StarLAN
StarLANwas the first IEEE 802.3 standard forEthernet over twisted pairwiring. It was standardized by theIEEE Standards Associationas802.3ein 1986, as the1BASE5version ofEthernet.The StarLAN Task Force was chaired by Bob Galin.
Description
[edit]An early version of StarLAN was developed by Tim Rock and Bill Aranguren atAT&T Information Systemsas an experimental system in 1983.[1] The name StarLAN was coined by the IEEE task force based on the fact that it used astar topologyfrom a centralhubin contrast to thebus networkof the shared cable10BASE5and10BASE2networks that had been based onALOHAnet.
The standard known as 1BASE5 was adopted as 802.3e in 1986 by members of theIEEE 802.3standards committee as the Twisted Pair Medium Access Control sublayer and Physical Signalling sublayer specification in section 12.[2] The original StarLAN ran at a speed of 1 Mbit/s.
A major design goal in StarLAN was reduction in Ethernet installation costs by the reuse of existing telephoneon-premises wiringand compatibility with analog and digital 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, where running new wire would disturb asbestos within the building infrastructure, and where the bus topology of coaxial bus Ethernet was not installable.
The wire positioning calledT568Bin the standardTIA/EIA-568(later calledANSI/TIA-568) was originally devised for StarLAN, and pair 1 (blue) was left unused to accommodate an analog phone pair. Pairs 2 and 3 (orange and green respectively) carry the StarLAN signals. This greatly simplified the installation of combined voice and data wiring in countries that usedregistered jackconnectors 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 toprivate branch exchange(PBX) equipment in the event that a StarLAN cable was plugged into the wrong device.
Since 1BASE5 reused existing wiring, maximum link distance was only approximated at 250 m; depending on cable performance up to 500 m was possible. Up to five chained hubs were allowed.[3]
Parts of the StarLAN technology were patented by AT&T[4]and were initially part of a wider vision from AT&T to link theirUNIX-basedAT&T 3B2minicomputers to a network of MS-DOS PCs.[5]A StarLAN card was also offered for theAT&T UNIX PC.
StarLAN 10
[edit]In 1988, AT&T released StarLAN 10 operating at 10 Mbit/s. The original StarLAN was renamed StarLAN 1, reflecting its 1 Mbit/s speed.[6]
It was adopted by other networking vendors such asHewlett-PackardandUngermann-Bass. Integrated circuitswere introduced starting in 1986 that reduced the cost of the interfaces.[7]
StarLAN 10 andSynOpticsLattisNetprovided the basis for the later 10 megabit per second standard10BASE-T.The 10BASE-T task force was chaired by Pat Thaler, a member of the StarLAN task force. 10BASE-T used the basic signalling of StarLAN 10 and added link beat. Some network interface cards such as the3Com3C-523 could be used with either StarLAN 10 or 10BASE-T, by switching link beat on or off.[8]
| Name | Standard | Status | Speed (Mbit/s) | Pairs required | Lanes per direction | Bits per hertz | Line code | Symbol rateper lane (MBd) | Bandwidth | Max distance (m) | Cable | Cable rating (MHz) | Usage |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| StarLAN-11BASE5 | 802.3e-1987 | obsolete | 1 | 2 | 1 | 1 | PE | 1 | 1 | 250 | voice grade | ~12 | LAN |
| StarLAN-10 | 802.3e-1988 | obsolete | 10 | 2 | 1 | 1 | PE | 10 | 10 | ~100 | voice grade | ~12 | LAN |
References
[edit]- ^Urs von Burg (2001).The triumph of Ethernet: technological communities and the battle for the LAN standard.Stanford University Press. pp. 175–176, 255–256.ISBN978-0-8047-4095-1.
- ^802.3a,b,c, and e-1988 IEEE Standards for Local Area Networks: Supplements to Carrier Sense Multiple Access With Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.IEEE Standards Association.1987.doi:10.1109/IEEESTD.1987.78883.ISBN978-0-471-61153-0.
- ^IEEE 802.3 Clause 12.1.4
- ^US 4674085Patent "Local area network" William L. Aranguren, Mario A. Restrepo, and Michael J. Sidney, Filed October 6, 1986, issued June 16, 1987.
- ^"Although expensive and slow, the system allows minis and PCs to share data",27 Oct 1987, p229, PC Mag
- ^StarLAN Technology Report, 4th Edition.Architecture Technology Corporation. 1991.ISBN9781483285054.
- ^Mary Petrosky (June 9, 1986)."Starlan nets: Chip set chips away at Interface cost".Network World.Vol. 3, no. 14. p. 4.RetrievedJune 10,2011.
- ^Ohland, Louis."3Com 3C523".Walsh Computer Technology.Retrieved1 April2015.
- ^Charles E. Spurgeon (2014).Ethernet: The Definitive Guide(2nd ed.). O'Reilly Media.ISBN978-1-4493-6184-6.
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