great article.but the problem with netflow is not all Cisco gear support it.for example most Nexus switches not support Netflow or support Sampled Netflow that is not effective for security monitoring.i think the good news is Cisco committed for put Netflow in new devices (like C3850-X and Nexus 93180-EX) .with that regards we will have army of network sensor in any part of network without any gaps.