767964fd86
CUBIC replaced NEWRENO as the default congestion control algorithm inbb1d472d79. Update man pages to reflect that. Fixes:bb1d472d79Reviewed by: imp Pull Request: https://github.com/freebsd/freebsd-src/pull/641
123 lines
4.3 KiB
Groff
123 lines
4.3 KiB
Groff
.\"
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.\" Copyright (c) 2009 Lawrence Stewart <lstewart@FreeBSD.org>
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.\" Copyright (c) 2010-2011 The FreeBSD Foundation
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.\" All rights reserved.
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.\"
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.\" Portions of this documentation were written at the Centre for Advanced
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.\" Internet Architectures, Swinburne University of Technology, Melbourne,
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.\" Australia by David Hayes under sponsorship from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 4, 2023
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.Dt CC_CUBIC 4
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.Os
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.Sh NAME
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.Nm cc_cubic
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.Nd CUBIC Congestion Control Algorithm
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.Sh DESCRIPTION
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The CUBIC congestion control algorithm was designed to provide increased
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throughput in fast and long-distance networks.
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The CUBIC congestion control algorithm is the default for TCP.
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It attempts to maintain fairness when competing with legacy NewReno TCP in lower
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speed scenarios where NewReno is able to operate adequately.
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.Pp
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The congestion window is increased as a function of the time elapsed since the
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last congestion event.
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During regular operation, the window increase function follows a cubic function,
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with the inflection point set to be the congestion window value reached at the
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last congestion event.
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CUBIC also calculates an estimate of the congestion window that NewReno would
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have achieved at a given time after a congestion event.
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When updating the congestion window, the algorithm will choose the larger of the
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calculated CUBIC and estimated NewReno windows.
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.Pp
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CUBIC also backs off less on congestion by changing the multiplicative decrease
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factor from 1/2 (used by standard NewReno TCP) to 4/5.
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.Pp
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The implementation was done in a clean-room fashion, and is based on the
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Internet Draft and paper referenced in the
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.Sx SEE ALSO
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section below.
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.Sh MIB Variables
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There are currently no tunable MIB variables.
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.Sh SEE ALSO
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.Xr cc_cdg 4 ,
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.Xr cc_chd 4 ,
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.Xr cc_dctcp 4 ,
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.Xr cc_hd 4 ,
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.Xr cc_htcp 4 ,
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.Xr cc_newreno 4 ,
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.Xr cc_vegas 4 ,
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.Xr mod_cc 4 ,
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.Xr tcp 4 ,
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.Xr mod_cc 9
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.Rs
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.%A "Sangtae Ha"
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.%A "Injong Rhee"
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.%A "Lisong Xu"
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.%T "CUBIC for Fast Long-Distance Networks"
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.%U "https://tools.ietf.org/id/draft-rhee-tcpm-cubic-02.txt"
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.Re
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.Rs
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.%A "Sangtae Ha"
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.%A "Injong Rhee"
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.%A "Lisong Xu"
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.%T "CUBIC: a new TCP-friendly high-speed TCP variant"
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.%J "SIGOPS Oper. Syst. Rev."
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.%V "42"
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.%N "5"
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.%D "July 2008"
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.%P "64-74"
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.Re
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.Sh ACKNOWLEDGEMENTS
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Development and testing of this software were made possible in part by grants
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from the FreeBSD Foundation and Cisco University Research Program Fund at
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Community Foundation Silicon Valley.
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.Sh HISTORY
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The
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.Nm
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congestion control module first appeared in
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.Fx 9.0 .
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.Pp
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This became the default congestion algorithm for FreeBSD in version
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.Fx 14.0 ,
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replacing
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.Xr cc_newreno 4 .
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.Pp
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The module was first released in 2009 by Lawrence Stewart whilst studying at
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Swinburne University of Technology's Centre for Advanced Internet Architectures,
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Melbourne, Australia.
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More details are available at:
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.Pp
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http://caia.swin.edu.au/urp/newtcp/
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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congestion control module and this manual page were written by
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.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org
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and
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.An David Hayes Aq Mt david.hayes@ieee.org .
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