Microsoft KB Archive/306876

= APPC/CPI-C Application Does Not Use APPC LU With Auto-activated Sessions =

Article ID: 306876

Article Last Modified on 3/23/2005

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APPLIES TO


 * Microsoft Host Integration Server 2000 Standard Edition

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This article was previously published under Q306876



SYMPTOMS
An Advanced Program-to-Program Communication (APPC) or Common Programming Interface for Communications (CPI-C) application may fail to allocate a conversation even though there are auto-activated (or pre-allocated) LU 6.2 sessions available for the remote APPC LU and APPC mode specified by the application.

The specific errors returned by the application may vary when this occurs. The following are typical APPC and CPI-C errors returned to the application.

If this occurs with an APPC application, the [MC_]ALLOCATE fails with the following error message:

primary_rc = 0x0003 (AP_ALLOCATION_ERROR)

secondary_rc = 0x00000005 (AP_ALLOCATION_FAILURE_RETRY)

A CPIC application fails with the following error message:

rc = 20 (CM_PRODUCT_SPECIFIC_ERROR)

In addition, the following event may also be logged in the Application Event log:

Event ID: 93

Source: SNA APPC Application

Description: APPC local conversation start failed:

Primary_rc = 0003

Secondary_rc = 00000005

TP_ID =

Dest TP name =

LU alias =

PLU alias =

Mode name =

FQ PLU name =

NOTE: These particular errors are fairly common APPC and CPI-C errors, so they may occur for reasons other then the one described here.

APPC or CPI-C applications that had been functioning correctly when the application was obtaining LU 6.2 sessions through a Microsoft SNA Server 3.0 or 4.0 system may start experiencing this problem when the SNA Server systems are upgraded to Host Integration Server 2000 because this particular problem does not exist in previous versions of SNA Server.



CAUSE
The SNA Server service (Snaservr.exe) in Host Integration Server 2000 does not properly initialize a variable under some circumstances. This prevents the SNA Server service from selecting the &quot;best&quot; local APPC LU for an LU 6.2 (APPC) session request.



RESOLUTION
To resolve this problem, obtain the latest service pack for Host Integration Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

328152 How to Obtain the Latest Host Integration Server 2000 Service Pack

The English version of this fix should have the following file attributes or later:

NOTE: Because of file dependencies, the most recent fix that contains the preceding files may also contain additional files.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Host Integration Server 2000 Service Pack 1.



MORE INFORMATION
The problem described here occurs under the following circumstances:
 * The APPC mode that is used by the APPC or CPI-C application is configured to auto-activate LU 6.2 sessions.
 * Explicit APPC partnerships are configured in the APPC mode that the application is using.
 * The local APPC LUs defined in SNA Manager have the Member of Default Outgoing Local APPC LU Pool option enabled.
 * The APPC or CPI-C application does not specify a default local APPC LU alias in its LU 6.2 session request.

The following is an example of such an SNA configuration:

Local APPC LUs:

Both of the local APPC LUs are configured to be members of the default outgoing local APPC LU pool.

Remote APPC LUs:

The session limits for APPC Mode APPCMODE are defined as follows:

The following explicit APPC partnerships are defined for APPCMODE:

When you are using this configuration, SNA Server 3.0 or 4.0 and Host Integration Server 2000 will auto-activate four sessions over each of the two explicit APPC partnerships that are defined for APPCMODE when the connection (HOST) is activated.

When SNA Server 3.0 or 4.0 receives a session request from an APPC or CPI-C application that specifies a remote APPC LU of REMOTE1 and mode APPCMODE, the SNA Server will return LOCAL1 as the local LU alias to use for the LU 6.2 conversation. This occurs because there are four contention winner sessions auto-activated for the APPC triplet LOCAL1/REMOTE1/APPCMODE that is currently available.

Under the same conditions, Host Integration Server 2000 may return LOCAL2 to the application as the local LU alias to use instead of LOCAL1. If LOCAL2 is not a valid APPC LU for the host application being used, the APPC [MC_]ALLOCATE will fail as described previously. Even if LOCAL2 is valid, it may not be desirable to use LOCAL2 with REMOTE1.

Any of the local APPC LUs that are members of the default outgoing local APPC LU pool are valid to use with any remote APPC LU and APPC mode because of the way that SNA Server 3.0/4.0 and Host Integration Server 2000 dynamically partner APPC LUs. However, a local APPC LU that has an available contention winner session with the requested remote APPC LU and mode should be the preferred local APPC LU. Auto-activated sessions are contention winner sessions.

Additional query words: HIS 2000

Keywords: kbbug kbfix kbhostintegserv2000sp1fix kbhostintegserv2000presp1fix KB306876

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