A local area network (LAN) is a computer network that interconnects
computers within a limited area such as a residence, school,
laboratory, university campus or office building. By contrast, a
wide area network (WAN) not only covers a larger geographic distance,
but also generally involves leased telecommunication circuits.
Wi-Fi are the two most common technologies in use for
local area networks. Historical technologies include ARCNET, Token
ring, and AppleTalk.
3 Wireless media
4 Technical aspects
5 See also
7 External links
The increasing demand and use 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
Lawrence Radiation Laboratory
Lawrence Radiation Laboratory detailing the growth of their
"Octopus" network gave a good indication of the situation.
A number of experimental and early commercial LAN technologies were
developed in the 1970s. Cambridge Ring was developed at Cambridge
University starting in 1974.
Ethernet was developed at Xerox PARC
between 1973 and 1974.
ARCNET was developed by Datapoint
Corporation in 1976 and announced in 1977. It had the first
commercial installation in December 1977 at
Chase Manhattan Bank
Chase Manhattan Bank in
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
generally to share storage and printers, which were both expensive at
the time. There was much enthusiasm for the concept and for several
years, from about 1983 onward, computer industry pundits would
regularly declare the coming year to be, “The year of the
In practice, the concept was marred by 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/cable types,
and a much more sophisticated operating system than most of its
competitors. Netware dominated the personal computer LAN business
from early after its introduction in 1983 until the mid-1990s when
Windows NT Advanced Server and Windows for
Of the competitors to NetWare, only
Banyan Vines had comparable
technical strengths, but Banyan never gained a secure base. Microsoft
3Com worked together to create a simple network operating system
which formed the base of 3Com's 3+Share, Microsoft's
LAN Manager and
LAN Server - but none of these was particularly successful.
In 1983, TCP/IP was first shown capable of supporting actual defense
department applications on a Defense Communication Agency LAN test bed
located at Reston, Virginia. The TCP/IP-based LAN successfully
supported Telnet, FTP, and a Defense Department Teleconferencing
application. 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. 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 this market segment is now much reduced, the
technologies developed in this area continue to be influential on the
Internet and in both
Linux and Apple
Mac OS X
Mac OS X networking—and the
TCP/IP protocol has replaced IPX, AppleTalk, NBF, and other protocols
used by the early PC LANs.
Early LAN cabling had generally been based on various grades of
coaxial cable. Shielded twisted pair was used in IBM's
Token Ring LAN
implementation, but in 1984,
StarLAN showed the potential of simple
unshielded twisted pair by using Cat3 cable—the same simple cable
used for telephone systems. This led to the development of 10BASE-T
(and its successors) and structured cabling which is still the basis
of most commercial LANs today.
While fiber-optic cabling is common for links between switches, use of
fiber to the desktop is rare.
Many LANs use wireless technologies that are built into Smartphones,
tablet computers and laptops. In a wireless local area network, users
may move unrestricted in the coverage area. Wireless networks have
become popular in residences and small businesses, because of their
ease of installation. Guests are often offered
Internet access via a
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. At the higher layers, NetBEUI, IPX/SPX,
AppleTalk and others were once common, but the
Internet Protocol Suite
(TCP/IP) has prevailed as a standard of choice.
Simple LANs generally consist of cabling and one or more switches. A
switch can be connected to a router, cable modem, or
ADSL modem for
Internet access. A LAN can include a wide variety of other network
devices such as firewalls, load balancers, and network intrusion
detection. 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 to segregate traffic with VLANs.
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
Computer networking portal
Computer Science portal
Network interface controller
^ Gary A. Donahue (June 2007). Network Warrior. O'Reilly.
^ Samuel F. Mendicino (1970-12-01). "Octopus: The Lawrence Radiation
Laboratory Network". Rogerdmoore.ca. Archived from the original on
^ "THE LAWRENCE RADIATION LABORATORY OCTOPUS". Courant symposium
series on networks. Osti.gov. 29 Nov 1970. OSTI 4045588.
^ "A brief informal history of the Computer Laboratory". University of
Cambridge. 20 December 2001. Archived from the original on 11 October
^ The History of Ethernet. NetEvents.tv. 2006. Retrieved September 10,
Ethernet Prototype Circuit Board". Smithsonian National Museum of
American History. 1973. Retrieved September 2, 2007.
ARCNET Timeline" (PDF). ARCNETworks magazine. Fall 1998. Archived
from the original (PDF) on 2010-10-11.
^ Lamont Wood (2008-01-31). "The LAN turns 30, but will it reach 40?".
Computerworld.com. Retrieved 2016-06-02.
^ "'The Year of The LAN' is a long-standing joke, and I freely admit
to being the comedian that first declared it in 1982...", Robert
Metcalfe, InfoWorld Dec 27, 1993
^ "...you will remember numerous computer magazines, over numerous
years, announcing 'the year of the LAN.'", Quotes in 1999
^ "...a bit like the Year of the LAN which computer industry pundits
predicted for the good part of a decade...", Christopher Herot
^ Wayne Spivak (2001-07-13). "Has
Microsoft Ever Read the History
Books?". VARBusiness. Archived from the original on 2010-10-11.
^ Scott, W. Ross (1984-05-01), "Updated Local Area Network
Demonstration Plan." (U) MITRE Corporation Working Paper No.
^ Havard (II.), Richard (17 June 1986). MITRENET: A Testbed Local Area
Network at DTNSRDC. Ft. Belvoir Defense Technical Information Center:
Defense Technical Information Center. pp. i.
^ Scott, W. Ross; Cavedo, Robert F. (1984-09-01), "Local Area Network
Demonstration Procedures." (U) MITRE Corporation Working Paper No.
^ Scott, W. Ross (1984-08-01), "Local Area Network Alternative "A"
Demonstration Analysis (DRAFT). (U) MITRE Corporation Working Paper
^ "Big pipe on campus: Ohio institutions implement a 10-Gigabit
Ethernet switched-fiber backbone to enable high-speed desktop
applications over UTP copper", Communications News, 2005-03-01, As
alternatives were considered, fiber to the desk was evaluated, yet
only briefly due to the added costs for fiber switches, cables and
NICs. "Copper is still going to be a driving force to the desktop for
the future, especially as long as the price for fiber components
remains higher than for copper."
^ "A Review of the Basic Components of a Local Area Network (LAN)".
NetworkBits.net. Retrieved 2008-04-08.
Wikimedia Commons has media related to Local area network.