Flow data is exported in UDP datagrams periodically (once per second) or as soon as a full UDP datagram of expired flows is available. The size of each flow record depends on the NetFlow version. Four versions of NetFlow Export currently are supported:
Version 1 (v1)— Version 1 format was the original format supported in the initial Cisco IOS software releases containing NetFlow functionality.
Version 5 (v5)— The Version 5 format added Border Gateway Protocol (BGP) autonomous system information and flow sequence numbers.
Version 7 (v7)— The Version 7 format is an enhancement that adds NetFlow support for Cisco Catalyst 5000 series switches equipped with a NetFlow feature card (NFFC). Version 7 is supported only by the Catalyst 5000 ...