How to Determine When 3270 RTM Data Should be Sent

• Microsoft SNA Server for Windows NT, versions 2.0, 2.1, 2.11, and 3.0

SUMMARY

SNA Server supports the ability to report an user's 3270 response time data to NetView, using standard NetView Response Time Monitor (RTM) Network Management vector data messages. This article documents the configuration options that determine when RTM data is reported to NetView.

When you configure 3270 Response Time Monitor (RTM) data in SNA Server Admin under Options and RTM Triggers, the option states the following:

   RTM Data Sent at:

   Select one or both of the following:

   Counter Overflow: To cause RTM data to be sent to the host when the
   number of host responses in a given time period overflows the size of
   the available counter, select this check box.

   End of Session: To cause RTM data to be sent to the host at the end of
   each LU-to-LU session, select this check box.

MORE INFORMATION

When the connection activates and the host is configured for RTM, the host sends NMVT major vector '8080' on the SSCP-PU session. This major vector includes subvector 92 (RTM Request) and optionally, subvector 94 (RTM Control). Subvector 94 indicates how RTM should be measured, when the PU should send RTM data, and the boundaries for measurement.

In some cases the host may send the RTM major vector and subvector 92, but not send subvector 94. In such instances, SNA Server uses the values defined in the "RTM Triggers" dialog box to determine how RTM should be handled. Any values indicated in the host subvector 94 will override the settings in SNA Admin.

The IBM SNA “Formats Guide” states that RTM Data subvector 93 is used to report RTM data. The counter overflow is the number of times that the maximum boundary of 65,535 is reached.

Four sets of counters for RTM data are used to measure RTM. Each of these may be incremented 65,535 times before the counter overflows. These sets are defined as ranges that may be set in increments of 0.1 seconds (for example, 0-0.5; 0.5-1.0; 1.0-1.5; 1.5-2.0). If a count would cause the maximum boundary for a set to overflow, and the SNA Server is configured to send RTM Data upon Counter Overflow, it will send an unsolicited NMVT with all the current counts, then initialize the sets.

If the RTM data is set to be sent at the end of the session, the SNA Server will not forward the counts except in response to a request from the host or at the end of the session. In this case, you cannot tell whether a particular counter set has overflowed, so counts will not reflect the number of times the sets have been initialized.

For additional information regarding SNA Server support for 3270 RTM data, please see the following: