Cisco IOS Flexible NetFlow is the next-generation in flow technology. It optimizes the network infrastructure, reducing operation costs and improving capacity planning and security incident detection with increased flexibility and scalability. The ability to characterize IP traffic and identify its source, traffic destination, timing, and application information is critical for network availability, performance, and troubleshooting. The monitoring of IP traffic flows increases the accuracy of capacity planning and ensures that resource allocation supports organizational goals. Flexible NetFlow helps Cisco customers determine how to optimize resource usage, plan network capacity, and identify the optimal application layer for Quality of Service (QoS). It plays a vital role in network security by detecting Denial of Service (DoS) attacks and network-propagated worms.