Error control

One of the roles of the Data Link Layer Protocol in which there exist 2 sub functions: Error Detection and Error Correction. There are several mechanisms to detect errors on a receiving side, in terms of communication. Parity, checksum, Cyclic Redundant Check (CRC), Vertical Redundancy Check, Horizontal Redundancy Check and Rectangular Redundancy Check are examples of varieties of error-checking mechanisms.

There are 2 ways to correct found errors: Forward Error Correction and Automatic Repeat Request (ARQ). The first one is practical in cases where the communication channel is remarkably long - with long dramatic delay - and is prone to errors. In this case, it is not practical to send retransmission requests. Instead, sets of redundant information is sent with the data, so that correction can be done on the fly. ARQ is an interactive way of correcting errors by bouncing back and forth between a sender and a receiver until accuracy is ensured.