Network-on-Chip (NoC) architectures employing packet-based communication are being increasingly adopted in System-on-Chip (SoC) designs. In addition to providing high performance, the fault-tolerance and reliability of these networks is becoming a critical issue due to several artifacts of deep sub-micron technologies. Consequently, it is important for a designer to have access to fast methods for evaluating the performance, reliability, and energy-efficiency of an on-chip network. Towards this end, first, we propose a novel pathsensitive router architecture for low-latency applications. Next, we present a queuing-theory-based model for evaluating the performance and energy behavior of on-chip networks. Then the model is used to demonstrate the effectiveness of our proposed router. The performance (average latency) and energy consumption results from the analytical model are validated with those obtained from a cycle-accurate simulator. Finally, we explore error detection and correction mechanisms that provide different energy-reliability- performance tradeoffs and extend our model to evaluate the on-chip network in the presence of these error protection schemes. Our reliability exploration culminates with the introduction of an array of transient fault protection techniques, both architectural and algorithmic, to tackle reliability issues within the router's individual hardware components. We propose a complete solution safeguarding against both the traditional link faults and internal router upsets, without incurring any significant latency, area and power overhead.