How to get a Cisco Router to export NetFlow data

Introduction
Getting NetFlow data into your network performance management system is something every network engineer working with Cisco equipment should consider. But perhaps you don’t know enough about NetFlow? If that is the case, you can find more about Cisco’s NetFlow technology and how to properly use it to monitor your system and its bandwidth.

Steps
Getting NetFlow data into your network performance management system is something every network engineer working with Cisco equipment should consider. But perhaps you don’t know enough about NetFlow? If that is the case, you can find more about Cisco’s NetFlow technology and how to properly use it to monitor your system and its bandwidth.

For those of you familiar with NetFlow, who want to turn it on in your Cisco devices, here are some steps you can take.

The number one question you should ask is if you have SNMP access to your router. In the case that you do, you can easily set up NetFlow using a free tool that can configure everything you need quickly.

Now, if you don’t have SNMP set up on your devices, you will need to configure them using the command line:

1.	Open a command prompt and telnet into your router. Login to the device.

2.	Go into privilege mode by typing in enable. This allows you to make configuration changes.

3.	Type in conf t to give the device configuration commands.

4.	You’ll see a banner to enter in configuration commands. You will now need to enter in 3 lines of commands to tell the router to start NetFlow and export the data: ip flow-export source fastethernet0/0 (export and source traffic to fastethernet0/0) ip flow-export source version 5 (this exports ver. 5 NetFlow, the best to start with) ip flow-export destination  (location of NMS to send the data to)

5.	Now you must specify the interface you want to analyze the traffic on by using the interface fastethernet0/0 command. 6.	Now you can tell that interface what traffic you require: ip flow egress (monitor outbound flow) ip flow ingress (monitor inbound flow) ip route-cache flow

7.	Now exit the interface, exit privilege mode, and type in one more important command: wr mem (saves configuration data)

You can also check out a full tutorial video on this topic called How to Configure Netflow, which features step-by-step instructions.