How can I optimize TCP window size settings for better throughput over high-latency networks?

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How can I optimize TCP window size settings for better throughput over high-latency networks?

Asked on Dec 18, 2025

Answer

Optimizing TCP window size settings for high-latency networks involves adjusting the TCP receive window to allow more data to be in transit before requiring an acknowledgment, thus improving throughput. This is particularly useful in environments where latency is high, such as satellite links or transcontinental connections.

Example Concept: The TCP window size determines the amount of data that can be sent before receiving an acknowledgment. In high-latency networks, increasing the TCP window size allows for more outstanding data, which can significantly improve throughput by keeping the pipeline full. This is often configured on routers or endpoints using TCP window scaling, a feature that extends the window size beyond the default 65,535 bytes, allowing for more efficient data flow over long distances.

Additional Comment:

TCP window scaling must be enabled on both ends of the connection for it to be effective.
Calculate the optimal window size using the formula: Bandwidth Delay Product (BDP) = Bandwidth (bps) * Round Trip Time (RTT) (seconds).
Ensure that your network devices and operating systems support TCP window scaling.
Monitor the network to verify that changes improve throughput without causing congestion or packet loss.

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