Reflect3d: An Adaptive and Fault-Tolerant Routing Algorithm for Vertically-Partially-Connected 3D-NoC

The combined benefits of the Three-Dimensional (3D) and Network-on-Chip (NoC) schemes enable designing a high-performance system in a limited chip area. The 3D-NoC major advantages are the average reductions of wire length and delay, resulting in lower power dissipation and higher performance. However, 3D-NoCs suffer from some reliability issues, such as the 3D-IC manufacturing variability. The low yield of vertical connection harms the design of 3D die stacks with many Through Silicon Via (TSV). Vertically-Partially-Connected NoCs have been gaining relevance to reduce the number of TSV links. This work introduces Reflect3d, an adaptive, scalable, and highly resilient routing algorithm targeting partially and vertically connected 3D-NoCs to route packets under such conditions. Reflect3d separates virtual channels in four reflected virtual networks to search for vertical connections dynamically and progressively, guaranteeing packet delivery as long as one healthy TSV connecting all layers is available anywhere in the network. The experimental results show that Reflect3d can ensure high performance in terms of latency, achieving more valid paths and better cost-effectiveness when compared to related work. Furthermore, the hardware synthesis performed using a commercial 28nm technology library shows few area and power overheads compared to other state-of-the-art routing algorithms.