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<html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><!--Converted with jLaTeX2HTML 2002 (1.62) JA patch-1.4patched version by: Kenshi Muto, Debian Project.LaTeX2HTML 2002 (1.62),original version by: Nikos Drakos, CBLU, University of Leeds* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan* with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --><HTML><HEAD><TITLE>31.4.0.0.3 Functions for Window Management</TITLE><META NAME="description" CONTENT="31.4.0.0.3 Functions for Window Management"><META NAME="keywords" CONTENT="everything"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"><META NAME="Generator" CONTENT="jLaTeX2HTML v2002 JA patch-1.4"><META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"><LINK REL="STYLESHEET" HREF="everything.css" tppabs="http://www.isi.edu/nsnam/ns/doc/everything.css"><LINK REL="next" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html"><LINK REL="previous" HREF="node394.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node394.html"><LINK REL="up" HREF="node392.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node392.html"><LINK REL="next" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html7453" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html7447" HREF="node392.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node392.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html7441" HREF="node394.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node394.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html7449" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html7451" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html7454" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html">31.4.0.0.4 Functions for Processing</A><B> Up:</B> <A NAME="tex2html7448" HREF="node392.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node392.html">31.4 Architecture and Internals</A><B> Previous:</B> <A NAME="tex2html7442" HREF="node394.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node394.html">31.4.0.0.2 Functions for Sending</A>   <B> <A NAME="tex2html7450" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html7452" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H4><A NAME="SECTION06240030000000000000">31.4.0.0.3 Functions for Window Management</A></H4><P>The usable send window at any time is given by the function <B>window()</B>.It returns the minimum of the congestion window and the variable <TT>wnd_</TT>,which represents the receiver's advertised window.<P><B>opencwnd()</B> - this function opens the congestion window. It is invokedwhen a new ACK arrives.When in slow-start, the function merely increments <TT>cwnd_</TT> by eachACK received.When in congestion avoidance, the standard configuration increments <TT>cwnd_</TT>by its reciprocal.Other window growth options are supported during congestion avoidance,but they are experimental (and not documented; contact Sally Floyd fordetails).<P><B>closecwnd(int how)</B> - this function reduces the congestion window. Itmay be invoked in several ways: when entering fast retransmit, due toa timer expiration, or due to a congestion notification (ECN bit set).Its argument <TT>how</TT> indicates how the congestion window shouldbe reduced. The value <B>0</B> is used for retransmission timeouts andfast retransmit in Tahoe TCP. It typically causes the TCP to enterslow-start and reduce <TT>ssthresh_</TT> to half the current window.The value <B>1</B> is used by Reno TCP for implementing fast recovery(which avoids returning to slow-start).The value <B>2</B> is used for reducing the window due to an ECN indication.It resets the congestion window to its initial value (usually causingslow-start), but does not alter <TT>ssthresh_</TT>.<P><HR><!--Navigation Panel--><A NAME="tex2html7453" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html7447" HREF="node392.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node392.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html7441" HREF="node394.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node394.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html7449" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html7451" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html7454" HREF="node396.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node396.html">31.4.0.0.4 Functions for Processing</A><B> Up:</B> <A NAME="tex2html7448" HREF="node392.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node392.html">31.4 Architecture and Internals</A><B> Previous:</B> <A NAME="tex2html7442" HREF="node394.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node394.html">31.4.0.0.2 Functions for Sending</A>   <B> <A NAME="tex2html7450" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html7452" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <!--End of Navigation Panel--><ADDRESS>2003-09-23</ADDRESS></BODY></HTML>⌨️ 快捷键说明
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