65 lines
2.1 KiB
HTML
65 lines
2.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type"
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content="text/html; charset=iso-8859-1">
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<meta name="Author" content>
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<meta name="GENERATOR" content="Microsoft FrontPage 2.0">
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<title>IPM Channel</title>
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</head>
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<body bgcolor="#C0C0C0" text="#000000" link="#0000EE"
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vlink="#551A8B" alink="#FF0000">
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<h3>IP Multicast Channel</h3>
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<p><b>Syntax</b></p>
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<p><tt>dp_connect ipm -group </tt><em><tt>ipAddr</tt></em><tt>
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-myport </tt><em><tt>myPort</tt></em><tt> -ttl </tt><em><tt>numHops</tt></em></p>
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<p><b>Comments</b></p>
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<p>IPM is the multicast version of UDP. It allows any
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number of machines to join a group and if a message is sent to
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the group address, all the machines will hear it.</p>
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<ul>
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<li><i>ipAddr</i> is the IP address of the group.
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This <b>must</b> be an multicast address in the range of
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224.0.0.0 to 239.255.255.255.</li>
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<li><i>myPort</i> is the local port and is optional.</li>
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<li><i>numHops</i> is the Time To Live value. The
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multicast packets will only cross <i>numHops</i>-1
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routers after which they are discarded by the
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router. To keep all multicast data on the local
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subnet, use a ttl value of 1. Proper netiquette
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maintains that this number be as low as possible.
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It is optional and defaults to 1.</li>
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</ul>
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<hr>
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<p>One can add and drop IPM group memberships using the
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fconfigure -group command. See below for examples and please note
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the use of the plus and minus symbol to signify add or drop. An
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IPM channel can be a member of any number of multicast groups
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(although it is usually limited by the OS to 20) so it is not
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necessary to drop a group in order to add a new one.</p>
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<hr>
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<p><b>Examples</b></p>
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<dl>
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<dt><tt>dp_connect ipm -group 224.76.0.119</tt></dt>
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<dt><tt>dp_connect ipm -group 225.23.120.87 -ttl 3</tt></dt>
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<dt><tt>dp_connect ipm -group 238.1.1.1 -port 1905 -ttl 255</tt></dt>
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<dt><tt>fconfigure $ipmChan -group +226.54.3.2</tt></dt>
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<dt><tt>fconfigure $ipmChan -group -232.56.198.6</tt></dt>
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</dl>
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</body>
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</html>
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