191 lines
5.6 KiB
HTML
Executable File
191 lines
5.6 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<!-- MUX.html (C) K. J. Turner 18/12/14 -->
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>Multiplexer</title>
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<link rev="made" href="http://www.cs.stir.ac.uk/~kjt/"/>
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<script type="text/javascript" language="JavaScript">
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<!--
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var simulator;
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var serviceCount;
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var serviceMode;
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function valid(count, mode, overwrite) {
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if (!count.match("\\d+") || count < 1 || count > 5) {
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alert ("Source/sink count " + count + " must be in range 0-5");
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return false;
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}
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else
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return true;
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}
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function set() {
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serviceCount = document.settings.serviceCount.value.toString();
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serviceMode = document.settings.serviceMode.checked;
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serviceOverwrite = document.settings.serviceOverwrite.checked;
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if (valid(serviceCount, serviceMode, serviceOverwrite)) {
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simulator.setParameter("serviceCount", serviceCount);
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simulator.setParameter("serviceMode", serviceMode);
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simulator.setParameter("serviceOverwrite", serviceOverwrite);
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simulator.restart();
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}
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}
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//-->
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</script>
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</head>
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<body background="simulator.jpeg"
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onload="simulator=document.ProtocolSimulator; set();">
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<div style="text-align: center">
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<h1>Multiplexer</h1>
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<img src="simulator.gif" alt="Simulator Logo"/>
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</div>
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<h2>Protocol Description</h2>
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<p>
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MUX (Multiplexer) illustrates how data can be multiplexed among multiple
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sources and sinks via a shared communications channel. Each source
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independently sends data indexed by its number to the corresponding sink
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with the same number. At the source end, a multiplexer combines data from
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the sources and sends it over a shared channel. At the sink end, a
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demultiplexer splits the incoming channel data and sends it to the
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corresponding sinks.
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</p>
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<center>
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<img src="multiplexer.gif" alt="Multiplexer Illustration"/>
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</center>
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<p>
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For this simulation, the communications channel is assumed to operate
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perfectly (no message corruption, loss or misordering). When the multiplexer
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sends a message, it therefore arrives directlyat the demultiplexer. It
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follows that acknowledgements, sequence number and timeouts are not
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applicable.
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</p>
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<p>
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The multiplexer and demultiplexer exchange messages in a format that depends
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on the kind of multiplexing:
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</p>
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<ul>
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<li>
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<p>
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For synchronous multiplexing, the multiplexer periodically sends all
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available data in a format such as <var>DT(D8,D4,...)</var>; this means
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that source <var>0</var> is sending data <var>D8</var>, source
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<var>1</var> is sending data <var>D4</var>, etc. If a source has not
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supplied data before the multiplexer has sent a message, this is shown
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as '-' (e.g. <var>DT(-,D4)</var> for data from source <var>1</var>
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only).
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</p>
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</li>
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<li>
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<p>
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For asynchronous multiplexing, the multiplexer sends individual source
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data as it arrives in a format such as <var>DT(2,D6)</var>; this means
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that source <var>2</var> is sending data <var>D6</var>.
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</p>
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</li>
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</ul>
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<p>
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Perfect multiplexing would always operate faster than sources supply data
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and sinks consume it. As an option, the simulation can allow multiplexing to
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be slower than this. The result is that new data can overwrite data that has
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been previously stored but not yet delivered.
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</p>
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<h2>Protocol Parameters</h2>
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<p>
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By default, multiplexing uses 2 sources/sinks, is synchronous, and does not
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overwrite previous data. You can modify the way in which the protocol works
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by modifying these settings (e.g. 1 to 5 sources/sinks). Click Change
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Settings after making these alterations. This will restart the whole
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simulation.
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</p>
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<form name="settings">
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<center>
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<table cellspacing="5">
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<tr>
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<td align="right">Number of Sources/Sinks:</td>
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<td><input name="serviceCount" size="4" value="2"></td>
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<td align="right">Asynchronous Multiplexing:</td>
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<td align="left"><input type="checkbox" name="serviceMode"></td>
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<td align="right">Data Overwriting:</td>
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<td align="left"><input type="checkbox" name="serviceOverwrite"></td>
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</tr>
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<tr>
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<td align="center" colspan="6">
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<input type="button" name="btnSet" value="Change Settings"
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onclick="set()"/>
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</td>
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</tr>
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</table>
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</center>
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</form>
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<h2>Protocol Simulation</h2>
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<p>
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The protocol simulation shows a time-sequence diagram with sources on one
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side and sinks on the other, the multiplexer and demultiplexer that support
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them, and a communications channel that carries messages. Sources request
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data transmission with
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<var>DATA(Source,Dn)</var>; the same messages arrive at sinks.
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Sources/sinks are numbered <var>0</var>, <var>1</var>, etc. Data
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messages are numbered <var>D0</var>, <var>D1</var>, etc.; no explicit data
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content is given. The source/sink number and data number are usually
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different (e.g. source <var>1</var> might sent data <var>D7</var>).
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</p>
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<center>
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<applet code="simulator.ProtocolSimulator.class"
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archive="ProtocolSimulator.jar" width="750" height="700"
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name="ProtocolSimulator">
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<param name="protocol" value="MUX"/>
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</applet>
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</center>
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<hr/>
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<p>
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<a href="index.html"><img src="uparrow.gif" alt="Up Arrow"/></a>
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Up one level to <a href="index.html">Protocol Simulators</a>
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</p>
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</body>
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</html>
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