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.