Sustainability is an important concept currently at the forefront of many policy agendas. Yet, the science of sustainability is still inchoate: What does it means for a system to be sustainable? What are the features of sustainable systems and how can they be quantified? The systems we deal with - ecological, economic, social, and integrated - are complex and operate by maintaining functional gradients away from equilibrium. While there are basic requirements regarding availability of input and output boundary flows and sinks, sustainability is centrally a feature of system configuration. A system must provide a basis of positionally-balancing, wholeness-enhancing centers of activity. One aspect of this system balance is between efficiency and redundancy which can be measured in ecological and economic systems using information-based network analysis. Specifically, the robustness indicator as developed by Robert Ulanowicz and colleagues offers deep insight into the structure and function of these self-sustaining autocatalytic configurations (through constant flows of energy and matter). In this paper, I overview these concepts and methods and provide examples from economic and ecological systems and discuss the meaning of the differences in outcome.