Information Technology Reference
In-Depth Information
A.
Normal pairs
D.
Crossed pairs
B.
Continuity (opens)
E.
Reversed pair
C.
Shorts
F.
Split pairs
FIGURE 15.3
The correct pinout/pairing and most of the common wiring.
the actual user equipment cables that will be attached to the hub, the workstation, or
whatever. For the field tester, this means that the Permanent Link must include the
test equipment cords at each end, but the Channel must terminate directly into the
tester (or somehow exclude the effect of test cables from the measurement).
The TIA-568-C standard requires a horizontal link to be 90 m (295 ft) or less,
with an allowance for an additional 10 m (33 ft) for all user cords, jumpers, and
patch cords. Because this horizontal link length cannot directly be measured electri-
cally by the field tester, which must somehow connect to the link under test, an
allowance is made for two 2-m test equipment cords. This means that the
Permanent Link is defined to have an acceptable length of 94 m. The Channel,
which includes the user cords, can be as much as 100 m. From a practical stand-
point, we would recommend that you use test cords that are exactly 2 m in length.
