What is WAN?A wan is a data communications network taht covers a relatively broad geopraphic area and that often uses transmission facilities provided by common carriers, such as telephone companies.wan technologies generally function at the lower three layers of the osi reference model: the physical layer,teh data link layer,adn the network layer.
WAN DEVICES
WAN use numerous types of devices that are specific to wan environments.wan switches,access servers,modems,csu/dsus,and isdn terminal adapters are duscussed in the following sections.other devices found in wan environments that are used in wan implementations include routers,atm switches and multiplexers.
Modem
A modem is a device that interprets digital and analog signals,enabling data to be transmitted over voice-grade telephone lines.at the source, digital signals are converted to a form suitable for transmission over analog communicaiton facilities.at the destination,these analog signals are returned to their digital form.
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