Symptoms

Consider the following scenarios:

  • The computers in a network environment run Windows 7 Service Pack 1 (SP1), Windows Server 2008 R2 SP1, Windows 8, Windows Server 2012, Windows 8.1, Windows Server 2012 R2, Windows RT 8.1.

  • Path MTU (PMTU) discovery (EnablePMTUDiscovery) is enabled on the computers.

  • The network environment is slow. Therefore, in order to increase the throughput, the MTU is required to be set to a value that is less than 576.

In this situation, the MTU is not set to less than 576 correctly. Therefore, data packets are dropped, and packet loss occurs during data transmission. This makes the network unreliable.

Cause

This issue occurs because PMTU discovery does not allow an MTU value that is less than 576. Therefore, data packets are fragmented excessively.

More Information

After you apply this hotfix you can use the Netsh.exe tool to verify the current minimum MTU for PMTU discovery. To do this, type

netsh interface ip show global


at the command prompt and press Enter. The value for "Minimum MTU" is the current minimum MTU for PMTU discovery.

To change the minimum MTU for PMTU discovery to a value such as 352, you can input

netshinterface ip set global minmtu=352

at the command prompt and press Enter.

To display the active setting for all interfaces you can also use the command

netsh interface ip show interfaces


For example:

Idx Met MTU State Name

--- ---------- ---------- ------------ ---------------------------

1 50 4294967295 connected Loopback Pseudo-Interface 1

14 5 1500 connected Local Area Connection 2

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:

http://support.microsoft.com/contactus/?ws=supportNote 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 SP1

  • Windows Server 2008 R2 SP1

  • Windows 8

  • Windows Server 2012

  • Windows RT 8.1

  • Windows 8.1

  • Windows Server 2012 R2

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 apply this hotfix, you do not have to make any changes to the registry.

Restart requirement

You might 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 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.

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:

    Version

    Product

    Milestone

    Service branch

    6.1.760
    0.16xxx

    Windows 7 and Windows Server 2008 R2

    RTM

    GDR

    6.1.760
    1.22xxx

    Windows 7 and Windows Server 2008 R2

    SP1

    LDR

  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.

  • 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

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.22477

240,576

10-Oct-13

11:51

x86

Fwpkclnt.sys

6.1.7601.22477

187,840

10-Oct-13

11:51

x86

Tcpip.sys

6.1.7601.22477

1,309,632

10-Oct-13

11:51

x86

Arp.exe

6.1.7600.16385

20,992

14-Jul-09

1:14

x86

Finger.exe

6.1.7600.16385

10,240

14-Jul-09

1:14

x86

Hostname.exe

6.1.7600.16385

8,704

14-Jul-09

1:14

x86

Mrinfo.exe

6.1.7600.16385

11,264

14-Jul-09

1:14

x86

Netiohlp.dll

6.1.7601.22477

178,688

10-Oct-13

11:47

x86

Netstat.exe

6.1.7601.22477

28,160

10-Oct-13

11:10

x86

Route.exe

6.1.7600.16385

17,920

14-Jul-09

1:14

x86

Tcpsvcs.exe

6.1.7600.16385

9,216

14-Jul-09

1:14

x86

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.22477

376,768

10-Oct-13

12:18

x64

Fwpkclnt.sys

6.1.7601.22477

288,192

10-Oct-13

12:18

x64

Tcpip.sys

6.1.7601.22477

1,896,896

10-Oct-13

12:18

x64

Arp.exe

6.1.7600.16385

24,064

14-Jul-09

1:38

x64

Finger.exe

6.1.7600.16385

11,264

14-Jul-09

1:39

x64

Hostname.exe

6.1.7600.16385

9,728

14-Jul-09

1:39

x64

Mrinfo.exe

6.1.7600.16385

12,800

14-Jul-09

1:39

x64

Netiohlp.dll

6.1.7601.22477

229,888

10-Oct-13

12:14

x64

Netstat.exe

6.1.7601.22477

33,792

10-Oct-13

11:30

x64

Route.exe

6.1.7600.16385

21,504

14-Jul-09

1:39

x64

Tcpsvcs.exe

6.1.7600.16385

10,240

14-Jul-09

1:39

x64

Arp.exe

6.1.7600.16385

20,992

14-Jul-09

1:14

x86

Finger.exe

6.1.7600.16385

10,240

14-Jul-09

1:14

x86

Hostname.exe

6.1.7600.16385

8,704

14-Jul-09

1:14

x86

Mrinfo.exe

6.1.7600.16385

11,264

14-Jul-09

1:14

x86

Netiohlp.dll

6.1.7601.22477

178,688

10-Oct-13

11:47

x86

Netstat.exe

6.1.7601.22477

28,160

10-Oct-13

11:10

x86

Route.exe

6.1.7600.16385

17,920

14-Jul-09

1:14

x86

Tcpsvcs.exe

6.1.7600.16385

9,216

14-Jul-09

1:14

x86

For all supported IA-64-based versions of Windows Server 2008 R2

File name

File version

File size

Date

Time

Platform

Netio.sys

6.1.7601.22477

711,104

10-Oct-13

11:21

IA-64

Fwpkclnt.sys

6.1.7601.22477

482,752

10-Oct-13

11:20

IA-64

Tcpip.sys

6.1.7601.22477

3,806,144

10-Oct-13

11:21

IA-64

Arp.exe

6.1.7600.16385

48,128

14-Jul-09

1:44

IA-64

Finger.exe

6.1.7600.16385

22,528

14-Jul-09

1:44

IA-64

Hostname.exe

6.1.7600.16385

14,336

14-Jul-09

1:44

IA-64

Mrinfo.exe

6.1.7600.16385

29,184

14-Jul-09

1:44

IA-64

Netiohlp.dll

6.1.7601.22477

406,016

10-Oct-13

11:17

IA-64

Netstat.exe

6.1.7601.22477

71,168

10-Oct-13

10:52

IA-64

Route.exe

6.1.7600.16385

45,568

14-Jul-09

1:44

IA-64

Tcpsvcs.exe

6.1.7600.16385

18,944

14-Jul-09

1:45

IA-64

Arp.exe

6.1.7600.16385

20,992

14-Jul-09

1:14

x86

Finger.exe

6.1.7600.16385

10,240

14-Jul-09

1:14

x86

Hostname.exe

6.1.7600.16385

8,704

14-Jul-09

1:14

x86

Mrinfo.exe

6.1.7600.16385

11,264

14-Jul-09

1:14

x86

Netiohlp.dll

6.1.7601.22477

178,688

10-Oct-13

11:47

x86

Netstat.exe

6.1.7601.22477

28,160

10-Oct-13

11:10

x86

Route.exe

6.1.7600.16385

17,920

14-Jul-09

1:14

x86

Tcpsvcs.exe

6.1.7600.16385

9,216

14-Jul-09

1:14

x86


  • 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:

    Version

    Product

    Milestone

    Service branch

    6.2.920 0.16 xxx

    Windows 8 and Windows Server 2012

    RTM

    GDR

    6.2.920 0.20 xxx

    Windows 8 and Windows Server 2012

    RTM

    LDR

  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.

  • 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 RT, Windows 8, and Windows Server 2012" 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 8

File name

File version

File size

Date

Time

Platform

Fwpkclnt.sys

6.2.9200.16384

271,088

26-Jul-2012

03:30

x86

Tcpip.sys

6.2.9200.20885

1,815,384

25-Nov-2013

23:56

x86

Arp.exe

6.2.9200.16384

22,016

26-Jul-2012

03:20

x86

Finger.exe

6.2.9200.20885

13,312

25-Nov-2013

23:32

x86

Hostname.exe

6.2.9200.16384

11,776

26-Jul-2012

03:20

x86

Mrinfo.exe

6.2.9200.16384

13,312

26-Jul-2012

03:20

x86

Netiohlp.dll

6.2.9200.20886

201,728

25-Nov-2013

23:32

x86

Netstat.exe

6.2.9200.16384

32,256

26-Jul-2012

03:20

x86

Route.exe

6.2.9200.16384

19,456

26-Jul-2012

03:20

x86

Tcpsvcs.exe

6.2.9200.16384

10,752

26-Jul-2012

03:20

x86

For all supported x64-based versions of Windows 8 and of Windows Server 2012

File name

File version

File size

Date

Time

Platform

Fwpkclnt.sys

6.2.9200.16384

411,888

26-Jul-2012

04:43

x64

Tcpip.sys

6.2.9200.20885

2,228,568

25-Nov-2013

23:40

x64

Arp.exe

6.2.9200.16384

25,088

26-Jul-2012

03:08

x64

Finger.exe

6.2.9200.20885

14,848

25-Nov-2013

23:29

x64

Hostname.exe

6.2.9200.16384

13,312

26-Jul-2012

03:08

x64

Mrinfo.exe

6.2.9200.16384

15,360

26-Jul-2012

03:08

x64

Netiohlp.dll

6.2.9200.20886

248,320

25-Nov-2013

23:28

x64

Netstat.exe

6.2.9200.16384

38,912

26-Jul-2012

03:08

x64

Route.exe

6.2.9200.16384

22,528

26-Jul-2012

03:08

x64

Tcpsvcs.exe

6.2.9200.16384

11,264

26-Jul-2012

03:08

x64

Arp.exe

6.2.9200.16384

22,016

26-Jul-2012

03:20

x86

Finger.exe

6.2.9200.20885

13,312

25-Nov-2013

23:32

x86

Hostname.exe

6.2.9200.16384

11,776

26-Jul-2012

03:20

x86

Mrinfo.exe

6.2.9200.16384

13,312

26-Jul-2012

03:20

x86

Netiohlp.dll

6.2.9200.20886

201,728

25-Nov-2013

23:32

x86

Netstat.exe

6.2.9200.16384

32,256

26-Jul-2012

03:20

x86

Route.exe

6.2.9200.16384

19,456

26-Jul-2012

03:20

x86

Tcpsvcs.exe

6.2.9200.16384

10,752

26-Jul-2012

03:20

x86


Important Windows 8.1 and Windows Server 2012 R2 hotfixes are included in the same packages.

  • 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:

    Version

    Product

    Milestone

    Service branch

    6.2.920 0.20 xxx

    Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2

    RTM

    LDR

  • 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 RT, Windows 8, and Windows Server 2012" 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 Windows RT 8.1

File name

File version

File size

Date

Time

Platform

Fwpkclnt.sys

6.3.9600.16384

278,888

22-Aug-2013

03:52

Not applicable

Tcpip.sys

6.3.9600.16477

1,753,440

27-Nov-2013

11:06

Not applicable

Arp.exe

6.3.9600.16384

21,504

22-Aug-2013

02:18

Not applicable

Finger.exe

6.3.9600.16477

13,312

27-Nov-2013

08:30

Not applicable

Hostname.exe

6.3.9600.16384

12,288

22-Aug-2013

02:18

Not applicable

Mrinfo.exe

6.3.9600.16384

13,824

22-Aug-2013

02:16

Not applicable

Netiohlp.dll

6.3.9600.16477

146,432

27-Nov-2013

08:12

Not applicable

Netstat.exe

6.3.9600.16384

29,696

22-Aug-2013

02:13

Not applicable

Route.exe

6.3.9600.16384

18,432

22-Aug-2013

02:14

Not applicable

Tcpsvcs.exe

6.3.9600.16384

10,752

22-Aug-2013

02:19

Not applicable

For all supported x86-based versions of Windows 8.1

File name

File version

File size

Date

Time

Platform

Fwpkclnt.sys

6.3.9600.16384

286,048

22-Aug-2013

05:20

x86

Tcpip.sys

6.3.9600.16477

1,883,992

27-Nov-2013

13:45

x86

Arp.exe

6.3.9600.16384

22,528

22-Aug-2013

02:52

x86

Finger.exe

6.3.9600.16477

13,312

27-Nov-2013

09:20

x86

Hostname.exe

6.3.9600.16384

12,288

22-Aug-2013

02:52

x86

Mrinfo.exe

6.3.9600.16384

14,848

22-Aug-2013

02:50

x86

Netiohlp.dll

6.3.9600.16477

167,936

27-Nov-2013

08:56

x86

Netstat.exe

6.3.9600.16384

32,768

22-Aug-2013

02:46

x86

Route.exe

6.3.9600.16384

19,968

22-Aug-2013

02:47

x86

Tcpsvcs.exe

6.3.9600.16384

10,752

22-Aug-2013

02:54

x86

For all supported x64-based versions of Windows 8 and of Windows Server 2012 R2

File name

File version

File size

Date

Time

Platform

Fwpkclnt.sys

6.3.9600.16384

428,896

22-Aug-2013

12:34

x64

Tcpip.sys

6.3.9600.16477

2,543,960

27-Nov-2013

15:32

x64

Arp.exe

6.3.9600.16384

25,088

22-Aug-2013

10:01

x64

Finger.exe

6.3.9600.16477

15,360

27-Nov-2013

09:47

x64

Hostname.exe

6.3.9600.16384

13,312

22-Aug-2013

10:02

x64

Mrinfo.exe

6.3.9600.16384

15,360

22-Aug-2013

09:59

x64

Netiohlp.dll

6.3.9600.16477

203,264

27-Nov-2013

09:10

x64

Netstat.exe

6.3.9600.16384

38,400

22-Aug-2013

09:52

x64

Route.exe

6.3.9600.16384

23,040

22-Aug-2013

09:53

x64

Tcpsvcs.exe

6.3.9600.16384

11,264

22-Aug-2013

10:03

x64

Arp.exe

6.3.9600.16384

22,528

22-Aug-2013

02:52

x86

Finger.exe

6.3.9600.16477

13,312

27-Nov-2013

09:20

x86

Hostname.exe

6.3.9600.16384

12,288

22-Aug-2013

02:52

x86

Mrinfo.exe

6.3.9600.16384

14,848

22-Aug-2013

02:50

x86

Netiohlp.dll

6.3.9600.16477

167,936

27-Nov-2013

08:56

x86

Netstat.exe

6.3.9600.16384

32,768

22-Aug-2013

02:46

x86

Route.exe

6.3.9600.16384

19,968

22-Aug-2013

02:47

x86

Tcpsvcs.exe

6.3.9600.16384

10,752

22-Aug-2013

02:54

x86


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

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