Standby controller
In addition to the active controller, another stack member is elected as the standby controller. If the active controller fails, the
standby controller takes over based on the following criteria:
1. If hitless-failover enable is not configured, the standby reloads all units, including itself. It reloads to become the active
controller.
2. If hitless-failover enable is configured, the standby immediately takes over the active controller role without reloading
any unit.
3. If the entire stack reloads and the active controller does not come up, the standby waits for four minutes to take over by
reloading every unit, including itself.
The standby controller synchronizes its configuration with the active controller at each reset.
Bootup role
When a stack unit boots, it boots in a particular role, active controller, standby controller, or stack member, or as a standalone
device. When the bootup role is standby controller or stack member, the CLI available to the unit is limited to show and stack
commands. A unit in the role of standby controller or stack member does not act without instructions from the active controller.
The last line of the show version output identifies the unit role unless the unit is in standalone mode.
My stack unit ID = 1, bootup role = active
My stack unit ID = 3, bootup role = standby
NOTE
To convert a standby controller or stack member to a standalone device, use the stack unconfigure me command
(refer to
on page 217).
Active controller and standby controller elections
Whenever there is a topology change in the stack (a reset occurs, a unit fails, a stacking port changes state, or members are
added or removed), elections are held to determine the status of the active controller and standby controller. The results of the
election take effect after the next stack reset.
Certain conditions, in a particular order, determine which units serve as active controller and standby controller after an election.
The hierarchy of factors achieves a predictable winner, regardless of the boot up sequence for a unit.
Active and standby controller elections are determined in a slightly different way when hitless failover (the default) is enabled.
The order reduces traffic interruptions during unit reset.
•
Boot as active controller - Indicates that a unit was previously active controller before the current boot sequence and will
again assume the role of active controller when two standalone units are combined into a stack. When a third
standalone unit joins the stack, the current active controller becomes subject to the other factors in this list. You can
upgrade your current active controller to "boot as active controller" status by executing the write memory command.
The system interprets the write memory action as a directive to maintain the current active controller role regardless of
resets or a new unit joining the stack.
•
Greater number of members - The unit that has control over the greater number of stack members.
•
Failover unit - In a two-unit stack, the unit that is active controller after a failover and has an up time of more than 10
minutes, when the second unit has an up time of less than three minutes.
•
Priority - The unit with the highest priority value.
Stack Management
Stack device roles and elections
Ruckus FastIron Stacking Configuration Guide, 08.0.90
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Part Number: 53-1005572-01
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