* Flow control: adjust and confirm data flow rate for successful transmission. * Error Control: a way to recover corrupted data .
Flow Control: is one important design issue for the Data Link Layer that controls the flow of data between sender and receiver. In Communication, there is communication medium between sender and receiver. When Sender sends data to receiver than there can be problem in below case : 1) Sender sends data at higher rate and receive is too sluggish to support that data rate. To solve the above problem, FLOW CONTROL is introduced in Data Link Layer. It also works on several higher layers. The main concept of Flow Control is to introduce EFFICIENCY in Computer Networks.
Error Control: Network is responsible for transmission of data from one device to another device. The end to end transfer of data from a transmitting application to a receiving application involves many steps, each subject to error. With the error control process, we can be confident that the transmitted and received data are identical. Data can be corrupted during transmission. For reliable communication, error must be detected and corrected. Error control is the process of detecting and correcting both the bit level and packet level errors. Types of Errors Single Bit Error The term single bit error means that only one bit of the data unit was changed from 1 to 0 and 0 to 1. Burst Error In term burst error means that two or more bits in the data unit were changed. Burst error is also called packet level error, where errors like packet loss, duplication, reordering.