SNA Server Rejects LU6.2 BIND over 2nd Connection

The information in this article applies to:

• Microsoft SNA Server for Windows NT, versions 3.0 and 3.0 SP1

SYMPTOMS

If SNA Server 3.0 is configured with more than one connection to a remote system, and that remote system attempts to serially activate an LU6.2 session using the same Local APPC LU /Remote APPC LU /APPC Mode name combination over each connection, the BIND over the first connection succeeds, but the BIND over the second connection is rejected by SNA Server with sense code = 083500xx, unless the SNA Server service is stopped and started.

SNA Server will log the following event when sending the negative response to the BIND arriving over the second connection:

   Event ID: 17
   Source:   SNA Server
   Description:
   APPC session activation failure: BIND negative response sent

   Sense data = 083500xx (where xx may be any value)

CAUSE

When SNA Server 3.0 accepts an LU6.2 BIND over a connection, the LU/LU/mode partnership is cached in SNA Server for that connection. After the session ends, SNA Server then rejects an LU6.2 BIND for this same LU/LU/mode partnership received over a different connection, because SNA Server already has a partnership defined over the first connection.

This problem did not exist in SNA Server 2.x, because the SNA Server Administrator program prevented the configuration of the same LU/LU/mode partnership over different connections owned by the same server. However, with SNA Server 3.0, no explicit APPC LU partnerships are defined, so this allows SNA Server to encounter this condition.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 3.0 and 3.0 Service Pack 1 (SP1). This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

MORE INFORMATION

With the hotfix applied, SNA Server will accept a BIND for a specific LU/LU/mode pairing over a connection even after the same LU/LU/mode session had previously been active over a different connection. Note that SNA Server does not support concurrent bound sessions using the same LU/LU/mode names over different connections.

When a BIND arrives for a Mode that is already partnered over another connection, SNA Server now checks the state of the partnered connection before failing the BIND. If the other connection is not active, SNA Server now points the partnership at the new connection (since the remote LU is obviously on this new connection now). It would continue to reject the BIND if the first connection is active, since it is definitely not legal to have the partnerships over two connections active at the same time.

NOTE: With this update applied, a separate problem occurs in SNA Manager; the APPC LU status information is not displayed properly when the LU-LU session is established over the alternate connection. This problem is only a cosmetic issue. This SNA Manager problem will be corrected in a future SNA Server 3.0 service pack.

Keywords          : snaappc snacpic snaserverservice kbfix3.00.sp2 kbnetwork
Version           : 3.0
Platform          : winnt