This is a running byte counter for traffic received on this pseudowire, giving finer-grained volume detail than the packet counter alone -- specifically useful for calculating actual throughput (bytes per second) when polled periodically, rather than just packet rate, which doesn't account for varying frame sizes. Comparing derived throughput against the pseudowire's configured or operational bandwidth (cienaCesMplsPwConfigBandwidth/OperBandwidth) tells an admin whether the customer is actually utilizing their provisioned capacity or running well under it. Because this is a 32-bit counter, on a high-bandwidth pseudowire it can wrap around relatively quickly, so monitoring tools need to poll it frequently enough to detect and account for rollovers.