2 .\" Copyright (c) 2009 Lawrence Stewart <lstewart@FreeBSD.org>
3 .\" Copyright (c) 2011 The FreeBSD Foundation
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38 .Nd NewReno Congestion Control Algorithm
40 .In netinet/cc/cc_newreno.h
42 The NewReno congestion control algorithm is the default for TCP.
43 Details about the algorithm can be found in RFC5681.
47 module supports a number of socket options under TCP_CCALGOOPT (refer to
50 .Xr moc_cc 9 for details)
58 socket options use this structure defined in
59 <sys/netinet/cc/cc_newreno.h>:
61 struct cc_newreno_opts {
66 .Bl -tag -width ".Va CC_NEWRENO_BETA_ECN"
67 .It Va CC_NEWRENO_BETA
68 Multiplicative window decrease factor, specified as a percentage, applied to
69 the congestion window in response to a congestion signal per: cwnd = (cwnd *
70 CC_NEWRENO_BETA) / 100.
72 .It Va CC_NEWRENO_BETA_ECN
73 Multiplicative window decrease factor, specified as a percentage, applied to
74 the congestion window in response to an ECN congestion signal when
75 .Va net.inet.tcp.cc.abe=1
76 per: cwnd = (cwnd * CC_NEWRENO_BETA_ECN) / 100.
79 The algorithm exposes these variables in the
80 .Va net.inet.tcp.cc.newreno
84 .Bl -tag -width ".Va beta_ecn"
86 Multiplicative window decrease factor, specified as a percentage, applied to
87 the congestion window in response to a congestion signal per: cwnd = (cwnd *
91 Multiplicative window decrease factor, specified as a percentage, applied to
92 the congestion window in response to an ECN congestion signal when
93 .Va net.inet.tcp.cc.abe=1
94 per: cwnd = (cwnd * beta_ecn) / 100.
109 .%T "TCP Congestion Control"
115 .%A "Grenville Armitage"
116 .%A "Gorry Fairhurst"
117 .%T "TCP Alternative Backoff with ECN (ABE)"
120 .%N "draft-ietf-tcpm-alternativebackoff-ecn"
121 .%O "work in progress"
124 Development and testing of this software were made possible in part by grants
125 from the FreeBSD Foundation and Cisco University Research Program Fund at
126 Community Foundation Silicon Valley.
130 congestion control algorithm first appeared in its modular form in
133 The module was first released in 2007 by James Healy and Lawrence Stewart whilst
134 working on the NewTCP research project at Swinburne University of Technology's
135 Centre for Advanced Internet Architectures, Melbourne, Australia, which was made
136 possible in part by a grant from the Cisco University Research Program Fund at
137 Community Foundation Silicon Valley.
138 More details are available at:
140 http://caia.swin.edu.au/urp/newtcp/
145 congestion control module was written by
146 .An James Healy Aq Mt jimmy@deefa.com ,
147 .An Lawrence Stewart Aq Mt lstewart@FreeBSD.org
149 .An David Hayes Aq Mt david.hayes@ieee.org .
151 Support for TCP ABE was added by
152 .An Tom Jones Aq Mt tj@enoti.me .
154 This manual page was written by
155 .An Lawrence Stewart Aq Mt lstewart@FreeBSD.org .