and ultimately help the end-user experience. Network managers perform many tasks; these include performance measurement, forensic analysis, capacity planning, and load-testing or load generation. They also work closely with application developers and IT departments who rely on them to deliver underlying network services. For performance measurement, operators typically measure the performance of their networks at different levels. They either use per-port metrics (how much traffic on port 80 flowed between a client and a server and how long did it take) or they rely on end-user metrics (how fast did the login page load for Bob.) Per-port metrics are collected using flow-based monitoring and protocols such as NetFlow (now standardized as IPFIX) or RMON. End-user metrics are collected through web logs, synthetic monitoring, or real user monitoring. An example is ART (application response time) which provides end to end statistics that measure Quality of Experience. For forensic analysis, operators often rely on sniffers that break down the transactions by their protocols and can locate problems such as retransmissions or protocol negotiations. For capacity planning, modeling tools such as Aria Networks, OPNET, PacketTrap, NetSim, NetFlow and sFlow Analyzer, or NetQoS that project the impact of new applications or increased usage are invaluable. According to Gartner, through 2018 more than 30% of enterprises will use capacity management tools for their critical IT infrastructures, up from less than 5% in 2014. These capacity management tools help infrastructure and operations management teams plan and optimize IT infrastructures and tools, and balance the use of external and cloud computing service providers. For load generation that helps to understand the breaking point, operators may use software or appliances that generate scripted traffic. Some hosted service providers also offer pay-as-you-go traffic generation for sites that face the public Internet. Next generation NPM tools Next-generation NPM tools are those that improve network management by automating the collection of network data, including capacity issues, and automatically interpreting it. Terry Slattery, editor at NoJitter.com, compares three such tools, VMWare's vRealize Network Insight, PathSolutions TotalView, and Kemp Flowmon, in the article The Future of Network Performance Management, June 10, 2021. The future of NPM The future of network management is a radically expanding area of development, according to Terry Slattery on June 10, 2021: "We're starting to see more analytics of network data at levels that weren’t possible 10-15 years ago, due to limitations that no longer exist in computing, memory,