A count of the number of frames that were dropped by the OAM
multiplexer. Since the OAM mulitplexer has multiple inputs
and a single output, there may be cases where frames are
dropped due to transmit resource contention. This counter is
incremented whenever a frame is dropped by the OAM layer.
When this counter is incremented, no other counters in this
MIB are incremented.
Discontinuities of this counter can occur at re-initialization
of the management system, and at other times as indicated by
the value of the ifCounterDiscontinuityTime.