High Availability (HA) Clustering

Eliminate the firewall as a single point of failure with FGCP active-passive and active-active HA.

Why HA

A single firewall is a single point of failure — if it dies, the site loses connectivity. FortiGate HA clusters two or more units so traffic keeps flowing if one fails.

FGCP modes

Active-Passive — one unit handles all traffic; the standby syncs state and takes over on failure. Simple and the most common.

Active-Active — the primary distributes session/UTM load across units for more throughput.

How it stays in sync

A dedicated heartbeat link carries HA control traffic and health signals between units.

Session synchronization copies the session table so failover does not drop established connections.

Device priority and override settings decide which unit becomes primary.

config system ha
    set mode a-p
    set group-name "HQ-CLUSTER"
    set hbdev "port3" 50
    set priority 200
end

Failover behavior

On failure, the cluster elects a new primary based on (in order) link status/uptime, device priority, and serial number. With session sync, most traffic continues uninterrupted.

What it means for you

HA is non-negotiable for any site that cannot tolerate downtime. Understanding heartbeat, session sync, and the primary-election process is essential for both the NSE 4 exam and real deployments.