1. Vertical Redundancy Check (VRC) :
Vertical Redundancy Check is the error detection method which is used by upper layers to detect error in data. The other name for VRC is Parity Check. A redundant bit which is also named as parity bit is added to each data unit. This method includes even parity and odd parity. When the total number of 1s in data is even that there is even parity and when the total number of 1s in data is to be odd that indicates there is odd parity in data.
2. Longitudinal Redundancy Check (LRC) :
Longitudinal Redundancy Check (LRC) is the error detection method which is used by upper layers to detect error in data. The other name for VRC is 2-D parity check. In this method, data which the user want to send is organized into tables of rows and columns. To detect an error, a redundant bit is added to the whole block after addition this block is transmitted to receiver side. This redundant bit is used by receiver to detect error. If there is no error, receiver accepts the data and discards the redundant row of bits.
Difference between VRC and LRC :
|S.No.||Vertical Redundancy Check (VRC)||Longitudinal Redundancy Check (LRC)|
|1.||It stands for Vertical Redundancy Check.||It stands for Longitudinal Redundancy Check.|
|2.||In this redundant bit called parity bit is added to each data unit.||In this redundant row of bits is added to the whole block.|
|3.||VRC can detect single bit errors.||LRC can detect burst errors.|
|4.||It is also known as parity checker.||It is also known as 2-D parity checker.|
|5.||The advantage of using VRC is that it can checks all single bit errors but can check odd parity only in the case of change of odd bits.||The advantage of using LRC over VRC is that it can check all the burst errors.|
|6.||It is not capable of checking the burst error in case of change of bits is even.||If two bits in data unit is damaged and also in other data unit the same bits are damaged at same position, then it is not capable of detecting such kind of error.|