Information Technology Reference
In-Depth Information
(0.5-in) ferrule spacing, which prevents it from mounting within the space of the RJ-
style module plates that have achieved almost universal acceptance.
The only alternative has been to redesign the plates, and often the modules,
so that a dual-insert 568-SC jack could be accommodated. Even so, the SC takes up
two module positions for one circuit connection, besides tying up a lot of real estate
on router and switch option blades.
The answer to mating two fibers within the modular footprint is obviously to
use one of the SFF connector designs that began to appear as soon as the SC prob-
lem was known. But there are now more than a half-dozen incompatible SFF con-
nectors, each with its own advantages, available from multiple manufacturers.
Moreover, the TIA now makes absolutely no recommendation, other than its general
fiber connector requirements. For a solution to this dilemma, one could turn to the
equipment manufacturers. Again, there is no unanimity, as switch and router manu-
facturers are split on SFF connector choices, and many continue to use the SC con-
nectors. Because the TIA has decided not to decide, the market will eventually show
a preference, but it will likely make no firm decision either. Just as there are many
different types of computers, and many different makes of automobiles, there will
continue to be many types of fiber connectors.
Over time, a few of the designs, perhaps two or three, will gain a majority of
the market. Since the leading manufacturers have each licensed other strong pro-
ducers to offer their designs, it is unlikely that only one will really emerge as a de
facto standard. So, how should you choose which connector style to use for your
network fiber?
The simple answer is to choose the connector that you believe will be the best
for your environment. In reality, fiber-optic transceivers are not actually connected
into the patch terminations or the work area outlets. You must use a patch cord, user
cord, or equipment cord to make the final connection. Also, it is unlikely that you will
have the same SFF connector styles on all your equipment and workstation inter-
faces. Since different fiber connectors offer near identical optical performance, you
can simply use a cord with the appropriate connectors at each end. Use a fixed con-
nector and fiber cable combination that you feel comfortable with for your horizon-
tal runs. Then get appropriate adapter cables for hub/switch/router equipment and
for workstation network interface cards.
Most manufacturers offer adapter cords to transition their SFF connectors to
virtually any other SFF design. It doesn't particularly matter if the cord ends are dif-
ferent, other than for arguing the fine points of connector performance. Fortunately,
the TIA's performance guidelines assure that connector alignment and return loss will
be well within that needed for almost all applications.
