Reliable UDP

This project is done as part of the Computer Networks course at Sharif University Fall 2023.

My project was implementing a reliable protocol to transfer packets on the UDP. So, I implemented RDT 3.0 based on the stop-and-wait method. There are two sides: receiver and sender.

Sender

• Listens on port 8050 localhost.
• Adds ack and seq_number headers to each packet received on port 8050.
• Sends it via a lossy link which I used from this repository: lossy_link.

Behaviour on Packet Loss

• If a packet is lost, the sender will resend it after 0.75 seconds.

Lossy Link

• Connects port 12345 to 54321 of localhost.
• Transfers data between the two sides but can lose packets or change the order.

Receiver

• Listens on port 54321.
• Checks the seq_number of each packet.
  • If the seq_number is correct, it will send the packet to port 5080.
  • If it's not correct, it will send the right ack_number to the sender.

Automata Images

The automata for the sender and receiver sides are provided by GeeksforGeeks, a comprehensive computer science resource:

• The automata of the sender side can be viewed here:

• The automata of the receiver side can be viewed here:

Images sourced from www.geeksforgeeks.org.