In telecommunications, a Datakit is a

virtual circuit A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is first established across the network between two endpoints. The network, rather than having a fixed data rate reser ...

switch developed by Sandy Fraser at

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

for both local-area and wide-area networks. It is currently used by the Regional Bell Operating Companies (RBOCs) in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Designing

A complete Datakit system measures approximately 19 inches wide and 5 feet tall. Datakit employs a cell relay protocol similar to

Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT) for digital trans ...

. (ATM). It is a connection-oriented switch, meaning that all data packets for a given call travel through the network using the same

. Datakit networks continue to be used by major telephone companies in the United States. Datakit interfaces include

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...

, UDP, X.25, asynchronous protocols, as well as several synchronous protocols such as SDLC,

HDLC High-Level Data Link Control (HDLC) is a communication protocol used for transmitting data between devices in Telecommunications, telecommunication and Computer network, networking. Developed by the International Organization for Standardization ...

, and

Bisync Binary Synchronous Communication (BSC or Bisync) is an IBM character-oriented, half-duplex link protocol, announced in 1967 after the introduction of System/360. It replaced the synchronous transmit-receive (STR) protocol used with second gener ...

These networks support a range of functions, including host-to-terminal communication, terminal-to-host communication, host-to-host traffic, file transfers, remote login, printing, and command execution. At the

physical layer In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechani ...

, Datakit operates over diverse media, ranging from slow-speed EIA-232 connections to high-speed 500 Mbps fiber optic links, including 10/100 Mbps Ethernet links. An adaptation protocol known as the Universal Receiver Protocol (URP) is utilized by Datakit. URP spreads protocol data unit (PDU) overhead across multiple cells and processes packets immediately. It assumes that cells arrive in the correct order; if they do not, it may force retransmissions. The Information Systems Network (ISN), developed by

AT&T Information Systems AT&T Information Systems (ATTIS), originally known as American Bell, was the fully separate subsidiary of American Telephone & Telegraph Company (AT&T) which focused on computer technology ventures and telephone sales, and other unregulated busine ...

, was a precursor to Datakit. ISN was a packet-switching network similar to the System 75 digital platform. For both LAN and WAN applications, ISN used devices called concentrators, which connected via fiber optics over distances of up to 15 miles. Speeds on these connections ranged from 1200 to 5600 baud, with most end-users relying on dumb terminals. Early support for ISN and Datakit came from the National Customer Support Center (NCSC) in Englewood, Colorado, before being handled by AT&T Information Systems after company restructuring and support from Bell Labs.

History

Bell Laboratories relied heavily on Datakit for internal networking. On top of Datakit’s transport services, several operating systems, including

UNIX Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

, implemented

UUCP UUCP (Unix-to-Unix Copy) is a suite of computer programs and communications protocol, protocols allowing remote execution of commands and transfer of computer file, files, email and netnews between computers. A command named is one of the prog ...

for email and remote login through dkcu (Datakit-based cu). Datakit’s design was similar to a telephone central office, using an area code plus a seven-digit numbering system. It was in production for at least three years before its full release. In 1996, AT&T rebranded Bell Labs as

Lucent Technologies Lucent Technologies, Inc. was an American Multinational corporation, multinational telecommunications equipment company headquartered in Murray Hill, New Jersey, Murray Hill, New Jersey. It was established on September 30, 1996, through the div ...

, which later merged with the French company Alcatel to become

Alcatel-Lucent Alcatel-Lucent S.A. () was a multinational telecommunications equipment company, headquartered in Boulogne-Billancourt, Paris, France. The company focused on Fixed line telephone, fixed, Mobile phone, mobile and telecommunications convergence, ...

Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...

ultimately acquired the company in 2016. By the late 1990s, Datakit was considered legacy technology and was gradually replaced by newer technologies such as IP and Ethernet. Lucent discontinued the Datakit product line, but a group of former employees formed Datatek Applications. Datatek licensed the technology from Lucent to support remaining Datakit users and to provide gateway solutions for transitioning to modern networks. However, due to a steady decline in Datakit users, Datatek Applications ceased operations in January 2018.{{cn, date=March 2025

References

Wide area networks Packets (information technology) Computer networking

Designing

History

See also

References