Microsoft KB Archive/939006

= You cannot use Verizon FiOS products at their full speed on a Windows Vista-based computer =

Article ID: 939006

Article Last Modified on 11/13/2007

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APPLIES TO


 * Windows Vista Business
 * Windows Vista Enterprise
 * Windows Vista Home Basic
 * Windows Vista Home Premium
 * Windows Vista Ultimate
 * Windows Vista Business 64-bit Edition
 * Windows Vista Enterprise 64-bit Edition
 * Windows Vista Home Basic 64-bit Edition
 * Windows Vista Home Premium 64-bit Edition
 * Windows Vista Ultimate 64-bit Edition

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SYMPTOMS
On a computer that is running Windows Vista, you try to use the Verizon speed optimizer tool to optimize network performance. When you do this, you may notice that the Windows Vista-based computer does not achieve the Internet connection speed improvement that is achieved in Windows XP. Therefore, you cannot use Verizon FiOS products at their full speed.



CAUSE
This problem occurs because of the TCP/IP protocol stack changes that were made in Windows Vista. On a Windows Vista-based computer, the TCP/IP protocol stack changes do not allow for registry key changes in some areas. Additionally, in the source code, the TCPAutoTuning feature is set to &quot;off.&quot; These changes cause the problem that is mentioned in the &quot;Symptoms&quot; section.



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

Prerequisites
There are no prerequisites for installing this hotfix.

Restart requirement
You do not have to restart the computer after you apply this hotfix. However, you should restart all instances of Windows Internet Explorer.

Hotfix replacement information
This hotfix does not replace a previously released hotfix.

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 item in Control Panel.

How to enable the hotfix
To use one of the hotfixes in this package, you must either create a registry key or modify a registry key.To do this, follow these steps.

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 XP and Windows Vista

 Click Start, click Run, type regedit, and then click OK. Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Internet Settings\

 On the Edit menu, point to New, and then click DWORD Value. In the details pane, type TcpAutoTuning, and then press ENTER. Right-click TcpAutoTuning, and then click Modify. In the Edit DWORD Value dialog box, click Decimal under Base. In the Value data box, type 1, and then click OK.</li> Close Registry Editor.</li></ol>

<div class="status_section">

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

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Keywords: kbqfe kbexpertisebeginner kbhotfixserver KB939006

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