Fault-tolerant design of Network-on-chip communication architectures requires the addressing of issues pertaining to different elements described at different levels of design abstraction -- these may be specific to architecture, interconnection, communication and application issues. Assessing the effectiveness of a particular fault-tolerant implementation can be a challenging task for designers, constrained with tight system performance specifications and other requirements In this paper, we provide a top-down view of fault-tolerance methods for NoC infrastructures, and present a range of metrics used for estimating their quality. We illustrate the use of these metrics by simulating a few simple but realistic fault-tolerant scenarios.