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Modifying SDLC link level 2 test z/OS Communications Server: SNA Diagnosis Vol 1, Techniques and Procedures GC27-3667-00 |
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To test NCP Synchronous Data Link Control (SDLC) links, use the SDLC link level 2 (LL2) test. If you run this test over an extended period of time, you can increase the possibility of repeating an intermittent error that is hard to re-create. Rule: If you want to test connectivity to a physical unit only, activate the physical unit instead of using an LL2 test. Depending on the SDLC link you want to test, do one of
the following tasks:
The MODIFY LL2 command causes the SSCP to send a test RU to the NCP to which the test terminal is connected. The NCP returns test results to the requesting SSCP in a Record Test Results RU. The test results include the following information:
If these three numbers are not the same, an error in the link or a physical unit has occurred. Use a line trace to further isolate the problem. To test the SDLC link, VTAM® sends test data over the link from the controlling NCP to the remote station, which is an NCP or a peripheral physical unit. The data is then echoed back to the sending NCP. This NCP then compares the data received with the data sent and forwards the results to VTAM. When VTAM receives the test results, it sends message IST549I to the initiating console to indicate how the link level 2 test ended: data returned without errors, data returned with errors, or no data returned because of an inoperative link or initialization error. See message IST549I in z/OS Communications Server: SNA Messages for a complete message description. |
Copyright IBM Corporation 1990, 2014
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