This is the byte-volume lifetime counterpart to cpwVcPerfTotalInHCPackets, giving the cumulative bytes this pseudowire has received from the PSN since its last counter discontinuity. Capacity-planning teams use this long-run total, divided by the VC's actual up-time (cpwVcUpTime), to estimate a realistic average utilization for trunk-sizing decisions rather than relying on short interval snapshots. A pseudowire showing tens of terabytes accumulated here over months of uptime confirms it's a heavily-used production circuit rather than a rarely-touched backup path.