3Com 3C16722A - Manual (Page 16)

16
Port Status LED not lit for a port that has a
connection. There is a problem with this particular
connection. Check that the equipment connected to the
hub is powered on, operating correctly, and contains a
100BASE-TX connection. The hub can only be directly
connected to equipment that can provide a 100Mbps
connection (not 10Mbps only). In particular, ensure that:
■ You are using a 100Mbps adapter in your workstation,
if connecting a workstation to the hub. If your adapter
can operate at various speeds, ensure that it is set to
operate at 100Mbps.
■ Any 10Mbps equipment that you want to link to the
hub, is connected through a 10/100 hub or switch.
■ You are using a ‘Straight-through’ 100BASE-TX cable that
is properly connected at both ends, and is not damaged.
Refer to Figure 5 to compare the wiring of a
straight-through and a crossover cable.
Figure 5 Straight-through Cable/Crossover Cable
1
Normal
port Pin Pin
Uplink
port
Rx+
Rx-
Tx+
Tx-
Rx-
Rx+
Tx-
Tx+
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
Normal
port Pin Pin
Normal
port
Rx+
Rx-
Tx+
Tx-
Rx+
Rx-
Tx+
Tx-
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
3C16721.book Page 16 Wednesday, July 7, 1999 3:05 PM