102 lines
3.1 KiB
HTML
102 lines
3.1 KiB
HTML
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<!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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<!-- STACK.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>Protocol Stack</title>
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<link rev="made" href="http://www.cs.stir.ac.uk/~kjt/"/>
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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>Protocol Stack</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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STACK (Protocol Stack) illustrates how data flows through a typical protocol
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stack. As an application message passes down through the layers towards the
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medium, each layer prefixes the message with its own control header.
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Eventually the message with all headers is sent via the medium to its
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destination. In the reverse direction, as a medium message passes up through
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the layers towards the application, each layer interprets and strips off its
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control header. Eventually the message with no headers is passed to the
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application.
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</p>
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<p>
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The Data Link layer is an exception because it usually adds a trailer
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(typically a checksum) as well as its header. This trailer and header are
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stripped off on reception..
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</p>
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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). There is also no
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fragmentation (layers do not split messages up) and no blocking (layers do
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not combine messages). It follows that each application message corresponds
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to one message over the medium.
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</p>
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<p>
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The elements of a message are simply numbered <var>0</var>, <var>1</var>,
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etc. withou explicit data content. An Application sends a message with data
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such as <var>A3</var>. This is then prefixed with a Transport header
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<var>T3</var>, a Network header <var>N3</var>, a Link header and trailer
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<var>L3</var>, and a Physical header <var>P3</var>. When sent over the
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medium, the whole message then looks like <var>P3:L3:N3:T3:A3:L3</var>. On
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reception, the headers (and Link trailer) are stripped off so that the
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receiving Application gets <var>A3</var> as sent.
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</p>
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<h2>Protocol Parameters</h2>
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<p>
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This simulation has no parameters.
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</p>
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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 the following
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layers: Application (e.g. File Transfer Protocol), Transport (e.g.
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Transmission Control Protocol), Network (e.g. Internet Protocol), Data Link
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(e.g. Ethernet), Physical (e.g. Ethernet) and Medium (e.g. Unshielded
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Twisted Pair cable).
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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="800" height="700"
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name="ProtocolSimulator">
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<param name="protocol" value="STACK"/>
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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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