History of the Osi Reference Model

History of the OSI Reference Model

Looking at the origins of the OSI Reference Model takes us back to several issues that were discussed in the Networking Fundamentals chapter of this Guide; specifically, I am talking about standards and standards organizations. The idea behind the creation of networking standards is to define widely-accepted ways of setting up networks and connecting them together. The OSI Reference Model represented an early attempt to get all of the various hardware and software manufacturers to agree on a framework for developing various networking technologies.

In the late 1970s, two projects began independently, with the same goal: to define a unifying standard for the architecture of networking systems. One was administered by the International Organization for Standardization (ISO), while the other was undertaken by the International Telegraph and Telephone Consultative Committee, or CCITT (the abbreviation is from the French version of the name). These two international standards bodies each developed a document that defined similar networking models.

In 1983, these two documents were merged together to form a standard called The Basic Reference Model for Open Systems Interconnection. That's a mouthful, so the standard is usually referred to as the Open Systems Interconnection Reference Model, the OSI Reference Model, or even just the OSI Model. It was published in 1984 by both the ISO, as standard ISO 7498, and the renamed CCITT (now called the Telecommunications Standardization Sector of the International Telecommunication Union or ITU-T) as standard X.200. (Incidentally, isn't the new name for the CCITT much catchier than the old one? Just rolls off the old tongue, doesn't it. J)

One interesting aspect of the history of the OSI Reference Model is that the original objective was not to create a model primarily for educational purposes--even though many people today think that this was the case. The OSI Reference Model was intended to serve as the foundation for the establishment of a widely-adopted suite of protocols that would be used by international internetworks--basically, what the Internet became. This was called, unsurprisingly, the OSI Protocol Suite.

However, things didn't quite work out as planned. The rise in popularity of the Internet and its TCP/IP protocols met the OSI suite head