tcp-flow-control

This is an implementation of the sliding window protocol used for TCP using the socket library in Python. The client (in client.py) sends packets and the server (in server.py) receives packets and send acknowledgements to the client. The client and server interact using a low-level protocol (in llp.py); the LLPEndpoint classes exposes a basic API for sending and receiving packets.

The sliding window protocol itself is implemented in swp.py. The sender side is responsible for transmitting packets, ensuring that the number of in-flight packets remains within a fixed bound and retransmitting packets if an acknowledgement is not received within a specified time-frame. The receiver side is responsible for sending cumulative acknowledgemnts (ACKs).

Running the tool

To run the protocol, start the server in one terminal window using:

./server.py -p PORT

where PORT needs to be >= 1024.

Then, start the client in another terminal window:

./client.py -p PORT -h 127.0.0.1

Whatever you now type in the client window should be transmitted to the server, and you should see the the server printing the received packets and sending acknowledgements.