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Q2:What are the major components of a Structured cabling system?
A2:A structured cabling system consists of outlets, which are usually
supplied as either one or two RJ45 connectors mounted in a standard single
gang faceplate, or as single snap in modules which can be fitted into
surface mount boxes or single/double gang faceplates.
Each user outlet is connected to a hub using a twisted pair cables, which
is named as the 'Horizontal Cabling. The structured cabling system can
be either unshielded, known as UTP (Unshielded Twisted Pair) or shielded,
known as STP (Shielded Twisted Pair) , SCTP (Screened Twisted Pair) or
FTP (Foiled Twisted Pair).
structured cabling system is connected to the back of the user outlet
by means of a connector.The maximum length of cable between the hub and
any outlet must be 90 metres or less for complying to EIA/TIA and ISO
standard. The standards allow a further 10 metres for connecting patch
cords, making a total distance of 100 metres or less.
At the hub, the 4 pair cables from the user outlets are terminated on
patch panel. These patch panel usually have IDC (Insulation Displacement
Connection) connectors on the rear for terminating the horizontal cables,and
provide an RJ45 presentation on the front for patching. Patch panels are
usually mounted in wall mounted or free standing 19 inch racks. RJ45 patch
panels usually come with 16, 24, 32, 48 or 96 connectors. The patch panel
provides 110 style, 8 pin modular connectors which are rack mounted to
allow cables to be neatly punched down. Patch panel and cross connect
hardware allow for:
means to connect station cables with jumper cables,
connection of active equipment to the UTP network,
identification of circuits for structured cabling system management.
An access point for circuit testing and monitoring,
An access point for reconnection of the wiring within the network.
The hubs are connected together back to the main equipment room using
backbone cables, which can either be copper or optical fibre cable. In
most structured cabling system, multicore optical cables ( usually 4 -
12 cores ) are used for the data backbone cables and Multipair ( usually
25 , 50 or 100 ) copper cables are used for the voice backbone cables.
The equipment racks and cabinets usually also contain active equipment
for the data network. Depending on the equipment used, the data channels
may be presented in one of two different ways.
Each data channel on the equipment may be fitted with an RJ45 connector,
so that channels can be patched directly to the patch panels terminating
the horizontal cables. Alternatively, the equipment may be fitted with
'Telco'connectors, these are 25 pair connectors each of which carries
several (usually 12) data channels. Even though the IEEE 802.3ab Gigabit
Ethernet specification has released and applications group's are turning
their attention towards next generation solutions, there is still a great
degree of uncertainty as to the capability of today's telecommunications
cabling systems to support tomorrow's high bit-rate applications. Fortunately,
the Telecommunications Industry Association (TIA) and International Organization
for Standardization (ISO) have made great strides in the specification
and clarification of the minimum structured cabling system performance
criteria necessary to support these next generation applications.
Additional requirements and recommendations for category 5 cable and class
D structured cabling system that are intended to supplement the existing
TIA/EIA-568-A and category ISO/IEC 11801 class specifications have recently
been published.These specifications address additional transmission performance
characterization required by structured cabling system developers to support
bi-directional and full four-pair transmission schemes (such as those
utilized by Gigabit Ethernet). Table 1 identifies these new structured
cabling system documents developed by the TIA and ISO technical committees.
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