3Com 3C16491 manual Fiber cable is connected, but the Module Active LED is off

■If the connection is to a workstation, that the workstation's network interface is installed and configured correctly.

■The correct category of cable is being used for the required link speed. Category 3 cables can be used for 10BASE-T operation only. Category 5 cable is required for 100BASE-TX or 1000BASE-T. 3Com recom- mends Category 5e or 6 cables for 1000BASE-T operation.

A fiber cable is connected, but the Module Active LED is off.

Verify that:

■The fiber cable is in good condition.

■The SFP module is correctly inserted.

■A 3Com SFP module is being used. Refer to “Approved SFP Transceivers” on page 19 for details.

■The equipment at the far end is installed and correctly configured.

Solving LED Issues 75

The Link/Activity LED is on, but network performance is poor

The Switch supports full-duplex autonegotia- tion. If the connected device does not support autonegotiation, ensure that it is configured for half-duplex operation only. If the connected device has autonegotiation disabled or overrid- den, and is configured as full-duplex, the Switch will configure the link as half-duplex, causing a mismatch that will reduce network performance when data is transmitting and receiving simultaneously on the same link.

Ensure that the connected device has either:

■Autonegotiation enabled, or

■The ports are configured for half-duplex operation