Characterization of a Fault-tolerant NoC Router

Abstract

With increasing reliability concerns for current and next generation VLSI technologies, fault-tolerance is fast becoming an integral part of system-on-chip (SoC) and multi-core architectures. Another concern for these architectures is increasing global wire lengths with associated issues leading to network-on-chips (NoC) becoming standard for on-chip global communication. We recognize these issues and present an on-chip generic fault-tolerant routing algorithm. The microarchitecture of a NoC router implementing the proposed routing algorithm for a k-ary 2-cube topology is provided. The proposed router works in two phases. In the first phase, the network is explored for an existing path between source-destination pairs after reset or during system reconfiguration after fault detection. Existing paths are cached and used in the second phase of data communication during normal system operation. The presented router architecture also proposes a concept of dynamic multiplexing of virtual channels on physical channels to efficiently utilize physical channel bandwidth. The above approaches complement each other and when combined together, result in an efficiently realizable high-performance NoC fault-tolerant router. An implementation characterization of this k-ary 2-cube torus router in terms of area, power and critical path delay in IBM Cu-08 technology is presented, along with bandwidth and latency characterization for relevant cases.