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TimGabaree's avatar
TimGabaree
Icon for Nimbostratus rankNimbostratus
Sep 11, 2019

Need to Disable Azure F5 LTM Pool's FQDN Node based on Subnet

We have the same Virtual F5 LTM FQDN nodes residing/duplicated in 2 diffent Azure regions. We would like to disable the nodes in a pool when the FQDN address resolves to a subnet in a different Azure region but keep it live if the subnet for the resolved node is located in the Virtual F5's local region. IE. normally, a node resides in Virginia and has an IP address in the 10.x.x.x subnet. The FQDN resolved node is also listed in a pool in Texas. The Texas version of the FQDN node will normally resolve to an IP address in the Virginia 10.x.x.x subnet. Because of this, we want to have the node in Texas automatically disabled when it normally resolves to an IP address in the 10.x.x.x subnet. If that node goes down in the Virginia region and we change the FQDN to give the node an IP address in the 11.x.x.x subnet (Texas region), we would like to automatically enable the node in Texas when it resolves to an IP address in the 11.x.x.x subnet... And then automatically disable it again if it later resolves back to an IP address in the 10.x.x.x subnet.

 

How do we do this via health check or iRule? Thanks for any pointers or help with this.

  • JG's avatar
    JG
    Icon for Cumulonimbus rankCumulonimbus
    Sep 12, 2019

    Your request is a bit hard to read, if only it were better formatted into a few paragraphs.....

     

    If I read your request correctly, you need an external health monitor which will disable the node when its name resolves to an address in the 10.x.x.x range in Texas.

  • TimGabaree's avatar
    TimGabaree
    Icon for Nimbostratus rankNimbostratus
    Sep 12, 2019

    "If I read your request correctly, you need an external health monitor which will disable the node when its name resolves to an address in the 10.x.x.x range in Texas."

    Correct. Thanks,

     

    Here it is broken down into paragraphs. Thanks for pointing it out:

     

    We have the same Virtual F5 LTM FQDN nodes residing/duplicated in 2 diffent Azure regions. We would like to disable the nodes in a pool when the FQDN address resolves to a subnet in a different Azure region but keep it live if the subnet for the resolved node is located in the Virtual F5's local region. IE. normally, a node resides in Virginia and has an IP address in the 10.x.x.x subnet.

     

    The FQDN resolved node is also listed in a pool in Texas. The Texas version of the FQDN node will normally resolve to an IP address in the Virginia 10.x.x.x subnet. Because of this, we want to have the node in Texas automatically disabled when it normally resolves to an IP address in the 10.x.x.x subnet.

     

    If the node goes down in the Virginia region and we change the FQDN to give the node an IP address in the 11.x.x.x subnet (Texas region), we would like to automatically enable the node in Texas when it resolves to an IP address in the 11.x.x.x subnet... And then automatically disable it again if it later resolves back to an IP address in the 10.x.x.x subnet.