Microsoft KB Archive/128037

= TCP/IP-32 Waits on Synchronous NCBs =

Article ID: 128037

Article Last Modified on 10/16/2003

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APPLIES TO


 * Microsoft Windows for Workgroups 3.11
 * Microsoft TCP/IP for Windows for Workgroups 3.11

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This article was previously published under Q128037



SUMMARY
When a NetBIOS application, running under Windows for Workgroups using TCP/IP-32, submits a synchronous command, all NetBIOS related network activity stops until the NCB is responded to, or the application submits a CANCEL or RESET command.



MORE INFORMATION
There are two types of NetBIOS commands; asynchronous and synchronous. All NetBIOS capable transports, such as TCP/IP-32, return immediately to the calling application for any asynchronous commands. The NetBIOS driver in TCP/IP-32 sets the NCB_RETCODE field to FFH to indicate that the command has been queued. When the command completes, the NCB_RETCODE field, as well as NCB_CMD_CPLT, are set to the final return code.

In the case of synchronous commands, the TCP/IP-32 NetBIOS driver waits and return only when the command has been satisfied or if the application submits a NetBIOS CANCEL or RESET. As a result, all NetBIOS commands submitted or received by the workstation are blocked until the outstanding command is processed.

To avoid blocking other NetBIOS related activity, applications should be written to submit asynchronous NCBs when possible.

Additional query words: 3.11 prodtcp32

Keywords: KB128037

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