81 lines
4.8 KiB
HTML
81 lines
4.8 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Maximum frame size of token ring" />
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<meta name="abstract" content="This topic contains a few guidelines and tips for specifying the maximum frame size." />
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<meta name="description" content="This topic contains a few guidelines and tips for specifying the maximum frame size." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="token-ring_frame_size" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Maximum frame size of token ring</title>
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</head>
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<body id="token-ring_frame_size"><a name="token-ring_frame_size"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Maximum frame size of token ring</h1>
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<div><p>This topic contains a few guidelines and tips for specifying the
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maximum frame size.</p>
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<p>First, here is some background information
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to help you understand the reasons for the guidelines and tips.</p>
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<p>Larger frames require less processing overhead than the same data that
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is divided up among many smaller frames. Therefore, the use of larger frame
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sizes can improve the performance of your system. However, the frame size
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that you select can be reduced if other entities within the communications
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path cannot support the frame size.</p>
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<p><strong>Maximum frame size fields:</strong></p>
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<p>You can use these fields to specify the maximum frame size (the parentheses
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show location of the field):</p>
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<ul><li>Maximum frame size (line description) affects all devices that use the
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line description.</li>
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<li>Source service access point (SSAP) maximum frame size (line description)
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affects only devices that use the SSAP and line description.</li>
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<li>Maximum frame size (controller description) affects all line descriptions
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that are associated with the controller description.</li>
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</ul>
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<p>If you specify a maximum frame size in two or more of these fields, the
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system selects the smallest size. To ease the frame size configuration of
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your line and controller descriptions, use these guidelines:</p>
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<ul><li>Use the largest possible frame size that the network connection supports.</li>
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<li>Specify the maximum frame size only in the Maximum frame size field of
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the line description. The system then uses this value for all other maximum
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frame size fields.</li>
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<li>Specify a size smaller than the maximum frame size of the input/output
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adapter (IOA) if you receive a frame rejection error.</li>
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</ul>
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<p><strong>Reduction of selected maximum frame size:</strong></p>
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<p>Other entities within the communications path can reduce your maximum frame
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size if they cannot support it. Some of these entities are:</p>
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<ul><li>Remote IOAs or other devices: Some support only smaller maximum frame
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sizes.</li>
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<li>Line or controller description: These descriptions on the remote system
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sometimes specify a smaller maximum frame size.</li>
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<li>Devices: Some do not support maximum frame size negotiations.</li>
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</ul>
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<p><strong>Solution:</strong></p>
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<p>If negotiation does not produce a common frame size, a frame reject (FRMR)
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condition occurs, and your system sends message CPA58E2 to message queue QSYSOPR.
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If you cannot change the frame size of the other entities, use an acceptable
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maximum frame size value in your line or controller description.</p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajuunderstandingtokenringsuppora.htm" title="After you understand token-ring support, you can plan how to configure the system.">Understand token-ring support</a></div>
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</div>
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</div>
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</body>
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</html>
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