69 lines
4.3 KiB
HTML
69 lines
4.3 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
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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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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="dc.language" scheme="rfc1766" content="en-us" />
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<meta name="dc.date" scheme="iso8601" content="2005-10-03" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Pacing (INPACING, OUTPACING, MAXINPACING) parameters</title>
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<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
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<link rel="stylesheet" type="text/css" href="ic.css" />
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</head>
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<body>
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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="rzahjper-pacingfacts"></a>
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<h4 id="rzahjper-pacingfacts">Pacing (INPACING, OUTPACING, MAXINPACING) parameters</h4>
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<p>Pacing is required if there is a possibility of overflowing data buffers
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internal to the controller or the host system. This typically occurs if the
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controller or host must pass the data to a device that operates at a slow
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speed. If the host system receives a pacing response, it sends more data frames
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up to the window size to the controller.</p>
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<ul>
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<li><img src="delta.gif" alt="Start of change" />Pacing determines how many message units (SNA RUs) can be
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transferred over a session before receiving an acknowledgment from the receiving
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system. An excessive number of pacing responses may adversely affect network
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performance. However, the absence of pacing can cause network congestion and
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unfair utilization of iSeries™ resources (buffers and central processing units).
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The values that you can use in negotiating the pacing values with the adjacent
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system are determined from the INPACING and OUTPACING values on the mode description.
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The iSeries will not allow these values to be negotiated to a higher value. If
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necessary, the receive pacing value negotiate to a lower value, matching the
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INPACING value.<img src="deltaend.gif" alt="End of change" /></li>
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<li>The pacing value is determined at session establishment time and is not
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changed for the duration of the session for the following reasons:
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<ul>
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<li>The adjacent system does not support adaptive pacing</li>
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<li>The transmission priority is low priority</li></ul></li>
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<li>If the adjacent system does support adaptive pacing, the minimum pacing
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value is set at session establishment time using the INPACING and OUTPACING
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values. The location that starts the session establishment (BIND request)
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is responsible for setting the values. No negotiation of the values is performed.
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However, support is provided by the system to change or adapt the pacing values
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based on the system's buffer resources and traffic patterns in the network.
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The system can now allocate its session buffers automatically to efficiently
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use its available resources. The MAXINPACING parameter defines the upper limit
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on the number of session buffers. The default value of *CALC sets an upper
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limit of 2 for the INPACING value.</li>
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<li>The iSeries system also has the ability to slow down the transfer of data
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or even stop receiving at any node of any session. This allows for more equity
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in the network by dynamically turning the flow of messages on to any hop for
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any session that may be contributing to congestion problems. In general, the
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value of the INPACING, OUTPACING, and MAXINPACING parameters on the mode description
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can affect the data rate, network congestion, buffer utilization, and central
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processing unit (CPU) utilization.</li></ul>
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<a id="Bot_Of_Page" name="Bot_Of_Page"></a>
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</body>
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