DSPU LU Not Reactivated After Host Outage

• Microsoft SNA Server, versions 2.0, 2.1, 2.11, and 2.11 Service Pack 1

SYMPTOMS

Downstream LUs can occasionally get stuck in inactive state after an outage on the host connection. Even though the host connection reactivates and host LUs are available, only the first LU will reestablish a session. The others will stay unavailable. This problem only occurs if the LUs are in session with a host application when the outage occurs. If the LUs are in SSCP mode then the problem does not occur.

MORE INFORMATION

Suppose you have a computer running SNA Server that is connected to the host using X.25/QLLC over an X.25 card. On this connection two LUs are configured on local addresses 05 and 06. Also on the SNA Server an 802.2 downstream connection has been configured and the two LUs from the X.25/QLLC connection have been assigned. The downstream connection goes over the Ethernet LAN to a DSPU such as an OS/2 Warp station running IBM Communication Manager with two LUs on local addresses 02 and 03.

The problem occurs if an outage occurs or we stop and restart the X.25 connection from the SNA Server Administrator. At this point there is an error message Event ID 29 in the application event log:

   Internal Gateway Error
    Sense code  = 4592
      Parameter 1 = 43
      Parameter 2 = 68
      Parameter 3 = 0
      Parameter 4 = 0
      Parameter 5 = 0
      Parameter 6 = 0

CAUSE

During the processing of messages from the HOST on the LU-SSCP session, there is a timing window in the Finite State Machine that can cause the LPI addresses to get confused. A code change was made to prevent this happening by reinitializing the connection LPI addresses prior to sending an OPEN(SSCP).

RESOLUTION

An update to SNA Server 2.11 Service Pack 1 corrects this problem. The updated module is Snaservr.exe.

STATUS

Microsoft has confirmed this to be a problem in SNA Server version 2.0, 2.1, 2.11, 2.11 SP1. A supported fix is now available for SNA Server 2.11, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.