Flow control (stop-and-wait, sliding window) in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of flow control in data communication?

Flow control ensures that the sender does not overwhelm the receiver by sending data faster than it can be processed, preventing data loss.

beginner

Explain the Stop-and-Wait flow control method.

In Stop-and-Wait, the sender sends one frame and waits for an acknowledgment before sending the next frame. This ensures reliable delivery but can be slow.

intermediate

What is the main disadvantage of Stop-and-Wait flow control?

It is inefficient for high-speed or long-distance networks because the sender must wait for an acknowledgment after each frame, causing delays.

intermediate

Describe the Sliding Window flow control technique.

Sliding Window allows the sender to send multiple frames before needing an acknowledgment, using a 'window' size to control how many frames can be sent at once, improving efficiency.

intermediate

How does the Sliding Window method improve over Stop-and-Wait?

Sliding Window increases data flow by allowing multiple frames to be sent without waiting for individual acknowledgments, reducing idle time and increasing throughput.

What does the sender do in Stop-and-Wait flow control after sending a frame?

A Sends all frames at once

B Waits for an acknowledgment before sending the next frame

C Sends the next frame immediately

D Sends a negative acknowledgment

In Stop-and-Wait, the sender waits for an acknowledgment after each frame before sending the next one.

Which flow control method allows sending multiple frames before receiving acknowledgments?

A Sliding Window

B Checksum

C Stop-and-Wait

D Parity Check

Sliding Window lets the sender send several frames within a window size before waiting for acknowledgments.

Why is Stop-and-Wait inefficient for long-distance communication?

A Because it sends too many frames at once

B Because it uses too large a window size

C Because it waits for acknowledgment after each frame, causing delays

D Because it does not check for errors

Waiting for acknowledgment after each frame causes delays especially when the round-trip time is long.

In Sliding Window, what controls how many frames can be sent before acknowledgment?

A Timeout value

B Frame size

C Packet priority

D Window size

The window size determines how many frames the sender can transmit before needing an acknowledgment.

Which of the following is a benefit of Sliding Window over Stop-and-Wait?

A Higher throughput

B Lower memory usage

C Simpler implementation

D No need for acknowledgments

Sliding Window improves throughput by allowing multiple frames to be sent without waiting for each acknowledgment.

Explain how Stop-and-Wait flow control works and mention one advantage and one disadvantage.

Think about sending one message at a time and waiting for a reply.

Describe the Sliding Window flow control method and how it improves data transmission efficiency.

Imagine sending several letters before waiting for a reply.