notifications from ONS in Oracle Restart when the node dies

I have a customer who is testing FAN-FCF failovers in a DataGuard configuration, and the problem is that when the ONS (Oracle Notification Service) dies along with the host on which the primary database resides, how is the FAN-FCF client informed of the failure?

Is there a way reference the ONS via a load balancer that is based on the ONS on both the host on which the DataGuard primary database resides as well as the ONS on the host on which the DataGuard standby database resides?

Everything is working well until the primary host goes down, so shouldn't the standby ONS take over and send the necessary notification?

Thoughts?

Thanks!