正解:C
CEF, or Cisco Express Forwarding, is a high-speed packet forwarding mechanism used in Cisco routers.
Unlike process switching, which involves the CPU making forwarding decisions for each individual packet, CEF makes use of two key components to expedite the process:
* FIB (Forwarding Information Base): This table contains pre-computed routes for packet forwarding, allowing for quick lookups and forwarding decisions.
* Adjacency Table: This table lists the next-hop addresses and associated Layer 2 information for all FIB entries, enabling efficient packet transmission to the next hop.
The combination of these tables allows CEF to bypass the CPU for most forwarding decisions, significantly reducing processing time and increasing the speed at which packets are forwarded through the router.
References: The explanation is based on the concepts outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, which detail the workings of CEF and its advantages over process switching.