72 lines
4.4 KiB
HTML
72 lines
4.4 KiB
HTML
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<title>Adjust LAN lines for optimum communications performance</title>
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<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
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<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
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<a name="rzajtper-lanlinfacts"></a>
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<h4 id="rzajtper-lanlinfacts">Adjust LAN lines for optimum communications performance</h4>
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<p>Several parameters that you can change in the line description (LIND) and
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the controller description (CTLD) play an important role in system performance.</p>
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<p>The following information can help you to understand the line considerations
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for local area networks.</p>
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<ul>
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<li>MAXFRAME on the line description (LIND) and the controller description
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(CTLD): Maximizing the frame size in a LAN environment supplies the best performance
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for large transfers. A large frame size does not negatively affect performance
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for small transfers. Configure both the iSeries™ system and the other link station for
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large frames. Otherwise, of the two maximum frame size values, the smaller
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is used when you transfer data. Bridges might also limit the maximum frame
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size. You should change the default value from 1994 to a larger size.</li>
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<li>LANMAXOUT on the CTLD (for advanced program-to-program communications
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(APPC) environments): This parameter governs how often the sending system
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waits for an acknowledgment. The LANACKFRQ parameter value on one system should
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never have a greater value than the LANMAXOUT parameter value on the other
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system. The parameter values of the sending system should match the values
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on the receiving system.</li>
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<li>Setting appropriate values for the LANMAXOUT parameter along with the
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LAN acknowledgment frequency (LANACKFRQ) parameter for both the sending stations
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and receiving stations is essential for optimal performance. Other values
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might decrease throughput by 50% or even more if conditions trigger time-outs.</li>
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<li>LANWDWSTP for advanced program-to-program communications (APPC) on the
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controller description (CTLD): If there are network congestion or overruns
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to certain target system adapters, then increasing the value from the default
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of *NONE to 2 or more might improve performance.</li></ul>
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<p>In general, setting the LANMAXOUT parameter value to *CALC or 2 offers
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the best performance for interactive environments and adequate performance
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for larger transfer environments.</p>
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<ul>
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<li>For large transfer environments, changing the LANMAXOUT value might significantly
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increase performance. As starting points, use the following guidelines:
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<ul>
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<li>When you are communicating with a recent model personal computer, increase
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the LANMAXOUT parameter, but keep the LANACKFRQ parameter set to *CALC. For
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older models of personal computers, use *CALC for both values to limit buffer
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overruns.</li>
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<li>If LANACKFRQ and LANMAXOUT parameter values are changed without noticeable
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performance improvements, change the values back to *CALC.</li></ul></li></ul>
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<p>For more information on iSeries server communications, see the <a href="../books/c4154010.pdf" target="_blank">Communications Configuration</a>
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<img src="wbpdf.gif" alt="Link to PDF" /> book.</p>
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