Secondary IP addresses to an interface

If an interface is configured with a manual or static IP address, you can also add secondary static IP addresses to the interface. Adding secondary IP addresses effectively adds multiple IP addresses to the interface. You can't assign secondary IP addresses using DCHP or PPPoE.

All of the IP addresses that you add to an interface are associated with the single MAC address of the physical interface, and all secondary IP addresses are in the same VDOM as the interface that they're added to. You configure interface status detection for gateway load balancing separately for each secondary IP addresses. As with all other interface IP addresses, secondary IP addresses can't be on the same subnet as any other primary or secondary IP address assigned to a FortiGate interface unless they are in separate VDOMs.

To configure a secondary IP address, go to Network > Interfaces, select Edit or Create New and enable the Secondary IP Address option.