NBF MaxFrameSize Calculated Incorrectly on Token Ring

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Article ID: 182444 - View products that this article applies to.
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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.

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


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.


To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack


Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.


Article ID: 182444 - Last Review: October 7, 2013 - Revision: 1.2
  • Microsoft Windows NT Server 4.0, Terminal Server Edition
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
kbnosurvey kbarchive kbhotfixserver kbqfe kbbug kbfix kbqfe kbwinnt400sp4fix KB182444

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