This read-only value is a 64-bit counter of received packets that were not fully accepted because the receive FIFO buffer overflowed. It indicates the port is receiving traffic faster than the hardware can drain it, a sign of either a burst beyond the port's buffering capacity or a downstream processing bottleneck. For example, a rising csEthStatsRxOvfCounts during traffic bursts leads an admin to consider whether that port needs a higher-capacity uplink or better upstream traffic shaping.