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 cmFlowStatsIBRA2N on flow 19 settles around 97 Mbps at the current interval, 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.