A count of the number of OAMPDUs received on this interface
with an unsupported op-code.
An unsupported opcode OAMPDU is indicated by a valid frame
with (1) destination MAC address equal to that of the reserved
MAC address for Slow Protocols (See 43B of [802.3ah]), (2) a
lengthOrType field equal to the reserved type for Slow
Protocols, (3) a Slow Protocols subtype equal to that of the
subtype reserved for OAM, and (4) an OAMPDU code equals the
opcode for a function that is not supported by the device.
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.