Information Technology Reference
In-Depth Information
From the dual coax outlet, connection to the workstation is made with two
coax jumper cables, with two BNC male connectors on each cable end. At the work-
station, a BNC-T is connected to the network adapter and the two cables connected
to the arms of the T. If the workstation is at the end of the coax segment, only one
cable is used and a 50-ohm terminator is placed on the other T position. If there is
no workstation in place, a short coax jumper cable is used to connect the two bulk-
head connectors on the outlet's faceplate, in order to complete the cable circuit to
the next workstation. If the workstation position would have been at the end of a
coax segment, a single terminator may be used instead. The 10Base2 system requires
end-to-end connectivity and dual-ended termination of the coax segment for proper
operation. Any disconnected cables or terminators may cause the entire cable seg-
ment to cease to function.
Outlet jacks should be clearly identified on the faceplate. The identification should
include a cable number and jack number, as well as an indication of whether the
jack supports data (such as a LAN connection) or telephone. Some jack inserts and
faceplates are marked to indicate “data” or “phone.” Telephone extension numbers
generally should not be marked on the plate, since many phone systems allow the
number to be assigned to any physical outlet. The same applies for data jacks that
correspond to a particular port number on a LAN hub or other network connec-
tion. You should keep a chart to match each extension or port number to each jack
number. The scheme in EIA/TIA-606 is a good basis for marking the jacks. The
markings should be clearly visible with bold lettering about 3/8 in high.
The standard calls for marking at the front of the jack position, above or below
the jack. However, you might also want to consider a neat marking on the top of
the plate, so it can be read from above. (If you ever have to peer down behind a desk
or a cabinet to identify an outlet, you will be thankful for the top markings.)
The outlet markings should identify the cable number, and, in a large facility,
the wiring closet as well. For example, a marking for wiring closet number 3, cable
42, might be W3-42, or W3-J42 to differentiate it from a cable number. It is best if
the outlet number corresponds to the cable number in the wiring closet. The cable
itself can also be marked with a variety of vinyl labels, but the type of label that is
part of a tiewrap should be avoided on Category 5 cables, for the reasons previously
mentioned. If all else fails, fine-point indelible markers will also effectively mark
cable numbers on a cable jacket. Station cables are usually either in the wall or at the
rear of termination blocks in the wiring closet, so the marking doesn't have to be
pretty. Neatness counts, however, as you must be able to read the cable number later.
