APPC or CPI-C TPs May Fail When Using Dependent LU 6.2 Sessions (180416)

SYMPTOMS

An APPC or CPI-C application may fail to get an active conversation with a host if a previous conversation over the same Local APPC LU has ended. For example, if there was a conversation over local LU LOCAL1 and remote LU REMOTE1, an APPC or CPI-C application may fail to get an active conversation over local LU LOCAL1 and remote LU REMOTE2 even if the previous conversation has ended.

When this occurs, the APPC or CPI-C application call to [MC_]ALLOCATE or CMALLC never completes because SNA Server has not unbound the previous dependent LU/LU session before attempting to solicit a bind to a different Remote APPC LU.

NOTE: This does not occur when you use Independent LU 6.2 sessions.

For additional information about a related problem in SNA Server versions 3.0 SP3, 4.0 SP1, and 4.0 SP2, please see the following article in the Microsoft Knowledge Base:

225207 APPC/CPIC App Unable To Allocate Conversation over Dependent LU

CAUSE

SNA Server is not ending the previous dependent APPC session by sending an UNBIND to the host. This causes any additional APPC sessions over the same local APPC LU and different remote APPC LUs to fail to get active conversations until the first APPC session is shut down.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 3.0, 3.0 SP1, 3.0 SP2, and 4.0.

This problem was corrected in the latest SNA Server versions 3.0 and 4.0 U.S. Service Packs. For information on obtaining Service Packs, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

MORE INFORMATION

The SNA Server service has been updated so that it will send an UNBIND Cleanup to the host to end the initial dependent APPC session if it is not active when it receives a request to open a new APPC session over the same local APPC LU and a different remote APPC LU.