VLAN Failsafe Functionality

Hi,

I would like to ask about the functionality of the VLAN failsafe and whether it is applicable to the client's request. We have three F5 devices, two located at the Head Office (HO) and one at the Disaster Recovery (DR) site. I will send you a simple diagram to provide some context (Please see image Original Traffic Flow (HO Active)).

The client wants to implement an Active-Standby-Standby (A-S-S) setup across the HO and DR sites. The DMZ servers, F5 devices, and the L3 switch will have the same configuration and segment.

To meet these requirements, we plan to include the three F5 devices in one sync group so they can operate in an A-S-S setup and be properly synchronized. There will also be VLANs (including the HA VLAN used by the F5 devices), and the ISN L2 switch will extend the VLANs from the HO to the DR site.

We have a question regarding a possible setup: If the L3 switch goes down, we are concerned that the backend servers might experience issues or enter a "split-brain" state while processing traffic, as they are on the same segments. To prevent this scenario, if the L3 switch goes down, we would like to automatically bring down the F5 devices located at the HO site, thereby forcing all traffic to be directed to the DR site. Given this, we would like to know if the VLAN failsafe would be applicable in this scenario. Your response will be a big help on us.

Thank you!