packet> packet) {

Encrypt(packet); // Symmetric decryption using XOR

}

Compression and Decompression

Replicate the simple compression procedures.

void PresentationLayer::Compress (ns3::Ptr<ns3::Packet> packet) {

// Simulate compression (reduce packet size by a factor, e.g., 50%)

uint32_t compressedSize = packet->GetSize() / 2;

packet->RemoveAtEnd(packet->GetSize() – compressedSize);

}

void PresentationLayer::Decompress (ns3::Ptr<ns3::Packet> packet) {

// Simulate decompression (restore original size)

uint32_t originalSize = packet->GetSize() * 2;

packet->AddAtEnd(ns3::Create<ns3::Packet>(originalSize – packet->GetSize()));

}

Step 4: Write a Helper Class

Build a helper class for incorporate the Presentation Layer in replication scripts.

#include “presentation-layer.h”

class PresentationLayerHelper {

public:

void Install (ns3::NodeContainer nodes) {

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

ns3::Ptr<PresentationLayer> presentation = ns3::CreateObject<PresentationLayer>();

(*it)->AggregateObject(presentation);

}

}

};

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 “presentation-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);

InternetStackHelper internet;

internet.Install(nodes);

PresentationLayerHelper presentationHelper;

presentationHelper.Install(nodes);

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:
   • Used for the tracking AsciiTraceHelper or PcapHelper packet transformations.
   • Validate the compression ratios or encode the designs.
2. Enhancements:
   • Apply the advanced encode such as AES or RSA.
   • Use the real compression procedures for instance Huffman coding, GZIP.
   • Increase the helps for several data formats for sample JSON, XML.

In the end, we had implemented the presentation layer that generates the layer and it handles the data translation and authentication among the application layer and session layer. If you have any doubts regarding the presentation layer we will provided.