Assessment of QoS Adaptation Capability of Complex Network Systems

The paper formulates methods to measure the trustworthiness of a network system.. under hostile environment conditions incident on S. How good is the system.. 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 external conditions. As a case study, we describe the model-based assessment of a CDN (content distribution network). The study focuses on the placement of content caching nodes in a distribution topology for optimal performance. Security and reliability of nodes are additional factors. The extent of domain knowledge needed in the assessment tools is also highlighted, with emphasis on their reusability in different network systems.