This read-only 64-bit counter tallies the total bytes that have passed through this priority queue on this port, avoiding the wraparound that a 32-bit counter would hit on very high-throughput queues. An admin uses this high-capacity counter instead of the 32-bit byte counter on fast interfaces where the standard counter would wrap too frequently to poll reliably. For example, on a 10 Gbps port carrying sustained traffic, an admin would prefer this counter over rsQueueBytes to avoid missing wraps between polling intervals.