The ISO internetwork protocol standard

A great deal has already been written about the development by the International Organization for Standardization of a Reference Model for Open Systems Interconnection. The Reference Model provides a framework for the development of standards for the interconnection of computer and terminal equipment. It describes an architecture wherein functions ascribed to providing communications are separated into a hierarchy of seven layers. Each layer provides services to the next higher layer, utilizing the services provided by subordinate layers in order to achieve that end. At each layer, protocols are employed to convey information between peer layer entities in individual systems. When in compliance with a suite of standard protocols prescribed for OSI, systems are considered to be "open".