NetFlow is a Cisco traffic accounting technology built into the software and hardware of many Cisco switches and routers.  NetFlow tracks traffic flowing in and out of enabled routers, switches, and security devices to help answer the who, what, where, when, and how of network traffic.

Beginning with ASA software 8.2, Cisco supports NetFlow in ASA devices using NSEL (NetFlow security event logging).  However, early versions of 8.2 have a bug that reports flows with incorrect interface assignments.  We recommend version 8.3 or higher for use with LiveAction flow visualization.  Make sure to verify the ASA memory requirements before planning any upgrades.

With LiveAction Flow 2.0 and greater, users can take advantage of ASA NSEL exports to perform flow visualization with LiveAction.  This technical note provides instructions on enabling and using ASA NetFlow exports in LiveAction software.  ASA instructions are provided for the CLI and ASDM.

Cisco ASA and NetFlow Application Note