Page 682 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

Often, waiting until a minor failure occurs before a repair is performed
is satisfactory, but waiting until a complete failure occurs before

replacement is an unacceptable security practice.

Wiring Closets

Wiring closets used to be a small closet where the telecommunications
cables were organized for the building using punch-down blocks.
Today, a wiring closet is still used for organizational purposes, but it

serves as an important infrastructure purpose as well. A modern
wiring closet is where the networking cables for a whole building or
just a floor are connected to other essential equipment, such as patch
panels, switches, routers, local area network (LAN) extenders, and
backbone channels. Other more technical names for wiring closets
include premises wire distribution room andintermediate
distribution facilities (IDF). It is fairly common to have one or more

racks of interconnection devices stationed in a wiring closet (see
Figure 10.1).

Larger buildings may require multiple wiring closets in order to stay
within the maximum cable run limitations. For the common copper-
based twisted-pair cabling, the maximum run length is 100 meters.
However, in electrically noisy environments, this run length can be
significantly reduced. Wiring closets also serve as a convenient

location to link multiple floors together. In such a multistory
configuration, the wiring closets are often located directly above or
below each other on their respective floor.