Data transmission protocols

Data transmission protocols are those that enable two entities to communicate over a telecommunications network. A protocol is a set of rules that must be respected so that these two entities can exchange information. These rules can be as simple as the coding technique used to recognize a character, or as complex as the protocols used to route blocks of information from one end of the network to the other.

Standardization has a considerable impact on protocols. For communication to take place, both ends must use the same rules. Several categories of protocols therefore exist: those standardized by international bodies (ISO, ITU-T...) and those that have achieved near-universal adoption, becoming "de facto standards", such as the TCP/IP (Transmission Control Protocol/Internet Protocol) protocols used on the Internet. There are also so-called "proprietary" protocols, developed and used by computer companies for their own specific architecture. These often include the whole range of protocols used in the architectures of major manufacturers, such as IBM's SNA, Bull's DSA or Digital's DNA.

We will focus on the protocols of the ISO reference architecture and compare them with those of the TCP/IP architecture. We will then outline the main trends, in particular those of the new reference model designed for Asynchronous Transfer Mode (ATM).