P

packet

An Open Systems Interconnection (OSI) network layer transmission unit that consists of binary information representing both data and a header containing an identification number, source and destination addresses, and error-control data.

packet header

In network protocol communications, a specially reserved field of a defined bit length that is attached to the front of a packet for carry and transfer of control information. When the packet arrives at its destination, the field is then detached and discarded as the packet is processed and disassembled in a corresponding reverse order for each protocol layer. See also packet.