RFC 9406

HyStart++: Modified Slow Start for TCP, May 2023

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P. Balasubramanian
Y. Huang
M. Olson
tcpm (wit)

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DOI:  https://doi.org/10.17487/RFC9406

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This document describes HyStart++, a simple modification to the slow start phase of congestion control algorithms. Slow start can overshoot the ideal send rate in many cases, causing high packet loss and poor performance. HyStart++ uses increase in round-trip delay as a heuristic to find an exit point before possible overshoot. It also adds a mitigation to prevent jitter from causing premature slow start exit.

For the definition of Status, see RFC 2026.

For the definition of Stream, see RFC 8729.

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