This PerfCounter64 counter reports the bits received in the most recent 1-second sample on the flow's access-side port, the sum of Bytes-In across all policers times 8, in the upstream (subscriber-to-network) direction. An admin compares it against the subscriber flow's provisioned capacity to see whether traffic is running near, over, or well under what the port or flow is supposed to carry. If cmFlowHistoryIBRA2N on flow 11 settles around 529 Mbps at the most recent completed bin, an operator sizing that flow for an upgrade has a concrete number to compare against its provisioned limit, rather than guessing from aggregate port utilization.