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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>7.3 Different types of Queue objects</TITLE><META NAME="description" CONTENT="7.3 Different types of Queue objects"><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="node70.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node70.html"><LINK REL="previous" HREF="node68.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node68.html"><LINK REL="up" HREF="node64.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node64.html"><LINK REL="next" HREF="node70.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node70.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html2376" HREF="node70.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node70.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html2370" HREF="node64.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node64.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html2364" HREF="node68.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node68.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html2372" 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="tex2html2374" 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="tex2html2377" HREF="node70.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node70.html">7.4 Commands at a</A><B> Up:</B> <A NAME="tex2html2371" HREF="node64.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node64.html">7. Queue Management and</A><B> Previous:</B> <A NAME="tex2html2365" HREF="node68.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node68.html">7.2 Example: Drop Tail</A>   <B> <A NAME="tex2html2373" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html2375" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H1><A NAME="SECTION03430000000000000000"></A><A NAME="sec:queueobjects"></A><BR>7.3 Different types of Queue objects</H1>A queue object is a general class of object capable of holding andpossibly marking or discarding packets as they travel through thesimulated topology. Configuration Parameters used for queue objects are:<DL><DT><STRONG>limit_</STRONG></DT><DD>The queue size in packets. <P></DD><DT><STRONG>blocked_</STRONG></DT><DD>Set to false by default, this is true if the queue isblocked (unable to send a packet to its downstream neighbor). <P></DD><DT><STRONG>unblock_on_resume_</STRONG></DT><DD>Set to true by default, indicates a queueshould unblock itself at the time the last packet packet sent has beentransmitted (but not necessarily received). </DD></DL><P>Other queue objects derived from the base class Queue are drop-tail, FQ,SFQ, DRR, RED and CBQ queue objects. Each are described as follows:<UL><LI>Drop-tail objects:Drop-tail objects are a subclass of Queue objects that implement simpleFIFO queue. There are no methods, configuration parameter, or statevariables that are specific to drop-tail objects. <P></LI><LI>FQ objects:FQ objects are a subclass of Queue objects that implement Fair queuing.There are no methods that are specific to FQ objects. Configuration Parameters are:<DL><DT><STRONG>secsPerByte_</STRONG></DT><DD></DD></DL>There are no state variables associated with this object. <P></LI><LI>SFQ objects:SFQ objects are a subclass of Queue objects that implement Stochastic Fairqueuing. There are no methods that are specific to SFQ objects. Configuration Parameters are:<DL><DT><STRONG>maxqueue_</STRONG></DT><DD><P></DD><DT><STRONG>buckets_</STRONG></DT><DD></DD></DL>There are no state variables associated with this object. <P></LI><LI>DRR objects:DRR objects are a subclass of Queue objects that implement deficit roundrobin scheduling. These objects implement deficit round robin schedulingamongst different flows ( A particular flow is one which has packets withthe same node and port id OR packets which have the same node id alone).Also unlike other multi-queue objects, this queue object implements asingle shared buffer space for its different flows. ConfigurationParameters are:<DL><DT><STRONG>buckets_</STRONG></DT><DD>Indicates the total number of buckets to be used forhashing each of the flows. <P></DD><DT><STRONG>blimit_</STRONG></DT><DD>Indicates the shared buffer size in bytes. <P></DD><DT><STRONG>quantum_</STRONG></DT><DD>Indicates (in bytes) how much each flow can send duringits turn. <P></DD><DT><STRONG>mask_</STRONG></DT><DD>mask_, when set to 1, means that a particular flow consistsof packets having the same node id (and possibly different port ids),otherwise a flow consists of packets having the same node and port ids. </DD></DL><P></LI><LI>RED objects:RED objects are a subclass of Queue objects that implement randomearly-detection gateways. The object can be configured to either drop or``mark'' packets. There are no methods that are specific to RED objects. Configuration Parameters are:<DL><DT><STRONG>bytes_</STRONG></DT><DD>Set to "true" to enable ``byte-mode'' RED, where the sizeof arriving packets affect the likelihood of marking (dropping) packets. <P></DD><DT><STRONG>queue-in-bytes_</STRONG></DT><DD>Set to "true" to measure the average queue size in bytes rather thanpackets. Enabling this option also causes thresh_ and maxthresh_ to beautomatically scaled by mean_pktsize_ (see below). <P></DD><DT><STRONG>thresh_</STRONG></DT><DD>The minimum threshold for the average queue size in packets. <P></DD><DT><STRONG>maxthresh_</STRONG></DT><DD>The maximum threshold for the average queue size in packets. <P></DD><DT><STRONG>mean_pktsize_</STRONG></DT><DD>A rough estimate of the average packet size in bytes. Used in updating thecalculated average queue size after an idle period. <P></DD><DT><STRONG>q_weight_</STRONG></DT><DD>The queue weight, used in the exponential-weighted moving average forcalculating the average queue size. <P></DD><DT><STRONG>wait_</STRONG></DT><DD>Set to true to maintain an interval between dropped packets. <P></DD><DT><STRONG>linterm_</STRONG></DT><DD>As the average queue size varies between "thresh_" and "maxthresh_", thepacket dropping probability varies between 0 and "1/linterm". <P></DD><DT><STRONG>setbit_</STRONG></DT><DD>Set to "true" to mark packets by setting the congestion indication bit inpacket headers rather than drop packets. <P></DD><DT><STRONG>drop-tail_</STRONG></DT><DD>Set to true to use drop-tail rather than randomdrop when the queueoverflows or the average queue size exceeds "maxthresh_". For a furtherexplanation of these variables, see [2]. </DD></DL>None of the state variables of the RED implementation are accessible. <P></LI><LI>CBQ objects:CBQ objects are a subclass of Queue objects that implement class-basedqueueing. <P><TT>$cbq insert class</TT><BR>Insert traffic class class into the link-sharing structure associated withlink object cbq. <P><TT>$cbq bind cbqclass id1 [$id2]</TT><BR>Cause packets containing flow id id1 (or those in the range id1 toid2 inclusive) to be associated with the traffic class cbqclass. <P><TT>$cbq algorithm alg</TT><BR>Select the CBQ internal algorithm. <alg> may be set to one of:"ancestor-only", "top-level", or "formal". <P></LI><LI>CBQ/WRR objects:CBQ/WRR objects are a subclass of CBQ objects that implement weightedround-robin scheduling among classes of the same priority level. Incontrast, CBQ objects implement packet-by-packet round-robin schedulingamong classes of the same priority level. Configuration Parameters are:<DL><DT><STRONG>maxpkt_</STRONG></DT><DD>The maximum size of a packet in bytes. This is used onlyby CBQ/WRR objects in computing maximum bandwidth allocations for theweighted round-robin scheduler. </DD></DL></LI></UL><P>CBQ<SMALL>CLASS </SMALL>O<SMALL>BJECTS</SMALL><BR>CBQClass objects implement the traffic classes associated with CBQobjects. <P><TT>$cbqclass setparams parent okborrow allot maxidle prio level</TT><BR>Sets several of the configuration parameters for the CBQ traffic class(see below). <P><TT>$cbqclass parent cbqcl|none</TT><BR>specify the parent of this class in the link-sharing tree. The parent maybe specified as ``none'' to indicate this class is a root. <P><TT>$cbqclass newallot a</TT><BR>Change the link allocation of this class to the specified amount (in range0.0 to 1.0). Note that only the specified class is affected. <P><TT>$cbqclass install-queue q</TT><BR>Install a Queue object into the compound CBQ or CBQ/WRR link structure.When a CBQ object is initially created, it includes no internal queue(only a packet classifier and scheduler).⌨️ 快捷键说明
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