TheN+1 High Availability (HA)architecture was introduced in FortiNAC-F version 7.6 to provide a more scalable and flexible redundancy model compared to the traditional 1+1 active/passive setup. In an N+1 configuration, a single secondary (standby) appliance can provide coverage for multiple primary (active) Control and Application (CA) appliances.

To set up an N+1 HA cluster, there are two fundamental structural requirements:

A FortiNAC-F Manager (FortiNAC-M):Unlike standard 1+1 HA, which can be configured directly between two CAs, N+1 management is centralized. The FortiNAC-M acts as the orchestrator that manages the failover groups, monitors the health of the primaries, and coordinates the promotion of the secondary server if a primary fails.

A FortiNAC-F device designated as a Secondary:The cluster must have one appliance explicitly configured with theSecondary failover role. This device remains in a standby state, receiving database replications from all N primaries in its group until it is called upon to take over the functions of a failed unit.

While a cluster can support multiple primaries (D), it does not strictly require " at least two " to function as an N+1 group; it simply requires N primaries (where N ≥ 1). Additionally, N+1 is typically a Layer 3 managed solution via the Manager, meaning it does not mandate a " dedicated VLAN " for synchronization like some Layer 2 HA deployments.

" In FortiNAC-F 7.6,FortiNAC-Mfunctions as a manager to manage the N+1 Failover Groups... enabling N+M high availability for CAs. To create an N+1 Failover group, you should add thesecondary CAto the FortiNAC-M first, then add the primary CAs. The secondary CA is designed to take over the functionality of any single failed primary component. " —FortiNAC-F 7.6.0 N+1 Failover Reference Manual.