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> Chapter 21 - Networking > Interfaces > Redundant interfaces

Redundant interfaces

On some models you can combine two or more physical interfaces to provide link redundancy. This feature enables you to connect to two or more switches to ensure connectivity in the event one physical interface or the equipment on that interface fails.

In a redundant interface, traffic is only going over one interface at any time. This differs from an aggregated interface where traffic is going over all interfaces for distribution of increased bandwidth. This difference means redundant interfaces can have more robust configurations with fewer possible points of failure. This is important in a fully-meshed HA configuration.

An interface is available to be in a redundant interface if:

  • it is a physical interface, not a VLAN interface
  • it is not already part of an aggregated or redundant interface
  • it is in the same VDOM as the redundant interface
  • it has no defined IP address
  • is not configured for DHCP or PPPoE
  • it has no DHCP server or relay configured on it
  • it does not have any VLAN subinterfaces
  • it is not referenced in any security policy, VIP, or multicast policy
  • it is not monitored by HA
  • it is not one of the FortiGate-5000 series backplane interfaces

When an interface is included in a redundant interface, it is not listed on the Network > Interfaces page. You cannot configure the interface individually and it is not available for inclusion in security policies, VIPs, or routing.