Problem Solving

Refer to the information about LEDs given earlier in this guide to see if the problem can be identified and rectified. Here are some common problems that can occur:

A link is connected but the Link/Activity Status LED for the port does not light

There is a problem with this connection. Check that:

■The device being connected to is powered on and operating correctly.

■The cable is connected at both ends.

■The cable is not damaged.

■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 cable can be used for 10BASE-T operation only. Category 5 cable is required for 100BASE-TX or 1000BASE-T. 3Com recommends Category 5e or 6 cable for 1000BASE-T operation.

A fiber cable is connected but the Module Active LED does not light

Check that:

■The Receive (RX) and Transmit (TX) cable connectors are not swapped.

■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 14 for details.

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

The Link/Activity LED is lit but the network performance of the Switch is poor

The Switch supports full-duplex auto-negotiation. If the connected device does not support auto-negotiation, ensure it is configured for half-duplex operation only. If the connected device has auto-negotiation disabled or over-ridden, and is configured as full duplex, the Switch will configure the link as half duplex, causing a mis-match that will reduce network performance when data is transmitting and receiving simultaneously on the same link.

Ensure that the connected device has either:

■Auto-negotiation enabled, or

■The ports are configured for half-duplex operation

All ports appear to show continual activity

There may be broadcast storms on the network. Remove port connections one at a time, waiting a few seconds between each port. If the LEDs go off after removing a port connection, the device that was connected to that port is introducing an excessive amount of broadcast frames to the network (some pieces of network equipment operate by sending out broadcast frames regularly). Refer to the documentation that accompanies the device for information on disabling the broadcast operation.