Compute the bandwidth-delay product: how many bytes are in flight on a link at any instant.
The product of rate and delay is the amount of data the path holds — the volume that has left the sender but has not yet been acknowledged. Dividing it by the MTU gives the packet count the path stores. The BDP is the single number that sizes TCP windows, socket buffers and switch buffers; anything smaller than it leaves the link idle waiting for acknowledgements.
Bandwidth Delay Product
BDP = bandwidth × RTT, converted from bits to bytes by dividing by 8.
BDP = bandwidth × RTT, converted from bits to bytes by dividing by 8. The product of rate and delay is the amount of data the path holds — the volume that has left the sender but has not yet been acknowledged. Dividing it by the MTU gives the packet count the path stores.
The BDP is the single number that sizes TCP windows, socket buffers and switch buffers; anything smaller than it leaves the link idle waiting for acknowledgements.
This calculator takes 3 inputs: Link bandwidth, Round-trip time, Packet size (MTU). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
No. Buffers much larger than the BDP cause bufferbloat: packets queue instead of being dropped, latency climbs and loss-based congestion control loses its feedback signal. Target the BDP, not a multiple of it.