Information Technology Reference
In-Depth Information
C
C
C
Category 3: Cat 3
3
Category 5: Cat 5
5
Category 5e: Cat 5e
5e
FIGURE 15.1
Category of performance markings for components.
nomenclature has evolved over a period of years from a loose general specification
to a very specific (and tough) measured-parameter specification. Originally, the pro-
gressive ratings of performance were called Levels 1 through 5. Over time, the term
“Category” was introduced and eventually adopted by several standards bodies,
including the EIA/TIA, the UL, and the ISO/IEC, which has a corresponding class
A-F system for links. Now, the performance parameters and testing methods have
been further tightened, although the existing Category terminology remains.
Participation in a continuous testing verification program by one of the major inde-
pendent labs is the best assurance that the latest standards are used.
You may have cable or connectors on hand that do not strictly meet the cur-
rent performance requirements of the categories. It is possible also that the testing
was done with outdated procedures. You would be confident that the latest per-
formance standards were met only if your hardware and cable were certified to meet
TIA-568-C. A reference to 568-A would probably suffice, since it was the revision
to the original EIA/TIA-568. In some cases, previously manufactured components
may reference the technical bulletins that were issued prior to being incorporated,
for the most part, into TIA-568-C. Test equipment that meets the TSB-67 require-
ments should be fine for Category 5, but you may need to update or replace your
test instrument to test for TSB-95, Cat 5e, or Cat 6.
One pitfall you should avoid is the use of components that diverge from the
recognized standards. For example, other styles of plugs and jacks may have much
better NEXT performance than the ubiquitous 8-pin modular hardware. Typically,
these other connectors and hardware are presented as having an advantage over the
standard product. This is, you see, a way to say “standard” so that it seems ordi-
nary. However, wiring standards are not only a set of performance parameters and
installation practices, but also a standard style of interface to the user equipment
Search WWH ::




Custom Search