NBF MaxFrameSize Calculated Incorrectly on Token Ring

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0
• Microsoft Windows NT Server version 4.0, Terminal Server Edition

SYMPTOMS

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

Drive x not available

• 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 latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the Microsoft Knowledge Base:

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Microsoft has confirmed this to be 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.

Keywords : NT4SP4Fix kbbug4.00 kbfix4.00.sp4 NTSrvWkst
Version : WinNT:4.0
Platform : winnt
Issue type : kbbug