This is a Counter64 preserving the total Phase-2 tunnel delete requests received by a now-expired control tunnel over its entire lifetime, per its description, the historical companion to the live per-tunnel delete-request counters elsewhere in this MIB. It tells an admin how much Phase-2 SA churn a since-closed IKE tunnel had underneath it before the control tunnel itself went away, useful when investigating whether persistent data-SA instability eventually led to the control tunnel's own termination. A tunnel history entry with a very high delete-request count alongside a failure-related termination reason suggests ongoing Phase-2 instability may have been a root cause.