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StarQuest Technical Documents

SQDR & SQDR Plus: TCP KeepAlive Settings

Last Update: 12 November 2021
Product: SQDR Plus
Version: 4.50 and later
Article ID: SQV00PL061

Abstract

In order for SQDR to react quickly to loss of connectivity to a source or destination system, or between tier 2 and 3 in a split-tier environment, we recommend examining and adjusting the TCP KeepAlive parameters. These recommendations apply to both Tier 2 and Tier 3 systems in a split-tier environment.

Solution

The following are our recommendations for Windows.

  1. Use regedit and open the key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
  2. Examine and modify the following values, noting the original value. You may need to create some of the values if they don't exist.
  • KeepAliveInterval: REG_DWORD = Interval between KeepAlive packets when one is dropped. Measured in milliseconds--the default is 1000 (1 second). This can remain at 1000.
  • KeepAliveTime: REG_DWORD = How often TCP attempts to verify the connection. Measured in milliseconds--the default is 7200000 (2 hours). We recommend changing this to 60000 (one minute)
  • TcpMaxDataRetransmissions: REG_DWORD = Number of retries TCP does for a packet before giving up. The default is 5. This can be increased to 30.
  1. Reboot the system.

Note that modifying the KeepAlive parameter settings may affect the operation of other applications on the computer.

For more information, see Configuring TCP KeepAlive Parameters.

DISCLAIMER

The information in technical documents comes without any warranty or applicability for a specific purpose. The author(s) or distributor(s) will not accept responsibility for any damage incurred directly or indirectly through use of the information contained in these documents. The instructions may need to be modified to be appropriate for the hardware and software that has been installed and configured within a particular organization.  The information in technical documents should be considered only as an example and may include information from various sources, including IBM, Microsoft, and other organizations.