wide area network
Wide Area Networks (WANs)
Wide Area Networks (WANs)
A wide area network (WAN) is a data network, usually used for connecting computers, that spans a wide geographical area. WANs can be used to connect cities, states, or even countries. WANs are often used by larger corporations or organizations to facilitate the exchange of data, and in a wide variety of industries corporations with facilities at multiple locations have embraced WANs. Increasingly, however, even small businesses are utilizing WANs as a way of increasing their communications capabilities.
Although WANs serve a purpose similar to that of local area networks (LANs), WANs are structured and operated quite differently. The user of a WAN usually does not own the communications lines that connect the remote computer systems; instead, the user subscribes to a service through a telecommunications provider. Unlike LANs, WANs typically do not link individual computers, but rather are used to link LANs. WANs also transmit data at slower speeds than LANs. WANs are also structurally similar to metropolitan area networks (MANs), but provide communications links for distances greater than 50 kilometers.
WANs have existed for decades, but new technologies, services, and applications have developed over the years to dramatically increase their efficacy for business. WANs were originally developed for digital leased-line services carrying only voice, rather than data. As such, they connected the private branch exchanges (PBXs) of remote offices of the same company. WANs are still used for voice services, but today they are used more frequently for data and image transmission (such as video conferencing). These added applications have spurred significant growth in WAN usage, primarily because of the surge in LAN connections to the wider networks.
HOW WANS WORK
WANs are either point-to-point, involving a direct connection between two sites, or operate across packet-switched networks, in which data are transmitted in packets over shared circuits. Point-to-point WAN service may involve either analog dial-up lines, in which a modem is used to connect the computer to the telephone line, or dedicated leased digital telephone lines, also known as "private lines." Analog lines, which may be either part of a public-switched telephone network or leased lines, are suitable for batch data transmissions, such as nonurgent order entry and point-of-sale transactions. Dedicated digital phone lines permit uninterrupted, secure data transmission at fixed costs.
Point-to-point WAN service providers include both local telephone companies and long-distance carriers. Packet-switched network services are typically chosen by organizations which have low volumes of data or numerous sites, for which multiple dedicated lines would be too expensive.
Depending on the service, WANs can be used for almost any data-sharing purpose for which LANs can be used. Slower transmission speeds, however, may make some applications less practical for WANs. The most basic uses of WANs are for electronic mail and file transfer, but WANs can also permit users at remote sites to access and enter data on a central site's database, such as instantaneously updating accounting records. New types of network-based software that facilitate productivity and production tracking, such as groupware and work-flow automation software, can also be used over WANs. Using groupware, workers at dispersed locations can more easily collaborate on projects. WANs also give remote offices access to a central office's other data communications services, including the Internet.
see also Communication Systems; Local Area Networks; Mobile Office; Virtual Private Networks
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Hillstrom, Northern Lights
updated by Magee, ECDI
Wide Area Network (WAN)
WIDE AREA NETWORK (WAN)
Wide Area Networks, or WANs, connect a geographically diverse group of computers within a state, country, or even across several states or countries. WANs typically are connected by telephone lines, other types of communication lines, or radio waves. Quite often, smaller local area networks (LANs) are linked together to form a WAN. This is accomplished via dedicated private lines, leased from telecommunications firms like Sprint and AT&T, or by Switched Multi-Megabit Data Services (SMDS) technology, developed in 1995 to eliminate the need for a leased line.
WAN technology has been refined over a period of several decades. It first emerged in the mid-twentieth century with the advent of networks like ARPAnet. Developed in 1969 by the Department of Defense, ARPAnet and several other networks eventually evolved into the Internet, the largest WAN in the world. The packet switching technology most commonly used with WANs surfaced in the 1960s, and standard packet switching protocol, known as X.25, was developed in 1976. To increase network
speed, packet switching allows for the parceling of data into smaller chunks, known as packets, prior to transmission. These packets can travel independently via alternate routes, and they are reassembled once they reach their target. Although X.25 remained the most popular WAN packet switching protocol for years, other packet switching protocols used with increasing frequency by WAN developers and administrators include the Internet standard, Transmission Control Protocol/Internet Protocol (TCP/IP), and Frame Relay, used most often by WANs connected via high speed T-1 and T-3 lines.
WANs are used for a variety of purposes. A corporation with offices in several locations may use a WAN to form an intranet. Quite often, the individual offices will use their own LANs for things like internal messaging, data processing functions, and hardware and software sharing. When these LANs are joined together to form a WAN, similar data sharing and messaging capabilities become possible across a much broader geographic area. Businesses wanting to link up with their suppliers or distributors may create a WAN as a means of establishing an extranet. For example, an extranet could provide a sales representative with electronic access to information in about the time it might take to deliver a product, or the availability of a product. Some WANs bring together various types of communications, such as data, video, and voice. Some organizations, including companies, universities, research centers, hospitals, and libraries, use WANs to connect to the Internet.
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SEE ALSO: ARPAnet; AT&T Corp.; Communication Protocols; Local Area Network (LAN)