Editing StarLAN

{{Short description|Standard for Ethernet over twisted pair wiring}}
'''StarLAN''' was the first IEEE 802.3 standard for [[Ethernet over twisted pair]] wiring. It was standardized by the [[IEEE Standards Association]] as '''802.3e''' in 1986, as the '''1BASE5''' version of [[Ethernet]]. The StarLAN Task Force was chaired by Bob Galin.

==Description==
An early version of StarLAN was developed by Tim Rock and Bill Aranguren at [[AT&T Information Systems]] as an experimental system in 1983.<ref name="urs">{{cite book |title= The triumph of Ethernet: technological communities and the battle for the LAN standard |author= Urs von Burg |publisher= Stanford University Press |year= 2001 |pages= 175–176, 255–256 |url= https://books.google.com/books?id=ooBqdIXIqbwC&pg=PA175 |isbn= 978-0-8047-4095-1 }}</ref>
The name StarLAN was coined by the IEEE task force based on the fact that it used a [[star network|star topology]] from a central [[Ethernet hub|hub]] in contrast to the [[bus network]] of the shared cable [[10BASE5]] and [[10BASE2]] networks that had been based on [[ALOHAnet]].

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 Access Control sublayer and Physical Signalling sublayer specification in section 12.<ref>{{cite book |title= 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 |year= 1987 |publisher= [[IEEE Standards Association]] |doi= 10.1109/IEEESTD.1987.78883 |url= https://ieeexplore.ieee.org/document/26520 |isbn= 978-0-471-61153-0 }}</ref>
The original StarLAN ran at a speed of 1&nbsp;Mbit/s.

A major design goal in StarLAN was reduction in Ethernet installation costs by the reuse of existing telephone [[on-premises wiring]] and 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&nbsp;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 called ''T568B'' in the standard [[ANSI/TIA-568|TIA/EIA-568]] (later called ''ANSI/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 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.

Since 1BASE5 reused existing wiring, maximum link distance was only approximated at 250&nbsp;m; depending on cable performance up to 500&nbsp;m was possible. Up to five chained hubs were allowed.<ref>IEEE 802.3 Clause 12.1.4</ref>

Parts of the StarLAN technology were patented by AT&T<ref>{{cite patent |country=US |number=4674085}} Patent "Local area network" William L. Aranguren, Mario A. Restrepo, and Michael J. Sidney, Filed October 6, 1986, issued June 16, 1987.</ref> and were initially part of a wider vision from AT&T to link their [[UNIX]]-based [[AT&T 3B2]] minicomputers to a network of MS-DOS PCs.<ref>[https://books.google.com/books?id=jE2OlZ9PkrkC "''Although expensive and slow, the system allows minis and PCs to share data''" ], 27 Oct 1987, p229, PC Mag</ref> A StarLAN card was also offered for the [[AT&T UNIX PC]].

===StarLAN 10===

In 1988, AT&T released StarLAN 10 operating at 10&nbsp;Mbit/s. The original StarLAN was renamed StarLAN 1, reflecting its 1&nbsp;Mbit/s speed.<ref>{{cite book |title= StarLAN Technology Report, 4th Edition |year= 1991 |publisher= Architecture Technology Corporation |url= https://books.google.com/books?id=wvsgBQAAQBAJ |isbn= 9781483285054 }}</ref>

It 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.<ref>{{cite news |author = Mary Petrosky |title = Starlan nets: Chip set chips away at Interface cost |url= https://books.google.com/books?id=aBwEAAAAMBAJ&pg=PA4 |newspaper = Network World |date = June 9, 1986 |volume= 3 |number= 14 |page= 4 |access-date= June 10, 2011 }}</ref>

StarLAN 10 and [[SynOptics]] [[LattisNet]] provided the basis for the later 10 megabit per second standard [[10BASE-T]]. The 10BASE-T task force was chaired by [[Pat Thaler]],<ref>{{cite web|title=TWISTED: The dramatic history of twisted-pair Ethernet|url=https://www.youtube.com/watch?v=f8PP5IHsL8Y&t?t=804s|website=Youtube|access-date=6 January 2025}}</ref> 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 the [[3Com]] 3C-523 could be used with either StarLAN 10 or 10BASE-T, by switching link beat on or off.<ref>{{cite web|last1=Ohland|first1=Louis|title=3Com 3C523|url=http://www.walshcomptech.com/ohlandl/NIC/3com_523.html|website=Walsh Computer Technology|access-date=1 April 2015}}</ref>

{| class="wikitable" style="line-height:110%;"
|+Comparison of [[Ethernet over twisted pair|twisted-pair-based Ethernet]] physical transport layers (TP-PHYs)<ref name="TDG_ETH_2nd">{{cite book |title=Ethernet: The Definitive Guide |edition=2nd |author=Charles E. Spurgeon |publisher=O'Reilly Media |year=2014 |isbn=978-1-4493-6184-6}}</ref>
! Name
! Standard
! Status
! Speed (Mbit/s)
! Pairs required
! Lanes per direction
! Bits per hertz
! [[Line code]]
! [[Symbol rate]] per lane (MBd) 
! Bandwidth
! Max distance (m)
! Cable
! Cable rating (MHz)
! Usage
|-
| StarLAN-1 ''1BASE5''
| {{nowrap|802.3e-1987}}
| {{N/A|obsolete}}
| align="right" | 1
| align="right" | 2
| align="right" | 1
| align="right" | 1
| align="right" | PE
| align="right" | 1
| align="right" | 1
| align="right" | 250
| align="center" | voice grade
| align="right" | ~12
| align="center" | [[Local area network|LAN]]
|-
| StarLAN-10
| {{nowrap|802.3e-1988}}
| {{N/A|obsolete}}
| align="right" | 10
| align="right" | 2
| align="right" | 1
| align="right" | 1
| align="right" | PE
| align="right" | 10
| align="right" | 10
| align="right" | ~100
| align="center" | voice grade
| align="right" | ~12
| align="center" | LAN
|}

==References==
{{Reflist}}

{{Ethernet}}

{{DEFAULTSORT:StarLAN}}
[[Category:Ethernet]]