A method for evaluating the effects of performance degradations on communications network application

A novel method and model for evaluating the combined effects of performance degradations and hardware/software failures on specific network tasks are presented. This approach to quantifying the performance of complex communications networks and services allows easier identification of the components and performance characteristics that most severely affect applications. The model can be used as an analysis tool to set objectives, evaluate new services, and improve the end-to-end availability/reliability for a given network application. A Markov model of component performance that allows for dependencies between degradations and the onset of failure is developed and used to determine the reliability and availability of individual network tasks. Network performance is then described by the performance of the various tasks which it supports. Closed-form expressions for availability, reliability, and the mean time to recover from impairment conditions are derived. An example is given to illustrate the method