What is the difference between CEF and process switching?

Question:
What is the difference between CEF and process switching?

• A. CEF processes packets that are too complex for process switching to manage.
• B. CEF is more CPU-intensive than process switching.
• C. CEF uses the FIB and the adjacency table to make forwarding decisions, whereas process switching punts each packet.
• D. Process switching is faster than CEF.

Explanation: “Punt” is often used to describe the action of moving a packet from the fast path (CEF) to the route processor for handling.

Cisco Express Forwarding (CEF) provides the ability to switch packets through a device in a very quick and efficient way while also keeping the load on the router‘s processor low. CEF is made up of two different main components: the Forwarding Information Base (FIB) and the Adjacency Table.

Process switching is the slowest switching methods (compared to fast switching and Cisco Express Forwarding) because it must find a destination in the routing table. Process switching must also construct a new Layer 2 frame header for every packet. With process switching, when a packet comes in, the scheduler calls a process that examines the routing table, determines which interface the packet should be switched to and then switches the packet. The problem is, this happens for the every packet.

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