You experience poor performance when you create an IPsec VPN site-to-site connection in Windows Server 2003

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Article ID: 2309312 - View products that this article applies to.
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SYMPTOMS

Consider the following scenario:
  • You create an Internet Protocol security (IPsec) virtual private network (VPN) site-to-site (S2S) connection between a computer that is running Windows Server 2003 and another computer.
  • Both computers are located behind Network Address Translation (NAT) devices.
  • You try to access network resources over the IPsec VPN tunnel.
In this scenario, you may experience a delay of 20 to 40 seconds when you access network resources. At the same time, the CPU usage of the computer that is running Windows Server 2003 is high.

CAUSE

This issue occurs because the Routing and Remote Access service (RRAS) selects an incorrect network interface to query the required maximum transmission unit (MTU) value. Therefore, an incorrect MTU value is used on the IPsec VPN site-to-site connection.

RESOLUTION

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
In addition to installing this hotfix, you have to create the ForceSyncMTU registry key to make the hotfix work. To do this, follow these steps:
  1. Click Start, click Run, type regedit , and then press ENTER.
  2. Locate and then click the following registry subkey:
    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\
  3. On the Edit menu, point to New, and then click DWORD (32-bit) Value.
  4. Type ForceSyncMTU, and then press ENTER.
  5. Right-click ForceSyncMTU, and then click Modify.
  6. In the Value data box, type 1, and then click OK.

    NoteThe default value of the ForceSyncMTU registry key is 0
  7. Exit Registry Editor.
Note The ForceSyncMTU registry key does not exist by default.

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 website:
http://support.microsoft.com/contactus/?ws=support
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.

Prerequisites

To apply this hotfix, your computer must be running Windows Server 2003 Service Pack 2. For more information about how to obtain a Windows Server 2003 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
889100 How to obtain the latest service pack for Windows Server 2003

Restart requirement

You may have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows Server 2003 file information notes
  • In addition to the files that are listed in these tables, this hotfix also installs an associated security catalog file (KBnumber.cat) that is signed with a Microsoft digital signature.
For all supported x86-based versions of Windows Server 2003
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatformSP requirement
Tcpip.sys5.2.3790.4776400,89616-Sep-201013:58x86SP2
W03a3409.dll5.2.3790.471544,54425-May-201016:37x86SP2
For all supported x64-based versions of Windows Server 2003
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Tcpip.sys5.2.3790.4776799,23217-Sep-201008:19x64SP2Not applicable
W03a3409.dll5.2.3790.471545,05617-Sep-201008:19x64SP2Not applicable
Ww03a3409.dll5.2.3790.471544,54417-Sep-201008:19x86SP2WOW
For all supported IA-64-based versions of Windows Server 2003
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Tcpip.sys5.2.3790.47761,336,83217-Sep-201008:19IA-64SP2Not applicable
W03a3409.dll5.2.3790.471543,52017-Sep-201008:19IA-64SP2Not applicable
Ww03a3409.dll5.2.3790.471544,54417-Sep-201008:19x86SP2WOW

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

MORE INFORMATION

For more information about software update terminology, 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
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
314496 The default MTU sizes for different network topologies
For more information about MTU, visit the following Microsoft website:
General information about the MTU

Properties

Article ID: 2309312 - Last Review: December 3, 2010 - Revision: 4.0
APPLIES TO
  • Microsoft Windows Server 2003 Service Pack 2, when used with:
    • Microsoft Windows Server 2003, Web Edition
    • Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
    • Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
    • Microsoft Windows Server 2003, Datacenter x64 Edition
    • Microsoft Windows Server 2003, Enterprise x64 Edition
    • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
    • Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
    • Microsoft Windows Server 2003, Standard x64 Edition
    • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
Keywords: 
kbautohotfix kbqfe kbhotfixserver kbfix kbsurveynew kbexpertiseadvanced KB2309312

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