54CHAPTER 4: PROBLEM SOLVING

Solving Problems

If the LEDs on the Switch indicate a problem, refer to the list of suggested

Indicated by LEDs

solutions below.

The Power LED does not light

Check that the power cable is firmly connected to the Switch and to the supply outlet. If the connection is secure and there is still no power, you may have a faulty power cord or an internal fault. Firstly, check the power cord by:

testing it in another device

connecting a working power cord to the ‘problem’ device

then contact your supplier for advice.

On powering-up, the Power/Self Test LED lights yellow

The Switch unit has failed its Power On Self Test (POST) because of an internal problem. The fault type will be indicated on the unit LEDs. Contact your supplier for advice.

A link is connected and yet the Status LED for the port does not light

Check that:

The Switch and the device at the other end of the link (or cable) are connected securely.

The devices at both ends of the link are powered-up

The quality of cable is satisfactory

Auto-negotiation settings are the same at both ends.

Auto-negotiation problems will occur with 10BASE-T or 100BASE-T where auto-negotiation is disabled and incorrect cables are being used (cross-over or straight)

Auto-negotiation problems will occur with fiber if:

The Receiver (RX) and Transceiver (TX) cable connectors are swapped

Fibers are broken

Auto-negotiation differs at either end (a link appears at the ‘fixed’ end and not at the auto-negotiation end)

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3Com DUA1770-0AAA04 manual Solving Problems, Indicated by LEDs, Solutions below, Power LED does not light