Ipfix is a physical device or virtual software? There is a feature Ipfix in nsx but don't know how to get it.
Depends on the vendor, here are some sample of IPFIX collectors:
https://www.plixer.com/blog/ipfix-configuration/configuring-vmware-nsx-ipfix/
2. NetFlow Logic - NetFlow Integrator (NFI)
3. SolarWinds NetFlow Traffic Analyzer
In addition the list Vrealize Network Insight uses Ipfix to collect flow from vDS, though it uses these flows for many use cases and visibility. To learn the details of IPfix protocol nTop, flowtools and nPrope on Linux could be used, they could need some initial configuration.
This link could help how IPfix is used for VRNI similarly