A New Router Architecture for High-Performance Intrachip Networks
Keywords:Networks on Chip, Switching Modes, Virtual Channels, Session Layer
For almost a decade now, Network on Chip (NoC) concepts have evolved to provide an interesting alternative to more traditional intrachip communication architectures (e.g. shared busses) for the design of complex Systems on Chip (SoCs). A considerable number of NoC proposals are available, focusing on different sets of optimization aspects, related to specific classes of applications. Each such application employs a NoC as part of its underlying implementation infrastructure. Many of the mentioned optimization aspects target results such as Quality of Service (QoS) achievement and/or power consumption reduction. On the other hand, the use of NoCs brings about the solution of new design problems, such to the choice of synchronization method to employ between NoC routers and application modules mapping. Although the availability of NoC structures is already rather ample, some design choices are at base of many, if not most, NoC proposals. These include the use of wormhole packet switching and virtual channels. This work pledges against this practice. It discusses trade-offs of using circuit or packet switching, arguing in favor the use of the former with fixed size packets (cells). Quantitative data supports the argumentation. Also, the work proposes and justifies replacing the use of virtual channels by replicated channels, based on the abundance of wires in current and expected deep sub-micron technologies. Finally, the work proposes a transmission method coupling the use of session layer structures to circuit switching to better support application implementation. The main reported result is the availability of a router with reduced latency and area, a communication architecture adapted for high-performance applications.