This Recommendation provides a framework of tools to obtain IP network performance, estimate the performance of user applications, and apply perceptual models to gauge user satisfaction with the end-to-end performance. The user-perceived performance of data applications on packet networks is dependent on many factors, including the end-to-end performance of the packet network, the application's dependency on the communications network, the performance of the terminals and other devices beyond the purview of the network operator(s), and the user's task and the extent of user interaction with the application. Network designers take these factors into account to assure user satisfaction. Once the application performance has been estimated, then perceptual models can be applied to interpret the level of end-to-end performance attained. This Recommendation assumes that the reader will be able to provide at least some level of detail about each of the key factors above, and then use the framework of tools to estimate end-to-end performance.