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Windows 2003 Scalable Networking pack and its possible effects on Exchange - Part 2

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The_Exchange_Team
Platinum Contributor
Mar 12, 2008

Note: Please see this blog post for the most updated recommendations on this subject.

I am sure many of you might have seen the issues that can be caused by the Windows Scalable Networking pack and incompatibilities with certain NIC drivers, as previously mentioned in http://msexchangeteam.com/archive/2007/07/18/446400.aspx.

As of yesterday, there is a new High Priority Windows update available that will turn off of the Scalable Networking Pack features once it is installed. If you have Windows Update setup to receive updates automatically, this update will be downloaded and automatically installed.  If you need to manually apply the update, you can reference http://support.microsoft.com/?kbid=948496 for more information as well as a link to the download. Note: Once this update is installed, you must reboot your server for these changes to take effect.

I would highly recommend applying this update to all Windows 2003 SP2 servers to help alleviate some of the connectivity issues that  can occur as a direct result of having the Scalable Networking Pack features enabled, and some incompatibilities with NIC drivers that we have seen.

In Windows 2008, these features are disabled by default and can be enabled if desired.

Have a great day!!

- Mike Lagase

Updated Jul 01, 2019
Version 2.0

18 Comments

  • How can I verify that "netsh int ip set chimney DISABLED" actually changed anything?  If I run "netsh int ip show offload" on my W2K3R2 servers they come back with "TCP Chimney Offload" listed as one of the settings, but it doesn't say ON or OFF.  Is there a registry key I should look at?
  • prior to the release of 948496 we have multiple server where we had set the tcp chimney per the documentation.

    We have cluster servers that are reverting back.  Are there other users out there having the problem of the settings reverting back to  enable the
  • PoS scalable Network pack has given me grief for the last few months with Broadcom NetExtreme II nics; I have all the registry keys set to disable the tcp IP chimney features among other changes and still no luck. I am ripping out the problematic Broadcom NICs and replacing them with Intel's.
  • Matt,

    This issue is really a combination of enabled features and specific device drivers, rather than a general issue that impact all of the systems where W2003 SP2 was installed. On systems that are not affected, having SNP enabled can be a beautiful thing. There are measurable performance benefits.
  • You have to question exactly what the point of the Scalable Network Pack is considering every blog or KB you read advises you to disable it!
  • dmackdaddy,

    Indeed - both E2003 and E2007 could be hit by symptoms of this problem.
  • Thx for the heads up!  Does this affect E2K7 as well or only E2K3?