The networking topology that connects each network device to a central forwarding appliance is the star topology.

In a star topology, every device (node) has its own dedicated link to a central device such as a hub, switch, or router, and that central device is responsible for forwarding traffic between the connected devices. This is exactly what “central forwarding appliance” refers to: a central node that receives frames or packets from one device and then forwards them to the appropriate destination device.