Forum Discussion

ushan's avatar
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Aug 14, 2022

Which IP initiates health monitoring of nodes when F5 are in HA?

Hi, I have two Big IP F5 in HA Active/Standby state.  I have configured the internal interface of Big IP as follows, Big IP 1 :  (Non-floating) Big IP 2: (Non-floating) Flo...
  • boneyard's avatar
    Aug 15, 2022

    this is how it works. both nodes have to be able to determine for themselves if a poolmember is reachable. it makes sense to always use the non floating for this. else the health monitor IP would change with a failover.

  • StephanManthey's avatar
    Aug 15, 2022

    As written by boneyard, the non-floating self-IPs are used for the monitoring. That´s the default behaviour and might be changed perhaps by using an external monitor.

    That´s why your internal ACLs have to permit access to the real servers (aka poolmembers) for both non-floating self IPs and the IP-address being used for SNAT (i.e. the floating self IP with SNAT automap).

    Be aware, that a monitor might even be fired through the out-of-band management interface (using the management IP). This will be the case, if there is a better route to the target and might be prevented by using route domains or the InTMM monitoring feature.