Model-Based Assessment Of Qos Adaptation In Complex Networked Systems

The paper formulates methods to measure the trustworthiness of a network system S under hostile environment conditions incident on S. How good is the system S in meeting the QoS expectations of applications (i.e., the QoS capability of S) is quantitatively measured - say, on a [0, 1] scale. We employ model-based assessment tools (e.g., PO-MDP) to benchmark the QoS capability by stress-testing S with artificially injected failure conditions. As a case study, we describe the model-based assessment of the performance and security of a CDN (content distribution network). The study focuses on the optimal placement of content caching nodes in a distribution topology under performance and security induced constraints.