Types of Redundancy Checks

o    Fig shows the process of using redundant bits to check the accuracy of data unit o    Once  the  data  stream has  been  generated, it  passes  through  a  device  that  analyzes  it and adds on an appropriately coded redundancy check o    The data unit now enlarged by several bits (7) travels over the link to the receiver o    The receiver puts the entire stream through a checking function o    If the received bit stream passes the checking criteria, the data portion of the data unit is accepted and the redundant bits are discarded •     Types of Redundancy Checks o    There are 4 types of redundancy checks used in data communication: -Vertical Redundancy Check (VRC) -Longitudinal Redundancy Check (LRC) -Cyclic Redundancy Check (CRC) -Checksum o    First 3 are normally implemented in the physical layer for use in data link layer o    Fourth is used by Upper layers