New VPN connections establish a session that has a smaller MTU value than expected in Windows Server 2008 R2 or in Windows 7

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Article ID: 2582284 - View products that this article applies to.
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SYMPTOMS

Consider the following scenario:
  • You install the Routing and Remote Access service (RRAS) role on a computer that is running Windows Server 2008 R2.
  • You configure the computer as a virtual private network (VPN) server.
  • You establish a session with the VPN server from a client device or a client computer that is running Windows 7 or Windows Server 2008 R2.
  • The Maximum Transmission Unit (MTU) value of the client device or client computer is less than the MTU value of the VPN server.
In this scenario, all new connections to the VPN server establish a session that has a smaller MTU value than what is expected.

For example, assume that the MTU value of a VPN server is 1400 bytes. If a client that has an MTU value of 1200 bytes connects to the VPN server, then all new VPN connections to the server establish a session that has an MTU value of 1200 bytes. In this example, even if the MTU value of a new client is 1400 bytes, the MTU of the new VPN session remains at the smaller value of 1200 bytes.

Note You may be unable to access some websites because of the issue.

RESOLUTION

To resolve the issue, install the following hotfix on both the VPN server and the VPN client.

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:
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, you must be running one of the following operating systems:
  • Windows 7
  • Windows 7 Service Pack 1 (SP1)
  • Windows Server 2008 R2
  • Windows Server 2008 R2 Service Pack 1 (SP1)
For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global 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 7 and Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    Collapse this tableExpand this table
    VersionProductMilestoneService branch
    6.1.760 0.21xxxWindows 7 and Windows Server 2008 R2RTMLDR
    6.1.760 1.21xxxWindows 7 and Windows Server 2008 R2SP1LDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 7 and for Windows Server 2008 R2" section. 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, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x86-based versions of Windows 7
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatform
Fwpkclnt.sys6.1.7600.21027187,24813-Aug-201104:38x86
Tcpip.sys6.1.7600.210271,301,36013-Aug-201104:38x86
Fwpkclnt.sys6.1.7601.21789187,76013-Aug-201105:57x86
Tcpip.sys6.1.7601.217891,303,92013-Aug-201105:57x86
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatform
Fwpkclnt.sys6.1.7600.21027288,11213-Aug-201105:36x64
Tcpip.sys6.1.7600.210271,886,57613-Aug-201105:36x64
Fwpkclnt.sys6.1.7601.21789288,62413-Aug-201105:27x64
Tcpip.sys6.1.7601.217891,912,68813-Aug-201105:28x64
For all supported IA-64-based versions of Windows Server 2008 R2
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatform
Fwpkclnt.sys6.1.7600.21027482,67213-Aug-201104:14IA-64
Tcpip.sys6.1.7600.210273,799,40813-Aug-201104:14IA-64
Fwpkclnt.sys6.1.7601.21789483,18413-Aug-201104:11IA-64
Tcpip.sys6.1.7601.217893,802,48013-Aug-201104:11IA-64

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

Additional file information

Additional file information for Windows 7 and for Windows Server 2008 R2

Additional files for all supported x86-based versions of Windows 7
Collapse this tableExpand this table
File nameUpdate.mum
File versionNot Applicable
File size2,773
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameX86_3471e8832f9c197044de7fd28e3d3057_31bf3856ad364e35_6.1.7600.21027_none_50644742bf89b486.manifest
File versionNot Applicable
File size702
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameX86_b9453eca2951ef13c93fbf82bad92339_31bf3856ad364e35_6.1.7601.21789_none_6359604cf5f05801.manifest
File versionNot Applicable
File size702
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameX86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21027_none_b3c0c6fce0a5263e.manifest
File versionNot Applicable
File size3,834
Date (UTC)13-Aug-2011
Time (UTC)05:00
PlatformNot Applicable
File nameX86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21789_none_b5686cecddfa393c.manifest
File versionNot Applicable
File size3,834
Date (UTC)13-Aug-2011
Time (UTC)06:26
PlatformNot Applicable
Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
Collapse this tableExpand this table
File nameAmd64_21d3d7ab775b12c53481c08a2af30fce_31bf3856ad364e35_6.1.7601.21789_none_a0b935461a9ea8cb.manifest
File versionNot Applicable
File size706
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameAmd64_a4baecc71789b355ac8ef145a912011e_31bf3856ad364e35_6.1.7600.21027_none_35342880e4c65604.manifest
File versionNot Applicable
File size706
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameAmd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21027_none_0fdf628099029774.manifest
File versionNot Applicable
File size3,838
Date (UTC)13-Aug-2011
Time (UTC)06:02
PlatformNot Applicable
File nameAmd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21789_none_118708709657aa72.manifest
File versionNot Applicable
File size3,838
Date (UTC)13-Aug-2011
Time (UTC)07:06
PlatformNot Applicable
File nameUpdate.mum
File versionNot Applicable
File size3,215
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
Additional files for all supported IA-64-based versions of Windows Server 2008 R2
Collapse this tableExpand this table
File nameIa64_59c75fbccb4acbda5bd4b66a356c750a_31bf3856ad364e35_6.1.7600.21027_none_43e94cd9adcf334b.manifest
File versionNot Applicable
File size704
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameIa64_6a2d0864531b0631be35777cc4110e38_31bf3856ad364e35_6.1.7601.21789_none_78934bbe591f0313.manifest
File versionNot Applicable
File size704
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable
File nameIa64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21027_none_b3c26af2e0a32f3a.manifest
File versionNot Applicable
File size3,836
Date (UTC)13-Aug-2011
Time (UTC)05:54
PlatformNot Applicable
File nameIa64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21789_none_b56a10e2ddf84238.manifest
File versionNot Applicable
File size3,836
Date (UTC)13-Aug-2011
Time (UTC)07:01
PlatformNot Applicable
File nameUpdate.mum
File versionNot Applicable
File size2,168
Date (UTC)14-Aug-2011
Time (UTC)17:47
PlatformNot Applicable

Properties

Article ID: 2582284 - Last Review: October 13, 2011 - Revision: 2.0
APPLIES TO
  • Windows Server 2008 R2 Enterprise
  • Windows Server 2008 R2 Datacenter
  • Windows Server 2008 R2 for Itanium-Based Systems
  • Windows Server 2008 R2 Foundation
  • Windows Server 2008 R2 Standard
  • Windows Web Server 2008 R2
  • Windows 7 Enterprise
  • Windows 7 Home Basic
  • Windows 7 Home Premium
  • Windows 7 Professional
  • Windows 7 Starter
  • Windows 7 Ultimate
Keywords: 
kbautohotfix kbqfe kbhotfixserver kbfix kbexpertiseadvanced kbsurveynew KB2582284

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