NAME

       mod_cc — Modular congestion control

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
       ascii(7) name.  Algorithm modules can be compiled into the kernel or loaded as kernel modules  using  the
       kld(4) facility.

       The  default algorithm is NewReno, and all connections use the default unless explicitly overridden using
       the TCP_CONGESTION socket option (see tcp(4) for details).  The default can be changed using a  sysctl(3)
       MIB variable detailed in the “MIB Variables” section below.

MIB Variables

       The framework exposes the following variables in the net.inet.tcp.cc branch of the sysctl(3) MIB:

       available  Read-only list of currently available congestion control algorithms by name.

       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 net.inet.tcp.cc.available MIB variable.

SEE ALSO

       cc_chd(4), cc_cubic(4), cc_hd(4), cc_htcp(4), cc_newreno(4), cc_vegas(4), tcp(4), mod_cc(9)

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.

HISTORY

       The mod_cc modular congestion control framework first appeared in FreeBSD 9.0.

       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:

       http://caia.swin.edu.au/urp/newtcp/

AUTHORS

       The mod_cc facility was written by Lawrence Stewart <lstewart@FreeBSD.org>, James Healy <jimmy@deefa.com>
       and David Hayes <david.hayes@ieee.org>.

       This  manual  page  was  written   by   David   Hayes   <david.hayes@ieee.org>   and   Lawrence   Stewart
       <lstewart@FreeBSD.org>.

Debian                                         September 15, 2011                                      MOD_CC(4)