Understanding the Sliding Window Mechanism

What is Sliding Windows Mechanism?

A sliding windows mechanism (also known as a flow control mechanism) is an algorithm used in networking to regulate data transmission between two network endpoints. It works by allowing the sender to send a predetermined amount of data without waiting for an acknowledgement (ACK) packet from the receiver before it can send more data. This process helps the sender adjust its sending rate to the receiving rate of the receiver, while also providing flow control so that the receiver doesn’t get overwhelmed with data.

How Does a Sliding Windows Mechanism Work?

In a sliding windows mechanism, the sender and receiver both maintain a “window” of data that has already been sent and received. The window is like a buffer — a place for data to be stored until it is ready for use. The sender maintains its own window, called the transmit window, which contains data that it has already sent but not yet received an ACK for. The receiver’s window is called the receive window, and it contains data that it has received but not yet acknowledged. Whenever the sender has some new data to send, it will check its transmit window to see how much data is currently stored there. It will then send only enough data to fill the window, up to the receiver’s advertised window size. Once the sender has sent all its available data, it will wait for the receiver to acknowledge the data in the window. Once it has received the ACK, the sender will move its window forward and start sending more data. The sliding windows mechanism is a key component of reliable transmission protocols like TCP, which is used for most internet applications today. It helps ensure that data sent over the network arrives safely and in order, while also allowing the sender to adjust its transmission rate to match the capacity of the receiver.