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TcpTimedWaitDelay Key is Missing or Non-default

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2007-03-13

The Microsoft Exchange Analyzer tool queries the Active Directory directory service to determine the value of the serialNumber attribute for all objects that have an object class of msExchExchangeServer. If the string value includes "Version 5.5", the computer is running Exchange Server 5.5. If the string value includes "Version 6.0", the computer is running Exchange 2000 Server. If the string value includes "Version 6.5", the computer is running Exchange Server 2003. If the string value includes "Version 8.0", the computer is running Exchange Server 2007.

The Exchange Analyzer tool then reads the following registry branch for each Exchange Server 2007 server found to determine if the value for the TcpTimedWaitDelay key is set to the default value of 60.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

The TcpTimedWaitDelay key determines the time that must elapse before TCP can release a closed connection and reuse its resources. This interval between closure and release is known as the TIME_WAIT state or 2MSL state. During this time, the connection can be reopened at much less cost to the client and server than establishing a new connection.

Reducing the value of this entry allows TCP to release closed connections faster, providing more resources for new connections. However, if the value is too low, TCP might release connection resources before the connection is complete, requiring the server to use additional resources to reestablish the connection.

If the Exchange Analyzer determines that the value for the TcpTimedWaitDelay key is missing or not equal to the default value of 60, the Exchange Analyzer displays a warning.

For optimal performance, we recommended that you set the TcpTimedWaitDelay key to its default value of 60 on Exchange Server 2007 servers.

importantImportant:
This topic contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.
To set the TcpTimedWaitDelay registry key to its default value
  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\Tcpip\Parameters

  3. Double-click the TcpTimedWaitDelay, and set the Value data field to 60 (decimal).

  4. Close the registry editor and restart the computer.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=256986).

This issue is related to the MaxUserPort Key is Missing or Non-default Analyzer issue.

For more information about the effect of the MaxUserPort and TcpTimedWaitDelay registry keys, see the "Transmission Control Protocol" topic in the Windows 2000 Resource Kit (http://go.microsoft.com/fwlink/?LinkId=85654).

 
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