A Distributed Switch Architecture for On-Chip Networks

It is well-known that current Chip Multiprocessor (CMP) and high-end MultiProcessor System-on-Chip (MPSoC) designs are growing in their number of components. Networks-on-Chip (NoC) provide the required connectivity for such CMP and MPSoC designs at reasonable costs. However, as technology advances, links become the critical component in the NoC. First, because the power consumption of the link is extremely high with respect the power consumption of the rest of components (mainly switches), becoming unacceptable for long global interconnects. Second, the delay of a link does not scale with technology, thus, degrading the performance of the network. To solve both problems, several solutions have been previously proposed. In this paper, we present a new switch architecture that reduces the negative impact of links on the NoC. We call our proposal distributed switch. The distributed switch moves the circuitry of a standard switch onto the links. Then, packets are buffered, routed, and forwarded at the same time they are crossing the link. Distributing a standard switch onto the link improves the trade off between the power consumption and the operating frequency of the entire network. In contrast, area requirements are increased. The distributed switch reduces up to 14.8% the peak power consumption while increases its area up to 22%. Furthermore, the distributed switch is able to increase the maximum achievable frequency with respect to the standard switch. In particular, the maximum operating frequency of the distributed switch can be increased up to 14.3%.