HA Overview
You can set up two Palo Alto Networks firewalls as an HA pair. HA allows you to minimize downtime by making sure that an alternate firewall is available in the event that the peer firewall fails. The firewalls in an HA pair use dedicated or in-band HA ports on the firewall to synchronize data—network, object, and policy configurations—and to maintain state information. Firewall-specific configuration such as management interface IP address or administrator profiles, HA specific configuration, log data, and the Application Command Center (ACC) information is not shared between peers. For a consolidated application and log view across the HA pair, you must use Panorama, the Palo Alto Networks centralized management system.
When a failure occurs on a firewall in an HA pair and the peer firewall takes over the task of securing traffic, the event is called a Failover. The conditions that trigger a failover are:
One or more of the monitored interfaces fail. ( Link Monitoring) One or more of the destinations specified on the firewall cannot be reached. ( Path Monitoring) The firewall does not respond to heartbeat polls. ( Heartbeat Polling and Hello messages) A critical chip or software component fails, known as packet path health monitoring.
You can use Panorama to manage HA firewalls. See Context Switch—Firewall or Panorama in the Panorama Administrator’s Guide.

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