A read-write value, in PDUs per second and defaulting to 0 (no limit), setting the rate at which the interface shuts down for a given tunneled protocol, and which cannot be set lower than the paired drop threshold. This gives an admin a stronger protective action than dropping alone, taking the interface itself down for that protocol if tunneled traffic keeps arriving at an excessive rate even after drops kick in, guarding against a sustained storm. An admin might set this to 500 PDUs/sec so a runaway BPDU storm that keeps exceeding even the drop threshold ultimately shuts the interface down rather than continuing to consume resources.