ASSIGNMENT
Explain Flow control Mechanism used in DLL
with the help of diagram.
Flow control is a technique that allows two stations working at different speeds to
communicate with each other. It is a set of measures taken to regulate the amount of
data that a sender sends so that a fast sender does not overwhelm a slow receiver. In
data link layer, flow control restricts the number of frames the sender can send before it
waits for an acknowledgment from the receiver.
Flow control can be broadly classified into two categories –
Feedback based Flow Control - In these protocols, the sender sends frames after it has
received acknowledgments from the user. This is used in the data link layer.
Rate based Flow Control - These protocols have built in mechanisms to restrict the rate
of transmission of data without requiring acknowledgment from the receiver. This is used
in the network layer and the transport layer.
Data link layer uses feedback based flow control mechanisms. There are two main
techniques –
Stop and Wait
This protocol involves the following transitions −
The sender sends a frame and waits for acknowledgment.
Once the receiver receives the frame, it sends an acknowledgment frame back to the
sender.
On receiving the acknowledgment frame, the sender understands that the receiver is
ready to accept the next frame. So it sender the next frame in queue.
