Software architectures are often claimed to be robust. However, there is no explicit and concrete definition of software architecture robustness. This paper gives a definition of software architecture robustness and presents a set of architecture metrics that were applied to real-time telecommunications software for the evaluation of robustness. The purpose of this study is to provide a structured method to support software architecture evaluations and downstream software implementations. The study also expands the software architecture research to quantitative and measurable evaluations as opposed to qualitative assessments. In addition, this paper presents an empirical case study of applying the metrics. The approach and the metrics data provide insights into software architecture sensitivity analysis on system qualities and trade-off analysis among a set of design alternatives to support product evolution.