How To Disable SNA NT Client Smart Multihoming

ID: Q234687

The information in this article applies to:

Microsoft SNA Server, versions 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SUMMARY

SNA Clients are configured by default to use smart multihoming. When an SNA Server is multihomed, a list of all the TCP/IP addresses for the SNA Servers are passed back to the SNA Client. The SNA Client chooses the TCP/IP address which is closest to its own TCP/IP subnet or TCP/IP address. Occasionally, the best TCP/IP address is not reachable because of network design. This causes a delay in the client connecting to the SNA Server. The time delay depends upon the TCP/IP retry timers configured on the client, but should be 45 to 55 seconds assuming the retry-timer settings have not been modified from their defaults.

MORE INFORMATION

For additional information, please see the following article in the Microsoft Knowledge Base:

Q182332 SNA Clients Experience Delay Connecting to Multihomed Server

Smart multihoming is enabled by default on all clients starting with SNA 3.0 Service Pack 2 clients.

To disable smart multihoming, the client needs to have the registry value ReadjustMultihomedAddresses (a REG_SZ) set to NO.

NOTE: This applies to SNA Windows NT Clients ONLY. Other SNA clients have no such registry value.

The above registry value is located in the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Snabase\Parameters\SnaTcp

If smart multihoming is disabled, then the client tries all addresses in the order in which the server has passed them to the client in the Service Table.

This feature is available in the latest service pack for SNA Server version 4.0. For additional information, please see the following article in the Microsoft Knowledge Base:

Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack

This feature was first included in SNA Server version 4.0 Service Pack 3.

Additional query words:

Keywords : sna4sp3fea sna3sp3 sna3sp4 sna4 sna4sp1 sna4sp2
Version : WINDOWS:3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Platform : WINDOWS
Issue type : kbinfo