Three-Dimensional Networks-on-Chips (3D-NoCs) have been proposed as an auspicious solution, merging the high parallelism of the Network-on-Chip (NoC) paradigm with the high-performance and low-power cost of 3D-ICs. However, as technology scales down, the reliability issues are becoming more crucial, especially for complex 3D-NoC which provides the communication requirements of multi and many-core systems-on-chip. Reliability assessment is prominent for early stages of the manufacturing process to prevent costly redesigns of a target system. In this paper, we present an accurate reliability assessment and quantitative evaluation of a soft-error resilient 3D-NoC based on a soft-error resilient mechanism. The system can recover from transient errors occurring in different pipeline stages of the router. Based on this analysis, the effects of failures in the network's principal components are determined.