StarLAN
Encyclopedia
StarLAN was the first implementation of 1 megabit
per second (1Mb/s) Ethernet over twisted pair
wiring. It was standardized by the standards association
of the Institute of Electrical and Electronics Engineers
(IEEE) as 802.3e in 1986, as the 1BASE5 version of Ethernet
.
around 1984.
The name comes from using a star topology
for a local area network
.
The standard known as 1BASE5 was adopted as 802.3e in 1986 by members of the IEEE 802.3
standards committee as the Twisted Pair Medium Specification in section 12.
StarLAN ran at a speed of 1 Mbit/s.
A major design goal in StarLAN was the reuse of existing telephony on-premises wiring
and compatibility with analog telephone signals in the same cable bundle. The signal modulation and wire pairing used by StarLAN were carefully chosen so that they would not affect or be affected by either the analog signal of a normal call, on hook and off hook transients, or the 20 Hz high-voltage analog ring signal. Reuse of existing wires was critical in many buildings where rewiring was cost prohibitive, or where running new wire would disturb asbestos within the building infrastructure.
The TIA-568B wiring pinout standard was devised for StarLAN, and pair 1 (blue) was left unused to accommodate an analog phone pair. Pairs 2 and 3 (orange and green) carry the StarLAN signals. This greatly simplified the installation of combined voice and data wiring in countries that used registered jack
connectors and American wiring practices for their phone service (connecting both to the same cable was a simple matter of using a pin-pin RJ45 splitter or punching down the same wires to two ports). This arrangement prevented harm to private branch exchange (PBX) equipment in the event that a StarLAN cable was plugged into the wrong device.
The technology was patented by AT&T, and was adopted by other networking vendors such as Hewlett-Packard
and Ungermann-Bass
.
Integrated circuit
s were introduced starting in 1986 that reduced the cost of the interfaces.
StarLAN never became popular by itself, but provided the basis for the later 10 megabit per second standard 10BASE-T
.
Megabit
The megabit is a multiple of the unit bit for digital information or computer storage. The prefix mega is defined in the International System of Units as a multiplier of 106 , and therefore...
per second (1Mb/s) Ethernet over twisted pair
Ethernet over twisted pair
Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...
wiring. It was standardized by the standards association
IEEE Standards Association
The Institute of Electrical and Electronics Engineers Standards Association is an organization within IEEE that develops global standards in a broad range of industries, including: power and energy, biomedical and health care, information technology, telecommunication, transportation,...
of the Institute of Electrical and Electronics Engineers
Institute of Electrical and Electronics Engineers
The Institute of Electrical and Electronics Engineers is a non-profit professional association headquartered in New York City that is dedicated to advancing technological innovation and excellence...
(IEEE) as 802.3e in 1986, as the 1BASE5 version of 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....
.
Description
StarLAN was developed by AT&T CorporationAT&T Corporation
AT&T Corp., originally American Telephone and Telegraph Company, is an American telecommunications company that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. AT&T is the oldest telecommunications company...
around 1984.
The name comes from using a star topology
Star network
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages...
for a 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...
.
The standard known as 1BASE5 was adopted as 802.3e in 1986 by members of the IEEE 802.3
IEEE 802.3
IEEE 802.3 is a working group and a collection of IEEE standards produced by the working group defining the physical layer and data link layer's media access control of wired Ethernet. This is generally a local area network technology with some wide area network applications...
standards committee as the Twisted Pair Medium Specification in section 12.
StarLAN ran at a speed of 1 Mbit/s.
A major design goal in StarLAN was the reuse of existing telephony on-premises wiring
On-premises wiring
In telecommunication, on-premises wiring is customer-owned communications transmission lines. It is also called customer premises wiring . The transmission lines can be metallic or optical fiber, and may be installed within or between buildings.Premises wiring may consist of horizontal wiring,...
and compatibility with analog telephone signals in the same cable bundle. The signal modulation and wire pairing used by StarLAN were carefully chosen so that they would not affect or be affected by either the analog signal of a normal call, on hook and off hook transients, or the 20 Hz high-voltage analog ring signal. Reuse of existing wires was critical in many buildings where rewiring was cost prohibitive, or where running new wire would disturb asbestos within the building infrastructure.
The TIA-568B wiring pinout standard was devised for StarLAN, and pair 1 (blue) was left unused to accommodate an analog phone pair. Pairs 2 and 3 (orange and green) carry the StarLAN signals. This greatly simplified the installation of combined voice and data wiring in countries that used registered jack
Registered jack
A registered jack is a standardized physical network interface — both jack construction and wiring pattern — for connecting telecommunications or data equipment to a service provided by a local exchange carrier or long distance carrier. The standard designs for these connectors and their wiring...
connectors and American wiring practices for their phone service (connecting both to the same cable was a simple matter of using a pin-pin RJ45 splitter or punching down the same wires to two ports). This arrangement prevented harm to private branch exchange (PBX) equipment in the event that a StarLAN cable was plugged into the wrong device.
The technology was patented by AT&T, and was adopted by other networking vendors such as Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
and Ungermann-Bass
Ungermann-Bass
Ungermann-Bass, also known as UB and UB Networks, was a computer networking company in the 1980s to 1990s. Located in Santa Clara, California, in Silicon Valley, UB was the first large networking company independent of any computer manufacturer. UB was founded by Ralph Ungermann and Charlie Bass...
.
Integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s were introduced starting in 1986 that reduced the cost of the interfaces.
StarLAN never became popular by itself, but provided the basis for the later 10 megabit per second standard 10BASE-T
10BASE-T
Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...
.