Open Systems Interconnection is an effort to standardize computer
networking that was started in 1977 by the International Organization for
Standardization, along with the ITU-T. History
Prior to OSI, networking was largely either government-sponsored or
vendor-developed and proprietary standards of IBM and DECnet of Digital
Equipment Corporation). A Experimental Packet Switched system in the UK circa
1973, also identified the need to define higher level protocols. The NCC
publication 'Why Distributed Computing' which came from considerable research
into future configurations for computer systems, resulted in the UK presenting
the case for an international standards committee to cover this area at the ISO
meeting in Sydney in March 1977. OSI was hence an industry effort, attempting to
get industry participants to agree on 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 interoperate with
other devices because of a lack of common protocols. However, while OSI
developed its networking standards, TCP/IP came into widespread use on
multivendor networks for internetworking, while on the local
network level both Ethernet and token ring gained prominence.
The OSI reference model was a major advance in the teaching of network
concepts. It promoted the idea of a consistent model of protocol layers,
defining interoperability between network devices and software. The OSI
model was defined in raw form in Washington, DC in February 1978 by
Hubert Zimmermann of France and the refined standard was published by the
ISO in 1984. Criticism
The OSI protocol suite that was specified as part of the project was
considered by many, such as computer scientist Andrew S. Tanenbaum, to be too
complicated and inefficient, 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 protocols included so many optional features that
many vendors' implementations were not interoperable.
Although the OSI model is often still referred to, the Internet's TCP/IP
protocol suite is used in lieu of the OSI protocols. TCP/IP's pragmatic
approach to computer networking and two independent implementations of
simplified protocols made it a practical standard. Some protocols and
specifications in the OSI stack remain in use, one example being IS-IS, which
was specified for OSI as ISO/IEC 10589:2002 and adapted for Internet use
as RFC 1142. ISO/IEC 7498
The standard ISO/IEC 7498 consists of the following parts:
ISO/IEC 7498-1 The Basic Model ISO 7498-2 Security Architecture
ISO/IEC 7498-3 Naming and addressing ISO/IEC 7498-4 Management framework
See also OSI model
OSI protocols Common Management Information Service
GOSIP, the Government Open Systems Interconnection Profile
References ^ Hubert Zimmermann. IEEE Transactions
on Communications 28: 425–432. doi:10.1109/TCOM.1980.1094702.
^ a b c Andrew S. Tanenbaum, Computer Networks, § 1.4.4.
Further reading John Day, "Patterns in Network
Architecture: A Return to Fundamentals" Marshall Rose, The Open Book
David M. Piscitello, A. Lyman Chapin, Open Systems Networking
Andrew S. Tanenbaum, Computer Networks, 4th Edition, ISBN 0-13-066102-3
Gary Dickson; Alan Lloyd. Open Systems Interconnection/Computer Communications
Standards and Gossip Explained. Prentice-Hall. ISBN 978-0136401117.
External links ISO/IEC 7498-1:1994, Information
technology—Open Systems Interconnection—Basic Reference Model:
The Basic Model ITU-T Recommendation X.200 [ISO/IEC
7498-1:1994], Open Systems Interconnection - Basic Reference Model.
Open System Interconnection