This notification is generated when an mplsTunnelOperStatus object for a tunnel in the gmplsTunnelTable is about to enter the down state from some other state (but not from the notPresent state). This other state is indicated by the included value of mplsTunnelOperStatus. The objects in this notification provide additional error information that indicates the reason why the tunnel has transitioned to down(2). Note that an implementation MUST only issue one of mplsTunnelDown and gmplsTunnelDown for any single event on a single tunnel. If the tunnel has an entry in the gmplsTunnelTable, an implementation SHOULD use gmplsTunnelDown for all tunnel-down events and SHOULD NOT use mplsTunnelDown. This notification is subject to the control of mplsTunnelNotificationEnable. When that object is set to false(2), then the notification must not be issued. Further, this notification is also subject to mplsTunnelNotificationMaxRate. That object indicates the maximum number of notifications issued per second. If events occur more rapidly, the implementation may simply fail to emit some notifications during that period, or may queue them until an appropriate time. The notification rate applies to the sum of all notifications in the MPLS-TE-STD-MIB and GMPLS-TE-STD-MIB modules applied across the whole of the reporting device. mplsTunnelOperStatus, mplsTunnelAdminStatus, mplsTunnelDown, mplsTunnelNotificationEnable, and mplsTunnelNotificationMaxRate objects are found in MPLS-TE-STD-MIB.