by Maureen Cutajar

Created on: December 29, 2009   Last Updated: September 04, 2010

Communications networks are categorised into distinct groups depending upon the physical or geographical areas that they cover. Typically, a LAN (Local Area Network) is a private network covering a limited geographical area, and a WAN (Wide Area Network) is usually based on a public telephony provider's services, which can cover the world.

◊ Wide Area Networks

Wide Area Networks provide national and international communications. Some WANs are specifically designed to transfer analogue signals (e.g. speech/telephone network) or to transfer digital information (e.g. computer data/Internet)

Some WANs provide a public sector service, for example, national telephone networks; others are private networks constructed to provide communications within single organisations located across different geographical locations. These networks are generally defined as WANs due to the large geographical areas that they cover.

◊ Local Area Networks

LANs are privately owned networks that offer reliable high-speed communications for interconnecting equipment in a limited geographic area; for example within an office or a building.

A LAN might be contained in a single room or across a single company site. Computers are connected to a common medium that provides a distributed network architecture by which all connected computers communicate. There may be multiple LANs on a single geographical site servicing different types of branches within the organisation. 

LANs do not require the national telephone companies to transfer data across connected computers 

◊ LAN Requirements

To achieve high levels of communication and efficiently being able to transfer information between computers, a great deal of investment and support is required:

- a need for extra expansion cards in PCs to facilitate connection to a network;

- rules of communication or protocols for systems to communicate;

- investment in a cabling infrastructure that covers a single company site;

- investment in additional equipment to be used solely for networking;

- technical support and maintenance personnel. 

◊ Sharing Physical Resources

LANs allow sharing of physical resources attached to the LAN. The primary motive behind all of these applications of LANs is cost reduction. Examples of shared resources are the following:

- File servers

- High cost peripherals, such as printers, plotters, scanners, fax machines, etc.

- Computing power, e.g. Making use of central computing resources to runt client-server applications

- External connectivity e.g. Connections to wide area networks, dedicated satellite links, etc.

- Video conferencing facilities.

◊ Security

On LANs security of transferred data is not so critical, but using WANs or the Internet requires confidential information to be protected. Either the information carried within protocols can be encrypted or the equipment used to transport messages, frames and packets can protect information by hardware instigated procedures (e.g. firewalls).

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