For an active-passive High Availability (HA) deployment, Fortinet strongly recommends a direct, back-to-back cable connection between the designated HA heartbeat interfaces of the two FortiADC units. This dedicated link is crucial for both heartbeat messages and data synchronization. Using a direct connection minimizes latency and eliminates intermediate network devices, such as switches, which could become single points of failure. This configuration provides the most reliable and fastest communication path, preventing false failovers and ensuring seamless state synchronization between the primary and secondary appliances.

A. Dedicated fiber channel: This specifies a connection medium. While a direct fiber connection is valid, the core recommendation is the direct topology, not the specific cable type (copper or fiber).

B. Same VLAN: Connecting through a switch on the same VLAN is explicitly discouraged as it introduces a potential point of failure (the switch) and adds unnecessary latency to the critical HA link.

C. Dedicated point-to-point VPN connection: This method is used for geographically dispersed HA (Geo-HA) deployments, not for standard co-located active-passive clusters, as it adds significant overhead and complexity.

1. Fortinet FortiADC Handbook - High Availability v6.2.0

Page 11

Section: "Deployment topologies > Active-Passive". The document states

"For the heartbeat and synchronization link

we recommend you use a crossover cable to directly connect the two appliances." The accompanying diagram (Figure 5) visually depicts this direct connection.

2. Fortinet FortiADC Administration Guide v6.2.0

Page 329

Section: "High Availability > Configuring HA". The guide's configuration steps and diagrams consistently illustrate a direct link for the HA heartbeat

reinforcing this as the standard and recommended practice.