Page 115 - DMGT505_MANAGEMENT_INFORMATION_SYSTEM

Management Information Systems

Notes 6.5.1 Local Area Network (LAN)

The Local Area Network (LAN) is the most common type of data network. As the name suggests,
a LAN serves a local area (typically the area of a floor of a building, but in some cases spanning
a distance of several kilometers). Usually, a LAN is installed in industrial plants, office buildings,
college or university campuses, or similar locations. In these locations, it is feasible for the
owning organisation to install high quality, high-speed communication links interconnecting
nodes. Typical data transmission speeds are one to 100 megabits per second.
A Local Area Network (LAN) is a group of computers and associated devices that share a
common communications line or wireless link and share the resources of a single processor or
server within a small geographic area usually within an office building. Usually, the server has
applications and data storage that are shared in common by multiple computer users. A local
area network may serve as few as two or three users (for example, in a home network) or as
many as thousands of users (for example, in an FDDI network). LANs have become commonplace
in many organisations for providing telecommunications network capabilities that link end
users in offices, departments, and other work groups. In summary, a LAN is a communications
network which is:

 Local i.e. one building or group of buildings
 Controlled by one administrative authority
 Assumes other users of the LAN are trusted

 Usually high speed and is always shared
A wide variety of LANs have been built and installed, but a few types have more recently
become dominant. The most widely used LAN system is the Ethernet system developed by the
Xerox Corporation. Major local area network technologies are:
 Ethernet
 Token Ring

 FDDI (Fibre Distributed Data Interface)
Ethernet is by far the most commonly used LAN technology. A number of corporations use the
Token Ring technology. FDDI is sometimes used as a backbone LAN interconnecting Ethernet
or Token Ring LANs. Another LAN technology, ARCNET, once the most commonly installed
LAN technology, is still used in the industrial automation industry. In some situations, a wireless
LAN may be preferable to a wired LAN because it is cheaper to install and maintain.
A suite of application programmes can be kept on the LAN server. Users who need an application
frequently can download it once and then run it from their local hard disk. Users can order
printing and other services as needed through applications run on the LAN server. A user can
share files with others at the LAN server; read and write access is maintained by a LAN
administrator. A LAN server may also be used as a Web server if safeguards are taken to secure
internal applications and data from outside access.
LAN provides access to more computing power, data, and resources than would be practical if
each user needed an individual copy of everything. LAN provides the benefits of personal
computing. One is not forced to do personal work through a central computer that may not be
able to respond to the users’ requests when many of them share its capacity.
LAN can link multiple workstations to one laser printer, fax machine, or modem. This makes a
single piece of equipment available to multiple users and avoids unnecessary equipment
purchases.

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