Site level HA works in a way independent to the virtual path state of the site with other sites. Meaning if the physical links are down while one appliance is serving as active, then it will be the same case for the standby as well (as the same physical link will be used by standby too) and hence that active assumes its state as it is instead of shifting. The NetScaler SD-WAN Virtual WAN HA RACP protocol works between the active and the standby appliances and the only situation the failover happens is when the standby stops receiving the heartbeat message from the active and vice versa, thereby determining the appropriate states of the 2 appliances in HA. Upon the hold timer expiry the standby assumes the role of active.

The following are some of the options to test HA failover:

1. Force Failover can be triggered by changing the setting under Configuration --> Appliance Settings --> Miscellaneous --> Switch HA Mode
2. Disable NetScaler SD-WAN Virtual WAN service on the active.
3. Restart NetScaler SD-WAN Virtual WAN service on the active (But this depends on the hold time configuration).
4. Reboot the active appliance.
5. Plug out the cables from the active appliance.
6. Remove the license from the active appliance, which stops the NetScaler SD-WAN Virtual WAN service in turn and hence failover triggered.