Allied Telesis AT-9448Ts/XP (Basic Layer 3) - Manual (Page 92)

Chapter 7: Troubleshooting
92
No Master Switch
After powering on the switches of a stack and waiting two to three minutes
for the stack to complete the discovery process, you observe that the
Stack MSTR LEDs on the front panels on all the switches are off. This
could indicate that the discovery process encountered a problem that
prevented the stack from selecting a master switch. For suggestions on
resolving the problem, refer to “Troubleshooting the Discovery Process”
on page 69.