TCP flow control (sliding window) in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of TCP flow control?

TCP flow control ensures that a sender does not overwhelm a receiver by sending more data than it can handle at a time.

intermediate

Explain the sliding window concept in TCP flow control.

The sliding window is a method where the sender can send multiple packets before needing an acknowledgment, but only up to a window size that the receiver can handle. The window 'slides' forward as acknowledgments arrive.

beginner

What does the 'window size' represent in TCP sliding window flow control?

The window size represents the amount of data (in bytes) that the sender is allowed to send without receiving an acknowledgment from the receiver.

intermediate

How does the receiver communicate its available buffer space to the sender in TCP?

The receiver sends the current window size value in the TCP header of acknowledgment packets, indicating how much more data it can receive.

beginner

What happens if the sender sends data faster than the receiver can process it in TCP flow control?

If the sender sends data too fast, the receiver's buffer may overflow, causing packet loss. TCP flow control prevents this by adjusting the window size to slow down the sender.

What does the sliding window in TCP allow the sender to do?

A Send multiple packets before receiving acknowledgments

B Send only one packet at a time

C Ignore receiver's buffer size

D Close the connection immediately

The sliding window allows the sender to send multiple packets up to the window size before needing acknowledgments.

In TCP flow control, what does the receiver use to tell the sender how much data it can receive?

A IP address

B Sequence number

C Port number

D Window size field in TCP header

The receiver communicates its available buffer space using the window size field in the TCP header.

What happens when the window size is zero in TCP flow control?

A Sender must stop sending data temporarily

B Sender sends data faster

C Connection is closed

D Receiver sends data

A window size of zero tells the sender to pause sending data until the receiver can accept more.

Why is TCP flow control important?

A To encrypt data

B To prevent receiver buffer overflow

C To increase IP address speed

D To assign port numbers

TCP flow control prevents the sender from overwhelming the receiver's buffer, avoiding data loss.

What does the 'sliding' in sliding window refer to?

A The window closes after one packet

B The window size stays fixed

C The window moves forward as data is acknowledged

D The window is ignored

The window slides forward as the receiver acknowledges data, allowing new data to be sent.

Describe how TCP uses the sliding window mechanism to control data flow between sender and receiver.

Think about how the sender knows how much data to send and when to wait.

Explain why TCP flow control is necessary and what could happen without it.

Consider what happens if the sender ignores the receiver's capacity.