Information Technology Reference
In-Depth Information
As the cabling installer, you are responsible for using only components of a
proper category, installing them properly, and for field testing of the installed cable
links to verify proper operation for the rated category. If you are an IT manager, this
process may be done by you, your installation contractor, or an independent third
party to “certify” compliance at the rated category.
If you expect to provide a LAN wiring system with a particular level of per-
formance, you must use only components and cable that have been certified for that
category of operation or higher. For example, for a Category 3 installation, you may
use Category 3, 5e, or 6 components, but you must use only Category 5e or higher
cable and connecting hardware for a Category 5e system.
A common misconception is that using Category 6 cable is always better than
using Category 5e cable for an application that requires only Cat 5e operation, such
as 100BaseT. However, if you use components and installation techniques that are
only appropriate for Category 3, you essentially get only that level of performance.
The performance of a cabling system is only as good as its weakest link, and a cate-
gory of performance is equal to the lowest certification and installation/workmanship
of any component. You could well argue that a higher category of cable will ensure
meeting a lower category of performance. The higher-grade cable may improve per-
formance margins a bit. It will, but the only gain to you is in those instances when a
lower category of cable might reveal other marginal conditions, such as interfering
electrical fields or longer-than-permitted cable runs. A much better reason for using a
higher category component is that you could at a later time upgrade to Category 5e/6
without repulling the wire. Be cautious, though, as this potential for later upgrade
might be wasted if other Category 5e/6 installation practices are not followed.
Performance Levels
What does component certification really mean? Because recognized performance
categories exist, a cable or connector that is marketed as meeting the requirements
of a certain category should be tested to verify that claim. Because the manufactur-
ers are responsible for testing these components themselves, they often provide typ-
ical test results in their literature. Some manufacturers will provide detailed test
reports upon request and offer product guarantees to back their claims.
In addition, independent laboratories offer manufacturer verification testing
programs that range from a one-time test report to a continuing test program with
random testing. Obviously, you are more ensured of quality components with a con-
tinuing verification program than with a single test sample.
TIA-568-C outlines the performance specifications and very detailed test pro-
cedures that must be followed to certify components to a particular category. TIA-
