Cisco Express Forwarding: Understanding the Key Concepts

Cisco Express Forwarding

Question

Which statement about Cisco Express Forwarding is true?

Answers

Explanations

Click on the arrows to vote for the correct answer

A. B. C. D.

C.

Cisco Express Forwarding (CEF) is a high-performance packet forwarding technology used in Cisco routers and switches. It is designed to improve forwarding performance by reducing the amount of time it takes to forward packets from one interface to another.

Of the four statements listed, the statement that is true about Cisco Express Forwarding is:

C. It maintains two tables in the data plane: the FIB and adjacency table.

The Forwarding Information Base (FIB) is a table that contains information about known networks and the best path to reach them. The FIB is built based on information from routing protocols and is used by the router to make forwarding decisions.

The adjacency table contains information about the next-hop router or switch for each network in the FIB. This information is used by the router to forward packets to the correct next-hop router or switch.

Option A is incorrect because CEF operates in the data plane, and the CPU is not directly involved with packet-switching decisions.

Option B is incorrect because CEF uses a fast cache called the Forwarding Information Base (FIB), not a cache in the router data plane.

Option D is incorrect because CEF makes forwarding decisions in the data plane, not through a process scheduled through the IOS scheduler.

In summary, CEF is a high-performance packet forwarding technology used in Cisco routers and switches that maintains two tables in the data plane: the FIB and adjacency table.