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  • 1.  Change in TCPKEEPALV of CHGTCPA

    Posted Mon August 05, 2024 03:58 PM
    Hello,
     
    A change in TCPKEEPALV from 120 to 5 minutes of CHGTCPA, what can be affected by this change?
     


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    Regards,

    Jorge Lee
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  • 2.  RE: Change in TCPKEEPALV of CHGTCPA

    Posted Mon August 05, 2024 09:41 PM
    Edited by Satid S Mon August 05, 2024 09:43 PM

    Dear Jorge

    Your question is a bit ambiguous. If my response below is not what you are looking for, please let me know. 

    Most changes in CHGTCPA (including the Keep Alive Timer) takes effect for any NEW TCP/IP connections established after the change.  All existing connections at the moment you make the change are NOT affected by the change.   

    How do you verify that the Keep Alive Timer works?  Use NETSTAT *CNN and page down to the link(s) of  your interest and press F5 to refresh the screen regularly and take note of the "Idle Time" of the link which should not exceed 5 minutes.  When it reaches nearly 5 minutes, the next F5 should show near zero value.  If Idle Time increases beyond 5 minutes, the Keep Alive is not active in that link(s).

    Why do you choose 5 minutes for Keep Alive Timer?   One most popular reason for setting Keep Alive Timer is that there is a firewall that kills all connections that idle more than a set value (called session idle timer)  and all persistent connection pools fall into this category as they are designed to be permanent links.  Setting TCP Keep Alive Timer within the Firewall's session idle timer helps prevent Firewall from killing these links.   Many firewall I worked with in the past uses 30 minutes as the session idle timer and I normally use 20 minutes for Keep Alive and it is better set at the node that initiates the links (which is mostly not IBM i but the Intel servers).  Setting 5 minutes for Keep Alive when Firewall's session idle timer is 30 minutes causes unnecessary traffic in the network.  If you do not have a lot of nodes with a lot of total persistent connections, this is not a big deal.



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    Satid S
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  • 3.  RE: Change in TCPKEEPALV of CHGTCPA

    IBM Champion
    Posted Tue August 06, 2024 08:08 AM

    See also:

    select IDLE_TIME,REMOTE_ADDRESS, REMOTE_PORT, REMOTE_PORT_NAME, LOCAL_ADDRESS, LOCAL_PORT
    from qsys2.netstat_info
    order by idle_time desc

    https://www.ibm.com/docs/en/i/7.5?topic=is-communication-services



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    Robert Berendt IBMChampion
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  • 4.  RE: Change in TCPKEEPALV of CHGTCPA

    IBM Champion
    Posted Tue August 06, 2024 08:09 AM

    I will say that is a very good answer Satid.



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    Robert Berendt IBMChampion
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