SNA Server 3270 LU is Available, But No Sign On Screen Appears (126396)

SYMPTOMS

After a positive response to an ACTLU (ACTLU +RSP), the SNA Server service submits a notify message to the host indicating that the LU can be activated. The SNA Server service waits for a response to the message by default. However, some VTAM/NCP versions do not respond properly to notify messages, causing 3270 LU session activation problems with SNA Server.

If the host system does not support notify messages, when you attempt to bind your computer to an LU using a 3270 emulator, the host sign on screen does not appear. The administrator can run SNA Server Administrator and observe that the LU status is Available.

If you run SNATRACE and turn on SNA Server SNA Format or Data Link Control tracing, the following message sequence occurs:

ACTPU RQD
ACTPU +RSP <Other messages>
ACTLU RQD
ACTLU +RSP
NOTIFY RQD
No NOTIFY +RSP is received

RESOLUTION

To correct this problem, add the following registry entry using REGEDT32, as described in Appendix C of the SNA Server 2.1 "Reference Guide" (page 198):

   \HKey_Local_Machine
      \System
         \CurrentControlSet
            \Services
               \SNAServr
                  \Parameters\NONOTIFYRSP:REG_SZ:YES

Stop and start the SNA Server service so the change can take effect.