Flow Control in Computer Networks 🎯

Welcome to our deep dive into Flow Control, a crucial aspect of computer networks! In this lesson, we'll explore two fundamental techniques: Stop-and-Wait and Sliding Window. Let's get started!

What is Flow Control? 📝

Flow control is a mechanism that helps to manage the data flow between two devices in a network. It ensures that data is transmitted smoothly without congestion or loss.

Stop-and-Wait (S-A-W) 💡

How does it work?

Stop-and-Wait is the simplest flow control technique. It works by sending a packet, waiting for an acknowledgement (ACK), and then sending the next packet only after receiving the ACK for the previous one.

python

# Pseudo code for Sender
while data:
    send_packet()  # Send a packet
    wait_for_ack()  # Wait for ACK
    ack_received += 1
    if ack_received == sent_packets:
        break

python

# Pseudo code for Receiver
while True:
    if packet_received:
        send_ack()  # Send ACK
        process_packet()
        packet_received = False
    else:
        continue

📝 Note: The main disadvantage of Stop-and-Wait is the high overhead due to repeated ACKs and waiting.

Quiz

Sliding Window 💡

How does it work?

Sliding Window is a more efficient flow control technique that allows the sender to send multiple packets without waiting for ACKs for each one. It uses a window size to determine how many packets can be outstanding at any given time.

python

# Pseudo code for Sender
while data:
    send_window_size_packets()  # Send packets up to window size
    wait_for_ack(window_size)  # Wait for ACKs for all packets

python

# Pseudo code for Receiver
while True:
    if packet_received:
        send_ack()  # Send ACK for the acknowledged packet
        process_packet()
        if not more_data_to_send():
            send_reset()  # Send reset if no more data is to be sent
    else:
        continue

📝 Note: The Sliding Window technique reduces the overhead compared to Stop-and-Wait but requires careful synchronization to avoid data loss.

Quiz

That's it for our introduction to Flow Control in computer networks! In the next lesson, we'll delve deeper into the Sliding Window technique, discussing its variations and optimizations. Keep learning and keep coding! ✅

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