129f269dcSLawrence Stewart.\" 229f269dcSLawrence Stewart.\" Copyright (c) 2009 Lawrence Stewart <lstewart@FreeBSD.org> 329f269dcSLawrence Stewart.\" Copyright (c) 2010-2011 The FreeBSD Foundation 429f269dcSLawrence Stewart.\" All rights reserved. 529f269dcSLawrence Stewart.\" 629f269dcSLawrence Stewart.\" Portions of this documentation were written at the Centre for Advanced 7891b8ed4SLawrence Stewart.\" Internet Architectures, Swinburne University of Technology, Melbourne, 8891b8ed4SLawrence Stewart.\" Australia by David Hayes under sponsorship from the FreeBSD Foundation. 929f269dcSLawrence Stewart.\" 1029f269dcSLawrence Stewart.\" Redistribution and use in source and binary forms, with or without 1129f269dcSLawrence Stewart.\" modification, are permitted provided that the following conditions 1229f269dcSLawrence Stewart.\" are met: 1329f269dcSLawrence Stewart.\" 1. Redistributions of source code must retain the above copyright 1429f269dcSLawrence Stewart.\" notice, this list of conditions and the following disclaimer. 1529f269dcSLawrence Stewart.\" 2. Redistributions in binary form must reproduce the above copyright 1629f269dcSLawrence Stewart.\" notice, this list of conditions and the following disclaimer in the 1729f269dcSLawrence Stewart.\" documentation and/or other materials provided with the distribution. 1829f269dcSLawrence Stewart.\" 1929f269dcSLawrence Stewart.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 2029f269dcSLawrence Stewart.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2129f269dcSLawrence Stewart.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2229f269dcSLawrence Stewart.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 2329f269dcSLawrence Stewart.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2429f269dcSLawrence Stewart.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2529f269dcSLawrence Stewart.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2629f269dcSLawrence Stewart.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2729f269dcSLawrence Stewart.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2829f269dcSLawrence Stewart.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2929f269dcSLawrence Stewart.\" SUCH DAMAGE. 3029f269dcSLawrence Stewart.\" 31*767964fdSTom Hukins.Dd February 4, 2023 3229f269dcSLawrence Stewart.Dt CC_CUBIC 4 3329f269dcSLawrence Stewart.Os 3429f269dcSLawrence Stewart.Sh NAME 3529f269dcSLawrence Stewart.Nm cc_cubic 3629f269dcSLawrence Stewart.Nd CUBIC Congestion Control Algorithm 3729f269dcSLawrence Stewart.Sh DESCRIPTION 3829f269dcSLawrence StewartThe CUBIC congestion control algorithm was designed to provide increased 3929f269dcSLawrence Stewartthroughput in fast and long-distance networks. 40bb1d472dSRichard ScheffeneggerThe CUBIC congestion control algorithm is the default for TCP. 4129f269dcSLawrence StewartIt attempts to maintain fairness when competing with legacy NewReno TCP in lower 4229f269dcSLawrence Stewartspeed scenarios where NewReno is able to operate adequately. 4329f269dcSLawrence Stewart.Pp 4429f269dcSLawrence StewartThe congestion window is increased as a function of the time elapsed since the 4529f269dcSLawrence Stewartlast congestion event. 4629f269dcSLawrence StewartDuring regular operation, the window increase function follows a cubic function, 4729f269dcSLawrence Stewartwith the inflection point set to be the congestion window value reached at the 4829f269dcSLawrence Stewartlast congestion event. 4929f269dcSLawrence StewartCUBIC also calculates an estimate of the congestion window that NewReno would 5029f269dcSLawrence Stewarthave achieved at a given time after a congestion event. 5129f269dcSLawrence StewartWhen updating the congestion window, the algorithm will choose the larger of the 5229f269dcSLawrence Stewartcalculated CUBIC and estimated NewReno windows. 5329f269dcSLawrence Stewart.Pp 5429f269dcSLawrence StewartCUBIC also backs off less on congestion by changing the multiplicative decrease 5529f269dcSLawrence Stewartfactor from 1/2 (used by standard NewReno TCP) to 4/5. 5629f269dcSLawrence Stewart.Pp 5729f269dcSLawrence StewartThe implementation was done in a clean-room fashion, and is based on the 5829f269dcSLawrence StewartInternet Draft and paper referenced in the 5929f269dcSLawrence Stewart.Sx SEE ALSO 6029f269dcSLawrence Stewartsection below. 6129f269dcSLawrence Stewart.Sh MIB Variables 6229f269dcSLawrence StewartThere are currently no tunable MIB variables. 6329f269dcSLawrence Stewart.Sh SEE ALSO 648ea5eeb9SMichael Tuexen.Xr cc_cdg 4 , 6529f269dcSLawrence Stewart.Xr cc_chd 4 , 668ea5eeb9SMichael Tuexen.Xr cc_dctcp 4 , 6729f269dcSLawrence Stewart.Xr cc_hd 4 , 6829f269dcSLawrence Stewart.Xr cc_htcp 4 , 6929f269dcSLawrence Stewart.Xr cc_newreno 4 , 7029f269dcSLawrence Stewart.Xr cc_vegas 4 , 71f772f9feSLawrence Stewart.Xr mod_cc 4 , 7229f269dcSLawrence Stewart.Xr tcp 4 , 73f772f9feSLawrence Stewart.Xr mod_cc 9 7429f269dcSLawrence Stewart.Rs 7529f269dcSLawrence Stewart.%A "Sangtae Ha" 7629f269dcSLawrence Stewart.%A "Injong Rhee" 7729f269dcSLawrence Stewart.%A "Lisong Xu" 7829f269dcSLawrence Stewart.%T "CUBIC for Fast Long-Distance Networks" 79b2dfb50fSWolfram Schneider.%U "https://tools.ietf.org/id/draft-rhee-tcpm-cubic-02.txt" 8029f269dcSLawrence Stewart.Re 8129f269dcSLawrence Stewart.Rs 8229f269dcSLawrence Stewart.%A "Sangtae Ha" 8329f269dcSLawrence Stewart.%A "Injong Rhee" 8429f269dcSLawrence Stewart.%A "Lisong Xu" 8529f269dcSLawrence Stewart.%T "CUBIC: a new TCP-friendly high-speed TCP variant" 8629f269dcSLawrence Stewart.%J "SIGOPS Oper. Syst. Rev." 8729f269dcSLawrence Stewart.%V "42" 8829f269dcSLawrence Stewart.%N "5" 8929f269dcSLawrence Stewart.%D "July 2008" 9029f269dcSLawrence Stewart.%P "64-74" 9129f269dcSLawrence Stewart.Re 9229f269dcSLawrence Stewart.Sh ACKNOWLEDGEMENTS 9329f269dcSLawrence StewartDevelopment and testing of this software were made possible in part by grants 9429f269dcSLawrence Stewartfrom the FreeBSD Foundation and Cisco University Research Program Fund at 9529f269dcSLawrence StewartCommunity Foundation Silicon Valley. 9629f269dcSLawrence Stewart.Sh HISTORY 9729f269dcSLawrence StewartThe 9829f269dcSLawrence Stewart.Nm 9929f269dcSLawrence Stewartcongestion control module first appeared in 10029f269dcSLawrence Stewart.Fx 9.0 . 10129f269dcSLawrence Stewart.Pp 102*767964fdSTom HukinsThis became the default congestion algorithm for FreeBSD in version 103*767964fdSTom Hukins.Fx 14.0 , 104*767964fdSTom Hukinsreplacing 105*767964fdSTom Hukins.Xr cc_newreno 4 . 106*767964fdSTom Hukins.Pp 10729f269dcSLawrence StewartThe module was first released in 2009 by Lawrence Stewart whilst studying at 108891b8ed4SLawrence StewartSwinburne University of Technology's Centre for Advanced Internet Architectures, 109891b8ed4SLawrence StewartMelbourne, Australia. 11029f269dcSLawrence StewartMore details are available at: 11129f269dcSLawrence Stewart.Pp 11229f269dcSLawrence Stewarthttp://caia.swin.edu.au/urp/newtcp/ 11329f269dcSLawrence Stewart.Sh AUTHORS 11429f269dcSLawrence Stewart.An -nosplit 11529f269dcSLawrence StewartThe 11629f269dcSLawrence Stewart.Nm 11729f269dcSLawrence Stewartcongestion control module and this manual page were written by 1186c899950SBaptiste Daroussin.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org 11929f269dcSLawrence Stewartand 1206c899950SBaptiste Daroussin.An David Hayes Aq Mt david.hayes@ieee.org . 121