This object counts the number of labels
that are in use at this point in time on this
interface in the incoming direction. If the interface
participates in the per-platform label space only,
then this instance of this object MUST be identical
with the instance with index 0. If the interface
participates in the per-interface label space, then this
this instance of this object MUST represent the number of
of per-interface labels that are in use at this point in
time on this interface.