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Comment: Cubic default in Windows Server 2019

An enhancement of BIC, this was added to the BIC implementation in Linux 2.6.16, and became the default algorithm in 2.6.19. In Linux 2.6.26, the algorithm was improved to converge faster on LFNs. In September 2009, a CUBIC implementation was announced as a patch to FreeBSD. In December 2018, Microsoft documented that Windows Server 2019 changed the "default TCP congestion provider to Cubic to give you more throughput".


  • CUBIC: A New TCP-Friendly High-Speed TCP Variant, S. Ha, I. Rhee and L. Xu, ACM SIGOPS Operating System Review, Volume 42, Issue 5, July 2008, Page(s):64-74
  • kernel diff for CUBIC TCP in Linux 2.6.26
  • RFC 8312, CUBIC for Fast Long-Distance Networks, Injong Rhee, Lisong Xu, Sangtae Ha, Alexander Zimmermann, Lars Eggert, Richard Scheffenegger, February 2018