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WAN
WIDE AREA NETWORKS
Wide Area Networks are built to provide
communication solutions for organizations or people who need
to exchange digital information between two distant places (in
one country or in two different countries). Since the distance
is long, the local telecommunication company is involved, in
fact, WANs are usually maintained by the country's public telecommunication
companies.
Dedicated lines have the advantage of being private, but they
are expensive, especially when many sites are to be connected.
Cloud services provide a meshed network that readily allows
connection from many different sites, at lower cost.
The most widely used connection lines are the T1, the basic
unit of the telco T-carrier system. A T1 consists of 24 64 Kbps
channels for a total capability of 1.544 Mbps. Each of the channels
may be used as a separate data or voice channel, or channels
may be combined for higher transmission rates. T3 lines are
also available and are equivalent to 28 T1 lines or 44.736 Mbps.
For higher bandwidth applications, optical carriers are used.
Synchronous Optical Network (SONET) was developed to connect
long-distance carriers and to unify different standards. Data
rates are defined in terms of Optical Carrier or OC levels.
The first level is OC-1 with a rate of 51.84 Mbps, and the most
widely used is OC-3 with a rate of 155.52 Mbps.
For businesses that do not require the network to be available
to all users at all times, dial-up services can be used to connect
remote users or branch offices. Most PCs are equipped with analog
modems to allow users to dial-up and connect to the Internet
or a private business network. Digital dial-up services like
Integrated Services Digital Network (ISDN) are also available
in most areas. For small businesses, ISDN offers Basic Rate
Interface (BRI) service that can provide data transmission at
128 Kbps with the proper equipment and software.
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