IP packets that have a frame size larger than 1,514 bytes are dropped in a bridged VLAN in Windows 7 or in Windows Server 2008 R2

Applies to: Windows 7 EnterpriseWindows 7 UltimateWindows Server 2008 R2 Enterprise More

Symptoms


Consider the following scenario:
  • You have a Branch Repeater Appliance that is running Windows Server 2008 R2 that has two network adapters (NICs) installed.
  • You connect the two NICs to two separate switches by using the same virtual LAN (VLAN) tag.
  • You create a network bridge for the connections between the two network adapters.
In this scenario, the VLAN-tagged IP traffic does not work correctly, and the IP packets that have a frame size that is larger than 1,514 bytes are dropped.

The following is an example:
  • You connect two client computers to each switch by using the same VLAN.
  • You try to ping one of the client computers from the other computer. To do this, you specify that the Internet Control Message Protocol (ICMP) payload is any value that is greater than or equal to 1469. (This value is equal to using ping -l 1469 on the command line).
In this example, you notice that the ping request times out.

Note
  • If you trace the packets over the network, you notice that the Internet Control Message Protocol (ICMP) request packets reach the bridged adapters but never cross the network bridge.
  • The total packet size of the ICMP request is 1,518 bytes in this scenario.
  • Make sure that the network adapter does not remove the VLAN tag from the IP packet.

    Note
    Most network adapters require a registry subkey setting to enable the VLAN tag to pass through.

Cause


This issue occurs because of a limitation in the Windows Network Bridge driver (Bridge.sys).

Resolution


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: 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)

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
  • 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:
    VersionProductMilestoneService branch
    6.1.760
    0.20xxx
    Windows 7 and Windows Server 2008 R2RTMLDR
    6.1.760
    1.21xxx
    Windows 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 Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. 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
File nameFile versionFile sizeDateTimePlatform
Bridge.sys6.1.7600.2086478,33622-Dec-201006:03x86
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04922-Dec-201006:49Not applicable
Bridge.sys6.1.7601.2162478,33618-Dec-201007:26x86
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04918-Dec-201008:13Not applicable
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Bridge.sys6.1.7600.2086495,23222-Dec-201006:33x64
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04922-Dec-201007:26Not applicable
Bridge.sys6.1.7601.2162495,23218-Dec-201008:11x64
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04918-Dec-201009:05Not applicable
For all supported IA-64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Bridge.sys6.1.7600.20864252,41622-Dec-201005:46IA-64
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04922-Dec-201006:37Not applicable
Bridge.sys6.1.7601.21624252,41618-Dec-201008:49IA-64
Microsoft-windows-networkbridge-ppdlic.xrm-msNot applicable3,04918-Dec-201009:47Not applicable

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
File nameUpdate.mum
File versionNot applicable
File size2,322
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameX86_2d4b024a63d1e719db0e42eac522c27a_31bf3856ad364e35_6.1.7601.21624_none_a1420e4156d43dae.manifest
File versionNot applicable
File size701
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameX86_876c8705bb492ae0e2f464d6e63a8cd4_31bf3856ad364e35_6.1.7600.20864_none_a4b501b80b44c887.manifest
File versionNot applicable
File size701
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameX86_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7600.20864_none_085e8aef807771c5.manifest
File versionNot applicable
File size10,164
Date (UTC)22-Dec-2010
Time (UTC)23:42
PlatformNot applicable
File nameX86_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7601.21624_none_0a7027a57d7d6ded.manifest
File versionNot applicable
File size10,164
Date (UTC)22-Dec-2010
Time (UTC)23:42
PlatformNot applicable
Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameAmd64_a24aca900e305a3ff52a8f353b7f8081_31bf3856ad364e35_6.1.7601.21624_none_c609d68e2541c5d8.manifest
File versionNot applicable
File size705
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameAmd64_ba59922f493b824b6e17cdfef645d5ce_31bf3856ad364e35_6.1.7600.20864_none_73887137301e2cfa.manifest
File versionNot applicable
File size705
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameAmd64_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7600.20864_none_647d267338d4e2fb.manifest
File versionNot applicable
File size10,170
Date (UTC)22-Dec-2010
Time (UTC)23:45
PlatformNot applicable
File nameAmd64_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7601.21624_none_668ec32935dadf23.manifest
File versionNot applicable
File size10,170
Date (UTC)22-Dec-2010
Time (UTC)23:45
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size2,338
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
Additional files for all supported IA-64-based versions of Windows Server 2008 R2
File nameIa64_7bea9297ba153c7f5f7d40d6ed696d2f_31bf3856ad364e35_6.1.7600.20864_none_53ff7d0e366c8cf1.manifest
File versionNot applicable
File size703
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameIa64_919105c4b8afd479ff6f2eebfe1d42d7_31bf3856ad364e35_6.1.7601.21624_none_75b29e38dbedb3e1.manifest
File versionNot applicable
File size703
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameIa64_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7600.20864_none_08602ee580757ac1.manifest
File versionNot applicable
File size10,167
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameIa64_microsoft-windows-networkbridge_31bf3856ad364e35_6.1.7601.21624_none_0a71cb9b7d7b76e9.manifest
File versionNot applicable
File size10,167
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,947
Date (UTC)22-Dec-2010
Time (UTC)23:39
PlatformNot applicable