Fortinet NSE6_FNC_AD-7.6 - Fortinet NSE 6 - FortiNAC-F 7.6 Administrator

The FortiNAC-FLogical Networkfeature is specifically designed to provide an abstraction layer between high-level security policies and the underlying physical network infrastructure. In large-scale deployments where different physical locations (like Building 1, 2, and 3 in the exhibit) use different local VLAN IDs for the same type of device (e.g., VLAN 10, 20, and 30 for printers), managing separate policies for each building would create significant administrative overhead.

By using aLogical Network, an administrator can create a single entity—for example, a logical network named " Printers " —and use it as the " Access Value " in a singleNetwork Access Policy. The mapping of this logical label to a specific physical VLAN occurs at theModel Configurationlevel for each network device. When a printer connects to a switch in Building 1, FortiNAC-F evaluates the policy, identifies that the printer should be in the " Printers " logical network, and checks the Model Configuration for that specific switch to see which VLAN ID is mapped to that label (VLAN 10). If the same printer moves to Building 3, the same single policy applies, but FortiNAC-F provisions it to VLAN 30 based on the local mapping for that building ' s switch.

This architectural approach ensures that policies remain consistent and easy to manage regardless of the complexity or variations in the local network topology.

" Logical Networks provide a way to define a network access requirement once and apply it across many different network devices that may use different VLAN IDs for that access... Each managed device can usedifferent VLAN IDs for the same Logical Network label. You can define the Logical Networks based on requirements and then associate the network to a VLAN ID when the managed device is configured in theModel Configuration. " —FortiNAC-F IoT Deployment Guide: Define the Logical Networks.

In FortiNAC-F, theLayer 3 Network typeis specifically designed for deployments where the isolation networks—such as Registration, Remediation, and Dead End—are separated from the FortiNAC appliance ' s service interface (port2) by one or more routers. This architecture is common in large, distributed enterprise environments where endpoints in different physical locations or branches must be isolated into subnets that are local to their respective network equipment.

The reason the Configuration Wizard allows for more than one DHCP scope for a single isolation network type (state) is thatthere can be more than one isolation network of each typeacross the infrastructure. For instance, if an organization has three different sites, each site might require its own unique Layer 3 registration subnet to ensure efficient routing and to accommodate local IP address management. By allowing multiple scopes for the " Registration " state, FortiNAC can provide the appropriate IP address, gateway, and DNS settings to a rogue host regardless of which site ' s registration VLAN it is placed into.

When an endpoint is isolated, the network infrastructure (via DHCP Relay/IP Helper) directs the DHCP request to the FortiNAC service interface. FortiNAC then identifies which scope to use based on the incoming request ' s gateway information. This flexibility ensures that the system is not limited to a single flat subnet for each isolation state, supporting a scalable, multi-routed network topology.

" Multiple scopes are allowed for each isolation state (Registration, Remediation, Dead End, VPN, Authentication, Isolation, and Access Point Management). Within these scopes, multiple ranges in the lease pool are also permitted... This configWizard option is used when Isolation Networks are separated from the FortiNAC Appliance ' s port2 interface by a router. " —FortiNAC-F Configuration Wizard Reference Manual: Layer 3 Network Section.