Protocol Functions
Error Control
- PDUs can be lost or damaged
- methods for detecting and correcting errors is required
- retransmission upon failure of acknowledgement of receipt is a common method for handling lost PDUs
- cyclic redundancy checks are often used to detect damaged PDUs
Addressing
- a protocol must have a means for identifying a particular user using a particular application on a particular host residing on some network
- addressing is a means for protocols to identify these needs