Cisco devices with NetFlow Support track the bandwidth usage of the network internally. The NetFlow protocol is supported by most Cisco routers and certain Cisco switches. These devices can be configured to send pre-aggregated data to the computer running a NetFlow monitor such as PRTG Network Monitor. Since the data is pre-aggregated, this is easier on the system than using the packet sniffer functionality. This makes NetFlow monitoring ideal for tracking bandwidth usage on high traffic networks.