Local area network

File:RJ-45-Stecker-und-Buechse.jpg{{Further|Twisted Pair|Ethernet}}Most wired network infrastructures utilize Category 5 or Category 6 twisted pair cabling with RJ45 compatible terminations. This medium provides physical connectivity between the Ethernet interfaces present on a large number of IP-aware devices. Depending on the grade of cable and quality of installation, speeds of up to 10 Mbit/s, 100 Mbit/s, 1 Gbit/s, or 10 Gbit/s are supported.

{{Further|IEEE 802.11}}

In a wireless LAN, users have unrestricted movement within the coverage area. Wireless networks have become popular in residences and small businesses because of their ease of installation, convenience, and flexibility.{{Cite web |title=When Did WiFi Become Popular {{!}} Beambox |url=https://beambox.com/townsquare/when-did-wifi-become-popular |access-date=2025-01-27 |website=beambox.com |language=en}} Most wireless LANs consist of devices containing wireless radio technology that conforms to 802.11 standards as certified by the IEEE. Most wireless-capable residential devices operate at both the 2.4 GHz and 5 GHz frequencies and fall within the 802.11n or 802.11ac standards.{{Cite web |title=What are 802.11 Standards? |url=https://www.cbtnuggets.com/blog/technology/networking/when-to-use-802-11-a-b-g-b-nc-wifi-standards |access-date=2025-01-27 |website=CBT Nuggets |language=en}} Some older home networking devices operate exclusively at a frequency of 2.4 GHz under 802.11b and 802.11g, or 5 GHz under 802.11a. Some newer devices operate at the aforementioned frequencies in addition to 6 GHz under Wi-Fi 6E. Wi-Fi is a marketing and compliance certification for IEEE 802.11 technologies.“Discover and Learn,” WiFi Alliance, http://www.wi-fi.org/discover_and_learn.php {{Webarchive|url=https://web.archive.org/web/20100704025608/http://www.wi-fi.org/discover_and_learn.php|date=2010-07-04}} (accessed June 30, 2010). The Wi-Fi Alliance has tested compliant products, and certifies them for interoperability. The technology may be integrated into smartphones, tablet computers and laptops. Guests are often offered Internet access via a hotspot service.

File:Simple_LAN_example_diagram_in_two_rooms.png, as well as a file server, and a mix of wired and wireless connections. This is the star topology.]]

Simple LANs in office or school buildings generally consist of cabling and one or more network switches; a switch is used to allow devices on a LAN to talk to one another via Ethernet. A switch can be connected to a router, cable modem, or ADSL modem for Internet access. LANs at residential homes usually tend to have a single router and often may include a wireless repeater. A LAN can include a wide variety of other network devices such as firewalls, load balancers, and network intrusion detection.{{cite web |title=A Review of the Basic Components of a Local Area Network (LAN) |url=http://networkbits.net/lan-components/local-area-network-lan-basic-components/ |url-status=usurped |archive-url=https://web.archive.org/web/20201026082752/http://networkbits.net/lan-components/local-area-network-lan-basic-components/ |archive-date=2020-10-26 |access-date=2008-04-08 |publisher=NetworkBits.net}} A wireless access point is required for connecting wireless devices to a network; when a router includes this device, it is referred to as a wireless router.

Advanced LANs are characterized by their use of redundant links with switches using the Spanning Tree Protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and their ability to segregate traffic with VLANs. A network bridge binds two different LANs or LAN segments to each other, often in order to grant a wired-only device access to a wireless network medium.

Network topology describes the layout of interconnections between devices and network segments. At the data link layer and physical layer, a wide variety of LAN topologies have been used, including ring, bus, mesh and star. The star topology is the most common in contemporary times. Wireless LAN (WLAN) also has its topologies: independent basic service set (IBSS, an ad-hoc network) where each node connects directly to each other (this is also standardized as Wi-Fi Direct), or basic service set (BSS, an infrastructure network that uses an wireless access point).{{Cite web |url=https://www3.nd.edu/~mhaenggi/NET/wireless/802.11b/topology.htm |title=Network Topologies |access-date=2024-12-11 |website=www3.nd.edu}}File:LAN topology.gif

DHCP is used to assign internal IP addresses to members of a local area network. A DHCP server typically runs on the router[http://www.whatismyip.com/ip-faq/what-is-dhcp/ What is DHCP?] {{Webarchive|url=https://web.archive.org/web/20131207234400/http://www.whatismyip.com/ip-faq/what-is-dhcp/|date=2013-12-07}}. whatismyip.com. with end devices as its clients. All DHCP clients request configuration settings using the DHCP protocol in order to acquire their IP address, a default route and one or more DNS server addresses. Once the client implements these settings, it will be able to communicate on that internet.{{Cite journal |last1=Roy G. Perry College of Engineering, Prairie View A&M University, Prairie View, TX 77446, United States |last2=Sadiku |first2=Matthew N. O. |last3=Tembely |first3=Mahamadou |last4=Roy G. Perry College of Engineering, Prairie View A&M University, Prairie View, TX 77446, United States |last5=Musa |first5=Sarhan M. |last6=Roy G. Perry College of Engineering, Prairie View A&M University, Prairie View, TX 77446, United States |date=2017-05-30 |title=Home Area Networks: A Primer |url=http://ijarcsse.com/docs/papers/Volume_7/5_May2017/SV7I5-0208.pdf |journal=International Journal of Advanced Research in Computer Science and Software Engineering |volume=7 |issue=5 |pages=634–635 |doi=10.23956/ijarcsse/SV7I5/208 |doi-broken-date=2024-11-12}}

At the higher network layers, protocols such as NetBIOS, IPX/SPX, AppleTalk and others were once common, but the Internet protocol suite (TCP/IP) has prevailed as the standard of choice for almost all local area networks today.

LANs can maintain connections with other LANs via leased lines, leased services, or across the Internet using virtual private network technologies. Depending on how the connections are established and secured, and the distance involved, such linked LANs may also be classified as a metropolitan area network (MAN) or a wide area network (WAN).

Local area networks may be connected to the Internet (a type of WAN) via fixed-line means (such as a DSL/ADSL modem{{Cite web |title=Configuration example for connecting a LAN to the Internet through an ADSL modem |url=https://support.hpe.com/techhub/eginfolib/networking/docs/routers/hsr6800/5200-3506_l2-wan_cg/content/482615561.htm |access-date=2024-12-06 |website=support.hpe.com}}) or alternatively using a cellular or satellite modem. These would additionally make use of telephone wires such as VDSL and VDSL2, coaxial cables, or fiber to the home for running fiber-optic cables directly into a house or office building, or alternatively a cellular modem or satellite dish in the latter non-fixed cases. With Internet access, the Internet service provider (ISP) would grant a single WAN-facing IP address to the network. A router is configured with the provider's IP address on the WAN interface, which is shared among all devices in the LAN by network address translation.

A gateway establishes physical and data link layer connectivity to a WAN over a service provider's native telecommunications infrastructure. Such devices typically contain a cable, DSL, or optical modem bound to a network interface controller for Ethernet. Home and small business class routers are often incorporated into these devices for additional convenience, and they often also have integrated wireless access point and 4-port Ethernet switch.

The ITU-T G.hn and IEEE Powerline standard, which provide high-speed (up to 1 Gbit/s) local area networking over existing home wiring, are examples of home networking technology designed specifically for IPTV delivery.{{cite book |author1=Berger, Lars T. |title=MIMO Power Line Communications: Narrow and Broadband Standards, EMC, and Advanced Processing |author2=Schwager, Andreas |author3=Pagani, Pascal |author4=Van Rensburg |author5=Piet Janse |date=February 2014 |publisher=CRC Press |isbn=9781466557529 |editor1=Berger, Lars T. |series=Devices, Circuits, and Systems |pages=3–38 |chapter=Introduction to the Power Line Communication Channel and Noise Characterisation |doi=10.1201/b16540-3 |access-date=2014-05-19 |editor2=Schwager, Andreas |editor3=Pagani, Pascal |editor4=Schneider, Daniel M |chapter-url=http://www.crcnetbase.com/doi/abs/10.1201/b16540-3?queryID= |archive-url=https://web.archive.org/web/20151017135609/http://www.crcnetbase.com/doi/abs/10.1201/b16540-3?queryID= |archive-date=2015-10-17 |url-status=live}}{{Relevance inline|date=December 2024}}

{{Home networking standards}}

The increasing demand and usage of computers in universities and research labs in the late 1960s generated the need to provide high-speed interconnections between computer systems. A 1970 report from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gave a good indication of the situation.{{cite web |url=http://www.rogerdmoore.ca/PS/OCTOA/OCTO.html |title=Octopus: The Lawrence Radiation Laboratory Network |author=Samuel F. Mendicino |publisher=Rogerdmoore.ca |date=1970-12-01 |archive-url=https://web.archive.org/web/20110706202409/http://www.rogerdmoore.ca/PS/OCTOA/OCTO.html |archive-date=2011-07-06 |url-status=dead}}{{cite journal |osti=4045588 |title=THE LAWRENCE RADIATION LABORATORY OCTOPUS |journal=Courant Symposium Series on Networks |date=29 Nov 1970 |publisher=Osti.gov |last1=Mendicino |first1=S. F.}}

A number of experimental and early commercial LAN technologies were developed in the 1970s. Ethernet was developed at Xerox PARC between 1973 and 1974.{{cite AV media |url=https://www.youtube.com/watch?v=g5MezxMcRmk |title=The History of Ethernet |publisher=NetEvents.tv |year=2006 |access-date=September 10, 2011}}{{cbignore}} Archived at [https://ghostarchive.org/varchive/youtube/20211211/g5MezxMcRmk Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20120113032536/http://www.youtube.com/watch?v=g5MezxMcRmk Wayback Machine]{{cbignore}}{{cite web |url=http://americanhistory.si.edu/collections/search/object/nmah_687626 |title=Ethernet Prototype Circuit Board |year=1973 |publisher=Smithsonian National Museum of American History |access-date=September 2, 2007 |archive-date=October 28, 2014 |archive-url=https://web.archive.org/web/20141028132431/http://americanhistory.si.edu/collections/search/object/nmah_687626 |url-status=live }} The Cambridge Ring was developed at Cambridge University starting in 1974.{{cite web|url=http://www.cl.cam.ac.uk/conference/EDSAC99/history.html |title=A brief informal history of the Computer Laboratory |publisher=University of Cambridge |date=20 December 2001 |archive-url=https://web.archive.org/web/20101113213834/http://www.cl.cam.ac.uk/conference/EDSAC99/history.html |archive-date=13 November 2010 |url-status=live }} ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977.{{cite web|url=http://www.arcnet.com/resources/HistoryATA.pdf|title=ARCNET Timeline|date=Fall 1998|publisher=ARCNETworks magazine|archive-url=https://web.archive.org/web/20100414155134/http://www.arcnet.com/resources/HistoryATA.pdf|archive-date=2010-04-14|url-status=dead}} It had the first commercial installation in December 1977 at Chase Manhattan Bank in New York.{{cite web |author=Lamont Wood |url=http://www.computerworld.com/article/2538907/networking/the-lan-turns-30--but-will-it-reach-40-.html |title=The LAN turns 30, but will it reach 40? |work=Computerworld |date=2008-01-31 |access-date=2016-06-02 |archive-date=2016-06-30 |archive-url=https://web.archive.org/web/20160630130355/http://www.computerworld.com/article/2538907/networking/the-lan-turns-30--but-will-it-reach-40-.html |url-status=live }} In 1979,{{Cite web|last=European Parliament Archives|date=January 25, 2021|title=Voting system Tender Specifications - 1979 |url=https://enricomassetti.com/the-european-parliament-electronic-voting-system/|archive-url=https://web.archive.org/web/20210616175401/https://enricomassetti.com/the-european-parliament-electronic-voting-system/|archive-date=June 16, 2021|url-status=dead}} the electronic voting system for the European Parliament was the first installation of a LAN connecting hundreds (420) of microprocessor-controlled voting terminals to a polling/selecting central unit with a multidrop bus with Master/slave (technology) arbitration.{{dubious|date=January 2021|Claim to first LAN/on of first LANs for Electronic voting systems for the European Parliament}} It used 10 kilometers of simple unshielded twisted pair category 3 cable—the same cable used for telephone systems—installed inside the benches of the European Parliament Hemicycles in Strasbourg and Luxembourg.{{Cite web |date=25 January 2021 |title=Italian TV network RAI on the voting system |url=https://vimeo.com/504531637 |url-status=live |archive-url=https://web.archive.org/web/20230117220933/https://vimeo.com/504531637 |archive-date=17 January 2023}}

The development and proliferation of personal computers using the CP/M operating system in the late 1970s, and later DOS-based systems starting in 1981, meant that many sites grew to dozens or even hundreds of computers. The initial driving force for networking was to share storage and printers, both of which were expensive at the time. There was much enthusiasm for the concept, and for several years, from about 1983 onward, computer industry pundits habitually declared the coming year to be, "The year of the LAN".{{cite journal|url=https://books.google.com/books?id=FzsEAAAAMBAJ&pg=PA46|title=Will The Year of the ISDN be 1994 or 1995?|first=Robert|last=Metcalfe|quote='The Year of The LAN' is a long-standing joke, and I freely admit to being the comedian that first declared it in 1982...|journal=InfoWorld|date=Dec 27, 1993|volume=15|issue=52|access-date=June 14, 2021|archive-date=June 14, 2021|archive-url=https://web.archive.org/web/20210614014127/https://books.google.com/books?id=FzsEAAAAMBAJ&pg=PA46|url-status=live}}{{cite web|url=http://www.ibiblio.org/java/quotes1999.html|title=Quotes in 1999|quote=...you will remember numerous computer magazines, over numerous years, announcing 'the year of the LAN.'|website=Cafe au Lait Java News and Resources|access-date=2011-02-25|archive-date=2016-04-14|archive-url=https://web.archive.org/web/20160414043142/http://www.ibiblio.org/java/quotes1999.html|url-status=live}}{{cite web|url=https://herot.typepad.com/cherot/2010/10/connected-health-symposium.html|title=Christopher Herot's Weblog|quote=...a bit like the Year of the LAN which computer industry pundits predicted for the good part of a decade...|first=Christopher|last=Herot|access-date=2023-10-21}}

In practice, the concept was marred by the proliferation of incompatible physical layer and network protocol implementations, and a plethora of methods of sharing resources. Typically, each vendor would have its own type of network card, cabling, protocol, and network operating system. A solution appeared with the advent of Novell NetWare which provided even-handed support for dozens of competing card and cable types, and a much more sophisticated operating system than most of its competitors.

Of the competitors to NetWare, only Banyan Vines had comparable technical strengths, but Banyan never gained a secure base. 3Com produced 3+Share and Microsoft produced MS-Net. These then formed the basis for collaboration between Microsoft and 3Com to create a simple network operating system LAN Manager and its cousin, IBM's LAN Server. None of these enjoyed any lasting success; Netware dominated the personal computer LAN business from early after its introduction in 1983 until the mid-1990s when Microsoft introduced Windows NT.{{cite web|url=http://guide.sbanetweb.com/press/varbiz07116001.html |title=Has Microsoft Ever Read the History Books? |publisher=VARBusiness |author=Wayne Spivak |date=2001-07-13 |archive-url=https://web.archive.org/web/20110716012211/http://guide.sbanetweb.com/press/varbiz07116001.html |archive-date=2011-07-16 |url-status=dead}}

In 1983, TCP/IP was first shown capable of supporting actual defense department applications on a Defense Communication Agency LAN testbed located at Reston, Virginia.{{cite journal|last=Scott|first=W. Ross|date=May 1, 1984|title=Updated Local Area Network Demonstration Plan|journal=MITRE Corporation Working Paper|issue=WP83W00222R1}}{{Cite book|title=MITRENET: A Testbed Local Area Network at DTNSRDC.|last=Havard (II.)|first=Richard|publisher=Defense Technical Information Center|date=17 June 1986|location=Ft. Belvoir Defense Technical Information Center|page=i}} The TCP/IP-based LAN successfully supported Telnet, FTP, and a Defense Department teleconferencing application.{{cite journal|last1=Scott|first1=W. Ross|last2=Cavedo|first2=Robert F.|date=September 1, 1984|title=Local Area Network Demonstration Procedures|journal=MITRE Corporation Working Paper|issue=WP83W00595}} This demonstrated the feasibility of employing TCP/IP LANs to interconnect Worldwide Military Command and Control System (WWMCCS) computers at command centers throughout the United States.{{cite journal|last=Scott|first=W. Ross|date=August 1, 1984|title=Local Area Network Alternative "A" Demonstration Analysis (DRAFT)|journal=MITRE Corporation Working Paper|issue=WP84W00281}} However, WWMCCS was superseded by the Global Command and Control System (GCCS) before that could happen.

During the same period, Unix workstations were using TCP/IP networking. Although the workstation market segment is now much reduced, the technologies developed in the area continue to be influential on the Internet and in all forms of networking—and the TCP/IP protocol has replaced IPX, AppleTalk, NBF, and other protocols used by the early PC LANs.

Econet was Acorn Computers's low-cost local area network system, intended for use by schools and small businesses. It was first developed for the Acorn Atom and Acorn System 2/3/4 computers in 1981.{{Cite web|title=Retro Isle - Acorn Econet|url=http://www.retroisle.com/general/acorn_econet.php|access-date=2020-10-28|website=www.retroisle.com}}{{Cite web|title=Chris's Acorns: Econet|url=http://chrisacorns.computinghistory.org.uk/Network/Econet.html|access-date=2020-10-28|website=chrisacorns.computinghistory.org.uk}}

In the 1980s, several token ring network implementations for LANs were developed.{{cite journal |title=Early Token Ring Work at MIT |author=J. Noel Chiappa |author-link=Noel Chiappa |journal=IEEE Annals of the History of Computing |volume=36 |issue=2 |date=April–June 2014 |pages=80–85 |doi=10.1109/MAHC.2014.14|s2cid=30761524 |doi-access=free }}{{cite web |url=https://historyofcomputercommunications.info/section/14.18/Proteon/ |title=14.18 Proteon in Chapter 14 - Internetworking: Emergence 1985-1988 |work=The History of Computer Communications |first=James |last=Pelkey}} IBM released its own implementation of token ring in 1985,{{Cite web|date=1985-10-15|title=IBM Token-Ring Network |url=https://www.ibm.com/docs/en/announcements/archive/ENUS185-123|access-date=2025-03-26|website=IBM |language=en-US}}{{cite magazine |url=https://books.google.com/books?id=lS8EAAAAMBAJ&dq=October+15+1985+token&pg=PA27 |title=Major Vendors Differ On Network Approach |first=Don |last=Crabb |magazine=InfoWorld |volume=8 |issue=12 |date=24 March 1986 |page=27}} It ran at {{val|4|ul=Mbit/s}}.{{cite web | url=https://books.google.com/books?id=AToEAAAAMBAJ&dq=ibm+token+ring+speed+4&pg=PA11 | title=InfoWorld | date=21 November 1988 }} IBM claimed that their token ring systems were superior to Ethernet, especially under load, but these claims were debated;{{cite book |title=IEEE 802.3 Local Area Network considerations |publisher=IBM |id=GG22-9422-0}}{{cite journal

|author1=David R. Boggs |author2=Jeffrey C. Mogul |author3=Christopher A. Kent | year = 1988

| title = Measured capacity of an Ethernet: myths and reality

| journal = ACM SIGCOMM Computer Communication Review

| volume = 25

| issue = 1

| pages = 123–136

| doi = 10.1145/205447.205460

|s2cid=52820607 | url = http://www.hpl.hp.com/techreports/Compaq-DEC/WRL-88-4.pdf

}} while the slow but inexpensive AppleTalk was popular for Macs, in 1987 InfoWorld said, "No LAN has stood out as the clear leader, even in the IBM world".{{Cite magazine |last=Satchell |first=Stephen |date=1987-08-17 |title=IBM PS/2 Model 25 |department=Short Looks |url=https://books.google.com/books?id=2jsEAAAAMBAJ&pg=PA44#v=onepage&q&f=true |access-date=2025-05-25 |magazine=InfoWorld |page=44 |volume=9 |issue=33}} IBM's implementation of token ring was the basis of the IEEE 802.5 standard.{{cite book | url=https://books.google.com/books?id=3Dn9KlIVM_EC&dq=ibm+802.5&pg=PA1009 | title=Internetworking Technologies Handbook | year=2004 | publisher=Cisco Press | isbn=978-1-58705-119-7 }} A 16 Mbit/s version of Token Ring was standardized by the 802.5 working group in 1989.{{cite web | url=https://standards.ieee.org/ieee/802.5/1100/ | archive-url=https://web.archive.org/web/20220817022518/https://standards.ieee.org/ieee/802.5/1100/ | url-status=dead | archive-date=August 17, 2022 | title=IEEE Standards Association }} IBM had market dominance over Token Ring, for example, in 1990, IBM equipment was the most widely used for Token Ring networks.{{cite journal |url=http://hcd.ucdavis.edu/faculty/webpages/kenney/articles_files/Sponsors,%20Communities,%20and%20Standards_%20Ethernet%20vs.%20Token%20Ring%20in%20the%20Local%20Area%20Networking%20Business.pdf |title=Sponsers, [sic] Communities, and Standards: Ethernet vs. Token Ring In The Local Area Networking Business |archive-url=https://web.archive.org/web/20180219041820/http://hcd.ucdavis.edu/faculty/webpages/kenney/articles_files/Sponsors,%20Communities,%20and%20Standards_%20Ethernet%20vs.%20Token%20Ring%20in%20the%20Local%20Area%20Networking%20Business.pdf |archive-date=2018-02-19 |url-status=dead |author1=Urs Von Burg |author2=Martin Kenny |journal=Industry and Innovation |volume=10 |issue=4 |pages=351–375 |date=December 2003 |doi=10.1080/1366271032000163621 |publisher=Taylor & Francis Ltd|s2cid=153804163 }}

Fiber Distributed Data Interface (FDDI), a LAN standard, was considered an attractive campus backbone network technology in the early to mid 1990s since existing Ethernet networks only offered 10 Mbit/s data rates and Token Ring networks only offered 4 Mbit/s or 16 Mbit/s rates. Thus it was a relatively high-speed choice of that era, with speeds such as 100 Mbit/s.

By 1994, vendors included Cisco Systems, National Semiconductor, Network Peripherals, SysKonnect (acquired by Marvell Technology Group), and 3Com.{{Cite news |title= Wading Through Plethora of Options Poses Challenge for Life on the Fast LAN |work= Network World |pages= 41, 44, 46–49 |author= Mark Miller |date= March 21, 1994 |url= https://books.google.com/books?id=eA0EAAAAMBAJ&pg=PA47 |access-date= August 15, 2013 }} FDDI installations have largely been replaced by Ethernet deployments.{{Cite book |title= Optical Fiber Communication: Principles and Systems |pages= 241–249 |author=A. Selvarajan |author2=Subrat Kar |author3=T. Srinivas |publisher= Tata McGraw-Hill Education |year=2003 |url= https://books.google.com/books?id=uyBSO4hf6DYC&pg=PA241 |isbn= 978-1-259-08220-7 }}

• Asynchronous Transfer Mode
• Chaosnet
• LAN messenger
• LAN party
• Network interface controller

{{Reflist}}

• {{commons category-inline|Local area networks (LAN)}}

{{Internet Access}}

{{Authority control}}

Category:Office equipment