DOCUMENT:Q103889  30-JUL-2001  [crossnet]
TITLE   :Trace Utilities Isolate Data Flow Problems Between Stations
PRODUCT :Windows for Workgroups and Windows NT Networking Issues
PROD/VER:
OPER/SYS:
KEYWORDS:

======================================================================
A number of problems can occur in the data flow path between two
network stations and they can cause errant, restricted or even
halted communication. Trace utilities make it possible to find
problems in vertical interfaces or peer protocols so that proper
network communications can be restored.

VERTICAL INTERFACE TRACE UTILITIES

Since layer entities within a station call layer entities above and
below through established service access points (SAPs) in order to pass
a defined interface data unit (IDU) structure, interface trace
utilities can be written to:

 - "Hook" the SAP entry point, saving the original entry point

 - Gain control when the SAP entry point is called

 - Examine the IDU structure being passed, "snapshot" all or part of the IDU and
   write the snapshot to a buffer or log file

 - Pass control to the original SAP entry point

If the data flow problem is due to an errant layer entity (passing
incorrect or incorrectly formatted ICI information, "freezing up,"
etc.), an examination of the log generated by the interface trace
utility should reveal the cause of the problem. An example of a
vertical interface trace utility used for LAN Manager troubleshooting
is the NBTRAP (NetBIOS interface trace) utility.

PEER PROTOCOL TRACE UTILITIES

A specially configured computer can connect to the physical medium to
receive and examine all frames sent to and from specified network
addresses. If you set the computer software to display frame header
information at any selected functional layer, then you can examine
peer protocol conversations between selected stations to see if the
data flow problem is due to peer protocol errors. An example of a peer
protocol trace utility is the Sniffer from Network General.

Additional query words:

======================================================================
Keywords          :  

=============================================================================

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.

Copyright Microsoft Corporation 2001.