Blog :: Network Operations

NetFlow Port Number

What is the preferred Cisco NetFlow Port Number to listen on?  Well, it depends.  The NetFlow RFC 3954 does not specify a specific NetFlow listening port, however, in my experience 2055 and 9995 or 9996 are the most popular.  Fortunately, our NetFlow solution, by default, will listen for any NetFlow/sFlow traffic sent to it on UDP ports 2055, 2056, 4432, 4739, 9995, 9996, and 6343.

  • 6343 is the default port to listen on for sFlow
  • 4739 is the default port to listen on for IPFIX

Although the above are the most popular NetFlow port numbers, they can certainly be changed.  To do this on a Cisco router, running NetFlow v5 or NetFlow v9, type in the command:

router(config)# ip flow-export destination [collector ip address] [collector port]

ex. router(config)# ip flow-export destination 4432

If you are using a Flexible NetFlow configuration, visit step 2 of the configuration “create an exporter” and use the syntax:

transport udp 2055

While you’re in your Flexible NetFlow (FNF) setup, why not enable Cisco Performance Monitoring or NBAR2?  This will improve your application performance management efforts.

Latency by Interface report

New to NetFlow?  Give us a call and we’ll help you navigate the complexities of NetFlow configurations, including NetFlow port numbers, and with our NetFlow Solution, help with your network traffic management.