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100Base-TX_2904's avatar
100Base-TX_2904
Icon for Nimbostratus rankNimbostratus
Sep 15, 2016

Active-Active non-floating IP requirement

Hi

 

I'm migrating a single F5 physical appliance to an Active-Active Virtual Edition pair, running LTM module. Running version 12.1.0.

 

Something i'm confused about is the apparent requirement to have non-floating self IP's on each F5 prior to configuring a floating IP. My understanding is that i need to use floating IP's in order for failover to work correctly, which seems logical. But if i just try to configure a floating IP, it throws an error saying that there is no non-floating IP in the same VLAN that i'm trying to configure a floating IP for.

 

Example:

 

VLAN 10

 

Floating IP: 10.10.10.1/24

 

Big IP 1 Non-Floating: 10.10.10.2/24

 

Big IP 2 Non-Floating: 10.10.10.3/24

 

I'm not sure what purpose the non-floating IP's serve. Surly the floating IP would be used for any actual forwarding for that VLAN. If the F5 was running something like VRRP, i'd understand, as it'd use those IP's to check for each others availability/status. In this case though, the F5 is using the "HA" VLAN as a heartbeat.

 

What am i missing here?

 

Thanks in advance.

 

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application delivery
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  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    Sep 15, 2016

    In theory, I think you're right. There's no technical reason at the IP level that a non-floating IP would be required.

     

    However you're usually using the non-floating IP's for monitoring. Without those, you couldn't monitor because the monitoring would move back & forth (Probably to the management interface which wouldn't be valid)

     

    Yeah, I've had situations too where I think the non-floating isn't being used. But I have yet to run into an issue with having them, while you're sure to run into issues somewhere if they were optional.