FortiGate NAC LAN Segments are a feature that allows users to assign different VLANs to different LAN segments without changing the IP address of hosts or bouncing the switch port. This provides physical isolation while maintaining firewall sessions and avoiding DHCP issues. One benefit of using FortiGate NAC LAN Segments is that it allows for assignment of dynamic address objects matching NAC policy. This means that users can create firewall policies based on dynamic address objects that match the NAC policy criteria, such as device type, OS type, MAC address, etc. This simplifies firewall policy management and enhances security by applying different security profiles to different types of devices. References: https://docs.fortinet.
com/document/fortigate/7.0.0/new-features/856212/nac-lan-segments-7-0-1
https://docs.fortinet.com/document/fortigate/7.0.0/new-features/856212/nac-lan-segments-7-0-1

https://docs.fortinet.com/document/fortiswitch/7.0.8/devices-managed-by-fortios/801194/deploying-mclag- topologies