User's Manual

Chapter 6: Troubleshooting

Twisted-Pair Port Link LED Is Off

When a twisted-pair port on the switch is connected to a properly

operating end node, the Link LED for the port should be on. If a Link LED

is off, do the following:

 Verify that the switch is not set to the power-saving mode by

pressing the ecoFriendly push-button on the front panel. Refer to

“AT-9000 Series Gigabit Ethernet Switches” on page 19 for the

ecoFriendly push-button location.

 Verify that the end node connected to the port is powered on and is

operating properly.

 Check that the twisted-pair cable is securely connected to the port

on the switch and to the port on the end node.

 Make sure that the twisted-pair cable does not exceed 100m (328

ft.).

 Verify that you are using the appropriate category of twisted-pair

cable. For information, refer to Table 1 on page 27.

 Determine if a crossover cable is required. Because the twisted-

pair ports feature auto MDI/MDI-X, you should be able to use a

straight-through cable, regardless of the type of device you

connect to a port. However, if you disable Autonegotiation on a port

and set a port’s speed and duplex mode manually, the port defaults

to MDI-X. Disabling Autonegotiation may require manually

configuring a port’s MDI/MDI-X setting or using a crossover cable.

 Make sure that the operating parameters of the port on the switch

(speed, duplex, or Autonegotiation) are compatible with the end

node to which the port is connected.