This counts instances of an invalid DXI2 control field in received frames, completing the set of granular DXI2 per-field validation counters alongside link ID, station ID, command/response, and address extension. An admin reviewing all five DXI2 invalids counters together gets a full picture of exactly which parts of the CPE's DXI2 frame construction are non-conformant, rather than a single opaque error count. For example, a CPE generating frames with a bad control field but otherwise correct link ID, station ID, and address fields would show activity isolated to lportSmdsCntDxi2CtrlInvalids alone.