This notification is generated when the
bfdSessState object for one or more contiguous
entries in bfdSessTable are about to enter the up(4)
state from some other state.  The included values of
bfdSessDiag MUST both be set equal to this
new state (i.e., up(4)).  The two instances of
bfdSessDiag in this notification indicate the range
of indexes that are affected.  Note that all the indexes
of the two ends of the range can be derived from the
instance identifiers of these two objects.  For the
cases where a contiguous range of sessions
have transitioned into the up(4) state at roughly
the same time, the device SHOULD issue a single
notification for each range of contiguous indexes in
an effort to minimize the emission of a large number
of notifications.  If a notification has to be
issued for just a single bfdSessEntry, then
the instance identifier (and values) of the two
bfdSessDiag objects MUST be identical.

This notification is generated when the
bfdSessState object for one or more contiguous
entries in bfdSessTable are about to enter the down(2)
or adminDown(1) states from some other state.  The included
values of bfdSessDiag MUST both be set equal to this new
state (i.e., down(2) or adminDown(1)).  The two instances
of bfdSessDiag in this notification indicate the range
of indexes that are affected.  Note that all the indexes
of the two ends of the range can be derived from the
instance identifiers of these two objects.  For
cases where a contiguous range of sessions
have transitioned into the down(2) or adminDown(1) states
at roughly the same time, the device SHOULD issue a single
notification for each range of contiguous indexes in
an effort to minimize the emission of a large number
of notifications.  If a notification has to be
issued for just a single bfdSessEntry, then
the instance identifier (and values) of the two
bfdSessDiag objects MUST be identical.