Information Technology Reference
In-Depth Information
two cross-connect terminations). Using the direct patch approach also saves space
in the wiring closet, saves installation labor, and provides for quick reconfiguration
of your network connections. On the other hand, you still have all the patch cables
to deal with, and each of your station cables is forever terminated in a single 8-pin
jack. You have no easy way to grab a pair or two to use for another purpose, such
as a modem line or a second network connection. In addition, the patch cords are
normally available only in standard length increments (unless you make your own),
and thus rarely fit a connection exactly.
On some points, the two opposing cable termination techniques each have dis-
advantages that compensate for their advantages. For example, the exclusive use of
cross-connect fields eliminates the crosstalk and contact resistance problems of
patch panel jacks, but it compensates by introducing two more terminations (each
end of the cross-connect wire) where the finest workmanship may still introduce
untwist to the link (thus causing more crosstalk, etc.). Also, the ease of moving con-
nections on the patch belies the fact that an average mature installation may actu-
ally need only 2% to 5% of its connections moved in a year.
Although we have mentioned two termination techniques—direct patch termi-
nation and cross-connect field termination—a third hybrid method uses a combina-
tion of both. In this method, the horizontal cable is terminated in a connecting block
(such as a 110 block). Then, a cross-connect is made between the connecting block
and a patch panel.
The patch panel may allow for directly connecting the cross-connect wire, or
it may be connectorized, requiring multipair cables that terminate in a second con-
necting block. The patch cords are connected from the patch panel to the hub equip-
ment. This hybrid method offers wiring flexibility between the station cable and the
patch: A cable may easily be reconfigured, shared, or moved to another patch posi-
tion. Equipment connections may be made quickly or reconfigured at will, because
of the use of patch cords. However, the patch jacks and cords are still there, with all
their other potential disadvantages.
It's almost impossible to take sides in this argument, as there are valid reasons
behind both viewpoints. However, you should know that there is a definite choice to
be made and you should have an understanding of the issues surrounding that choice.
The next few sections will describe cross-connect wiring (the connecting blocks were
covered in Chapter 7), multipair jumper cables, patch panels, and patch cords.
Patch panels are used to provide flexible connections between horizontal station
cables and the equipment ports in the wiring closet. Patch panels have modular
