5 June, 2009, 08:24 AM
LAN and WAN
Local Area Network (LAN)
Configuration: In many cases, data are transmitted between Web Design Firm computers, terminals, word processing stations and other devices that are located within a compact area such as office building or a headquarters. The communication system used to link these nearby devices is referred to as LAN.
Transmission Lines: Two common configurations of LAN are: a Star-LAN and a Bus-LAN. In case of Star-LAN, there is central controller (file-server) and all network terminal hookups radiate out from this central node like the points of a star. In a Bus-LAN, however a single cable (or bus) is routed from station to station provided the network linkage. Other configurations are Ring-LAN and Tree LAN. Transmission channel may use everything from pairs of twisted wires to coaxial and fibre-optic cables. The speed of transmission and the network cost varies widely depending upon type of LAN manufactured by different vendors, while others are restricted to components made by a single vendor.
Categories: Most of LANs can be placed in one of the following categories:
High Speed Network: Over 20 million bits per second (MBps) can be transmitted, which provide links between mainframe computers.
Medium Speed Networks: Transmission speeds for these LANs very between 1 MBps and 20 MBps. Suitable for use with mini-computers, these LANs can support a few hundred workstations and other devices.
Low Speed Personal Computer Network: Transmission rates are generally less than 1 MBps. Prices and capabilities very considerable. There are no LANs that will link all brands of personal computers together. Some of the LANs that support more than one brand will allow the different makes to share printers and other peripherals, but they may not allow the different to talk to each other.
Wide Area Network (WAN): The term was introduced in the 80ís in order to distinguish such a network from LAN, to describe a network which spans a large geographic area, such as an entire continent (eg APRANET). Such networks use high bandwidth (eg 50 KBps) communication lines which are lower than those used for LANs. WANs include public-switched telephone networks, circuit switched data network, and packet switched data networks. Generally, WANs are mixed media networks, using combination of terrestrial lines and satellites.
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