Master And Member Switches; Selection Of The Master Switch - Allied Telesis XS900MX Series Installation Manual

Master and Member Switches

Selection of the
Master Switch
The stack has one master switch. The functions of the master switch
include:
 Coordinating and monitoring stack operations.
 Verifying that the switches are using the same version of
management software. It automatically downloads its management
software over the stacking cables to switches with different
software versions.

Verifying that the switches have different ID numbers. It
automatically assigns new ID numbers to resolve situations where
two or more switches have the same ID number.

Verifying that the stacking transceivers that connect the switches
together are cabled correctly.
The other switch is called a member switch. There can be only one
member switch in addition to the master switch. The member switch
automatically transitions to the master role if the current master switch is
removed from the stack or powered off.
The switches of a stack select the master switch by comparing the
following numbers whenever the stack is reset or powered on:

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.You can adjust the value before or after
you assemble the stack, or leave the setting at the default value.
If the switches have the same priority value, they select the master switch
by comparing their MAC addresses. 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.
If you power on the stack for the first time without adjusting the priority
values, they select the master switch using their MAC addresses if the
units are powered on simultaneously. If you power on the switches one at
a time, the master switch is the first switch to be powered on. This is
explained in Chapter 7, "Stacking with the Default Trunk Ports" on page
91.
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