Parity checking is used to check
weather data has been changed or
corrupted following transmission from
one device to another
A byte of data is allocated a parity bit o
Systems that use even parity have an
even number of 1-bits o Systems that use
odd parity have an even number of 1-bits
Automatic Repeat Request (ARQ)
ARQ used acknowledgment to indicate
data receiver correctly.
It uses and acknowledgement (message
sent by the receiver indicating that data
has been received correctly)
Checksum
Data is sent in blocks and an additional
value sent at the end of the block
An additional value called Checksum, is end at the end of the block of data.
The checksum is based on the number of bytes in the block
If the checksum at the receiver’s end doesn’t match
the checksum at the end of the data block, then an
error in transmission has occurred