Short Technical Note on WHAT / WHY on OB2IPCKEEPALIVE=1 is set + OS 'keepalive'.
When DP has an open connection it may be disconnected by the operating system or any hardware that is in the data transport chain.
Typical disconnection timeouts are 1 or 2 hours depending of the platform, firewall or complex network. When such a silent disconnection occurs DP will loose the connection and not always be able to recover.
To keep such a connection alive we have a possibility to open the connection with a ‘keepalive’ option. Then the lower level IPC layer will send out ‘keepalive’ packages to stimulate the connection in order to prevent a silent disconnection.
The ‘keepalive’ packets are part of TCP protocol and are transparent to the program opening or using the connection. They are handled by the system and are not seen by application.
It must be clear that connections with ‘keepalive’ functionality are not a property of DP but from the lower level system code.
To open the connections with the ‘keepalive’ option the user must set OB2IPCKEEPALIVE=1 in the omnirc file of each host in the cell that can potentially suffer from a disconnection.
The issue is that by default the ‘keepalive’ interval (the time between two packets) is set to two hours on many systems, rendering them ineffective in some cases if other parties control the connection. This interval can be changed.
For a standard operating system the ‘keepalive’ packages are send out every 2 hours however some network hardware, monitoring software and firewalls may disconnect the connection already earlier.
So ‘keepalive’ packages should be interchanged at a shorter interval.
Set the ‘keepalive’ package transmit to 15 minutes = 900000 If this solves the disconnection issue you know the connectivity layer disconnects earlier than the default system value.
Example : WINDOWS
To change the parameter on Windows, check the KeepAliveTime in the registry.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;120642
KeepAliveTime
Key: Tcpip\Parameters
Value Type: REG_DWORD - Time in milliseconds Valid Range: 1 - 0xFFFFFFFF
Default: 7,200,000 (two hours)
Description: The parameter controls how often TCP attempts to verify that an idle connection is still intact by sending a keep alive packet. If the remote system is still reachable and functioning, it will acknowledge the keep alive transmission. Keep alive packets are not sent by default. This feature may be enabled on a connection by an application.
NOTE : Please check the Microsoft KB for the specific WINDOWS OS version on registry parameters.