Brocade FastIron Ethernet Switch Stacking Configuration Guide - Manual (Page 98)

Active controller and standby controller resets
If the active controller is reset or removed from the stack, the entire stack reloads and active controller
and standby controller elections are initiated. If the unit functioning as the previous active controller is
no longer part of the stack, the standby controller unit becomes the new active controller. After a reset,
if no stack member qualifies as active controller, the existing standby controller waits 30 seconds and
then assumes the role of active controller.
NOTE
The details in the preceding paragraph apply to the default setup, with hitless stacking failover not
enabled.
If both active and standby controllers are removed the rest of the stack will continue to function
because they are operating on whatever is programmed in the hardware. The stack members will not
be able to learn any new addresses. You will see the following message every few minutes.
Stack member is non-operational because of no Active or standby controller
You can recover to standalone mode by "stack unconfigure me"
Use stack unconfigure me to restore the units into standalone devices with a pre-stacking
configuration.
Selecting a standby stack unit
You can choose a standby controller by configuring a stack unit priority to be the second highest, or
the same as the active controller. If the priorities are configured the same for both, when the original
active controller fails, the standby controller takes over. If the original active controller becomes active
again, it will not win back its active role, which helps to minimize interruption of the stack. However, if
the original active controller has the higher priority, it will win back its role and reset all of the stack
units.
Standby controller election criteria
The standby controller election is based on the following criteria.
• The highest priority
• Bootup as active controller
• Bootup as standby controller
• The lowest boot ID
• The lowest MAC address
Because standby election candidates must have startup configurations that have been synchronized
with the active controller, if the active controller does not have a startup-config.txt file, there will not be
a standby controller. Once a write memory is performed on the active controller, the startup-config.txt
file is written and synchronized to all stack members, and a standby controller can be elected.
Hitless stacking
Hitless stacking is supported on FCX and ICX units in a traditional stack. It is a high-availability feature
set that ensures sub-second or no loss of data traffic during the following events:
• Active controller failure or role change
• Software failure
Active controller and standby controller resets
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