Resilient routing implementation in 2D mesh NoC

Abstract

With the rapid shrinking of technology and growing integration capacity, the probability of failures in Networks-on-Chip (NoCs) increases and thus, fault tolerance is essential. Moreover, the unpredictable locations of these failures may influence the regularity of the underlying topology, and a regular 2D mesh is likely to become irregular. Thus, for these failure-prone networks, a viable routing framework should comprise a topology-agnostic routing algorithm along with a cost-effective, scalable routing mechanism able to handle failures, irrespective of any particular failure patterns. Existing routing techniques designed to route irregular topologies efficiently lack flexibility (logic-based), scalability (table-based) or relaxed switch design (uLBDR-based). Designing an efficient routing implementation technique to address irregular topologies remains a pressing research problem. To address this, we present a fault resilient routing mechanism for irregular 2D meshes resulting from failures. To handle irregularities, it avoids using routing tables and employs a few fixed configuration bits per switch resulting in a scalable approach. Experiments demonstrate that the proposed approach is guaranteed to tolerate all locations of single and double-link failures and most multiple failures. Also, unlike uLBDR it is not restricted to any particular switching technique and does not replicate any extra messages. Along with fault tolerance, the proposed mechanism can achieve better network performance in fault-free cases. The proposed technique achieves graceful performance degradation during failure. Compared to uLBDR, our method has 14% less area requirements and 16% less overall power consumption.