APPC Program Never Retries New Local LU From Pool

ID: Q245487

The information in this article applies to:

Microsoft SNA Server, versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3

SYMPTOMS

If an APPC application supplies a blank Local APPC LU alias to TP_STARTED and calls [MC_]ALLOCATE multiple times using rtn_ctl = AP_WHEN_SESSION_FREE (where all sessions on a Local APPC LU become in use), [MC_]ALLOCATE requests may start to fail even though other Local APPC LUs from the default pool are available.

CAUSE

If an APPC application calls TP_STARTED once and receives a default Local APPC LU, all subsequent conversations that use that tp_id will use the same Local APPC LU alias. The APPC DLL (WAPPC32.dll) was not written to try a different default Local APPC LU in this case.

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next SNA Server 4.0 Service Pack 4 that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

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

File name	Date	Time
WAPPC32.DLL	10/21/99	9:59a

NOTE: The version of WAPPC32.dll is different for SNA Server Windows NT Clients and SNA Windows 9x clients. The customer requesting the hotfix wanted to apply the fix on top of SNA Server 4.0 SP1 Windows NT and Windows 9x clients. The following dependent modules from retail SNA 4.0 SP3 needed to be applied for this updated WAPPC32.dll to function on the SNA 4.0 SP1 client platform:

Windows NT Client dependencies: WAPPC32.dll, SNABASE.exe, SNADMOD.dll, WINMGT.dll

Windows 9x Client dependencies: WAPPC32.dll, DMODAPPC.dll, SNABASE.exe, SNADMOD.dll, SNAKRNL.dll, WINMGT32.dll
NOTE: Because of file dependencies, the most recent fix that contains the above files may also contain additional files.

WORKAROUND

An APPC application may work around this problem by calling TP_STARTED before every [MC_]ALLOCATE request (and by calling TP_ENDED after each conversation is not allocated).

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server version 4.0, 4.0 SP1, 4.0 SP2 and 4.0 SP3.

MORE INFORMATION

This specific problem won't occur with a CPIC application since CPIC doesn't support the equivalent of the APPC "AP_WHEN_SESSION_FREE" return control setting.

Additional query words:

Keywords : kbDSupport kbsna
Version : WINDOWS:4.0,4.0 SP1,4.0 SP2,4.0 SP3
Platform : WINDOWS
Issue type : kbbug