DOCUMENT:Q90180  30-JUL-2001  [lanman]
TITLE   :NCB Performance and Piggybackacks
PRODUCT :Microsoft LAN Manager
PROD/VER:
OPER/SYS:
KEYWORDS:

======================================================================
SUMMARY
=======

On file servers and workstations that are heavily used, be sure that
PIGGYBACKACKS is set to 1 (default value, ON). When "piggybacked"
acknowledgments are used, a computer that receives a request for data can send
an acknowledgment of the request and the data itself in the same frame, cutting
down on network traffic overhead. Using piggybacked acknowledgments increases
file-transfer performance.

MORE INFORMATION
================

Tests indicate poor performance when you send data in one direction only or do a
very simple send-wait-receive ping-pong with piggybackack turned on. This occurs
because the receiving NetBEUI stack does not send its acknowledgment until the
T2 timer pop, thus slowing the network traffic.

By turning PIGGYBACKACKS off, these tests perform as expected.

In real-world scenarios, PIGGYBACKACKS should be left on. In most cases, data is
transferred in both directions and is not contingent on the completion of an
earlier request.


Turning PIGGYBACKACKS off will result in higher network traffic and degraded
performance.

Additional query words: 2.0 2.00 2.1 2.10

======================================================================
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.