Allied Telesis 8100S Series - Manual (Page 54)

Chapter 2: Stacking Overview
54
Master Switch
A stack must have a master switch to coordinate and monitor stack
operations. It verifies that the switches are using the same version of
management software, that no two switches have the same ID number,
and that the stacking ports are cabled correctly.
The selection of the master switch is based on the ID numbers. The
master switch is the switch with the lowest ID number of all the switches in
the stack. The selection occurs during the discovery process, described in
“Initialization Process” on page 59, which the stack performs whenever
you power on or reset it. If the master switch is removed from the stack or
fails, the member switch with the next lowest ID number automatically
becomes the new master switch. If that switch fails or is removed from the
stack, then the switch with the next lowest ID number becomes the new
master switch, and so on.