There are two commands to implement NETFLOW on a interface

ip flow ingress

ip route-cache flow

you can use them for each purpose.

if you apply “ip route-cache flow” on a interface, then the sub interfaces also are applied

but if you want to apply on specific interfaces, you can use “ip flow ingress” on each interfaces.


there are also global commands to implement NETFLOW.

ip flow-export version x (x=1,5,9)

ip flow-cache entries x (x=from 1024 to 524288)

ip flow-cache timeout active x (x=from 1 to 60 minutes)

ip flow-cache timeout inactive x (x=from 10 to 600 seconds)


if you use NETFLOW version 9, you can use “ip flow egress” on a interface.


if you have a plan to install NETFLOW server in the future, you need to consider the below commands

ip flow-export source

ip flow-export destination


you can check the list of cached flow using below

show ip cache flow


if you are interested in impact on a router, you can check this link


there is easy way to find out which traffic is the chatty in global command

ip flow-top-talkers

top number x (from 1 to 20)


and then you can check the list of top talkers using below

show ip flow top-talkers


don’t forget to configure ip flow ingress or ip cache flow command on your interface.