This read-only 64-bit counter tallies the total frames that have passed through this priority queue on this port, avoiding the wraparound a 32-bit counter would hit at very high packet rates. An admin uses this high-capacity counter on high-throughput ports for the same reason as the byte counter, to get reliable long-interval polling without counter wraps. For example, a monitoring system polling once per hour on a busy port would use this counter rather than the 32-bit frame counter to avoid undercounting due to wraparound.