CEF, FIB, Routing Table

Cisco Express Forwarding separates the control plane software from the data plane hardware, thereby achieving higher data throughput. The control plane is responsible for building the FIB table and adjacency tables in software. The data plane is responsible for forwarding IP unicast traffic using hardware.
Each change in the IP routing table triggers a similar change in the FIB table. This is because the FIB table contains all next-hop addresses that are associated with all destination networks.
Cisco Express Forwarding uses special strategies to switch data packets to their destinations. It caches the information that is generated by the Layer 3 routing engine even before the router encounters any data flows. Cisco Express Forwarding caches routing information in the FIB table.
The FIB table is updated after each network change. However, it is updated only once after each network change, not multiple times, and contains all known routes.
The FIB is derived from the IP routing table and is arranged for maximum lookup throughput. The FIB table is not created from IGP and BGP databases.