Information Technology Reference
In-Depth Information
Telecommunications networks
require state-of-the-art computer
software technology to continuously
monitor the flow of voice, data, and
image transmission over billions of
circuit-miles worldwide.
(Source: © Roger Tully/Getty
Images.)
front-end processor
A special-purpose computer that
manages communications to and
from a computer system serving
hundreds or even thousands of
users.
private branch exchange (PBX)
A telephone switching exchange
that serves a single organization.
switch
A telecommunications device that
uses the physical device address in
each incoming message on the net-
work to determine to which output
port it should forward the message
to reach another device on the same
network.
Front-End Processors
Front-end processors
are special-purpose computers that manage communications to and
from a computer system serving hundreds or even thousands of users. They poll user devices
to see if they have messages to send; facilitate efficient, error-free communications; perform
message and transaction switching; multiplexing; transaction security; and end-to-end trans-
action management and reporting—important functions needed to support mission critical
transaction environments such as banking, point-of-sale, and healthcare applications. By
performing this work, the front-end processor relieves the primary computer system of much
of the overhead processing associated with telecommunications.
Private Branch Exchange (PBX)
A
private branch exchange (PBX)
is a telephone switching exchange that serves a single
organization. It enables users to share a certain number of outside lines (trunk lines) to make
telephone calls to people outside the organization. This sharing reduces the number of trunk
lines required, which reduces the organization's telephone expense. With a PBX, you typically
need to dial three or four digits to reach anyone else within the organization. The PBX can
also provide many other functions such as voice mail, voice paging, three-way calling, call
transfer, and call waiting. Centrex is a form of PBX with all switching occurring at the local
telephone office instead of on the organization's premises.
bridge
A telecommunications device that
connects one LAN to another LAN
using the same telecommunications
protocol.
Switches, Bridges, Routers, and Gateways
Telecommunications hardware devices switch messages from one network to another at high
speeds. A
switch
uses the physical device address in each incoming message on the network
to determine to which output port it should forward the message to reach another device on
the same network. A
bridge
connects one LAN to another LAN that uses the same telecom-
munications protocol. A
router
forwards data packets across two or more distinct networks
toward their destinations through a process known as routing. Often, an Internet service
provider (ISP) installs a router in a subscriber's home that connects the ISP's network to the
network within the home. A
gateway
is a network device that serves as an entrance to another
network.
router
A telecommunications device that
forwards data packets across two or
more distinct networks toward their
destinations, through a process
known as routing.
gateway
A telecommunications device that
serves as an entrance to another
network.
Telecommunications Software
A
network operating system (NOS)
is systems software that controls the computer systems
and devices on a network and allows them to communicate with each other. The NOS
performs the similar functions for the network as operating system software does for a com-
puter, such as memory and task management and coordination of hardware. When network
equipment (such as printers, plotters, and disk drives) is required, the NOS makes sure that
network operating system
(NOS)
Systems software that controls the
computer systems and devices on a
network and allows them to com-
municate with each other.
