Cisco does not support NetFlow on the following devices:

• Cisco 2900
• Cisco 3500
• Cisco 3750
• Cisco 4500
• Cisco 4948

It is possible to configure NetFlow export, but no flows are send to the collector. Only the first packet of the data flow was exported in the older IOS version.

Alternatively, you can use Packet Analysis instead, through a mirrored port (SPAN) or via Ethernet splitter (TAP).