A Windows Server 2003 Service Pack 2-based computer may drop packets when the computer is working as a bridge and as a router

Consider the following scenario:

• Multiple network adapters are installed on a Windows Server 2003 Service Pack 2-based computer.
• These network adapters are bridged together.
• You edit the registry to enable TCP/IP forwarding on the computer.
• The Windows Firewall service is running.

In this scenario, some packets may be dropped when this Windows Server 2003 Service Pack 2-based computer is working both as a bridge and as a router. This problem may cause application functional failure or unexpected behavior.

This problem occurs because of a race condition in the TCP/IP protocol driver.

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 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 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 Web site: 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 have Windows Server 2003 Service Pack 2 installed on the computer.

Restart requirement

You must restart the computer after you apply 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 item in Control Panel.

Windows Server 2003 with Service Pack 2, x86-based versions

Windows Server 2003 with Service Pack 2, Itanium-based versions

Windows Server 2003 with Service Pack 2, x64-based versions

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 enable TCP/IP forwarding, click the following article number to view the article in the Microsoft Knowledge Base: To check the number of discarded packets, follow these steps:

1. Run the following command at a command prompt:
   netstat �s -p
2. Check the value of the Received Packets Discarded item in the command output.

To check whether packets are dropped while you are performing an operation, run the netstat command before you perform the operation, and then run the netstat command again after you perform the operation. In this scenario, you can verify that some packets are dropped if the value of the Received Packets Discarded item has increased after the operation.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: