NetFlow version 9

Cisco IOS NetFlow efficiently provides a key 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. NetFlow provides valuable information about network users and applications, peak usage times, and traffic routing. Cisco invented NetFlow and is the leader in IP traffic flow technology.


The basic output of NetFlow is a flow record. Several different formats for flow records have evolved as NetFlow has matured. The most recent evolution of the NetFlow flow-record format is known as NetFlow version 9. The distinguishing feature of the NetFlow Version 9 format, which is the basis for an IETF standard, is that it is template-based. Templates provide an extensible design to the record format, a feature that should allow future enhancements to NetFlow services without requiring concurrent changes to the basic flow-record format. Using templates provides several key benefits:


  • New features can be added to NetFlow more quickly, without breaking current implementations.
  • NetFlow is "future-proofed" against new or developing protocols, because the NetFlow version 9 format can be adapted to provide support for them.
  • NetFlow version 9 is the IETF standard mechanism for information export.
  • Third-party business partners who produce applications that provide collector or display services for NetFlow will not be required to recompile their applications each time a new NetFlow feature is added; instead, they may be able to use an external data file that documents the known template formats.

Technical Support and Documentation

Review additional information about NetFlow version 9 in the Technical Support site area.

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