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diff --git a/static/freebsd/man4/cc_cdg.4 3.html b/static/freebsd/man4/cc_cdg.4 3.html new file mode 100644 index 00000000..2a9418e1 --- /dev/null +++ b/static/freebsd/man4/cc_cdg.4 3.html @@ -0,0 +1,129 @@ +<table class="head"> + <tr> + <td class="head-ltitle">CC_CDG(4)</td> + <td class="head-vol">Device Drivers Manual</td> + <td class="head-rtitle">CC_CDG(4)</td> + </tr> +</table> +<div class="manual-text"> +<section class="Sh"> +<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> +<p class="Pp"><code class="Nm">cc_cdg</code> — <span class="Nd">CDG + Congestion Control Algorithm</span></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> +<p class="Pp">CAIA-Delay Gradient (CDG) is a hybrid congestion control algorithm + which reacts to both packet loss and inferred queuing delay. It attempts to + operate as a delay-based algorithm where possible, but utilises heuristics + to detect loss-based TCP cross traffic and will compete effectively as + required. CDG is therefore incrementally deployable and suitable for use on + shared networks.</p> +<p class="Pp">During delay-based operation, CDG uses a delay-gradient based + probabilistic backoff mechanism, and will also try to infer non congestion + related packet losses and avoid backing off when they occur. During + loss-based operation, CDG essentially reverts to + <a class="Xr">cc_newreno(4)</a>-like behaviour.</p> +<p class="Pp">CDG switches to loss-based operation when it detects that a + configurable number of consecutive delay-based backoffs have had no + measurable effect. It periodically attempts to return to delay-based + operation, but will keep switching back to loss-based operation as + required.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="MIB_Variables"><a class="permalink" href="#MIB_Variables">MIB + Variables</a></h1> +<p class="Pp">The algorithm exposes the following variables in the + <var class="Va">net.inet.tcp.cc.cdg</var> branch of the + <a class="Xr">sysctl(3)</a> MIB:</p> +<dl class="Bl-tag"> + <dt id="version"><var class="Va">version</var></dt> + <dd>Current algorithm/implementation version number.</dd> + <dt id="beta_delay"><var class="Va">beta_delay</var></dt> + <dd>Delay-based window decrease factor as a percentage (on delay-based + backoff, w = w * beta_delay / 100). Default is 70.</dd> + <dt id="beta_loss"><var class="Va">beta_loss</var></dt> + <dd>Loss-based window decrease factor as a percentage (on loss-based backoff, + w = w * beta_loss / 100). Default is 50.</dd> + <dt id="exp_backoff_scale"><var class="Va">exp_backoff_scale</var></dt> + <dd>Scaling parameter for the probabilistic exponential backoff. Default is + 2.</dd> + <dt id="smoothing_factor"><var class="Va">smoothing_factor</var></dt> + <dd>Number of samples used for moving average smoothing (0 means no + smoothing). Default is 8.</dd> + <dt id="loss_compete_consec_cong"><var class="Va">loss_compete_consec_cong</var></dt> + <dd>Number of consecutive delay-gradient based congestion episodes which will + trigger loss-based CC compatibility. Default is 5.</dd> + <dt id="loss_compete_hold_backoff"><var class="Va">loss_compete_hold_backoff</var></dt> + <dd>Number of consecutive delay-gradient based congestion episodes to hold the + window backoff for loss-based CC compatibility. Default is 5.</dd> + <dt id="alpha_inc"><var class="Va">alpha_inc</var></dt> + <dd>If non-zero, this enables an experimental mode where CDG's window increase + factor (alpha) is increased by 1 MSS every <var class="Va">alpha_inc</var> + RTTs during congestion avoidance mode. (Setting + <var class="Va">alpha_inc</var> to 1 results in the most aggressive growth + of the window increase factor over time. Use higher + <var class="Va">alpha_inc</var> values for slower growth.) Default is + 0.</dd> +</dl> +</section> +<section class="Sh"> +<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE + ALSO</a></h1> +<p class="Pp"><a class="Xr">cc_chd(4)</a>, <a class="Xr">cc_cubic(4)</a>, + <a class="Xr">cc_dctcp(4)</a>, <a class="Xr">cc_hd(4)</a>, + <a class="Xr">cc_htcp(4)</a>, <a class="Xr">cc_newreno(4)</a>, + <a class="Xr">cc_vegas(4)</a>, <a class="Xr">h_ertt(4)</a>, + <a class="Xr">mod_cc(4)</a>, <a class="Xr">tcp(4)</a>, + <a class="Xr">khelp(9)</a>, <a class="Xr">mod_cc(9)</a></p> +<p class="Pp"><cite class="Rs"><span class="RsA">D. A. Hayes</span> and + <span class="RsA">G. Armitage</span>, <span class="RsT">Revisiting TCP + Congestion Control using Delay Gradients</span>, <i class="RsJ">Networking + 2011 Proceedings, Part II</i>, <span class="RsP">328-341</span>, + <span class="RsD">May 2011</span>.</cite></p> +<p class="Pp"><cite class="Rs"><span class="RsA">N. Khademi</span> and + <span class="RsA">G. Armitage</span>, <span class="RsT">Minimising RTT + across homogeneous 802.11 WLANs with CAIA Delay-Gradient TCP (v0.1)</span>, + <span class="RsR">CAIA Technical Report 121113A</span>, + <a class="RsU" href="http://caia.swin.edu.au/reports/121113A/CAIA-TR-121113A.pdf">http://caia.swin.edu.au/reports/121113A/CAIA-TR-121113A.pdf</a>, + <span class="RsD">November 2012</span>.</cite></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="ACKNOWLEDGEMENTS"><a class="permalink" href="#ACKNOWLEDGEMENTS">ACKNOWLEDGEMENTS</a></h1> +<p class="Pp">Development and testing of this software were made possible in + part by grants from the FreeBSD Foundation and The Cisco University Research + Program Fund, a corporate advised fund of Silicon Valley Community + Foundation.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1> +<p class="Pp">The <code class="Nm">cc_cdg</code> congestion control module first + appeared in <span class="Ux">FreeBSD 9.2</span>.</p> +<p class="Pp">The module was first released in 2011 by David Hayes whilst + working on the NewTCP research project at Swinburne University of + Technology's Centre for Advanced Internet Architectures, Melbourne, + Australia. More details are available at:</p> +<p class="Pp">http://caia.swin.edu.au/urp/newtcp/</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1> +<p class="Pp">The <code class="Nm">cc_cdg</code> congestion control module was + written by <span class="An">David Hayes</span> + <<a class="Mt" href="mailto:david.hayes@ieee.org">david.hayes@ieee.org</a>>. + This manual page was written by <span class="An">Lawrence Stewart</span> + <<a class="Mt" href="mailto:lstewart@FreeBSD.org">lstewart@FreeBSD.org</a>> + and <span class="An">Grenville Armitage</span> + <<a class="Mt" href="mailto:garmitage@swin.edu.au">garmitage@swin.edu.au</a>>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1> +<p class="Pp">The underlying algorithm and parameter values are still a work in + progress and may not be optimal for some network scenarios.</p> +</section> +</div> +<table class="foot"> + <tr> + <td class="foot-date">May 13, 2021</td> + <td class="foot-os">FreeBSD 15.0</td> + </tr> +</table> |