Allied Telesis AT-S63 - Manual (Page 80)

Chapter 3: Enhanced Stacking
80 Section I: Basic Operations
Master and Slave Switches
An enhanced stack must have at least one master switch. This switch is
your management access point to the switches of a stack. After you have
started a local or remote management session on a master switch, you
can redirect the session to any of the other switches.
The other switches in the stack are known as slave switches. They can be
managed through the master switch or directly, such as from a local
management session.
An enhanced stack can have more than one master switch. Multiple
master switches can lessen the impact on your network management
should you need to remove a master switch from the network, such as for
maintenance purposes.