Bandwidth-Delay Product

The bandwidth-delay product tells you how many bits can be traveling across a network path at once if the link is kept busy continuously. It comes from multiplying the sending rate by the time it takes a signal to make a round trip, so it estimates the amount of unacknowledged data a sender must have outstanding to fully utilize the path. In practice, it gives the minimum window size needed to avoid leaving the link idle.

Use this when sizing TCP windows, buffers, or other flow-control limits for high-speed, high-latency links. It is especially useful for long-distance WANs, satellite links, and any situation where throughput depends on keeping enough data in flight.

• Using one-way delay instead of round-trip time
• Mixing units without converting milliseconds to seconds or megabits to bits
• Treating BDP as the actual throughput rather than the in-flight data needed to achieve it