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Q148971: TR-attached IPX SNA Client Not Find Server Across FDDI Bridge

Article: Q148971
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,2.11 SP1
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 2.11 SP1, on platform(s):
   - the operating system: Microsoft Windows NT 
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SYMPTOMS
========

When you run the SNA Server client software configured to use the Novell NetWare
IPX/SPX client interface on Token Ring, the client is unable to find a SNA
Server located across an FDDI transitional bridge.

When the problem occurs on a SNA Server Microsoft Windows 3.x client, Wnap.exe
will display the following error when it is started:

  SNA Server Error: 546 Cannot establish connection with SNA Server
  <servername>.

Microsoft Windows NT and Microsoft Windows 95 clients will indicate that the
SnaBase service is not started.

CAUSE
=====

When you connect a SNA Server IPX/SPX client from a Token Ring network to a SNA
Server located on FDDI, the intervening FDDI bridge may bit-swap the destination
address of the IPX/SPX connection request, causing the SNA client to fail to
connect to the SNA Server.

This problem only occurs when SNA Server clients are configured to use NetWare
IPX/SPX on Token Ring, where the server's IPX address is based on the network
card adapter address installed in the SNA Server.

Ethernet-attached IPX clients will not encounter this problem because the FDDI
bridge does not bit-flip destination addresses when bridging frames. Also, all
other client-server connection methods supported by SNA Server (for example,
named pipes, TCP/IP sockets, Banyan IP, and AppleTalk) do not directly refer to
the server's adapter address when it connects to the server and will not
encounter this problem.

RESOLUTION
==========

To support this configuration, an update to the SNA Server client software is
available that supports "bit flipping" of the SNA Server's IPX address. It will
try if the following new SNA Server client setting is enabled:

  FlipMacAddress=Yes

For Windows 3.x clients, this setting must be added to the [WNAP] section of the
Win.ini file.

For Windows NT clients, this setting must be as follows:

 HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/SnaBase/ 
  Parameters/SnaSpx/ 

  FlipMacAddress: REG_SZ: Yes

For Windows 95 clients, this setting must be as follows:

  HKEY_LOCAL_MACHINE/Software/Microsoft/SnaBase/Parameters/SnaSpx/ 

  FlipMacAddress: REG_SZ: Yes

If this value is set to Yes, the SNA Server client NetWare transport first tries
the bit flipped server address, and if it fails, it retries with the original
non-flipped address.

For additional information on the algorithm for bit-flipping network addresses,
please see the following article in the Microsoft Knowledge Base:

  Q123791 SNA Server Remote Station Discovery Process

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server 2.0, 2.1, 2.11, and
2.11.sp1.
This problem was corrected in the latest Microsoft SNA Server 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:

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch
Version           : WINDOWS:2.0,2.1,2.11,2.11 SP1
Issue type        : kbbug
Solution Type     : kbfix

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