106 lines
6.6 KiB
HTML
106 lines
6.6 KiB
HTML
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<meta name="DC.Title" content="Timing considerations" />
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<meta name="abstract" content="Timing considerations during startup can affect network communications." />
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<title>Timing considerations</title>
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<body id="rzakutiming"><a name="rzakutiming"><!-- --></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">Timing considerations</h1>
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<div><p>Timing considerations during startup can affect network communications.</p>
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<div class="section"><p>i5/OS™ has the capability to automatically start the
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necessary subsystems, the TCP/IP stack, lines, interfaces, and servers at
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the appropriate times during IPL. In most situations, your network communications
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will start smoothly using this automatic startup process.</p>
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<div class="p">However, depending
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on your unique hardware and software configuration you might have problems
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starting the network communication due to timing problems during IPL. Timing
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problems can occur for several different reasons. For example: <ul><li>The processing speed and the number of input-output processors (IOPs)
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can affect the startup of the network hardware resource. If your hardware
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resource is slow to start, it might not be ready when TCP/IP tries to start.
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Your network communications fail because the TCP/IP interfaces cannot be started.</li>
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<li>You might encounter timing problems if you have customized your server
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so that you are using subsystems other than the IBM-supplied subsystems. Many
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subsystems are typically started by the IPL startup program. However, if you
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are using customized subsystems that are not recognized by the IPL startup
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program, they will not be automatically started at IPL. Your network communications
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fail because these subsystems have not been started.</li>
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</ul>
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</div>
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<p>If these types of timing problems occur, you can automatically
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start the subsystems, the TCP/IP stack, interfaces, and servers in the correct
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order by <a href="../rzal2/rzal2chgiplstartup.htm">creating
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a customized IPL startup program</a>. You might need to put delays in the
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startup program to ensure that each step of the startup process is initiated
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at the appropriate time. For example, the subsystems should be started before
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the TCP/IP stack, and the interfaces should be started after the communications
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resources are available.</p>
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<p>To change from using the default IPL startup
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program to using a customized startup program, follow these steps:</p>
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</div>
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<ol><li class="stepexpand"><span>Create a customized startup program.</span> Things to consider
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when creating a new startup program:<div class="note"><span class="notetitle">Note:</span> These steps are defined to ensure
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that all required resources are active before the next step. </div>
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<ul><li>Start the subsystems.</li>
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<li>Allow delays after the subsystems start.</li>
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<li>Use the <a href="../apis/qwdrsbsd.htm">Retrieve Subsystem Information (QWDRSBSD)</a> API to ensure
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that the subsystems are active. Although this API is not required, it can
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help you avoid timing problems.</li>
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<li>Start TCP/IP specifying STRSVR *NO, STRIFC *NO and STRPTPPRF(*NO).<div class="note"><span class="notetitle">Note:</span> You
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will start TCP/IP for both IPv4 and IPv6 by performing this step. If you do
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not want start IPv6, specify STRIP6 (*NO) on the STRTCP command.</div>
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</li>
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<li>Start the interfaces with STRTCPIFC *AUTOSTART. Remember that TCP/IP should
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vary on your <a href="rzakuvryon.htm#vryon">communication lines, controllers,
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and devices</a>.</li>
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<li>Allow delays to ensure the required interfaces are active.</li>
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<li>Start the TCP/IP point-to-point session jobs with STRTCPPTP *AUTOSTART.</li>
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<li>Start the servers with STRTCPSVR *AUTOSTART.</li>
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<li>Start any other servers that are not started with the STRTCPSVR command.
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Use STRHOSTSVR *ALL.</li>
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</ul>
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</li>
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<li class="stepexpand"><span>Test the customized startup program by calling the program. To
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properly test the program you need to end TCP/IP and the subsystems. However,
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be aware this can terminate the connections that other users are using. Plan
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accordingly to test when the system is dedicated to the test.</span></li>
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<li class="stepexpand"><span>Change the QSTRUPPGM system value to point to your customized start-up
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program. It is not recommended to directly change QSTRUP.</span></li>
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<li class="stepexpand"><span>Change the IPL attribute to no longer start TCP/IP automatically
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when the system is started. To change the IPL attribute, follow these steps:</span><ol type="a"><li><span>At the command line, type <samp class="codeph">CHGIPLA</samp> (Change IPL
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Attributes), and press F4.</span></li>
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<li><span>For the <em>Start TCP/IP</em> prompt, type <samp class="codeph">*NO</samp>.
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This prevents TCP/IP from starting at IPL, letting your startup program control
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the startup.</span></li>
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</ol>
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</li>
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</ol>
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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="rzakustrnwk.htm" title="Learn how to start subsystems, TCP/IP, interfaces, and servers in the correct order and learn how to locate problems associated with startup.">Verify system startup considerations for networking</a></div>
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</div>
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</div>
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