NetFlow

Cisco NetFlow technology is used to gather information about data flowing through a network. NetFlow information can be likened to a phone bill for your network traffic. It shows you who and what devices are in your network, as well as when and how users and devices accessed your network. NetFlow is an important component in behavior-based detection and analysis. Cisco switches, routers, and firewalls equipped with NetFlow can report information about data entering, leaving, and travelling through the network. Information is sent to NetFlow Collectors that collect, store, and analyze NetFlow records.
NetFlow is able to collect information on usage through many different characteristics of how data is moved through the network, as shown in the figure. By collecting information about network data flows, NetFlow is able to establish baseline behaviors on more than 90 different attributes.