Pipelined Reliable Transfer Protocol — Mini Project 2

This repository contains an implementation and analysis for a connection-oriented, reliable, pipelined transport protocol (course Mini-Project 2). The project implements a custom reliable transport with flow control, congestion control, and simulated loss/error for testing.

Repository layout

• src/: Python source code for the protocol and helper scripts.
  • sender.py, receiver.py, transport.py, channel.py, packet.py — core protocol code.
  • run_sender.py, run_receiver.py, run_sender_2.py, run_receiver_2.py — example runners for experiments.
• Wireshark Traces/: packet capture files used for traffic analysis (pcapng files).
• CMPT371 Mini Project 2 Report - Alfred Goh Euluna Gotami.pdf: project specification, protocol description, test procedures, analysis, and results.

Assignment summary

• Design & Implement your protocol (40 pts): design and implement a connection-oriented, reliable, pipelined transport protocol similar in spirit to TCP but of your own design. The implementation must include:

  • Connection establishment and teardown (connection-oriented behavior).
  • Reliable delivery with sequence numbers and ACKs.
  • Pipelining to allow multiple in-flight packets.
  • Flow control to prevent receiver buffer overflow.
  • Congestion control to respond to network conditions.

• Analyze traffic (20 pts): capture and analyze packet traces (e.g., with Wireshark) to demonstrate the protocol's properties:

  • Show connection setup/teardown (connection-oriented).
  • Show correct reliability (retransmissions, ACK behavior).
  • Show flow control and congestion control behavior.
  • Evaluate performance (throughput, delay) using captured traces.

• Simulating loss/errors: because local testing may not expose packet loss or corruption, you must simulate loss/errors (drop packets randomly, corrupt bits, etc.) in the channel layer so protocol mechanisms can be tested.

• Bonus — Fairness (5 pts): test your protocol coexisting with other traffic (e.g., TCP flows) and argue whether your protocol is fair.

Deliverables

• Source code (.py) — all code in src/.
• Packet capture(s) — .pcapng files in Wireshark Traces/.
• Report PDF — specification of the protocol, test procedures, traffic analysis, and results (CMPT371 Mini Project 2 Report - Alfred Goh Euluna Gotami.pdf).

These are packaged together for submission.

How to run (basic)

1. Open a PowerShell terminal and change to the src directory:

cd .\src

2. Start the receiver (in one terminal):

python .\run_receiver.py

3. Start the sender (in another terminal):

python .\run_sender.py

4. Alternative runners: run_sender_2.py and run_receiver_2.py provide variant configurations or tests — inspect them to choose parameters.

Notes:

• If you need to see packet captures, open files in Wireshark Traces/ with Wireshark.
• The report PDF documents protocol design, experimental setup, and the captured-traffic analysis — see it for test descriptions and expected outputs.

Objectives to check when validating the implementation

• Connection-oriented handshake and teardown are visible in traces.
• Retransmissions occur when simulated loss happens (reliability).
• Flow control prevents buffer overrun at receiver side.
• Congestion control reduces sending rate under loss or delay.
• Fairness experiments (bonus) show coexistence behavior.

Testing

• Read the report PDF for the exact spec used in this implementation.

• Quick notes on where to change common test settings:

  • Sender loss rate: edit src/run_sender.py where ReliableTransport is constructed (e.g. ReliableTransport(sock, loss_rate=0.2)).
  • Receiver loss rate: edit src/run_receiver.py and change the loss_rate passed to ReliableTransport there.
  • Corruption rate: edit src/channel.py (the UnreliableChannel constructor has a corrupt_rate parameter) or modify transport.py to pass an explicit corrupt_rate when creating UnreliableChannel.
  • Advertised (receiver) window: edit src/receiver.py and change advertised_window (default 64) to a smaller value (e.g., 2) to test receiver-limited flow control.

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Created to summarize the assignment and point to the implementation and analysis in this repository.