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Definition
As today's communication networks become more
complex-as more users share peripherals, as more mission-critical tasks are accomplished
over networks and as the need for faster access to information increases-a good
foundation for these networks becomes increasingly important. The first step toward
the adaptability, flexibility and longevity
required of today's networks begins
with structured cabling-the foundation of any information system. It is vital
that communications cabling be able to support a variety of applications and last
for the life of a network. If that cabling is part of a well-designed structured
cabling system, it can allow for easy administration of moves, adds and changes
and smooth migration to new network topologies. On the other hand,"worry-about-it-when-you-need-to"
systems will make moves, adds and changes a hassle and make new network topologies
too difficult to implement. Network problems occur more often, and are more difficult
and timeconsuming to troubleshoot.When communication systems fail, employees and
assets sit idle, causing a loss of revenues and profits. Even worse, the perceptions
of customers and suppliers can be adversely affected.
The
purpose of this white paper is to present the advantages of using a standards-based
structured cabling system for a business enterprise. The paper will cover a brief
historical perspective of structured cabling, a review of the current standards,
media types and performance criteria, system design and installation recommendations.
Particular attention
will be given to the ANSI/TIA/EIA-568-A standard and
the horizontal cabling subsystem in that standard. The
Evolution of Structured Cabling
In
the early 1980s, when computers were first linked together in order to exchange
information, many different cabling designs were used. Some companies built their
systems to run over coaxial cables. Others thought that twinaxial or other cables
would work best. With these cables, certain parameters had to be followed in order
to make the system
work. Certain connectors had to be used, maximum cable
distances had to be established and particular topologies were necessary.
By defining every aspect of their system, manufacturers
"locked" customers into a proprietary system. One manufacturer's system
would not work with another, or run over any other type of cabling. If a customer
decided to change systems, not only would new electronics and software need to
be purchased, but new cabling would need to be installed as well. Troubleshooting
proprietary systems was very difficult and time-consuming compared to today's
structured systems. A problem at one workstation could bring the entire proprietary
system down, leaving no indication to the network manager where the problem may
have occurred. In the case of a daisy-chain topology, troubleshooting consisted
of starting at one machine and physically tracing the cables to each of the other
machines on the network. Eventually, the cause
of the problem, such as a broken connection,was found. Once repairs were completed,
the system would be back on line. This troubleshooting process could last hours-or
days-leaving users sitting idle. Moves, adds or changes were also difficult with
a proprietary system. Each time a new machine was added to the network, new cable
had to be installed and inserted into the ring or attached to the bus. Furthermore,
the whole system might have had to come down to add the new user.
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