Master And Member Switches - Allied Telesis x330 Series Installation Manual

Chapter 2: Virtual Chassis Stacking

Master and Member Switches

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Stacks have a master switch. It coordinates and monitors stack
operations, and assigns switch ID numbers during the initial formation of
the stack and when new switches are added. The other switches of the
stack are referred to as member switches. Stacks of x330 Switches can
have one master switch and up to five member switches. Member
switches can become the master switch if they detect that the active
master switch has stopped managing the stack.
How you power on the switches of the stack determines how they select
the master switch. You can power them on simultaneously or sequentially.
When you power on or reset all the switches of the stack simultaneously,
they select the master switch based on these values:
Stack priority numbers

MAC addresses

The stack priority number is an adjustable value from 0 to 255, where the
lower the number, the higher the priority. The switch with the lowest
priority number (highest priority) becomes the master switch of a stack.
The default priority value is 128.
If the switches have the same priority values, they compare their MAC
addresses to select the master switch. As with the priority value, the lower
the MAC address, the higher the priority. The switch with the lowest MAC
address becomes the master switch.
The other method for powering on the switches of the stack is one at a
time or sequentially. Here, the first switch powered on becomes the
master switch. It remains the master switch even after all the switches are
powered on and the stack is operational.
Depending on how you power on the stack, it is possible for a different
switch to become the master switch. However, this does not change the ID
numbers or configurations of the switches, or how you manage the stack.