Netflow is a flow-based traffic accounting protocol defined by Cisco Systems. It is widely used to support various applications such as usage-based billing, traffic analysis, or capacity planning. The latest version, Netflow v9, is used as a basis for the IPFIX (IP Flow Information eXport) protocol that is currently being standardized in the IETF (see [Cla05]). Only version 9 of Netflow is designed to export IPv6 flows towards the Netflow collector.

IPv6 support in Netflow v9 is now available in the 12.3T CISCO IOS train. But the transport used for the data export is still over IPv4 only. On the GSR series Netflow v9 is implemented but is not yet able to export IPv6 flows.

Netflow Collectors are also available for IPv6 either from Cisco (NFCv5.0) or from academic organizations (UTC, France).