SNA Server SDLC Connection Fails to Reactivate After Host IPL

• Microsoft SNA Server, versions 2.11, 2.11 Service Pack 1 (SP1), 2.11 SP2, 3.0, 3.0 SP1, 3.0SP2, and 4.0

SYMPTOMS

An SDLC connection from SNA Server to a front-end processor (FEP) remains in a pending state after the host performs an IPL. The only means of recovery is to stop and restart the SNA Server service.

SNA Server may post an Event 23 in the Windows NT application event log with a qualifier of 00A1 or 0025 as a result of these symptoms.

CAUSE

SNA Server is erroneously handling the non-activation XIDs sent from the FEP on an SDLC connection and treating this as a connection outage.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11 Service Pack 1 (SP1), and 2.11 SP2. A supported fix is now available for 2.11 SP2, 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.

Microsoft has confirmed this to be a problem in SNA Server versions 3.0, 3.0 SP1, 3.0 SP2, and 4.0. A supported fix is now available, 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 Product Support Services for more information.

MORE INFORMATION

With the fix applied, the Ibmsdlc.DLL interface allows for the correct handling of SDLC non-activation XIDs.

The SNA Server Ibmsdlc.dll (SDLC Link Service) file supports a "dumb card" driver interface that is published in the appendix of the SNA Device Interface Specification (SNADIS) guide. This link service will work with any dumb card implementation, such as Ibmsync.sys (the IBMSDLC driver), Microgate, DCA ISCA, Attachmate SDLC, as well as others.

Other SDLC link services implement the full SNADIS interface so the Ibmsdlc.dll is not used. Some examples of these link services include Eicon SDLC and Barr SDLC.