Allied Telesis AT-x510-28GTX Installation Manual page 124

Chapter 9: Troubleshooting
124
Verify that VCStack is activated on the switches. For instructions,

refer to Chapter 5, "Verifying the Status of VCStack" on page 85.
It could be that the switches have incompatible versions of the

management software. When a stack forms or a new switch is
added to an existing stack, the master switch downloads its
management software to member switches that do not have the
same version. If the master switch encounters a problem
downloading the management software to a member switch, it
does not allow the device to join the stack.
Problem 4: A twisted pair port on the switch is connected to a network
device, but the port's LINK/ACT LED is off.
Solutions: The port is unable to establish a link to a network device. Try
the following:
Verify that the port is connected to the correct twisted pair cable.

This is to eliminate the possibility that the port is connected to the
wrong network device.
Verify that the network device connected to the twisted pair port is

powered on and is operating properly.
Try connecting another network device to the twisted pair port with

a different cable. If the twisted pair port is able to establish a link,
then the problem is with the cable or the other network device.
Verify that the twisted pair cable does not exceed 100 meters (328

feet).
Verify that you are using the appropriate category of twisted pair

cable. The cable types are listed in Table 1 on page 26 for the 10/
100/1000Base-T ports.
Note
A 1000Base connection may require five to ten seconds to establish
a link.
Problem 5: The LINK/ACT LED for an SFP or SFP+ transceiver is off.
Solutions: The fiber optic port on the transceiver is unable to establish a
link to a network device. Try the following:
Verify that the remote network device connected to the fiber optic

port is operating properly.
Verify that the fiber optic cable is securely connected to the port on

the SFP or SFP+ module and to the port on the remote network
device.
Check that the transceiver is fully inserted in the slot.
