2 Connections Using Same Link Service and Destination Address

ID: Q140840

The information in this article applies to:

Microsoft SNA Server, versions 2.0, 2.1, 2.11
on the following platforms: NT

SYMPTOMS

When SNA Server has two connections configured to use the same underlying link service and same Remote Network Address, the remote end deactivates the first connection as soon as an XID packet to activate the second connection arrives.

It is true that two link stations cannot use the same source service access point (SAP) address to the same destination link station. However, SNA Server should not disrupt an already active connection when another request arrives for the same Network address (or SAP) for the same link service.

With SNA Server 2.11 the following message appears when attempting to configure two connections in this way:

The same Remote Network Address and SAP have already been specified for this link service in connection <connection name>. To create more than one connection to the same remote machine, add one of more 802.2/DLC link services via SNA Server Setup over the same adapter with different local SAP addresses. This will auto-create additional connections in SNA Server Admin. Alternatively, if further SAPs are available at the remote machine, choose a different remote SAP for this connection. OK.

After you choose OK, SNA Server does not force the Administrator to change the the configuration. Therefore, the above problem results.

RESOLUTION

Microsoft has a fix that does not prevent an Administrator from configuring two connections for the same remote network address using the same link service. The 808.2 Link Service now detects the address conflict and disables the second connection with the following event id:

Event ID: 205 - "An address pair is already in use."

Note that it also detects the case where the address pair is first "in use" due to an incoming call as well as an outbound one.

Microsoft has updated the following files to correct this problem:

<snaroot>\SYSTEM\SNASERVR.EXE
<snaroot>\SYSTEM\TRCSERVR.EXE
<snaroot>\SYSTEM\SNADLC.DLL
<snaroot>\SYSTEM\SNAEVENT.DLL

STATUS

Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This problem was corrected in the latest SNA Server for Windows NT, 2.11 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Additional query words: prodsna 2.00 2.10 2.11 snatrace

Keywords : ntnetserv
Version : WINDOWS:2.0,2.1,2.11
Platform : WINDOWS
Issue type :