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These resources may be hardware resources such as printers or software resources such as application programs or
data. One of the computers often acts as a server and responds to requests from other computers. The computers
requesting the server are called clients. For example, suppose you have a printer and a few computers. If all computers
need a printer, they can access it via a LAN (see Figure 6.11 (a)).
(a) LAN within a building (b) LAN within a campus
PC2
PC3 Router PC1
Switch or
PC4
PC5
Printer
Figure 6.11 Local Area Network (LAN)
The most commonly used topologies in LANs are bus, ring and star. The transmission media used in LANs are
twisted-pair, coaxial cable, and fibre optic. Figure 6.11 (a) shows a LAN within a building. Figure 6.11 (b) shows a LAN
within a campus. LANs typically operate at speeds in the range of 10 Mbps to 1 Gbps.
6.4.3 MAN
A Metropolitan Area Network (MAN) can span a radius of up to 50 kilometres. A MAN typically connects various local
area networks within a city. A single organisation may own a MAN or it may be a public network that many individuals
or organisations use. MANs usually operate at higher speeds than LANs. Typical transmission media for a MAN include
Ethernet cable, microwave, radio wave, and fibre optic.
Computer Networks 229

