Microsoft KB Archive/942861

= Error message when an application connects to SQL Server on a server that is running Windows Server 2003: &quot;General Network error,&quot; &quot;Communication link failure,&quot; or &quot;A transport-level error&quot; =

Article ID: 942861

Article Last Modified on 11/27/2007

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APPLIES TO


 * Microsoft SQL Server 2005 Standard Edition
 * Microsoft SQL Server 2005 Workgroup Edition
 * Microsoft SQL Server 2005 Developer Edition
 * Microsoft SQL Server 2005 Enterprise Edition
 * Microsoft SQL Server 2000 Personal Edition
 * Microsoft SQL Server 2000 Standard Edition
 * Microsoft SQL Server 2000 Workgroup Edition
 * Microsoft SQL Server 2000 Enterprise Edition

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Important This article contains information about how to modify the registry. Make sure that you 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:

322756 How to back up and restore the registry in Windows XP and Windows Vista



SYMPTOMS
Consider the following scenario. A server is running Windows Server 2003 and Microsoft SQL Server. You have an application that connects to SQL Server by using TCP/IP. In this scenario, you may intermittently receive one of the following error messages when the application connects to SQL Server:

Error message 1

[Microsoft][ODBC SQL Server Driver][DBNETLIB] General Network error. Check your network documentation

Error message 2

ERROR [08S01] [Microsoft][SQL Native Client]Communication link failure

Error message 3

System.Data.SqlClient.SqlException: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)

You may also receive one of these error messages when the network load on SQL Server is high. For example, you may receive one of these error messages when you replicate databases in SQL Server. Or, you may receive one of these error messages when a multiple-user application accesses databases in SQL Server.



CAUSE
This problem occurs because the TCP Chimney Offload feature is enabled on the server. The TCP Chimney Offload feature is enabled by the Windows Server 2003 Scalable Networking Pack.

Typically, this problem occurs when the network adapter uses the Broadcom 5708 chipset. For example, the following network adapters use the Broadcom 5708 chipset:
 * Broadcom NetXtreme II
 * Hewlett-Packard NC373i Multifunction Gigabit Server Adapter

This problem may also occur when the network adapter uses other chipsets.



RESOLUTION
To resolve this problem, ask the hardware vendor if the hardware vendor has the following updates:
 * The latest basic input/output system (BIOS) update for the server
 * The latest firmware update for the network adapter
 * The latest driver update for the network adapter

If the hardware vendor has no updates, see the &quot;Workaround&quot; section to work around this problem.



WORKAROUND
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 the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To work around this problem, disable the TCP Chimney Offload feature. To do this, follow these steps:  Click Start, click Run, type cmd, and then press ENTER. At the command prompt, type the following command, and then press ENTER:

Netsh int ip set chimney DISABLED

Note You do not have to restart the server after you run this command.

If the performance of Windows Server 2003 decreases after you disable the TCP Chimney Offload feature, follow these additional steps:  Click Start, click Run, type Regedit, and then click OK. Locate the following registry subkey:

 Double-click the EnableTCPChimney registry entry.</li> In the Edit DWORD Value dialog box, type 0 in the Value data box, and then click OK.</li> Double-click the EnableRSS registry entry.</li> In the Edit DWORD Value dialog box, type 0 in the Value data box, and then click OK.</li> Double-click the EnableTCPA registry entry.</li> In the Edit DWORD Value dialog box, type 0 in the Value data box, and then click OK.</li> Restart the server.</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.

<div class="moreinformation_section">

MORE INFORMATION
The Windows Server 2003 Scalable Networking Pack provides the following features:
 * TCP Chimney Offload
 * Receive-Side Scaling (RSS)
 * Network Direct Memory Access (NetDMA)

These features optimize the performance of Windows Server 2003 when Windows Server 2003 is processing network traffic.

To obtain the Windows Server 2003 Scalable Networking Pack, you must install Windows Server 2003 Service Pack 2 (SP2). Or, you must install the update that is described in Microsoft Knowledge Base article 912222. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

912222 The Microsoft Windows Server 2003 Scalable Networking Pack release

To enable the TCP Chimney Offload feature, the server must have a network adapter that supports offload technologies.

How to use a network trace to determine whether the TCP Chimney Offload feature is enabled
When you directly capture a network trace on the server, the network trace contains only TCP three-way handshakes and UDP traffic if the TCP Chimney Offload feature is enabled. The network trace does not contain other traffic because the TCP Chimney Offload feature lets the network traffic bypass that specific part of the TCP/IP stack. The driver that captures packets resides in that specific part of the TCP/IP stack.

The information and the solution in this document represents the current view of Microsoft Corporation on these issues as of the date of publication. This solution is available through Microsoft or through a third-party provider. Microsoft does not specifically recommend any third-party provider or third-party solution that this article might describe. There might also be other third-party providers or third-party solutions that this article does not describe. Because Microsoft must respond to changing market conditions, this information should not be interpreted to be a commitment by Microsoft. Microsoft cannot guarantee or endorse the accuracy of any information or of any solution that is presented by Microsoft or by any mentioned third-party provider.

Microsoft makes no warranties and excludes all representations, warranties, and conditions whether express, implied, or statutory. These include but are not limited to representations, warranties, or conditions of title, non-infringement, satisfactory condition, merchantability, and fitness for a particular purpose, with regard to any service, solution, product, or any other materials or information. In no event will Microsoft be liable for any third-party solution that this article mentions.

Keywords: kbexpertiseadvanced kbtshoot kbprb KB942861

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