local area network

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local area network

(LAN), a computer networknetwork,
in computing, two or more computers connected for the purpose of routing, managing, and storing rapidly changing data. A local area network (LAN), which is restricted by distances of up to one mile, and a metropolitan area network (MAN), which is restricted to distances
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 dedicated to sharing data among several single-user workstations or personal computerspersonal computer
(PC), small but powerful computer primarily used in an office or home without the need to be connected to a larger computer. PCs evolved after the development of the microprocessor made possible the hobby-computer movement of the late 1970s, when some computers
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, each of which is called a node. A LAN can have from two to several hundred such nodes, each separated by distances of several feet to as much as a mile, and should be distinguished from connections among computers over public carriers, such as telephone circuits, that are used for other purposes. Because of the relatively small areas involved, the nodes in a LAN can be connected by special high-data-rate cables. A metropolitan area network (MAN) is defined as being restricted to a larger area (maximum distances of 50–60 miles) than a LAN but one still small enough so that dedicated links (such as microwave links) can be used. See also modemmodem
[modulator/demodulator], an external device or internal electronic circuitry used to transmit and receive digital data over a communications line normally used for analog signals.
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See W. Stallings, Local and Metropolitan Area Networks (1993); M. N. O. Sadiku, Metropolitan Area Networks (1995).

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local area network

(LAN) A data communications network which is geographically limited (typically to a 1 km radius) allowing easy interconnection of terminals, microprocessors and computers within adjacent buildings. Ethernet and FDDI are examples of standard LANs.

Because the network is known to cover only a small area, optimisations can be made in the network signal protocols that permit data rates up to 100Mb/s.

See also token ring, wide area network, metropolitan area network..

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This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)


(Local Area Network) A communications network that is confined to a building or building complex. A LAN is a local network, whereas a WAN is a wide area network that spans long distances (see WAN). A wireless router generally has four or more LAN ports that create a small local network in the home or office (see wireless router).

The "clients" in a LAN are the user's computers running Windows, Mac or Linux, while the "servers" hold programs and data shared by the clients. Servers come in a wide range of sizes from PCs to mainframes (see server). The Internet hosts millions of them.

The Transport
Data transfer over a LAN is managed by the TCP/IP transport protocol, and the physical transmission by cable is Ethernet. Mobile devices are connected by Wi-Fi, Ethernet's wireless counterpart. See twisted pair, optical fiber, TCP/IP and Ethernet.

Thick and Thin Clients
In a company LAN, the client machines are typically Windows or Mac, possibly some Linux, and each platform has many installed applications. These "thick" clients are the norm; however, some organizations use "thin" clients, whereby their PCs function like terminals to a server (see Remote Desktop Services). See thin client and client/server.

The Network OS
The software that enables sharing between machines is the network operating system, typically Linux, Windows or Unix. The network OS is in the servers with a component in each client, allowing each to access files from each other. Folders must be made "sharable" for file transfers to work.

Clients and Servers in a LAN
This shows the private employee-facing side and the public-facing site. In large companies, multiple servers are used for each type of service. Today, it is uncommon to see a remote access server for dial-up connections.

Software in a Network Client
These are examples of common applications found in a user's machine. Printers may be connected to clients or servers wired or wireless (see print server).

Software in a Network Server
These are the common services in a network server.

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References in periodicals archive ?
The remote sensors monitor all wireless LAN activities 24x7 and communicate with the server appliance, which correlates and analyzes the data to provide scalable, centralized management of real-time rogue detection, policy enforcement, intrusion protection and health monitoring of the wireless LAN.
One of the biggest challenges in laying out a wireless LAN lies in designing the layout of the access points and ensuring that adequate coverage is provided throughout the service area.
People logging on, searching for a LAN connection, downloading data, are sucking even more energy from their laptop's batteries than conventional computing, meaning two hours of life or less for many units.
Like a frame switch, this device interfaces directly to traditional LANs and is transparent to existing applications and network operating systems (NOSs).
Enter the Internet, which is analogous to a LAN, except it runs on phone lines, not special LAN cables, and its reach is worldwide--extending to all of the millions of computers linked to the Internet.
The computers even may be attached to several different LANs.
Together, your users and your LAN administrator can help your organization's LANs be what they are meant to be-a well-run, valuable, reliable tool in your business.
Another aspect of LANs is that system backup and restoration are much easier to perform; each backup must be done only once, as opposed to relying upon individual users to back up their data or having one person assigned to backing up many stand-alone machines.
Another aspect of Level I LANs is the notion of a factory service network (sometimes called a remote service network).
A Virtual Private Network (VPN) creates a secure transport tunnel for data in motion between two LANs using high-level encryption.
For the past few years that's been an uncontested rank held by Chile's LAN. Aerolineas will test-fly its first foreign subsidiary, Aerolineas del Sur, which will try to steal away clients from LANS ironclad grip on Chiles domestic market.
Using the patent-pending AirDefense technology platform, NCS DataCom has introduced its AirPatrol managed service to offer mid-tier enterprises a comprehensive solution that secures 802.11 wireless LANs with 24x7 monitoring to identify rogue wireless LANs, detect intruders and attacks, enforce network security policies, deflect intruders from the network and monitor the health of the wireless LAN.