NetFlow is a feature that was first introduced by Cisco Systems in the 1990s. NetFlow collects specific data about packets as they enter or exit an interface of a router or switch. This data is then sent to a NetFlow Collector via a NetFlow Exporter, which is often made part of switches or routers. The NetFlow Collector then aggregates and stores the flow data for analysis. This data is often leveraged by network and systems administrators to troubleshoot bandwidth issues, identify network congestion, and to observe the flow of data.
A sample NetFlow output is included next. What is included with flow data can vary from network device manufacturers as there are several versions in the commercial market. The following screenshot shows some of the basic information that is captured as part of a NetFlow dataset:
The following components of a NetFlow record are...
