NetFlow is a Cisco IOS feature that can be used to monitor traffic flows. A traffic flow is defined as a series of packets with the same source IP address, destination IP address, protocol, and Layer 4 information. NetFlow gathers flowbased statistics such as packet counts, byte counts, and protocol distribution. The data gathered by NetFlow is typically exported to management software. You can then analyze the data to facilitate network planning, customer billing, and traffic engineering.

Flow caching collects IP data flow information and prepares the information for export. A traffic flow can be identified based on the combination of the following attributes:
- Source IP address
- Destination IP address
- Source port number
- Destination port number
- Protocol value
- Type of Service (ToS) value
- Input interface
A flow collector collects the exported data from multiple devices so that it can be aggregated and stored for analysis by a data analyzer. NetFlow can be used to perform all three functions, or it can export the data to a thirdparty product that can read the data that is stored within FlowCollector files.