As far as I know, NetFlow can collect data from physical interfaces and its subinterfaces, right?
Not from loopback, VLAN, tunnel or any virtual interface.
Network Engineering Stack Exchange is a question and answer site for network engineers. It only takes a minute to sign up.
Sign up to join this communityThat depends on the device. Some devices will let you collect NetFlow information on certain virtual interfaces, e.g. a Cisco 4K switch can have NetFlow on the port channel, and that is usually preferred over the individual channel member ports.
Also, a subinterface is a virtual interface.