Cisco's NetFlow is being tapped more and more by network managers to get more granular metrics on which applications are used most, on how to bill back services and on ways to better secure networks. And more network management vendors are enhancing their products to tap the Cisco feature for this critical data.According to Cisco, "NetFlow provides a set of services for IP applications, including network traffic accounting, usage-based network billing, network planning, security, denial-of-service monitoring capabilities, and network monitoring." The networking giant included the feature in its router operating systems to help customers get "valuable information about network users and applications, peak usage times, and traffic routing," Cisco says.Two vendors are hoping to tap network manager interest in the data collected by NetFlow. AdventNet last week made available a free edition of its NetFlow Analyzer bandwidth monitoring software that taps Cisco NetFlow. According to the company, the new release will appeal to small and midsize companies that "need to account for bandwidth usage across a comparatively smaller network." The free Edition can analyze and report on data collected from a maximum of two interfaces, and can be downloaded from AdventNet's Web site.NetScout last week introduced a new nGenius Performance Manager Appliance designed to address NetFlow-enabled network environments. NetScout says the appliance\u00a0will handle aggregating and analyzing NetFlow data from switches and routers on large enterprise networks. The appliance is delivered either on Windows 2003 or Red Hat Linux platforms, and scales to support data from thousands of devices, NetScout says.The nGenius Performance Manager Appliance for NetFlow is currently available for $140,000 on either Windows or Linux-based appliances.