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Q156441: NetBIOS Applications Stop Receiving Data Running on TCP/IP 32

Article: Q156441
Product(s): Windows for Workgroups and Windows NT Networking Issues
Version(s): 
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft TCP/IP-32 for Windows for Workgroups, versions 3.11, 3.11a, 3.11b 
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SYMPTOMS
========

NetBIOS applications running on Microsoft TCP/IP 32 for Windows For Workgroups
may stop receiving data from server-side applications. The problem will only
occur if the client pauses before receiving data for more than one NetBIOS
Session KeepAlive interval.

NOTE: The default NetBIOS Session KeepAlive interval for TCP/IP 32 is 60 minutes.

CAUSE
=====

The problem occurs because of the NetBIOS over TCP/IP Vxd's (VNBT) handling of
Session KeepAlive packets when application data is also pending in TCP. If VNBT
posts a receive for application data pending in TCP and a NetBIOS Session
KeepAlive packet also resides in the TCP pending queue, VNBT would incorrectly
determine the state of the lower TCP connection resulting in all future NetBIOS
Receives being placed in a pending state.

RESOLUTION
==========

Vnbt.386 was modified to correctly handle NetBIOS KeepAlive packets in TCP's
pending queue.

STATUS
======

Microsoft has confirmed this to be a problem in TCP/IP 32 version 3.11B. A
supported fix is now available, but is not fully regression tested and should be
applied only to systems experiencing this specific problem. Contact Microsoft
Product Support Services for more information.

Additional query words:

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbTCPIPSearch kbZNotKeyword3 kbTCPIP311 kbTCPIP311a kbTCPIP311b
Issue type        : kbbug

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