3Com OfficeConnect 3C16700A User Manual page 16

Port Status LED not lit for a 10BASE-T port that has a
connection. There is a problem with this connection.
Check that you are using a straight-through 10BASE-T cable
which is properly connected at both ends, and is not
damaged. If the cable is connected to port 4, ensure that
the Uplink/Normal switch is set to Normal (out). Also check
that the equipment being connected to the hub is powered
on and operating correctly. Refer to Figure 6 below to
compare the wiring of a straight-through and a crossover
cable.
Figure 6 Straight-through Cable/Crossover Cable
Straight-through
TxD+ 1 1 TxD+
TxD- 2 2 TxD-
RxD+ 3 3 RxD+
RxD- 6 6 RxD-
Pins 4, 5, 7 and 8 are not used
Crossover
TxD+ 1 1 TxD+
TxD- 2 2 TxD-
RxD+ 3 3 RxD+
RxD- 6 6 RxD-
Pins 4, 5, 7 and 8 are not used
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