The information‟s which has to be used in multimedia system either for storage purpose or for transmission from one system to another system are generally larger than bandwidth of communication channel or larger than the system, writing capacity size of the system. Hence the system divides the information into small chunks or units. The sequence of these chunks or packets forms the data streams and these are called information units.
Logical data units (LDU):
When the information units are used for reading or writing the information from or to the storage device then the information units are known as logical data unit.
Protocol data unit (PDU):
When the information units are produced for transmission and are going to be loaded on communication channel then each unit (packets) are called protocol data unit (PDU). Since in each unit some protocol layered stamps, error control code and flow control code including destination address are added in the information unit so its name is protocol data unit.
