What Are the Components of CEF?

CEF has two main data structures: the Forwarding Information Base (FIB) and the adjacency table. The FIB is also referred to as just the CEF table. Look at Figure 6-2 to see an overview of CEF and its components.

Figure 6-2. Overview of CEF

The Adjacency Table

The adjacency table is the CEF component that is responsible for the MAC or Layer 2 rewrite. When routers and hosts are adjacent, they learn about each other by some means. They can discover each other dynamically or by means of configuration. If routers are adjacent across a point-to-point connection, they discover each other trivially. However, on a ...

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