- General information about the Microsoft Scalable Networking Pack (SNP)
- Errors that your application may receive when it connects to an instance of Microsoft SQL Server that is hosted on a Windows-based computer that has some of or all the networking performance improvements enabled
Note This article also includes recommendations for preventing these errors on computers that are running various versions of Windows.
- Additional references
The SNP is a set of high-speed networking features that were introduced as part of Windows Server 2003 Service Pack 2 (SP2). These features also were included as part of Windows Server 2008 and later versions.
Note Because these features are part of the base TCP/IP stack in Windows Server 2008 and later versions, they are no longer known as Scalable Networking Pack features.
The important SNP features relevant to this article are as follows:
- TCP Chimney Offload This feature transfers TCP/IP protocol processing from the CPU to a network adapter during network data transfer.
- Receive Side Scaling This feature enables the network load from a network adapter to be distributed across multiple CPUs in a multiprocessor computer.
- NetDMA This feature provides services for offloading the memory copy operation that is performed by the networking subsystem to a dedicated direct memory access (DMA) engine when receiving network packets.
You may receive one or more of the following error messages when your network hardware is incompatible with SNP features.
Note You may receive one or more of these error messages when one of the following conditions is true:
- The computer on which the hardware is installed hosts the instance of SQL Server.
- An application connects to the instance of SQL Server by using TCP/IP.
Error message 2
Error message 3
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.
Verify the current configuration
To display the current TCP global parameters, at a command prompt, type the following command, and then press Enter:
The output of this command resembles the following:
To display the network adapters that have the TCP Chimney Offload feature enabled, at a command prompt, type the following command, and then press Enter:
The output of this command resembles the following:
Recommendations for using SNP or other network offload features in SQL Server environments
If you receive intermittent network errors as described in this section, refer to the following tables for guidance on how to realize the maximum benefits when you use the networking performance improvement features in SQL Server environments.
Table 1: Common guidance for all versions of Windows Server
|All versions of Windows starting with Windows Server 2003 Service Pack 2|
Table 2: Windows Server version-specific guidance.
|Windows Server 2003 Service Pack 2||We recommend that you disable SNP features by installing the hotfix that is documented in the following article in the Microsoft Knowledge Base:|
948496 Update to turn off SNP features for Windows Server 2003 and Windows SBS 2003If network performance is very important, we recommend that you consider migrating to a later version of Windows Server that is included with the next generation of the TCP/IP stack. If you cannot immediately upgrade to a newer version but have to maximize network performance, we recommend that you follow these steps on all the affected servers:
|Windows Server 2008|
|Windows 7 and Windows Server 2008 R2|
|Window 8 and Windows Server 2012||Currently, there are no known issues. We recommend that you use the default configuration for high-speed networking features.|
Note By default, the TCP Chimney Offload feature is disabled in Windows Server 2012.
Turn off SNP/high-speed networking features
We do not recommend that you turn off SNP features on newer versions of Windows Server. However, you may have to disable SNP on your Windows Server-based computer as a troubleshooting step or because you lack hardware support for all the RSS features. For more information, see the following table:
|Windows Server version||More information|
|Windows Server 2003||See the following article in the Microsoft Knowledge Base: |
948496 Update to turn off SNP features for Windows Server 2003 and Windows SBS 2003
|Windows Server 2008||See the following article in the Microsoft Knowledge Base: |
951037 Information about the TCP Chimney Offload, Receive Side Scaling, and Network Direct Memory Access features in Windows Server 2008
|Windows Server 2008 R2||Do not disable|
|Windows Server 2012||Do not disable|
Note We recommend that you use the default configuration for the high-speed networking features in Windows Server 2008 R2 and Windows Server 2012 environments. However, you can disable the TCP Chimney Offload feature if you know that you do not want to use it or if you want to keep settings consistent across a mix of different operating systems in your environment.
For information about Receive Side Scaling, go to the following Microsoft TechNet website:
For more information about how to deploy high-speed networking features, go to the following TechNet website:
For more information about the high-speed networking features in Windows Server 2008 R2, click the following article number to view the article in the Microsoft Knowledge Base:
For more information about how to deploy and monitor high-speed networking features, go to the following Microsoft website:
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