This read-only PerfTotalCount reports the count of frames discarded because of receiver overruns on the DSL port, scoped to the running total for the current calendar day so far. Operationally, overruns mean the receive buffer filled up faster than frames could be processed, causing outright data loss. For example, checking today's running overrun total against known peak-usage hours helps an admin decide whether congestion, not a hardware fault, is the likely cause.