Information Technology Reference
In-Depth Information
of telephone cable that had two twists per foot or less, making it totally inadequate
for LAN data use.
To use twisted pair with confidence, the LAN manager and the LAN installer
needed to be certain that a LAN cable would perform adequately. Performance spec-
ifications evolved that categorized cable performance by intended use. An early
attempt to indicate expected performance by setting up cable manufacturing qual-
ity “levels” eventually led to a well-researched and detailed set of industry-standard
performance specifications in five “categories.” The LAN user now could know
with certainty that a Category 3 cable would operate well on LANs up to 16 mega-
hertz (MHz) bandwidth, and that a Category 5e cable would perform to 1000 Mbps
(1 Gbps).
Many connector and wire specifications have evolved in this way, along with
standardized workmanship practices, to provide a platform of internationally rec-
ognized standards that virtually guarantee a properly performing LAN wiring sys-
tem. This process is not difficult to understand, but the LAN manager, installer, and
technician must have a thorough understanding of the standards, procedures, and
specifications needed for a network cabling plan that complies with LAN operating
standards. The careful planning of a standards-compliant cabling system is called
structured wiring
.
This chapter will give you an overview of the philosophies in designing, plan-
ning, and estimating a LAN wiring system. The items in these sections should be
ready knowledge before you delve into the rest of the topic. A central theme of this
topic is that any wiring design should be a standard installation that supports at
least the minimum performance criteria, is simple to install and maintain, and pro-
vides adequate future expandability and growth.
Maintaining the proper standards in your cable installation is the key to getting the
most from your LAN cabling system. The internationally recognized standards exist
to ensure that the combination of wiring, connectors, hubs, and network adapters
will all perform properly in a completed network. The newly revised wiring stan-
dards make special note of specific cable installation guidelines and workmanship
practices that have been found necessary for the more demanding modern networks
at speeds of 100 Mbps and beyond.
1
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Throughout this topic, we concentrate on the advanced structured wiring system embodied in the
standards from the Telecommunications Industry Association (e.g., TIA/EIA-568-B) and the
International Standards Organization (e.g., ISO/IEC 11801).
