NetFlow Testers are small programs that simply dump the data of all NetFlow packets that a computer receives from a Cisco router. This can be useful when debugging bandwidth monitoring configurations based on Cisco’s NetFlow protocol (both v5 and v9).
First the NetFlow protocol must be enabled and configured on the router. The router must be given the IP address of the computer running NetFlow tester so that the UDP data packets with NetFlow data are sent to this computer.
For NetFlow5Tester, it is important to distinguish between the actual NetFlow v5 packets (the UDP packets sent from the router to PRTG that contain the NetFlow data) and the "flows" (the information inside the UDP packets which shows the data passing through the router).