The cause is due to logic designed to detect when two or more control board interrupts occur within one second. When this event occurs, a major alarm is raised and further interrupts are disregarded by the system. This logic is intended to detect known interrupt storm conditions and prevent other undesired behavior, which can be triggered by these excessive interrupts. Hardware interrupts are generated, when any of the following events occur:
A button is pressed on the front panel of the router.
The RE online/offline button is pressed (this button is located on the RE).
The FPM ACO (Alarm Cut Off) button is pressed.
A FRU in the following list of FRUs is inserted into a slot where one was removed from the router: