Broadband Integrated Services Digital Network
Encyclopedia
In the 1980s the telecommunication
s industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network
, and conceived a grandiose end-to-end circuit switched
services, known as Broadband Integrated Services Digital Network (B-ISDN). This was designed in the as a logical extension of the end-to-end circuit switched data service, Integrated Services Digital Network
(ISDN), which was conceived and implemented by Telcordia Technologies (formerly Bellcore).
Before B-ISDN, the original ISDN attempted to substitute the analog telephone system with a digital system which was appropriate for both voice and non voice traffic. Obtaining worldwide agreement on the basic rate interface
standard was expected to lead to a large user demand for ISDN equipment, hence leading to mass production and inexpensive ISDN chips. However, the standardization process took years while computer network
technology moved rapidly. Once the ISDN standard was finally agreed upon and products were available, it was already obsolete.
For home use the largest demand for new services was video and voice transfer, but the ISDN basic rate lacks the necessary channel capacity
. For business, ISDN's 64 kbit/s data rate compared unfavorably to 10 Mbit/s local area network
s such as Ethernet
.
This led to introduction of B-ISDN, by adding the word broadband
. Although the term had a meaning in physics and engineering (similar to wideband
), the CCITT defined it as: "Qualifying a service or system requiring transmission channels capable of supporting rates greater
than the primary rate" referring to the primary rate
which ranged from about 1.5 to 2 Mbit/s.
Services envisioned included video telephone and video conferencing. Technical papers were published in early 1988.
Standards were issued by the Comité Consultatif International Téléphonique et Télégraphique
, (CCITT, now known as ITU-T), and called "Recommendations". They included G.707-709, and I.121 which defined the principal aspects of B-ISDN, with many others following through the 1990s.
The designated technology for B-ISDN was Asynchronous Transfer Mode
(ATM), which was intended to carry both synchronous
voice and asynchronous data services on the same transport.
The B-ISDN vision has been overtaken by other disruptive technologies
used in the Internet
.
The ATM technology survived as a low-level layer in most Digital Subscriber Line
(DSL) technologies, and as a payload type in some wireless technologies such as WiMAX
. The term "broadband" became a marketing term for any digital Internet access
service.
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
, and conceived a grandiose end-to-end circuit switched
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
services, known as Broadband Integrated Services Digital Network (B-ISDN). This was designed in the as a logical extension of the end-to-end circuit switched data service, Integrated Services Digital Network
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
(ISDN), which was conceived and implemented by Telcordia Technologies (formerly Bellcore).
Before B-ISDN, the original ISDN attempted to substitute the analog telephone system with a digital system which was appropriate for both voice and non voice traffic. Obtaining worldwide agreement on the basic rate interface
Basic rate interface
Basic Rate Interface is an Integrated Services Digital Network configuration intended primarily for use in subscriber lines similar to those that have long been used for plain old telephone service...
standard was expected to lead to a large user demand for ISDN equipment, hence leading to mass production and inexpensive ISDN chips. However, the standardization process took years while computer network
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
technology moved rapidly. Once the ISDN standard was finally agreed upon and products were available, it was already obsolete.
For home use the largest demand for new services was video and voice transfer, but the ISDN basic rate lacks the necessary channel capacity
Channel capacity
In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...
. For business, ISDN's 64 kbit/s data rate compared unfavorably to 10 Mbit/s local area network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
s such as Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
.
This led to introduction of B-ISDN, by adding the word broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
. Although the term had a meaning in physics and engineering (similar to wideband
Wideband
In communications, wideband is a relative term used to describe a wide range of frequencies in a spectrum. A system is typically described as wideband if the message bandwidth significantly exceeds the channel's coherence bandwidth....
), the CCITT defined it as: "Qualifying a service or system requiring transmission channels capable of supporting rates greater
than the primary rate" referring to the primary rate
Primary rate interface
The Primary Rate Interface is a standardized telecommunications service level within the Integrated Services Digital Network specification for carrying multiple DS0 voice and data transmissions between a network and a user....
which ranged from about 1.5 to 2 Mbit/s.
Services envisioned included video telephone and video conferencing. Technical papers were published in early 1988.
Standards were issued by the Comité Consultatif International Téléphonique et Télégraphique
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
, (CCITT, now known as ITU-T), and called "Recommendations". They included G.707-709, and I.121 which defined the principal aspects of B-ISDN, with many others following through the 1990s.
The designated technology for B-ISDN was Asynchronous Transfer Mode
Asynchronous Transfer Mode
Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
(ATM), which was intended to carry both synchronous
Synchronous circuit
A synchronous circuit is a digital circuit in which the parts are synchronized by a clock signal.In an ideal synchronous circuit, every change in the logical levels of its storage components is simultaneous. These transitions follow the level change of a special signal called the clock...
voice and asynchronous data services on the same transport.
The B-ISDN vision has been overtaken by other disruptive technologies
Disruptive technology
A disruptive technology or disruptive innovation is an innovation that helps create a new market and value network, and eventually goes on to disrupt an existing market and value network , displacing an earlier technology there...
used in the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
.
The ATM technology survived as a low-level layer in most Digital Subscriber Line
Digital Subscriber Line
Digital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...
(DSL) technologies, and as a payload type in some wireless technologies such as WiMAX
WiMAX
WiMAX is a communication technology for wirelessly delivering high-speed Internet service to large geographical areas. The 2005 WiMAX revision provided bit rates up to 40 Mbit/s with the 2011 update up to 1 Gbit/s for fixed stations...
. The term "broadband" became a marketing term for any digital Internet access
Internet access
Many technologies and service plans for Internet access allow customers to connect to the Internet.Consumer use first became popular through dial-up connections in the 20th century....
service.
See also
- Dynamic synchronous transfer modeDynamic synchronous Transfer ModeDynamic synchronous transfer mode is an optical networking technology standardized by the European Telecommunications Standards Institute in 2001 with specification ETSI ES 201 803-1. DTM is a time division multiplexing and a circuit-switching network technology that combines switching and...
, a revival of circuit switching technology for broadband traffic