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I
C
NITIAL
ONFIGURATION
•
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.
Master Backup Unit
Once the Master unit finishes booting up, the Slave unit in the stack with
the lowest MAC address functions as the primary backup unit. The stack
Master immediately downloads all configuration information to the
backup unit and continues to update it with information about any
subsequent configuration changes made to any unit in the stack. If the
Master unit fails or is powered off, the backup unit will take control of the
stack without any loss of configuration settings.
The Slave unit with the lowest MAC address always functions as the
backup unit. If you want to ensure a logical fail over to the next unit down
in the stack, place the Slave unit with the lowest MAC address directly
beneath the Master unit in the stack.
Recovering from Stack Failure or Topology Change
When a link or unit in the stack fails, a trap message is sent and a failure
event is logged. The stack will reboot after any system failure or topology
change. It takes two to three minutes for the stack to reboot. If the Master
unit fails, the backup unit will take over operations as the new Master unit,
reboot the stack, and then select another backup unit after the stack
finishes rebooting. Also note that powering down a unit or inserting a new
unit in the stack will cause the stack to reboot. If a unit is removed from
the stack (due to a power down or failure) or a new unit added to the stack,
the original unit IDs are not affected after rebooting, and a new unit is
assigned the lowest available unit ID.
Broken Link for Line and Wrap-around Topologies
All units in the stack must be connected via stacking cable. You can
connect the units in a simple cascade configuration from the top to the
bottom unit. Using this kind of line topology, if any link or unit in the stack
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