Network managers have long been challenged with optimizing their network to respond to changing demands from applications, systems and end users. But now more than ever the end-user, or client, experience is something network managers must capture to prove their network is delivering services as it should (see "User experience is key").

And to be clear, performance management from the end-user perspective is not simply amped-up desktop management, which entails many other technologies such as software distribution, application packaging tools and asset management software. The client perspective represents how well all the parts and pieces of network, systems and applications work together to deliver a service to the end user, whether the client is connected on the LAN, WAN or via wireless or mobile technologies. The growing complexity of applications increases the challenge to gain this view of performance and increases the need for network managers to do so as well.

"Today applications are much more complex and no longer tightly coupled to the underlying infrastructure," writes George Hamilton, director of enterprise computing and networking at the Yankee Group in a paper entitled, "Application Diversity, Complexity Drive Client-Side Performance Management Need." He goes on to say that the distributed nature of applications makes capturing the end-user experience difficult. "The correlation of infrastructure performance to end-user experience has broken down, driving the need for better management of applications within a production environment and active management of the end-user experience."

To gain this insight, network managers often had to cobble together metrics collected across various IT domains - network, servers, databases and so on - but not until recently have vendors also been working to provide this perspective with their network tools. And they need to somehow get data from end-user machines - in many cases that means putting an agent on the client.

Companies such as ProactiveNet, Coradiant and Symphoniq have been continuously fine-tuning their application performance management wares to gather an accurate take on the end-user experience, with and without agents in some cases. And companies such as Citrix, with its acquisition of Reflectent Software, are buying the technology needed to measure the end-user experience down to the client machine, either a desktop or a laptop.

Ann Bednarz is associate news editor at Network World.