WAN - Wide Area Network

A Wide Area Network is a data communications network that spans a relatively large geographic area eg linking LANs between buildings, cities or countries.

WANs make use of public networks, such as the Internet, phone lines or dedicated communication lines and may be privately owned or rented. WAN technologies generally function at the lower three layers of the OSI reference model: physical, data link and network layers.

Connection types:

• Frame Relay - Operates at the OSI physical and data link layers and is an example of a packet-switched technology where a defined communication exists between each pair of devices. End stations dynamically share the network medium and the available bandwidth providing flexibility and efficient use of the link.
• ISDN - Integrated Services Digital Network. A digital telephony system allowing simultaneous voice and data transmission up to 128K. There are two standard types: Basic Rate Interface (BRI) is a basic service suitable for most individual users. Primary Rate Interface (PRI) offers greater capacity than BRI.
• Leased line - A fixed point-to-point data link, usually of a much higher data rate than ISDN. As the connection is permanent, and often costly, it is most suited for linking branch offices to a central office.
• ADSL -Asymmetric Digital Subscriber Line. A method for moving data at high bandwidths over existing phone lines whilst providing an 'always-on' connection. ADSL technology is an asymmetric technology, meaning that the outward speed of the link is generally not the same speed as the connection coming back, for example, data can be received at 512K with an upload speed of 256K.
• SDSL - Symmetric Digital Subscriber Line. The same technology as ADSL but it is symmetric rather than asymmetric. Therefore, the upward and downward connection speeds are the same.

Benefits:

• Information can be easily shared between locations allowing for quick and informed decisions to be made, saving time and money.
• A more productive and competitive environment is achieved through greater teamwork across the organisation.
• Network-based communication such as email is considerably cheaper than using the phone or fax.
• Standard versions of procedures and directories can be made accessible and implemented across the organisation.
• IT administration can be centralised.
• Data can be backed-up from a single point on a scheduled basis ensuring consistency.
• Everyone is working from real-time shared information and so reducing the risk of error.