In both cases, the receiver does not receive the correct data-frame and sender does not know anything about any loss.In such case, both sender and receiver are equipped with some protocols which helps them to detect transit errors such as loss of data-frame. When data-frame is transmitted, there is a probability that data-frame may be lost in the transit or it is received corrupted. As we learnt, stop and wait flow control mechanism wastes resources, this protocol tries to make use of underlying resources as much as possible. In this flow control mechanism, both sender and receiver agree on the number of data-frames after which the acknowledgement should be sent.

This flow control mechanism forces the sender after transmitting a data frame to stop and wait until the acknowledgement of the data-frame sent is received. Two types of mechanisms can be deployed to control the flow: What if the speed (hardware/software) of the sender or receiver differs? If sender is sending too fast the receiver may be overloaded, (swamped) and data may be lost. That is, sender sends at a speed on which the receiver can process and accept the data. When a data frame (Layer-2 data) is sent from one host to another over a single medium, it is required that the sender and receiver should work at the same speed. Data-link layer is responsible for implementation of point-to-point flow and error control mechanism.

The missing link icp