PictureTel III ISA - Manual (Page 90)

C-2 A PPENDIX C: C ROSSOVER C ABLE T ROUBLESHOOTING T IPS
2 To make a crossover cable, connect TD+ to RD+ and
TD– to RD–.
The cable performs the crossover that is usually performed by the
hub.
Figure C-1 shows the pinouts for the crossover cable:
.
Figure C-1 Straight-Through and Crossover Cable Pinouts
If the file server and client PC function together as a small
network, then either the existing cabling or the hub is failing.
■ With a correct crossover connection, the LED lights.
■ With a straight-through connection, the LED does not light.
■ With a polarity mismatch (that is, TD+ to RD– instead of TD+
to RD+), the LED blinks.
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Straight-through
10BASE-T cable Crossover
10BASE-T cable
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TD+
RD+
TD
RD
TD+
RD+
TD
RD