https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/high-availability/set-up-activeactive-ha/prerequisit These are the two links that can be used to configure an active/active high availability pair. An active/active high availability pair consists of two firewalls that are both active and share the traffic load between them1. To configure an active/active high availability pair, the following links are required2:
* HA1: This is the control link that is used for exchanging heartbeat messages and configuration synchronization between the firewalls. It can be a dedicated interface or a subinterface. It can also have a backup link for redundancy.
* HA2: This is the data link that is used for forwarding sessions from one firewall to another in case of failover or load balancing. It can be a dedicated interface or a subinterface. It can also have a backup link for redundancy.
* HA3: This is the session owner synchronization link that is used for synchronizing session information between the firewalls in different virtual systems. It can be a dedicated interface or a subinterface. It is only required for active/active high availability pairs, not for active/passive pairs.