Applications that use the UDP protocol may encounter poor performance on a computer that is running Windows Server 2003

Consider the following scenario:

• You install a Gigabit Ethernet adapter on a computer that is running Windows Server 2003 Service Pack 2 (SP2) or an x64-based version of Windows XP Service Pack 2 (SP2).
• You install the network adapter driver that is Network Driver Interface Specification (NDIS) 5.1 or 5.2 compliant.
• You have an application that transfers data by using the UDP protocol through the Gigabit Ethernet adapter.

Under a heavy stress situation, the UDP packets are randomly dropped. This issue leads to a decrease in performance and to lots of UDP retransmissions.

The Ndis.sys driver queues the deferred procedure call (DPC) routines at a low importance level on the same processor that services the interrupt service routine (ISR). Therefore, the UDP related DPC routine goes to the end of the queue, and this DPC routine is processed last. Additionally, the DPC queue of the processor may not be empty, and these DPCs for other I/O drivers are processed first. If the DPC rate is sufficiently high for all I/O drivers, not just for NDIS, there can be a noticeable delay.

Under a heavy stress situation, this delay can cause the system to drop packets when the Ethernet adapter's receive buffers fill while the receive buffers wait for the queued DPC routine to finish.

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 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, your computer must be running Windows Server 2003 Service Pack 2 (SP2).

Restart requirement

You must restart the computer after you apply this hotfix.

Registry information

You do not have to make any change to the registry.

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.

For all supported x86-based versions of Windows Server 2003

For all supported x64-based versions of Windows Server 2003 and of Windows XP

For all supported Itanium-based versions of Windows Server 2003

To work around the issue, enable the receive-side scaling (RSS) feature on the affected computer.

Note The NDIS miniport must be 5.2 capable to use any Scalable Networking Pack new feature or improvement including RSS.

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

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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