Page 74 - Intelligent Communication Systems

CHAPTER 7/NEWLY DEVELOPED TELECOMMUNICATION SERVICES 57
in stand-alone use. Linking the equipment enables resource sharing and functional
distribution.
The main characteristics of the local area network are as follows.

(1) Coverage of the network is within a room, a floor, a building, or an area
up to 10 kilometers.
(2) Transmission speed is over 1 kbs.
(3) The number of nodes connecting to the network is about 10-1000.
(4) Network topology is rather simple and the network has high flexibility
and reliability.
(5) Communication control is simple and inexpensive. The network can be
expanded by linking to additional networks via gateways or routers.
(6) All kinds of terminals or computers can be accommodated in the
network.
An example of the local area network is shown in Figure 7.4.
Supercomputers, database machines, file servers, terminals, and workstations
are linked together by a local area network. By accommodating a variety of work-
stations in the local area network, functions such as file transfer, message handling,
logging-in to a remote terminal by a virtual terminal, and/or distributed file systems
using network file system (NFS) can be achieved.
Through the evolution of workstations, personal computers, and local area
networks, users have come to prefer the small computers, such as personal comput-
ers, to large-scale computers. This has contributed to the downsizing of computers,

FIGURE 7.4 Local area network.