Technical Summary
CUBIC is a standard TCP congestion control algorithm that uses a cubic function instead of a linear congestion window increase function to improve scalability and stability over fast and long-distance networks. CUBIC has been adopted as the default TCP congestion control algorithm by the Linux, Windows, and Apple stacks.
This document updates the specification of CUBIC to include algorithmic improvements based on these implementations and recent academic work. Based on the extensive deployment experience with CUBIC, it also moves the specification to the Standards Track, obsoleting RFC 8312. This also requires updating RFC 5681, to allow for CUBIC's occasionally more aggressive sending behavior.
Working Group Summary
Although there was a broad consensus in the WG, it was not unanimous. Dissenters argued that the process in RFC5033 was not rigorously observed,
and that strictly speaking, Cubic may not be fair to Reno as required in that document.
There was rough consensus to publish anyway, as (1) Cubic is widely deployed as a de facto standard, (2) broadly speaking, Reno continues to function effectively despite widespread Cubic deployment and analytical results that suggest unfairness, and (3) many were satisfied by the document's attempt to comply with RFC5033.
Document Quality
All major OSes support Cubic. It is the default for Linux and Windows.
Personnel
The document shepherd is Yoshifumi Nishida. The Responsible AD is Martin Duke.