Allied Telesis AlliedWare Plus Installation Manual page 199

Verify that the operating specifications of the fiber optic ports on

the transceiver and remote network device are compatible.
Verify that the correct type of fiber optic cabling is being used.

Verify that the port is connected to the correct fiber optic cable.

This is to eliminate the possibility that the port is connected to the
wrong remote network device.
Try connecting another network device to the fiber optic port using

a different cable. If the port is able to establish a link, then the
problem is with the cable or with the other network device.
Use the switch's management software to verify that the port is

enabled.
If the remote network device is a managed device, use its

management firmware to determine whether its port is enabled.
Test the attenuation of both directions on the fiber optic cable with

a fiber optic tester to determine whether the optical signal is too
weak (sensitivity) or too strong (maximum input power).
Problem 5: The SHOW STACK command is not displaying all the
switches in the stack.
Solutions: One or more switches cannot join the stack. If the switches are
stacked with the S1 and S2 ports, try the following:
Verify that you are using only Allied Telesis SFP+ transceivers or

AT-SPI0TW direct connect cables. The switches will not form a
stack with any other type of transceiver or cable.
Verify that the SFP+ transceivers or direct connect cables are fully

inserted into the S1 and S2 ports.
Verify that the fiber optic cables are securely connected to the

ports on the SFP+ transceivers.
Verify that the transceivers or cables are properly cabled. The

cables must crossover to different ports on the switches. Port S1
on one switch must crossover to port S2 on another switch.
Verify that VCStack is activated on the switches. For instructions,

refer to Chapter 10, "Displaying the AlliedWare Plus Version
Number" on page 141.
If the switches are stacked with AT-StackQS Cards and AT-QSFPICU
Cables, try the following:
Verify that the AT-StackQS Cards are fully seated in the slots of

the back panels of the switches.
Verify that the AT-QSFPICU Cables are fully seated in the ports in

the AT-StackQS Cards.
x930 Series Installation Guide for Virtual Chassis Stacking
199