Error Detection & Correction
There are many reasons such as noise, cross-talk etc., which may help data to get corrupted during transmission. The upper layers work on some generalized view of network architecture and are not aware of actual hardware data processing.Hence, the upper layers expect error-free transmission between the systems. Most of the applications would not function expectedly if they receive erroneous data. Applications such as voice and video may not be that affected and with some errors they may still function well.
Data-link layer uses some error control mechanism to ensure that frames (data bit streams) are transmitted with certain level of accuracy. But to understand how errors is controlled, it is essential to know what types of errors may occur.
Types of Errors
There may be three types of errors:
1.Single bit error:
In a frame, there is only one bit, anywhere though, which is corrupt.
2.Multiple bits error:
Frame is received with more than one bits in corrupted state.
3.Brust error:
Frame contains more than1 consecutive bits corrupted.
Error Detection
Errors in the received frames are detected by means of Parity Check and Cyclic Redundancy Check (CRC). In both cases, few extra bits are sent along with actual data to confirm that bits received at other end are same as they were sent. If the counter-check at receiver’ end fails, the bits are considered corrupted.
https://www.tutorialspoint.com/data_communication_computer_network/error_detection_and_correction.htm
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