TCP/IP or OSI - Which one came first

The TCP/IP model, which is realistically the Internet Model, came into existence about 10 years before the OSI model.

History of TCP

       From 1973 to 1974, Cerf's networking research group at Stanford worked out details of the idea, resulting in the first TCP specification. A significant technical influence was the early networking work at Xerox PARC, which produced the PARC Universal Packet protocol suite, much of which existed around that time.

        In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. In 1985, the Internet Advisory Board (later renamed the Internet Architecture Board) held a three-day workshop on TCP/IP for the computer industry, attended by 250 vendor representatives, promoting the protocol and leading to its increasing commercial use.

        In 1985, the first Interop conference focused on network interoperability by broader adoption of TCP/IP. The conference was founded by Dan Lynch, an early Internet activist. From the beginning, large corporations, such as IBM and DEC, attended the meeting. Interoperability conferences have been held every year since then. Every year from 1985 through 1993, the number of attendees tripled

History of OSI

       Prior to OSI, networking was largely either government-sponsored (ARPANET in the US, CYCLADES in France) or vendor-developed and proprietary standards (such as the System network architecture (SNA) of IBM and DECnet of Digital Equipment Corporation). In the UK work on the Experimental Packet Switched system circa 1973, the need to define higher level protocols and the content of an NCC (UK) publication 'Why Distributed Computing' resulting 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 multi vendor networks for internet working, 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.