This carries the administrative state of the tunnel at the moment the trap was generated. Including this snapshot in the trap lets the receiver immediately tell whether an operational-state alarm is expected (because someone had already administratively disabled the tunnel) or a genuine surprise failure on a tunnel that was supposed to be up — and since this field is only accessible-for-notify, that snapshot is the only way to see this value tied to the specific event rather than the tunnel's current live state. A trap might show admin state up(1) alongside an operational fault, telling the operator this failure was unexpected rather than the result of planned maintenance.