The value of vRtrMplsLspPathMBBState specifies the state of the
most recent invocation of the make-before-break functionality.
Possible states are:
none (1) - no make-before-break invoked
success (2) - make-before-break successful
inProgress (3) - make-before-break in progress
fail (4) - make-before-break failed.
This object was made obsolete in release 6.0 R4 and replaced
with vRtrMplsLspPathLastMBBState.