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Kranthi's avatar
Kranthi
Icon for Nimbostratus rankNimbostratus
Jan 07, 2020

VIP Failover and Failback Process with back end servers

Hi Team,

 

We got a typical requirement from client as below.

 

F5 Load Balancer VIP with 4 backend servers total, two servers with priority group 10 and 2 servers with priority group 5

 

the scenario is, if all backend servers fails on priority group 10 then failover to backend servers with priority group 5, which is already in place and is working as expected.

 

the requirement now from client is, if the high priority group backend servers come online traffic shouldn't failback to higher priority group servers, VIP requests needs to be forwarded only to Priority group 5 only, it has to switch back higher priority group servers again only if all backend servers failed in lower priority group 5.

 

Now challenge for us is as soon as high priority group backend servers come online traffic is switching to them directly which we don't want.

 

Hope i explained correctly. Please provide your expert knowledge and provide me a suggestions on this design

 

 

 

application delivery
BIG-IP
LTM

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  • Mitheor's avatar
    Mitheor
    Icon for Cirrus rankCirrus
    Jan 08, 2020

    Hi Kranthi,

     

    i don´t think there is a way to achieve this via GUI.

     

    One thing you could try is use "manual resume" for the priority group and a iRule to enable it again when needed.

     

    So, in the end, it would work like this:

     

    Priority group 10 --> "A"

    Priority group 5 --> "B"

     

    A is UP and B is standby.

    A fails (and gets disabled).

    B takes control of the traffic.

    When B fails a iRules enables A again.

     

    Does it makes sense?

     

    Hope it helps.

     

    Br

    • Kranthi's avatar
      Kranthi
      Icon for Nimbostratus rankNimbostratus
      Jan 08, 2020

      HI Mitheor,

       

      Thanks for your update. but how we can perform auto disable and what will be the irule in such cases.

      • Mitheor's avatar
        Mitheor
        Icon for Cirrus rankCirrus
        Jan 08, 2020

        Hi,

         

        regarding manual resume:

         

        https://support.f5.com/csp/article/K83316932

         

        However, i´ve taking a look and it seems it´s not possible to change a node status via iRule.

         

        You could probably achieve this via iCall but it´s not an easy task i´m afraid.

         

        If a have more time these days i´ll try to think about it.

         

        Sorry mate.

         

        Br