GISP: GIAC Information Security Professional Certification

Routers and firewalls are both associated with the Network layer (Layer 3) of the OSI model. Routers operate at Layer 3, using IP addresses to determine the best path for forwarding packets between different networks. Packet-filtering firewalls likewise operate at Layer 3 (and often Layer 4), inspecting IP header information such as source and destination addresses to permit or deny traffic. In contrast, a hub is a Layer 1 (Physical) device that simply repeats signals to all ports without processing addresses, and MAC addresses belong to the Layer 2 (Data Link) layer, used by switches and bridges for local frame forwarding.