Definition
From an end user’s perspective, network performance boils down to how well an application executes. Application availability and response times are critical metrics. Application health clearly influences performance, but it is far from the only factor. Events deeper in the seven-layer network stack have a profound impact on end user productivity.
The physical network infrastructure can serve as a data source that offers the broadest visibility into behavior that affects the enterprise’s operational environment. Specifically, switches, routers, and other components collect and maintain information about traffic traversing the network. The information pertains to logical, end-to-end flows between source and destination servers, as well as physical, point-to-point flows between core network elements. This traffic-based information is known as netflow.
Netflow is a rich, real-time data source that is always available and conveys a wealth of vital information about network traffic. All of the major equipment vendors provide netflow tracking capabilities. Cisco NetFlow is Cisco’s IPFIX-compatible implementation, and is included as part of the Cisco IOS. Juniper calls theirs jFlow. Others such as HP, Foundry, and Extreme refer to their flow technologies as sFlow. IPFIX is the Internet Engineering Task Force’s standard for netflow.
Applications
Regardless of its moniker, the scope of netflow data is substantial. Netflow delivers insight into source and destination p