Selecting The Backup Unit - SMC Networks TigerStack II SMC8848M Management Manual

S O
TACK PERATIONS
- If Master/Slave push button is depressed on more than one unit, the
system will select the unit with the lowest MAC address from those
with the push button depressed as the stack Master.
- If Master/Slave push button is not depressed on any unit, the system
will select the unit with the lowest MAC address as the stack Master.
• When the stack is initially powered on, the Master unit is designated as
unit 1 for a ring topology. For a line topology, the stack is simply
numbered from top to bottom, with the first unit in the stack
designated at unit 1. This unit identification number appears on the
Stack Unit ID LED on the front panel of the switch. It can also be
selected on the front panel graphic of the web interface, or from the
CLI.
• If the Master unit fails and another unit takes over control of the stack,
the unit numbering will not change.
• If a unit in the stack fails or is removed from the stack, the unit
numbers will not change. This means that when you replace a unit in
the stack, the original configuration for the failed unit will be restored
to the replacement unit.
• If a unit is removed from the stack and later reattached to the stack, it
will retain the original unit number obtained during stacking.
• If a unit is removed from the stack, and powered up as a stand-alone
unit, it will also retain the original unit number obtained during
stacking.

Selecting the Backup Unit

Once the Master unit finishes booting up, it continues to synchronize
configuration information to all of the Slave units in the stack. If the
Master unit fails or is powered off, a new master unit will be selected based
on the election rules described in the preceding section. The backup unit
elected to serve as the new stack Master will take control of the stack
without any loss of configuration settings. To ensure a logical fail over to
next unit down in the stack, place the Slave unit with the lowest MAC
address directly beneath the Master unit in the stack.
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