The Open Systems Interconnection (usually abbreviated to OSI) was a new effort in networking started in 1982 by the International Organization for Standardization (ISO), along with the ITU-T. Jump to: navigation, search A computer network is a system for communication between computers. ... Jump to: navigation, search 1982 (MCMLXXXII) is a common year starting on Friday of the Gregorian calendar. ... Logo of the International Organization for Standardization The International Organization for Standardization (ISO or iso) is an international standard-setting body composed of representatives from national standards bodies. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ...

Prior to OSI, networking was completely vendor-developed and proprietary, with protocol standards such as SNA and Decnet. OSI was a new industry effort, attempting to get everyone to agree to common network standards to provide multi-vendor interoperability. It was common for large networks to support multiple network protocol suites, with many devices unable to talk to other devices because of a lack of common protocols between them. In networking, a communications protocol or network protocol is the specification of a set of rules for a particular type of communication. ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... Jump to: navigation, search DECnet is a proprietary suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers. ...

The OSI reference model (which actually predates the OSI protocol work, dating to 1977) was the most important advance in the teaching of network concepts. It promoted the idea of a common model of protocol layers, defining interoperability between network devices and software. Jump to: navigation, search For the album by Ash, see 1977 (album). ...

However, the actual OSI protocol stack that was specified as part of the project was considered by many to be too complicated and to a large extent unimplementable. Taking the "forklift upgrade" approach to networking, it specified eliminating all existing protocols and replacing them with new ones at all layers of the stack. This made implementation difficult, and was resisted by many vendors and users with significant investments in other network technologies. In addition, the OSI protocols were specified by committees filled with differing and sometimes conflicting feature requests, leading to numerous optional features. Because so much was optional, many vendors' implementations simply could not interoperate, negating the whole effort. A protocol stack is a particular software implementation of a computer networking protocol suite. ...

The OSI approach was eventually eclipsed by the Internet's TCP/IP protocol suite. TCP/IP's pragmatic approach to computer networking and two independent implementations of simplified protocols made it a practical standard. For example, the definition for OSI's X.400 e-mail standards took up several large books, while the Internet e-mail (SMTP) definition took only a few dozen pages in RFC-821. It should be noted, however, that over time there have been numerous RFCs which extended the original SMTP definition, so that its complete documentation finally takes up several large books as well. Jump to: navigation, search The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ... A protocol stack is a particular software implementation of a computer networking protocol suite. ... In computing, X.400 is a OSI standard developed by the ITU-T (at the time the CCITT) and promulgated by ISO for the exchange of email (at the time called IPMs - Inter Personal Messages). ... Wikipedia does not yet have an article with this exact name. ... Jump to: navigation, search Simple Mail Transfer Protocol (SMTP) is the de facto standard for email transmission across the Internet. ... A Request for Comments (RFC) document is one of a series of numbered Internet informational documents and standards very widely followed by both commercial software and freeware in the Internet and Unix communities. ...

Many of the protocols and specifications in the OSI stack are long-gone or have been superseded, such as token-bus media, CLNP packet delivery, FTAM file transfer, and X.400 e-mail. Some still survive, often in significantly simplified forms. The X.500 directory structure still remains with significant usage, mainly because the original unwieldy protocol has been stripped away and effectively replaced with LDAP. IS-IS also continues as a network routing protocol used by larger telecommunications companies, having been adapted for use with the Internet Protocol. Many legacy SONET systems still use TARP (TID Address Resolution Protocol - utilizes CLNP and IS-IS) to translate Target Identifier of a SONET node. Often protocols and specifications in the OSI stack remain in use in legacy systems, unless or until such legacy systems are eventually upgraded, replaced or decomissioned. Token bus is token ring over a virtual ring on a coaxial cable. ... CLNS is an abbreviation of Connectionless Network Service. ... FTAM, an ISO 8571 standard, is an OSI Application layer protocol for File Transfer Access and Management. ... In computing, X.400 is a OSI standard developed by the ITU-T (at the time the CCITT) and promulgated by ISO for the exchange of email (at the time called IPMs - Inter Personal Messages). ... X.500 is the set of ITU-T computer networking standards covering electronic directory services such as white pages, Knowbot and whois. ... Lightweight Directory Access Protocol (LDAP) is a protocol for accessing on-line directory services. ... Intermediate system to intermediate system (IS-IS), is an IGP routing protocol originally designed for CLNS as part of the OSI protocol stack and described in ISO 10589 . ... Jump to: navigation, search The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. ... Synchronous Optical Networking, commonly known as SONET, is a standard for communicating digital information over optical fiber. ... A tarpaulin or tarp is a large sheet of strong, flexible, water resistant or waterproof cloth, often canvas coated with plastic or latex. ...

The collapse of the OSI project in 1996 severely damaged the reputation and legitimacy of the organizations involved, especially ISO. The worst part was that OSI's backers took too long to recognize and accommodate the dominance of the TCP/IP protocol suite.

Further reading

• Marshall T. Rose, The Open Book (Prentice-Hall, Englewood Cliffs, 1990)
• David M. Piscitello, A. Lyman Chapin, Open Systems Networking (Addison-Wesley, Reading, 1993)

Reference

• ISO 7498:1984 Open Systems Interconnection - Basic Reference Model