Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches or high-capacity routers offer a similar functionality where layer-3 switching or routing is done in hardware (in an ASIC) instead of by software and the (central) CPU.
CEF is mainly used to increase packet switching speed by reducing the overhead and delays introduced by other routing techniques.
CEF consists of two key components: The Forwarding Information Base (FIB) and adjacencies.
This avoids the need for querying the main processor or routing table in order to get the next-hop information.
CEF currently supports Ethernet, Frame Relay, ATM, PPP, FDDI, tunnels, and Cisco HDLC.