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Various problems between VTAM and iSeries AS/400 due to AS/400 TG Negotiation error

Troubleshooting


Problem

Multiple symptoms, including: IST1085I BF-TG ACTIVATION ERROR CP as400_cpname SENSE = 10160016 IST467I CONTACTED ERROR TYPE 0A FOR ID = as400_puname

Symptom

In addition to the CONTACTED error type 0A with sense 10160016, the following symptoms have been seen:


  • IST1086I APPN CONNECTION FOR as400_cpname IS ACTIVE - TGN = 1

    • IST1488I INACTIVATION OF RTP ........ AS PASSIVE TO as400_cpname
    IST1488I is issued every few seconds with dots identifying the RTP resource that is going inactive, but there is no RTP activation message (IST1488I).


  • After recycling an Enterprise Extender (EE) XCA major node with a connection to an AS/400, APPN connectivity was established between VTAM and the AS/400, but CP-CP and DLUR/DLUS sessions do not come up. Recovery requires varying the HPR and Host controllers on the iSeries AS/400 off, then varying them back on again.



  • DISPLAY APING or session setup to the AS/400 fails with sense 087D0001 (due to failure sense 8014001), even though there are CP-CP sessions active. If the link on the AS/400 is stopped and started a second time, the CP-CP sessions come up and the session setup is successful.

    • Cause

    When an iSeries AS/400 negotiates a TG number with VTAM in XID exchanges, the final XID3 received from the AS/400 contains the negotiated TG number in the XID+x'10' (XID3 TG number) but a different TG number in the CV4680 contained in the XID3. VTAM uses the TG number in the CV4680, but the AS/400 uses the TG number in the XID3 TG number field.

    Diagnosing The Problem

    • For the case where IST467I CONTACTED ERROR TYPE 0A FOR ID = as400_puname is issued, the following messages will display the XID received by VTAM from the AS/400 and the XID sent by VTAM to the AS/400:


  • For the case where message IST1488I INACTIVATION OF RTP ........ AS PASSIVE TO as400_cpname is issued,VTAM internal trace shows that the AS/400 sends in an HPR connection setup with TGN 21 (x'15') in the Switching Info Segment in a control vector x'85'. VTAM sets sense 08550004 indicating that an unknown TG was specified in the RSCV.



  • For other symptoms, the XID3 received from the AS/400 can be seen in the VTAM internal trace in the XIDI entry, LCS entry, or CONTACTED PIU entry. This is an example of the PIU entry:


    • Resolving The Problem

    The issue is resolved in iSeries base AS/400 beginning at R610 (PTR: 9B44451, closed UR1, or Fixed Next Release). For earlier versions, R540 and R545, there is no PTF available but there is a circumvention. In the AS/400 Controller Description, change the APPN transmission group number on the APPN controller to *CALC, which indicates that the AS/400 is to negotiate the TG number rather than using a pre-defined TG number.

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    Document Information

    Modified date:
    22 June 2018

    UID

    swg21382764

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