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Amar_A_361783's avatar
Amar_A_361783
Icon for Nimbostratus rankNimbostratus
Aug 21, 2018

Why is Persistence required for long-live connection too?

I need to understand is even persistence required for application like SSH? SSH & say other stateful protocol which holds session with the client for long period, what is the use of applying persistence.

 

application delivery
LTM
  • Andy_McGrath's avatar
    Andy_McGrath
    Icon for Cumulonimbus rankCumulonimbus
    Aug 22, 2018

    None most of the time, if the connection is long live and you are happy for any re-connection to be load balanced again you do not need persistence.

     

    However if you do want to ensure a re-connection by the client goes to the same pool member you would need some persistence configured to provide some level of protection.

     

  • youssef1's avatar
    youssef1
    Icon for Cumulonimbus rankCumulonimbus
    Aug 22, 2018

    Hi,

     

    If you have multiple backend (Statfull Web Services) you need to be redirect to the same server. In this case you need persistence:

     

    • WEB Service (you can use L7 persistance as cookie)
    • TCP Service as SSH (you can use sourceadress persistance)

    In your case with ssh you need to use source address pers. And if you have only one Pool memeber (backend) or several pool memebers (stateless) you don't need persistance.

     

    But you have to pay attention to your TCP profile. you have to keep in mind that your SSH VS has a TCP profile. TCP use a 5 minute (300 seconds) idle timeout value. So you will probably deconnected each F5 (I'am not sure but for FTP or SFTP I already had this behaviour). To fix this, create a new TCP profile for your SSH VS and change the idle timeout to something that makes sense for your environment (30mn).

     

    Info: Overview of BIG-IP idle session time-outs

     

    https://support.f5.com/csp/article/K7606

     

    Regards