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IP packets that are transferred over aggregated links may be dropped by the Multilink feature on a Windows XP-based computer
Article ID: 946775 - View products that this article applies to.
Consider the following scenario:
For example, assume that you use three wireless modems to connect to your Internet service provider (ISP). Each of these modems supports a data transfer rate of 3 megabits per second (Mbps). When you aggregate the links of these three modems, you expect a maximum transfer rate of 9 Mbps in total. However, when the actual transfer rate reaches 6 Mbps, the IP packets over the aggregated links may be dropped intermittently.
The Ndiswan.sys driver maintains a buffer that is responsible for holding the received packets for reassembly. There are 64 of these buffers. This number is sufficient for dial-up modems. When the combined bandwidth exceeds 6 Mbps, fragments are likely to be dropped before they are reassembled.
Hotfix informationA 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 this specific problem.
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, submit a request to 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=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.
PrerequisitesTo apply this hotfix, you must have Windows XP Service Pack 2 (SP2) or a later service pack installed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/322389/ )How to obtain the latest Windows XP service pack
Restart requirementYou must restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.
Registry informationImportant 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:
322756After you apply this hotfix, you can use a registry entry to configure the size of the reassembly buffer in the Ndiswan.sys driver. To do this, follow these steps:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
File informationThe 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.
Windows XP with Service Pack 2, x86-based versions
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Windows XP with Service Pack 3, x86-based versions
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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about how to set up multiple-device dialing in Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:
307849For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/307849/ )How to set up multiple-device (Multilink) dialing in Windows XP
(http://support.microsoft.com/kb/824684/LN/ )Description of the standard terminology that is used to describe Microsoft software updates