Microsoft KB Archive/152954

= XCLN: Network Errors w/ Microsoft Exchange Windows 3.1 Client =

Article ID: 152954

Article Last Modified on 10/28/2006

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APPLIES TO


 * Microsoft Exchange Client 5.5

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This article was previously published under Q152954





SYMPTOMS
When you are running the Microsoft Exchange Windows 3.x client on Windows 3.1 and using Novell's NetWare IPX/SPX protocol stack, the following error message may appear:

A network error has occurred. Please contact your administrator.

This usually happens when accessing the Address Book, trying to check details of names in the Global Address Book, synchronizing local Schedule+ file to server, sending and receiving large attachments, or moving messages from PST to server-based folder. It is also more likely to happen on Token Ring.



CAUSE
The computer running Microsoft Exchange Server is sending packets that are larger than the MaxFrameSize of the Windows 3.1 client.

When Windows 3.1 was written, there was only one interface with Novell's IPX/SPX stack, using ECB's programmed with assembly language. ECBs only support SPX I. SPX I does not allow packet size negotiation.

With the release of NetWare 4.x, another interface with Novell's IPX/SPX stack was introduced, using TLI programmed with C. TLI supports both SPX I and SPX II. SPX II does allow packet size negotiation.

Since Windows 3.1 was written before the TLI interface came out, it was written to use ECBs, so its version of RPC can't negotiate packet sizes. Therefore, the computer running Microsoft Exchange Server doesn't "know" that the client's MaxFrameSize is not the same as its MaxFrameSize and it sends packets that are too large for the client.



RESOLUTION
One possible workaround is to make sure the maximum frame size on the Exchange clients is at least the same size a,s or up to 120 bytes larger than, the maximum frame size on the computer running Microsoft Exchange Server.

Windows 95 does not exhibit this problem.



STATUS
Microsoft does not plan to add TLI support to Windows 3.1.

Additional query words: token ring win16

Keywords: kberrmsg kbusage KB152954

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