A fix is available
APAR status
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Closed as unreproducible in next release.
Error description
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LU 6.2 device is defined off an NCP. Attempted to establish a session from 6.2 dependent LU by sending an INIT-SELF. The session hangs PSESSST.
Local fix
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Remove ISTCOSDF from ISTINCLM.
Problem summary
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**************************************************************** * USERS AFFECTED: Anytime session requests are received * * with a blank or unknown logon mode name, * * particulary in mixed Subarea/APPN networks. * **************************************************************** * PROBLEM DESCRIPTION: 1. LU 6.2 dependent LU sessions hang * * PSESST when the original request does * * not specify a logon mode name (null * * or blanks.) * * 2. CLSDST pass across APPN fails with * * sense 08210000 because the blank mode * * name specified on the initiating * * request is not being forwarded through * * the APPN network. * **************************************************************** * RECOMMENDATION: * **************************************************************** 1. The mode name is looked up many times by VTAM during a session setup, each time for a different purpose. In this case the first lookup is done in ISTSSCZE to obtain the class of service, and since the specified mode name could not be found, a second lookup using ISTCOSDF was done by ISTSSCZE, which was successful. Later another lookup is done, this time for BIND parameters, but the design which implemented ISTCOSDF as a 'default' for unknown mode names did not add the second lookup in any place other than ISTSSCZE. When the mode name cannot be found a generic set of LU BIND parameters are used - this is what eventually causes the session to hang. 2. Prior to VTAM 4.1 the logmode name was only resolved in the SLU domain, but with APPN it is also resolved when the SLU is in APPN. However, it is only in the case when we are truly in the SLU domain that we want to save the resolved logmode name in the session information block. In this case the mode name was being done because the SLU was in APPN, but we also saved the resolved name in the SIB. This meant that the name was passed into APPN and it was not known in the other node, resulting in the sense code of 08210000.
Problem conclusion
Temporary fix
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********* * HIPER * *********
Comments
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This PTF includes fixes for P108070, P109126, P108282, P111420, and P112359. P108070 was fixed by making sure that the mode name is only saved in the SIB when we are in the domain of the SLU. P111420 was fixed by moving the logic to use ISTCOSDF into ISTINCSH. This way any time the FINDMODE macro is invoked ISTCOSDF will be used as the default if it can be found in the table(s) and if the START option allows it for this type of resource. The other PTMs are new function which is described in the following section. VTAM 4.1 shipped with a LOGMODE table entry, ISTCOSDF, which was used: 1. During Subarea LOGMODE resolution when the LOGMODE specified on the request could not be found in the LOGMODE table(s) 2. During APPN LOGMODE resolution when the LOGMODE specified on the request could not be found in the LOGMODE table(s) or when the LOGMODE specified on the request was NULL or blanks. This use of ISTCOSDF was only allowed when the SLU was an independent LU (APPN or LEN.) For APPN this meant that the LOGMODE did not have to be defined at interchange nodes. ISTCOSDF as shipped in ISTINCLM was coded with LU 6.2 parameters since most APPN SLUs would be LU 6.2. Several problems exist with this implementation. First, the only way the customer could disable it was to remove ISTCOSDF from ISTINCLM. Second, the restriction to only allow ISTCOSDF to be used for independent LUs need to be relaxed to satisfy some new customer requirements, but not all customers want ISTCOSDF to be used when the specified LOGMODE is unknown. Last of all, there was no way for the user to know if a successful session setup had used ISTCOSDF as a default. In order to overcome these shortcomings, this PTF introduces a new START option and a new message. The ISTCOSDF START option controls the use of ISTCOSDF. It can be used to disable it completely or allow it for any combination of APPLs, independent LUs, and dependent LUs. The default is ISTCOSDF=INDLU since that is how ISTCOSDF was allowed to be used originally when 4.1 VTAM was first released. The syntax is: +--ISTCOSDF=INDLU---------------------------+ | | >>--+-------------------------------------------+---------->< | | +--ISTCOSDF=-+-ALL-----------------+--------+ | | +-APPL----------------+ | | +-DEPLU---------------+ | | +-INDLU---------------+ | | +-NONE----------------+ | __,_____ | | | | | | V | | +-(-+-APPL---+-)------+ | | +-DEPLU--+ | | +-INDLU--+ This START option can be displayed/modified via VTAMOPTS. When a session uses ISTCOSDF as the default logmode during session setup the logmode specified on the request is still retained in the logmode field in the session control block, but an indicator is set so that we know ISTCOSDF was used for this session in this node. The VTAM Dump Analysis tool recognizes this new indicator in ISTSIB (SIBB_COSDF), when the SIBCHECK function is invoked. A display (by session ID) of a session which uses ISTCOSDF as the default logmode in this node will result in message IST1438I (as part of message group IST879I) which states: LOGMODE logmode UNKNOWN IN THIS DOMAIN, DEFAULT IS ISTCOSDF No operator/programmer action is required for this message unless the logmode should have been known in this domain or the ISTCOSDF START option should have not allowed it to be used for this resource. Last of all, the following questions/answers help explain how ISTCOSDF fits into the overall LOGMODE/COS picture. Where is the logon mode name resolved to session parameters and =============================================================== Subarea Class Of Service (COS)? =============================== Session parameters/Subarea COS are determined in the SSCP that is closest to the Secondary Logical Unit (SLU). This includes the following cases: o This VTAM owns the SLU (the SLU is an application or a dependent LU in this VTAM's domain.) o This VTAM owns the boundary function in the direction of a LEN-attached independent SLU. o This VTAM owns the boundary function in the direction of an APPN-attached independent SLU: - This VTAM owns the Primary Logical Unit (PLU) and the SLU is elsewhere in (or through) the APPN network. - This VTAM is an InterChange Node (ICN) with the PLU in (or through) the Subarea network and the SLU elsewhere in (or through) the APPN network. - This VTAM is part of a Composite Network Node (CNN) which is an intermediate node on the BIND path of the session. In this case the COS is needed to determine the Subarea route through the CNN. How are the session parameters/Subarea COS resolved from the ============================================================ logon mode name? ================ *** NOTE *** This is an updated version of Figure 58 in VTAM V4R1 Network Implementation Guide. Start | v +--- Does input No| logon mode | name equal | zeroes or | blanks? | | | |Yes | v No No No | Is a DLOGMOD ------>Is this an ------->Is this SLU --+ | operand independent defined as | | specified for SLU? an SNA SLU? | | this SLU? | | | | | |Yes |Yes | | |Yes +------------------>| | | v v | | Use DLOGMOD +- Is a MODETAB | | value for Yes| operand | | logon mode | specified for | | name | this logical | +---->| | unit? | +-------->| | | | | v Yes | |No | | Is a MODETAB --------+ | | | | operand | | | | | specified for | | | | | this SLU? v | | | | | Is the logon | | | | |No No mode name found | | | | |<---------------- in table | | | | v specified by | | | | +--- Is logon mode MODETAB? | | | | No| name found in Yes | | | | | | logon mode ----->|Yes | | | | | table ISTINCLM? | +---------+ | | | v | | | | | Is the logon ---+ +--+ | +---+ +------+ | mode name |Yes | | | | | ISTCOSDF? | | | | | | | | | | | | | |No | | | | | | v No | | | | | | START option -->| | | | | | ISTCOSDF | | | | | | allows default | | | | | | for this type | | | | | | of resource? | | | | | | | | | | | | | |Yes | | | | | | v v v v v v | Use ISTCOSDF Return Use Use Use Use IBM | for logon error session session session supplied | mode name condition param- param- param- session | | eters eters eters param- | | in the from from eters | | asso- first first for non- | | ciated entry in entry in SNA SLUs +---+ table specified logon entry logon mode mode table table ISTINCLM Where is the logon mode name resolved to an APPN COS? ===================================================== The APPN COS is determined in the APPN Control Point (CP) closest to the session Originating Logical Unit (OLU) which has the ability to perform the determination. For VTAM this includes the following cases: o This VTAM has the OLU in its domain and the Destination Logical Unit (DLU) is elsewhere in (or through) the APPN network. o This VTAM is the Network Node Server (NNS) for an End Node (EN) which owns the OLU but is not capable of determining the APPN COS itself, and the DLU is owned by this NNS or is elsewhere in (or through) the APPN network. o This VTAM is an ICN with the OLU in (or through) the Subarea network and the DLU elsewhere in (or through) the APPN network. How is the APPN COS resolved from the logon mode name? ====================================================== Start | v Yes Does input ----------------------------------+ logon mode | name equal | zeroes or | blanks? | | | |No | +-------->| | | v Yes | | Is a MODETAB --------+ | | operand | | | specified for | | | the OLU? 1 v | | | Is the logon | | |No No mode name found | | |<---------------- in table | | v specified by | | +--- Is logon mode MODETAB? | | No| name found in Yes | | | | logon mode ----->|Yes | | | table ISTINCLM? | | | v v Yes | | Is the logon ---+ Does the logon ---+ | | mode name |Yes mode definition | | | ISTCOSDF? | have a valid APPN | | | | | COS value for the | | | | | APPNCOS operand? 2| | | |No | | | | | v No | |No | | | START option -->| No v | | | ISTCOSDF |<------- Is a default | | | allows default | specified by the | | | for independent | APPNCOS START | | | LUs? | option? | | | | | | | | | |Yes | |Yes | | | v v v v v | Use ISTCOSDF Return Use APPNCOS Use APPNCOS Use #CONNECT | for logon error START option operand for APPN COS | mode name condition value for value from | | APPN COS logon mode +---+ definition for APPN COS The following footnotes apply to the above figure: 1. "Is a MODETAB operand specified for the OLU?" This will be changed to say "Is a MODETAB operand specified for the SLU?" as soon as the ability to specify DLOGMOD for the APPN SLU (dynamic or predefined) is enabled. 2. "Does the logon mode definition have a valid APPN COS value for the APPNCOS operand?" The value assigned to the APPNCOS operand depends on which operands are specified on the logon mode table definition. When APPNCOS is specified then its value is assigned to the APPNCOS operand. When APPNCOS is not specified, but COS is, the COS operand value is assigned to the APPNCOS operand. If neither operand is specified, #CONNECT is assigned to the APPNCOS operand. See VTAM V4R1 Resource Definition Reference, APPNCOS operand, for more details.
APAR Information
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APAR number
OW02621
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Reported component name
VTAM V4 MVS/ESA
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Reported component ID
569511701
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Reported release
101
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Status
CLOSED UR1
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PE
NoPE
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HIPER
YesHIPER
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Special Attention
NoSpecatt / Xsystem
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Submitted date
1994-02-21
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Closed date
1994-04-25
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Last modified date
1995-03-28
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APAR is sysrouted FROM one or more of the following:
-
APAR is sysrouted TO one or more of the following:
UW06190
Modules/Macros
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FINDMODE ISTATCVT ISTCFCML ISTCFCMM ISTCICPR ISTCICST ISTFNDSP ISTINCLM ISTINCNO ISTINCSH ISTLUCBB ISTLUCIQ ISTMSGCN ISTNOCDC ISTNOCPR ISTRAFDJ ISTRAFDN ISTRTPF ISTSIB ISTSITCB ISTSLBTC ISTSLRND ISTSLRTC ISTSSCZE ISTTREVR ISTTRRCF ISTVTMEU MSG1400 RAFDN
Fix information
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Fixed component name
VTAM V4 MVS/ESA
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Fixed component ID
569511701
Applicable component levels
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R101 PSY UW06190
UP94/06/13 P F406 Ž
Fix is available
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Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
28 March 2021