About Hybrid Interfaces
You can configure logical hybrid interfaces on managed devices that allow the Firepower System to bridge traffic between virtual routers and virtual switches. If IP traffic received on interfaces in a virtual switch is addressed to the MAC address of an associated hybrid logical interface, the system handles it as Layer 3 traffic and either routes or responds to the traffic depending on the destination IP address. If the system receives any other traffic, it handles it as Layer 2 traffic and switches it appropriately. You cannot configure logical hybrid interfaces on an NGIPSv device.
Note that hybrid interfaces that are not associated with both a virtual switch and a virtual router are not available for routing, and do not generate or respond to traffic.