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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>37.3.1.0.3 Delay and Loss Modules</TITLE><META NAME="description" CONTENT="37.3.1.0.3 Delay and Loss Modules"><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="previous" HREF="node534.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node534.html"><LINK REL="up" HREF="node532.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node532.html"><LINK REL="next" HREF="node536.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node536.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html9630" HREF="node536.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node536.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html9624" HREF="node532.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node532.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html9620" HREF="node534.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node534.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html9626" 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="tex2html9628" 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="tex2html9631" HREF="node536.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node536.html">37.3.2 Packet Forwarding</A><B> Up:</B> <A NAME="tex2html9625" HREF="node532.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node532.html">37.3.1 Object Linkage</A><B> Previous:</B> <A NAME="tex2html9621" HREF="node534.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node534.html">37.3.1.0.2 Session Helper</A>   <B> <A NAME="tex2html9627" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html9629" 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="SECTION08131030000000000000">37.3.1.0.3 Delay and Loss Modules</A></H4><P>Each receiver in a group requires a delay module thatreflects its delay with respect to the particular source.When the receiver joins a group, []join-group identifies all session helpers in <TT>session_</TT>.If the destination index matches the group addressthe receiver are joining, then the following actions are performed.<OL><LI>A new slot of the session helper is created and assigned to the receiver.</LI><LI>The routine computes the accumulated bandwidth and delay between the source and receiver using the SessionSim instance procedures []get-bw and []get-delay.</LI><LI>A constant random variable is created; it will generate random delivery times using the accumulative delay as an estimate of the average delay.</LI><LI>A new delay module is created with the end-to-end bandwidth characteristics, and the random variable generator provides the delay estimates.</LI><LI>The delay module in inserted into the session helper and interposed between the helper and the receiver.</LI></OL>See Section <A HREF="node527.html#sec:loss-config" tppabs="http://www.isi.edu/nsnam/ns/doc/node527.html#sec:loss-config">37.1.2</A> for similarlyinserting a loss module for a receiver.<P><PRE>SessionSim instproc join-group { agent group } { $self instvar session_ foreach index [array names session_] { set pair [split $index :] if {[lindex $pair 1] == $group} { # Note: must insert the chain of loss, delay, # and destination agent in this order: $session_($index) insert $agent # insert destination agent into session replicator; set src [lindex $pair 0] # find accum. b/w and delay; set dst [[$agent set node_] id] set accu_bw [$self get-bw $dst $src] set delay [$self get-delay $dst $src] set random_variable [new RandomVariable/Constant] # set delay variable ; $random_variable set avg_ $delay set delay_module [new DelayModel] # configure the delay module; $delay_module bandwidth $accu_bw $delay_module ranvar $random_variable $session_($index) insert-module $delay_module $agent # insert the delay module; } }}</PRE><P><HR><!--Navigation Panel--><A NAME="tex2html9630" HREF="node536.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node536.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html9624" HREF="node532.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node532.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html9620" HREF="node534.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node534.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html9626" 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="tex2html9628" 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="tex2html9631" HREF="node536.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node536.html">37.3.2 Packet Forwarding</A><B> Up:</B> <A NAME="tex2html9625" HREF="node532.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node532.html">37.3.1 Object Linkage</A><B> Previous:</B> <A NAME="tex2html9621" HREF="node534.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node534.html">37.3.1.0.2 Session Helper</A>   <B> <A NAME="tex2html9627" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html9629" 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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