Maintaining active TCP connections in a network environment

If your deployment of CDC Replication is in a network environment that uses a firewall, VPN gateway, or local system tools to detect idle TCP connections, it may be necessary to configure the product to prevent these connections from being closed during periods of application inactivity between the source and target.

About this task

By default, CDC Replication sends a message over TCP connections every 20 seconds to ensure these connections remain active during periods of inactivity. If your network policies close TCP connections for idle periods of less than 20 seconds, you must change the configuration of each instance of CDC Replication to ensure the TCP connections remain open.


  1. For each instance of CDC Replication, navigate to one of the following directories depending on your operating system:

    UNIX :

    <CDC Replication installation directory>/instance/<instance_name>/conf
    <CDC Replication installation directory>\instance\<instance_name>\conf
  2. Open the comms.ini file in a text editor.
  3. Change the KEEP_ALIVE_TIMEOUT parameter to a value that is less than the time used to detect idle connections in your network. For example, if your network disables idle TCP connections after 15 seconds, you can change the KEEP_ALIVE_TIMEOUT parameter to a value of 10 seconds:
  4. Save the comms.ini file.
  5. For the changes to take effect, use the configuration tool to restart each CDC Replication instance for which the parameter was changed.

What to do next

CDC Replication will now send messages over the TCP connection every 10 seconds.