Articles

Arpanet, Ethernet

Part: 2

Ethernet cableAs computer hardware became available the challenge of connecting them to make better use of the facilities became a focus for concern, ARPA engaged a young networking specialist, Larry Roberts, to lead a team responsible for linking computers via telephone lines. Four university and research sites would be connected and it was decided to build Interface Message Processors (IMPs, devised by Wesley Clark), smaller computers talking a common language dedicated to handle the interfacing between their hosts and the Network. Thus the first gateways were constructed and the precursor to the Internet was born under the name of the ARPANET in 1969.

The '70s saw the emergence of the first networks. As the ARPANET grew it adopted Network Control Protocol (NCP) on its host computers and File Transfer Protocol (FTP) is released by the Network Working Group as a user-transparent mechanism for sharing files between host computers.

And, significantly, the first Terminal Interface Processor (TIP) is implemented, permitting computer terminals to connect directly to ARPANET. Users at various sites could log on to the Network and request data from a number of host computers.

Communications Protocols

In 1972 Vinton Cerf is called to the chairmanship of the newly-formed Inter-Networking Group (INWG), a team setup to develop standards for the ARPANET. He and his team built upon their NCP communications system and devised TCP (Transmission-Control Protocol) in an effort to facilitate communications between the ever-growing number of networks now appearing – satellite, radio, ground-based like Ethernet, etc.

They conceived of a protocol that could be adopted by all gateway computers and hosts alike which would eliminate the tedious process of developing specific interfaces to diverse systems. They envisaged an envelope of information, a 'datagram', whose contents would be immaterial to the transmission process, being processed and routed until they reached their destination and only then opened and read by the recipient host computer. In this way different networks could be linked together to form a network of networks.

By the late '70s the final protocol was developed - TCP/IP (Internet Protocol) - which would become the standard for internet communications.

Ethernet

One final piece of computer networking came together under Bob Metcalfe's: Ethernet He submitted a dissertation on the ARPANET and packet switching networks for his Harvard graduate dissertation but was disappointed to have his paper junked. After taking a position at Xerox's Palo Alto Research Center (PARC) he read a paper on Alohanet, the university of Hawaii's radio network.

Alohanet was experiencing problems with packet collision (information was being lost due to the nature of radio broadcasting). Metcalfe examined the problem then refined the principles of packet collision, adopted cable as the communications medium, formed 3Com and marketed his invention as Ethernet. The take-up was almost immediate and the '80s witnessed the explosion of Local Area Networks (LANs). First educational establishments then businesses employed Ethernet as the business communications networking standard, and once connected through communications servers to the Internet, the World Wide Web was just an initiative away.

"Arpanet, Ethernet Part 2" The Internet Explained. 23 Novermber 2005. Written by and Mike Pepper