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.

Joanne Ghidoni

Joanne is a Software Quality Assurance Engineer at Plixer. She has also held positions as Technical Support Engineer and Sales Engineer since joining Plixer in 2005. Prior to joining Plixer, Joanne has had numerous positions in the IT field, including data entry, computer operator, PC coordinator and support, mainframe programmer, and also Technical Support and web programmer at Cabletron Systems. In her spare time, Joanne enjoys traveling, always seeking out new and interesting places to visit.