No sessions are negotiated although the AS/400 connection is active (126400)

SYMPTOMS

When you try to connect from an SNA Server client or from a Host Integration Server client by using a 5250 emulator, you receive the following error message:

There is a problem with the configuration of the connection to the AS/400

Primary return code = 0003[AP_ALLOCATION_ERROR]
Secondary return code = 00000005 [AP_ALLOCATION_FAILURE_RETRY]

According to SNA Manager, although the AS/400 connection is active, the connection has not negotiated any sessions.

Note You can determine how many sessions have been negotiated. To do this, perform an LU-LU test on the mode that is in question. This mode may be an APPC mode, or a Local APPC LU mode, or a Remote APPC LU mode.

To find the LU-LU test tool in SNA Manager, click APPC - 3270 Session Viewer on the Tools menu. A list that is similar to the following is displayed:

   Partner LU    Mode       Connection          Sessions   Limit
   -------------------------------------------------------------
   <remote LU>   QPCSUPP    <connection_name>   0          64
   <remote LU>   SNASVCMG   <connection_name>   0          2

The value for the limit on the QPCSUPP mode is typically 64. However, the value may be different if the QPCSUPP mode has been modified in SNA Manager and on the AS/400. If the limit on the QPCSUPP mode is 0, SNA Server or Host Integration Server have not successfully negotiated any sessions.

The maximum parallel-session limit that the QPCSUPP mode supports on the AS/400 is 512. This limit was imposed by IBM.

CAUSE

This problem may occur for various reasons. The following configurations cause 0 sessions to be negotiated:

The Local APPC LU is not paired with a Remote APPC LU in SNA Manager.
The LU name of the APPC remote LU does not match the AS/400 Local Control Point Name as defined in the Network Attribute screen of the AS/400.
The QPCSUPP mode:
- The LU-LU pairing is not using the QPCSUPP mode.
  
  AS/400 connections on SNA Server or Host Integration Server require that the QPCSUPP mode be used. However, LU6.2 connections that are configured to other SNA devices do not necessarily have to use the QPCSUPP mode.
- Although the LU-LU pairing is using the QPCSUPP mode, the QPCSUPP mode has been modified in SNA Server or in Host Integration Server or on the AS/400 so that the two LUs in the LU-LU pairing no longer match.
  
  For example, the parallel-session limit parameter on the SNA Server is different from the parallel-session limit parameter on the AS/400.

RESOLUTION

To resolve this problem, determine the cause of the problem from the list earlier in this article, and then reconfigure your system accordingly.

Alternatively, if the link is a synchronous data link control (SDLC) connection to the AS/400, force the AS/400 to become the primary link station. You can use either of the following ways to force the AS/400 to become the primary link station:

Create a SDLC line description that specifies *PRI (primary) for the Data link role parameter.
Create a controller description for SNA Server or Host Integration Server that specifies *SEC (secondary) for the Data link role parameter.