The ISO/OSI Reference Model

With computer networks we require protocols to "meet" new computers, ask for information, agree to share data, etc.

The complexity of protocols can be simplified by separating some of the functions required into different protocols, and isolating "layers of responsibility" into different protocol modules.

For example,

• at the lowest level we are concerned with correctly transmitting bits (0's and 1's) of data.

• at another level we may be interested in transferring files between different computers which support different data type representations.

One solution to such separation of responsibilities is provided by the Open Systems Interconnection / International Standards Organization OSI/ISO reference model.
(This model was finally agreed upon and standardized in 1983).

Until about twenty years ago (until the end of the last millenium), the OSI protocol suite was still actively sought in all tender specifications by the Australian and U.S. governments.

Today, the Transmission Control Protocol/Internet Protocol (TCP/IP) suite meets nearly all of our networking needs. While TCP/IP employs a 4-layer model, in contrast to the 7-layer ISO/OSI model, many identical concepts may be observed.