NBF MaxFrameSize Calculated Incorrectly on Token Ring

 Last reviewed: March 16, 1998
Article ID: Q182444
The information in this article applies to:
  • Microsoft Windows NT Workstation version 4.0
  • Microsoft Windows NT Server version 4.0

SYMPTOMS

In a Token Ring network, NBF clients are disconnected from the server after receiving the following message: 

   Drive x not available
A network trace shows either:
  • An NBF REJ frame from the client because the server skips an NBF sequence number sending data. The server and the client never recover from this state and the server finally disconnects.

    -or-

  • The client sends an SMB read raw and the server no longer answers. the server and client exchange POLL - FINAL frames and finally disconnect.

CAUSE

In a Token Ring source routing network, NBF uses the source routing information to calculate the maximum datasize it can use. During the stages of the NBF connection setup, frames are received through different paths containing a different amount of source routing information. Because of the different amount of Token Ring source routing information, the maximum datasize was calculated incorrectly.

If NBF tries to send the maximum calculated amount of data after setting up the connection, the network card discards these packets because they are too long. NBF retries several times and then disconnects.

RESOLUTION

To resolve this problem, obtain the following fix or wait for the next Windows NT service pack.

This fix should have the following time stamp: 

   03/03/98  11:42p               100,144 Nbf.sys (Intel)
   03/03/98  11:39p               183,376 Nbf.sys (Alpha)

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. A supported fix is now available, but has not been fully regression tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information. 

Keywords          : kbbug4.00 kbfix4.00 NTSrvWkst
Version           : WinNT:4.0
Platform          : winnt
Issue type        : kbbug
Solution Type     : kbfix

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Last reviewed: March 16, 1998
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