You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
191 lines
5.6 KiB
HTML
191 lines
5.6 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
|
|
<!-- MUX.html (C) K. J. Turner 18/12/14 -->
|
|
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|
|
|
<head>
|
|
|
|
<title>Multiplexer</title>
|
|
|
|
<link rev="made" href="http://www.cs.stir.ac.uk/~kjt/"/>
|
|
|
|
<script type="text/javascript" language="JavaScript">
|
|
<!--
|
|
var simulator;
|
|
var serviceCount;
|
|
var serviceMode;
|
|
|
|
function valid(count, mode, overwrite) {
|
|
if (!count.match("\\d+") || count < 1 || count > 5) {
|
|
alert ("Source/sink count " + count + " must be in range 0-5");
|
|
return false;
|
|
}
|
|
else
|
|
return true;
|
|
}
|
|
|
|
function set() {
|
|
serviceCount = document.settings.serviceCount.value.toString();
|
|
serviceMode = document.settings.serviceMode.checked;
|
|
serviceOverwrite = document.settings.serviceOverwrite.checked;
|
|
if (valid(serviceCount, serviceMode, serviceOverwrite)) {
|
|
simulator.setParameter("serviceCount", serviceCount);
|
|
simulator.setParameter("serviceMode", serviceMode);
|
|
simulator.setParameter("serviceOverwrite", serviceOverwrite);
|
|
simulator.restart();
|
|
}
|
|
}
|
|
//-->
|
|
</script>
|
|
|
|
</head>
|
|
|
|
<body background="simulator.jpeg"
|
|
onload="simulator=document.ProtocolSimulator; set();">
|
|
|
|
<div style="text-align: center">
|
|
|
|
<h1>Multiplexer</h1>
|
|
|
|
<img src="simulator.gif" alt="Simulator Logo"/>
|
|
|
|
</div>
|
|
|
|
<h2>Protocol Description</h2>
|
|
|
|
<p>
|
|
MUX (Multiplexer) illustrates how data can be multiplexed among multiple
|
|
sources and sinks via a shared communications channel. Each source
|
|
independently sends data indexed by its number to the corresponding sink
|
|
with the same number. At the source end, a multiplexer combines data from
|
|
the sources and sends it over a shared channel. At the sink end, a
|
|
demultiplexer splits the incoming channel data and sends it to the
|
|
corresponding sinks.
|
|
</p>
|
|
|
|
<center>
|
|
|
|
<img src="multiplexer.gif" alt="Multiplexer Illustration"/>
|
|
|
|
</center>
|
|
|
|
<p>
|
|
For this simulation, the communications channel is assumed to operate
|
|
perfectly (no message corruption, loss or misordering). When the multiplexer
|
|
sends a message, it therefore arrives directlyat the demultiplexer. It
|
|
follows that acknowledgements, sequence number and timeouts are not
|
|
applicable.
|
|
</p>
|
|
|
|
<p>
|
|
The multiplexer and demultiplexer exchange messages in a format that depends
|
|
on the kind of multiplexing:
|
|
</p>
|
|
|
|
<ul>
|
|
|
|
<li>
|
|
<p>
|
|
For synchronous multiplexing, the multiplexer periodically sends all
|
|
available data in a format such as <var>DT(D8,D4,...)</var>; this means
|
|
that source <var>0</var> is sending data <var>D8</var>, source
|
|
<var>1</var> is sending data <var>D4</var>, etc. If a source has not
|
|
supplied data before the multiplexer has sent a message, this is shown
|
|
as '-' (e.g. <var>DT(-,D4)</var> for data from source <var>1</var>
|
|
only).
|
|
</p>
|
|
</li>
|
|
|
|
<li>
|
|
<p>
|
|
For asynchronous multiplexing, the multiplexer sends individual source
|
|
data as it arrives in a format such as <var>DT(2,D6)</var>; this means
|
|
that source <var>2</var> is sending data <var>D6</var>.
|
|
</p>
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
<p>
|
|
Perfect multiplexing would always operate faster than sources supply data
|
|
and sinks consume it. As an option, the simulation can allow multiplexing to
|
|
be slower than this. The result is that new data can overwrite data that has
|
|
been previously stored but not yet delivered.
|
|
</p>
|
|
|
|
<h2>Protocol Parameters</h2>
|
|
|
|
<p>
|
|
By default, multiplexing uses 2 sources/sinks, is synchronous, and does not
|
|
overwrite previous data. You can modify the way in which the protocol works
|
|
by modifying these settings (e.g. 1 to 5 sources/sinks). Click Change
|
|
Settings after making these alterations. This will restart the whole
|
|
simulation.
|
|
</p>
|
|
|
|
<form name="settings">
|
|
|
|
<center>
|
|
|
|
<table cellspacing="5">
|
|
|
|
<tr>
|
|
<td align="right">Number of Sources/Sinks:</td>
|
|
<td><input name="serviceCount" size="4" value="2"></td>
|
|
<td align="right">Asynchronous Multiplexing:</td>
|
|
<td align="left"><input type="checkbox" name="serviceMode"></td>
|
|
<td align="right">Data Overwriting:</td>
|
|
<td align="left"><input type="checkbox" name="serviceOverwrite"></td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td align="center" colspan="6">
|
|
<input type="button" name="btnSet" value="Change Settings"
|
|
onclick="set()"/>
|
|
</td>
|
|
</tr>
|
|
|
|
</table>
|
|
|
|
</center>
|
|
|
|
</form>
|
|
|
|
<h2>Protocol Simulation</h2>
|
|
|
|
<p>
|
|
The protocol simulation shows a time-sequence diagram with sources on one
|
|
side and sinks on the other, the multiplexer and demultiplexer that support
|
|
them, and a communications channel that carries messages. Sources request
|
|
data transmission with
|
|
<var>DATA(Source,Dn)</var>; the same messages arrive at sinks.
|
|
Sources/sinks are numbered <var>0</var>, <var>1</var>, etc. Data
|
|
messages are numbered <var>D0</var>, <var>D1</var>, etc.; no explicit data
|
|
content is given. The source/sink number and data number are usually
|
|
different (e.g. source <var>1</var> might sent data <var>D7</var>).
|
|
</p>
|
|
|
|
<center>
|
|
|
|
<applet code="simulator.ProtocolSimulator.class"
|
|
archive="ProtocolSimulator.jar" width="750" height="700"
|
|
name="ProtocolSimulator">
|
|
<param name="protocol" value="MUX"/>
|
|
</applet>
|
|
|
|
</center>
|
|
|
|
<hr/>
|
|
|
|
<p>
|
|
<a href="index.html"><img src="uparrow.gif" alt="Up Arrow"/></a>
|
|
Up one level to <a href="index.html">Protocol Simulators</a>
|
|
</p>
|
|
|
|
</body>
|
|
|
|
</html>
|
|
|