Work out shaping and policing rate instantly with clear inputs, formula shown and shareable results.
Shaping buffers traffic above the committed rate and releases it later, converting excess into delay; policing discards or remarks it, converting excess into loss. Burst size is the committed rate multiplied by the tolerance window, and it must be at least a few round trips' worth of data or TCP will be penalised for its normal ramp-up behaviour.
Shaping and policing
burst bytes = CIR x tolerance / 8; excess = offered - CIR; shaping delay = burst bits / CIR
Shape outbound traffic you control, so TCP sees delay and backs off gracefully. Police inbound traffic you cannot shape, accepting that drops will trigger retransmission.
Slow start deliberately sends bursts. A tight policer drops them, TCP interprets that as congestion and collapses its window, so measured throughput falls far below the committed rate.