What can you determine based on this information?

An organization decides to implement NetFlow on its network to monitor the fluctuation of traffic that is disrupting core services. After reviewing the output of NetFlow, the network engineer is unable to see OUT traffic on the interfaces.

What can you determine based on this information?
A . Cisco Express Forwarding has not been configured globally.
B . NetFlow output has been filtered by default.
C . Flow Export version 9 is in use.
D . The command ip flow-capture fragment-offset has been enabled.

View Answer

Answer: A

Explanation:

We came across a recent issue where a user setup a router for NetFlow export but was unable to see the OUT traffic for the interfaces in NetFlow Analyzer. Every NetFlow configuration aspect was checked and nothing incorrect was found. That is when we noticed the ‘no ip cef’ command on the router. CEF was enabled at the global level and within seconds, NetFlow Analyzer started showing OUT traffic for the interfaces. This is why this topic is about Cisco Express Forwarding.

What is switching?

A Router must make decisions about where to forward the packets passing through. This decision-making process is called “switching”. Switching is what a router does when it makes the following decisions: