Microsoft KB Archive/816045

= Group Policies may not apply because of network ICMP policies =

Article ID: 816045

Article Last Modified on 8/29/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
 * Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Professional
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 3
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 3

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Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry



SYMPTOMS
When you use Group Policy to determine whether a link is fast or slow, fast links may be incorrectly flagged as slow links.



CAUSE
This problem may occur when a network that you are trying to detect a slow link to is configured to control the size and flow of Internet Control Message Protocol (ICMP) packets. For example, if a router allows for only ICMP ping packets that have a size of 1,024 bytes, the slow-link detection feature may flag the connection as a slow link. This is because the router discards ICMP packets that are larger than 1,024 bytes. If the router discards the packet because it exceeds the allowed size, fast links may be reported as slow links.

The Microsoft Knowledge Base article that is listed in the &quot;More Information&quot; section describes how slow link detection works. On Microsoft Windows 2000-based computers or Windows XP-based computers that do not have the hotfix that is described in this article installed, the client computer pings a domain controller three times with a zero-byte packet. If the response time is more than 10 milliseconds (ms), the client computer then pings with packet size of 2048.If the larger ping response time is more than 10 ms, this indicates a slow link. If the results of this procedure indicated a slow link all three times, then the link is flagged as a slow link.



RESOLUTION
To resolve this problem, configure Windows to use smaller ICMP ping packets for fast-link detection. The hotfix described here enables configuring a custom ICMP ping packet size.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

Service pack information
To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, 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

Service pack information
To resolve this problem, obtain the latest service pack for Windows XP. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Hotfix information
A supported hotfix is now 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 this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or 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. To create a separate service request, visit the following Microsoft Web site:

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

Restart requirement
You must restart your computer after you install this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

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 tool in Control Panel.

Service pack information
To resolve this problem, obtain the latest service pack for Windows 2000. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows 2000 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

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

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

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 tool in Control Panel.

Installation notes
After you install this hotfix, you can resolve the symptom that is described in this article by configuring Windows to use a smaller ICMP ping packet size. To manually change the ICMP ping packet size, create the following registry subkey:

Value name: PingBufferSize

Value type: DWORD (decimal)

Value range: 500 - 2048

Default Value: 2048 '''

Note''' If you do not set this registry subkey or if you set the value out of range, the default ICMP ping packet size of 2048 is used. You can view the packet size in the Userenv.log file. If your network routers are configured to ignore large ICMP packets, be sure to reduce the PingBufferSize to a smaller value.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Windows Server 2003
This problem was first corrected in Windows Server 2003 Service Pack 1.

Windows 2000
This problem was first corrected in Windows 2000 Service Pack 4.



MORE INFORMATION
Administrators can use fast link detection to control the application of Group Policy to slow links. This functionality uses ICMP to determine whether a link is fast or slow. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

227260 How a slow link is detected for processing user profiles and Group Policy

For more information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base:

265173 The Datacenter program and Windows 2000 Datacenter Server product

Keywords: kbhotfixserver kbqfe kbwinserv2003sp1fix kbwinxppresp3fix kbsysadmin kbwin2ksp4fix kbwin2000presp4fix kbfix kbbug KB816045

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