Allied Telesis AT-9448Ts/XP - Manual (Page 84)

Chapter 5: Troubleshooting
84
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 LED on the front panel of all the switches is 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 71.