International Journal of Advanced Research in Computer Science and Software Engineering (IJARCSSE)
Due to the urgency in the need for standards for heterogeneous computer networks, International Standard Organization (ISO) created a new subcommittee for "Open System Interconnection" (ISO/TC97/SC16) in 1977. The first priority of subcommittee 16 was to develop architecture for open system interconnection which could serve as a frame work for the definition of standard protocols. As a result 18 months of studies and discussions, SC16 adopted a layered architecture comprising seven layers (physical, data link, network, transport, session, presentation, and application). In July 1979, the specifications of this architecture, established by SC16, were passed under the name of "OSI Reference Model" to Technical Committee 97 "Data Processing" along with recommendations to start officially, on this basis a set of protocols standardizations to start projects to cover the most urgent needs.