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AlexDeMarco's avatar
AlexDeMarco
Icon for Nimbostratus rankNimbostratus
Jan 24, 2017

Trying to force down a VIP via a health monitor, is there a better way?

I have a vip that does not have default pool assigned (for a variety of reasons). We use an irule to direct traffic to 1 of 2 pools based on certain criteria. However, I need to be able to disable the vip if there are zero nodes available in either pool. I have an external monitor created that checks the number of available pool members and can disable the vip. My problem is that if I assign this monitor to either pool the script runs for the number of nodes in each pool. So if have have 2 nodes in 2 pools it runs 4 times. I only want it to run once. Would I be better off moving this check to the irule associate with the vip instead? Or is there a better way to accomplish this? Thank you in advance.

 

application delivery
devops
LTM

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  • AlexDeMarco's avatar
    AlexDeMarco
    Icon for Nimbostratus rankNimbostratus
    Jan 24, 2017

    I think I may be over complicating things..

     

    If I add this to the Irule attached to the vip: when CLIENT_ACCEPTED { if { [active_members DEV_7099] < 1 and [active_members DEV_7002] < 1 }{ reject log local0. "[IP::client_addr] - Client rejected. Active members of MyPoolName dropped below 3." } else { return } }

     

    Is this the same as the same behavior as if the vip was disabled??

     

  • KeesvandenBos's avatar
    KeesvandenBos
    Icon for MVP rankMVP
    Jan 24, 2017

    The only difference is that when a vip is down or disabled it won't accept any traffic.

     

    Your iRule will have to finish the 3way handshake to execute the reject.

     

    Cheers,

     

    Kees

     

  • IheartF5_45022's avatar
    IheartF5_45022
    Icon for Nacreous rankNacreous
    Jan 24, 2017

    It will behave the same, however it won't show as 'disabled'.

     

    BTW the 'reject' is CLIENT_ACCEPTED is fine - you don't need to complete 3-way handshake.

     

    HOWEVER active_members won't work unless you have monitors assigned - there's something wrong with the logic here.......