HyStart++: Modified Slow Start for TCP

Document Type Replaced Internet-Draft (individual)
Authors Praveen Balasubramanian  , Yi Huang  , Matt Olson 
Last updated 2020-04-26
Replaced by draft-ietf-tcpm-hystartplusplus
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Intended RFC status (None)
Expired & archived
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This informational memo describes HyStart++, a simple modification to the slow start phase of TCP congestion control algorithms. HyStart++ combines the use of one variant of HyStart and Limited Slow Start (LSS) to prevent overshooting of the ideal sending rate, while also mitigating poor performance which can result from false positives when HyStart is used alone. This memo also describes the details of the current implementation in the Windows operating system.


Praveen Balasubramanian (pravb@microsoft.com)
Yi Huang (huanyi@microsoft.com)
Matt Olson (maolson@microsoft.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)