3Com 3C16721A Switch User Manual


 
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