This read-only PerfTotalCount reports the count of frames discarded because of receiver overruns on the DSL port, scoped to the most recent rolling 24-hour period ending at the moment of the poll. Operationally, overruns mean the receive buffer filled up faster than frames could be processed, causing outright data loss. For example, a monitoring system polling this rolling 24-hour overrun total once daily gets a consistent full-day figure to feed into an alerting threshold.