Disabling NDIS 5 Task Offload from a NDIS 5 Intermediate Driver

Microsoft Guidance

If a NDIS 5 IM driver performs any modifications on the data that it passes through, it should fail a query for OID_TCP_TASK_OFFLOAD instead of passing it through to the miniport below. This is to avoid problems with incorrect sequence of operations performed on data.

This guidance is expressed in the Windows WDK PassThru NDIS IM sample as a comment in the MPQueryInformation handler in miniport.c:

NOTE on OID_TCP_TASK_OFFLOAD - if this IM driver modifies the contents of data it passes through such that a lower miniport may not be able to perform TCP task offload, then it should not forward this OID down, but fail it here with the status NDIS_STATUS_NOT_SUPPORTED. This is to avoid performing incorrect transformations on data.

 

Other Approaches

If you carefully study the NDIS 5 specification you may be able to adapt your driver's implementation so that it can coexist with certain task offload functionality. Generally this would be preferred if possible.

 

Topic Status
September 16, 2009 Reviewed. This is specific to NDIS 5 IM filter drivers.
January 2, 2003 Reviewed (shortened) and moved to NDIS.com.
May 29, 2001 Added suggestion from Microsoft.
May 28, 2001 Information posted.
 

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