Stacking unit role transition considerations

An active or standby controller contains the stacking system configuration and its internal data structures. When an active or standby controller becomes a member, the configuration and data structures are not cleared. This does not affect its capability to function as a member. However, if the user changes the configuration, this member unit cannot become a standby again because of the difference in configuration. A member unit can become a standby only if the member was never a standby or active controller (with no configuration) or if it has the same configuration as the current active controller.