Challenge Your Networking Knowledge with Our OSI Model Quiz!

The Development and Significance of the OSI Model

• The OSI model was developed in the late 1970s to support the emergence of diverse computer networking methods that were competing for application in large national networking efforts.
• The model became a working product of the Open Systems Interconnection group at the International Organization for Standardization (ISO) in the 1980s.
• The model failed to garner reliance during the design of the Internet, which is reflected in the less prescriptive Internet Protocol Suite sponsored by the Internet Engineering Task Force (IETF).
• Before the development of the OSI model, networking was largely either government-sponsored or vendor-developed with proprietary standards.
• Public data networks began to use the X.25 standard in the late 1970s, and the Experimental Packet Switched System in the UK identified the need for defining higher-level protocols.
• The UK presented the case for an international standards committee to cover this area at the ISO meeting in Sydney in March 1977, leading to the ISO initiating a program to develop general standards and methods of networking.
• The OSI model was first defined in raw form in Washington, D.C., in February 1978 by French software engineer Hubert Zimmermann, and the refined but still draft standard was published by the ISO in 1980.
• The rate of technological change made it necessary to define standards that new systems could converge to rather than standardizing procedures after the fact, which was the reverse of the traditional approach to developing standards.
• In 1983, the CCITT and ISO documents were merged to form The Basic Reference Model for Open Systems Interconnection, usually referred to as the Open Systems Interconnection Reference Model, OSI Reference Model, or simply OSI model.
• The OSI model promoted the idea of a consistent model of protocol layers, defining interoperability between network devices and software, and was a major advance in the standardization of network concepts.
• A networking system was divided into layers, and within each layer, one or more entities implemented its functionality. Each entity interacted directly only with the layer immediately beneath it and provided facilities for use by the layer above it.
• The OSI standards documents are available from the ITU-T as the X.200 series of recommendations, and some of the protocol specifications were also available as part of the ITU-T X series. The equivalent ISO/IEC standards for the OSI model were available from ISO.