Some TCP connections between an NLB server that is running Windows Server 2008 and its clients are broken after the Port Scalability feature is enabled on the NLB server

Consider the following scenario:
  • The Network Load Balancing (NLB) feature is enabled on a computer that is running Windows Server 2008.
  • The Port Scalability feature is also enabled on the computer.
In this scenario, some TCP connections between the NLB server and its clients are broken.
This problem occurs because the Remote Procedure Call service incorrectly selects an NLB virtual IP address as the source IP address when the Port Scalability feature is enabled.
To resolve this problem, install this hotfix on the affected NLB servers that are running Windows Server 2008. After you install this hotfix, the Remote Procedure Call service skips virtual IP addresses when it enumerates the IP addresses on the NLB servers.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the “Hotfix Request” page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.


To apply this hotfix, the computer must be running one of the following operating systems:
  • Windows Server 2008
  • Windows Server 2008 Service Pack 2 (SP2)
Additionally, the computer must have the Network Load Balancing (NLB) feature installed.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately . MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. The security catalog files (attributes not listed) are signed with a Microsoft digital signature.
For all supported x86-based versions of Windows Server 2008
File nameFile versionFile sizeDateTimePlatform
For all supported Itanium-based versions of Windows Server 2008
File nameFile versionFile sizeDateTimePlatformService branch
Rpcrt4.dll6.0.6001.224753,307,52018-Jul-200911:53IA-64Not Applicable
Rpcrt4.dll6.0.6002.221803,307,52018-Jul-200911:42IA-64Not Applicable
For all supported x64-based versions of Windows Server 2008
File nameFile versionFile sizeDateTimePlatformService branch
Rpcrt4.dll6.0.6001.224751,320,44818-Jul-200912:24x64Not Applicable
Rpcrt4.dll6.0.6002.221801,305,60018-Jul-200911:46x64Not Applicable
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional file information for Windows Server 2008

Additional files for all supported Itanium-based versions of Windows Server 2008

File nameFile versionFile sizeDateTimePlatform
Ia64_microsoft-windows-rpc-local_31bf3856ad364e35_6.0.6001.22475_none_b43f37885e6431e4.manifestNot Applicable28,48118-Jul-200922:15Not Applicable
Ia64_microsoft-windows-rpc-local_31bf3856ad364e35_6.0.6002.22180_none_b615d8125b972446.manifestNot Applicable28,48118-Jul-200921:52Not Applicable
Package_for_kb973780_sc_0~31bf3856ad364e35~ia64~~ Applicable1,42519-Jul-200910:22Not Applicable
Package_for_kb973780_sc_1~31bf3856ad364e35~ia64~~ Applicable1,53019-Jul-200910:22Not Applicable
Package_for_kb973780_sc~31bf3856ad364e35~ia64~~ Applicable1,70619-Jul-200910:22Not Applicable
Package_for_kb973780_server_0~31bf3856ad364e35~ia64~~ Applicable1,42919-Jul-200910:22Not Applicable
Package_for_kb973780_server_1~31bf3856ad364e35~ia64~~ Applicable1,53319-Jul-200910:22Not Applicable
Package_for_kb973780_server~31bf3856ad364e35~ia64~~ Applicable1,71819-Jul-200910:22Not Applicable
Package_for_kb973780_winpesrv_0~31bf3856ad364e35~ia64~~ Applicable1,42619-Jul-200910:22Not Applicable
Package_for_kb973780_winpesrv~31bf3856ad364e35~ia64~~ Applicable1,43419-Jul-200910:22Not Applicable
Wow64_microsoft-windows-rpc-local_31bf3856ad364e35_6.0.6001.22475_none_1ab0d9684b245c19.manifestNot Applicable26,08918-Jul-200922:09Not Applicable
Wow64_microsoft-windows-rpc-local_31bf3856ad364e35_6.0.6002.22180_none_1c8779f248574e7b.manifestNot Applicable26,08918-Jul-200921:47Not Applicable

Article ID: 973780 - Last Review: 10/14/2009 08:58:21 - Revision: 2.0

Windows Server 2008 Datacenter, Windows Server 2008 Enterprise, Windows Server 2008 Standard, Windows Server 2008 Datacenter without Hyper-V, Windows Server 2008 Enterprise without Hyper-V, Windows Server 2008 for Itanium-Based Systems, Windows Server 2008 Standard without Hyper-V

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