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.\"
.\" Copyright (c) 2010-2011 The FreeBSD Foundation
.\" All rights reserved.
.\"
.\" This documentation was written at the Centre for Advanced Internet
.\" Architectures, Swinburne University of Technology, Melbourne, Australia by
.\" David Hayes and Lawrence Stewart under sponsorship from the FreeBSD
.\" Foundation.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd September 15, 2011
.Dt MOD_CC 4
.Os
.Sh NAME
.Nm mod_cc
.Nd Modular congestion control
.Sh DESCRIPTION
The modular congestion control framework allows the TCP implementation to
dynamically change the congestion control algorithm used by new and existing
connections.
Algorithms are identified by a unique
.Xr ascii 7
name.
Algorithm modules can be compiled into the kernel or loaded as kernel modules
using the
.Xr kld 4
facility.
.Pp
The default algorithm is NewReno, and all connections use the default unless
explicitly overridden using the TCP_CONGESTION socket option (see
.Xr tcp 4
for details).
The default can be changed using a
.Xr sysctl 3
MIB variable detailed in the
.Sx MIB Variables
section below.
.Sh MIB Variables
The framework exposes the following variables in the
.Va net.inet.tcp.cc
branch of the
.Xr sysctl 3
MIB:
.Bl -tag -width ".Va available"
.It Va available
Read-only list of currently available congestion control algorithms by name.
.It Va algorithm
Returns the current default congestion control algorithm when read, and changes
the default when set.
When attempting to change the default algorithm, this variable should be set to
one of the names listed by the
.Va net.inet.tcp.cc.available
MIB variable.
.El
.Sh SEE ALSO
.Xr cc_chd 4 ,
.Xr cc_cubic 4 ,
.Xr cc_hd 4 ,
.Xr cc_htcp 4 ,
.Xr cc_newreno 4 ,
.Xr cc_vegas 4 ,
.Xr tcp 4 ,
.Xr mod_cc 9
.Sh ACKNOWLEDGEMENTS
Development and testing of this software were made possible in part by grants
from the FreeBSD Foundation and Cisco University Research Program Fund at
Community Foundation Silicon Valley.
.Sh HISTORY
The
.Nm
modular congestion control framework first appeared in
.Fx 9.0 .
.Pp
The framework was first released in 2007 by James Healy and Lawrence Stewart
whilst working on the NewTCP research project at Swinburne University of
Technology's Centre for Advanced Internet Architectures, Melbourne, Australia,
which was made possible in part by a grant from the Cisco University Research
Program Fund at Community Foundation Silicon Valley.
More details are available at:
.Pp
http://caia.swin.edu.au/urp/newtcp/
.Sh AUTHORS
.An -nosplit
The
.Nm
facility was written by
.An Lawrence Stewart Aq lstewart@FreeBSD.org ,
.An James Healy Aq jimmy@deefa.com
and
.An David Hayes Aq david.hayes@ieee.org .
.Pp
This manual page was written by
.An David Hayes Aq david.hayes@ieee.org
and
.An Lawrence Stewart Aq lstewart@FreeBSD.org .
|
