Reliable Data Transfer (RDT 3.0) over UDP

📌 Overview

This project implements a Reliable Data Transfer protocol (RDT 3.0) over UDP using Python socket programming.

Since UDP is unreliable, this project ensures reliable communication using:

• Stop-and-Wait protocol
• Acknowledgements (ACKs)
• Retransmissions
• Packet loss simulation

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🚀 Features

• Reliable file transfer over UDP
• Packet loss simulation
• Timeout handling and retransmission
• Client-server communication
• Logging for packet tracking

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🛠️ Tech Stack

• Python
• Socket Programming
• UDP Protocol
• Wireshark (optional analysis)

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📂 Project Structure

src/
  client_basic.py
  server_basic.py
  client_reliable.py
  server_reliable.py

docs/
  output.png

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▶️ How to Run

Start Server

python src/server_reliable.py

Run Client

python src/client_reliable.py

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📸 Output

See docs/output.png

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📊 Wireshark Analysis

To further validate the implementation, network traffic was analyzed using Wireshark during the file transfer process.

🔍 Observations

• UDP packets were exchanged between the client and server on port 9999
• Each data packet sent by the server was followed by an ACK from the client
• Sequence numbers (0 and 1) were observed, confirming the Stop-and-Wait protocol
• Retransmissions occurred when packets were lost (simulated), verifying reliability

📈 Key Insights

• Communication is connectionless (UDP), but reliability is achieved through application-layer logic
• ACK packets ensure correct delivery and ordering of data
• Timeout and retransmission mechanisms successfully handle packet loss

🧠 Conclusion

The Wireshark analysis confirms that the implemented system successfully mimics reliable data transfer (RDT 3.0) over an unreliable protocol like UDP.

🧠 Key Concepts

• Reliable Data Transfer (RDT 3.0)
• Stop-and-Wait Protocol
• UDP vs TCP
• Packet Loss Handling

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💡 Future Improvements

• Sliding Window Protocol
• GUI-based visualization
• Performance analysis

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👨‍💻 Author

Prasann Kumar