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mbrandon32's avatar
mbrandon32
Icon for Cirrus rankCirrus
Jan 06, 2022

LTM Self IP Netmask Update

We will be making some network changes that will require us to update the netmask for our self IPs. Based on the following article - https://support.f5.com/csp/article/K14123529 - the steps to update self IPs in an HA pair a fairly straight forward but I am looking for clarification on the order of the changes.

 

When we force the standby offline, are we making the self IP changes on the standby unit only? or on the standby and active units when the standby is offline? Or do we perform he work on the standby, bring it online, then failover, and repeat the steps on the HA peer?

application delivery
BIG-IP
LTM
  • CA_Valli's avatar
    CA_Valli
    Icon for MVP rankMVP
    Jan 07, 2022

    Hello mbrandon, just a heads up: the articole you quoted details operation to change HA self-ip's -- so the only way to do it would be rebuilding HA.

     

    One of the devices will be put offline (to avoid split brain or active/active connections) and will not receive traffic, but before rebuilding HA both units must have been configured with the correct self IP's ; doing it one unit at a time would mean rebuild cluster twice.

     

    If you're changing a self-ip of one of your traffic networks, you should be able to do so without all of that operation.

    Just remove any floating IP's, update netmask on self (both nodes) and reconfigure floatings.

    Adding/deleting floatings should have the unit sent GARP advertisements, but to be sure you can follow K19910045 instruction (create fake vlan+self and remove them)

     

    Last thing, I'd recommend a maintenance window if the network you're changing has traffic on it. And 110% recommend maintenance window if you need to rebuild HA.