A tutorial on protocols

Protocols are common tools for controlling information transfer between computer systems. The concept of a protocol, which grew out of experimental computer networking, is now fundamental to syatem design. In this paper, basic protocol functions are explained and discussed. Then, the concept of a distributed system architecture is presented. It provides the framework for layers and protocols to operate across heterotgeneous systems. The purpose and functions of each protocol layer such as, transmission, transport, virtual terminal, are described. Interactions between design and performance are discussed, and typical mechanisms are reviewed. CCITT and ISO relevant standards are summarized. Finally, the similarity between protocols and programming languages is emphasized as it points to the major impact brought about by protocols in system design.