This read-only PerfTotalCount reports the count of frames discarded because of receiver overruns on the DSL port, scoped to the full previous calendar day's totals for the DSL port. Operationally, overruns mean the receive buffer filled up faster than frames could be processed, causing outright data loss. For example, an admin can check whether yesterday's total overrun count was unusually high compared to prior days, suggesting an isolated one-day traffic spike rather than a chronic issue.