Introduction to the OSI Model

   The OSI Open Standard

The OSI model was created by the International Standards Organization (ISO). ISO is composed of members from national standards organizations of many countries, including the American National Standards Institute (ANSI), the principal nongovernment U.S. standards organization. The standard was intended to allow the interconnection of networks without regard to the underlying hardware, as long as the communication software used adheres to the standard. In other words, the OSI model defines a neutral set of rules for data communication. Products that follow those rules can usually work together, even if they are made by different manufacturers.

The OSI model is an open standard. The term "open" means the standard's specifications are publicly available. Compliance with the standard is also voluntary; new products are not required to adhere to the standard. However, many manufacturers have found that standards-based products are more competitive. Customers want the flexibility of hardware and software that is "interoperable" with other manufacturers' products, and do not want to be locked into a single vendor's proprietary solutions. 

The OSI standard was patterned after, and is similar to, the IBM layered networking scheme called "Systems Network Architecture (SNA)." IBM introduced SNA in the early 1970s to provide a consistent standard for its product platforms. However, the OSI model is simpler and more elegant than SNA.