TCP/IP-32 Waits on Synchronous NCBs

 Last reviewed: September 9, 1996
Article ID: Q128037
The information in this article applies to:
  • Microsoft Windows for Workgroups version 3.11
  • Microsoft TCP/IP-32 for Windows for Workgroups versions 3.11 and 3.11a

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.

KBCategory: kbnetwork
KBSubcategory: nttcp
Additional reference words: 3.11 prodtcp32



THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: September 9, 1996
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.