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Article ID: 927695 - Last Review: December 4, 2007 - Revision: 4.7

SYMPTOMS

Transmission Control Protocol (TCP) connections are reset when Receive Side Scaling is enabled in Microsoft Windows Server 2003 with Service Pack 2 (SP2). This problem occurs if you use Network Address Translation (NAT), if you use Windows Firewall, or if the host computer is configured to be an Internet Connection Sharing host server computer.

Note This problem may also occur when you use the following products:
  • Windows Server 2003 Service Pack 1 (SP1) together with the Windows Server 2003 Scalable Networking Pack
  • Microsoft Internet Security and Acceleration (ISA) Server 2004 or ISA Server 2006
  • Other add-on Firewall or network address translation (NAT) software

CAUSE

This problem is caused when the software hash code for the connection and the hardware hash code for the connection do not match. Receive Side Scaling works by offloading the TCP secure hash function to the network adapter hardware. Therefore, the network adapter calculates the hash value for the connection when Receive Side Scaling is enabled. Internet Connection Sharing also modifies the addresses and the ports that are provided by the IP header for the connection. When this occurs, the hash value that is generated by the network adapter is invalidated. When the invalidated hash value is used, the TCP connection is reset.

This problem may also occur if the IP source address, the IP destination address, the TCP source port, or the TCP destination port are modified during receive processing. These addresses and ports are provided in the TCP and IP headers for the connection. This problem may occur in some NAT scenarios.

WORKAROUND

Important 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:
322756  (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows


To work around this problem, disable Receive Side Scaling when the computer is configured as an Internet Connection Sharing gateway. To do this, follow these steps:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following registry subkey:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
  3. On the Edit menu, point to New, click DWORD Value, and then type EnableRSS.
  4. Double-click EnableRSS, type 0, and then click OK.
  5. Restart the computer on which you changed the EnableRSS value.

STATUS

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

REFERENCES

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
936594  (http://support.microsoft.com/kb/936594/ ) You may experience network-related problems after you install Windows Server 2003 S or the Scalable Networking Pack on a Windows Server 2003-based computer
For more information, visit the following Microsoft Web site:
http://blogs.technet.com/sbs/archive/2007/03/19/vpn-securenat-nat-and-outlook-clients-not-working-after-installing-windows-service-pack-2-in-sbs-2003-premium.aspx (http://blogs.technet.com/sbs/archive/2007/03/19/vpn-securenat-nat-and-outlook-clients-not-working-after-installing-windows-service-pack-2-in-sbs-2003-premium.aspx)

APPLIES TO
  • Microsoft Windows Server 2003 Service Pack 2, when used with:
    • Microsoft Windows Server 2003, 64-Bit Datacenter Edition
    • Microsoft Windows Server 2003, Enterprise x64 Edition
    • Microsoft Windows Server 2003, Standard x64 Edition
    • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
    • Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
    • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
    • Microsoft Compute Cluster Pack
    • Microsoft Windows Server 2003 Compute Cluster Edition
  • Microsoft Windows Server 2003 Service Pack 1, when used with:
    • Microsoft Windows Server 2003, 64-Bit Datacenter Edition
    • Microsoft Windows Server 2003, Enterprise x64 Edition
    • Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
    • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
    • Microsoft Windows Server 2003 Compute Cluster Edition
  • Microsoft Windows Small Business Server 2003 Premium Edition
  • Microsoft Windows Small Business Server 2003 Standard Edition
  • Microsoft Windows Small Business Server 2003 R2 Premium Edition
  • Microsoft Windows Small Business Server 2003 R2 Standard Edition
Keywords: 
kbregistry kbwinservnetwork kbconnection kbnat kbclustering kbtshoot kbprb KB927695
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