Efficient lookahead routing and header compression for multicasting in networks-on-chip

As technology advanced, Chip Multi-processor (CMP) architectures have emerged as a viable solution for designing processors. Networks-on-Chip (NOCs) provide a scalable communication method for CMP architectures as the number of cores is increasing. Although there has been significant research on NOC designs for unicast traffic, the research on the multicast router design is still in infancy stage. Considering that one-to-many (multicast) and one-to-all (broadcast) traffic are more common in CMP applications, it is important to design a router providing efficient multicasting. In this paper, we propose an efficient lookahead routing with limited area overhead for a recently proposed multicast routing algorithm, Recursive Partitioning Multicast (RPM) [17]. Also, we present a novel compression scheme for a multicast packet header that becomes a big overhead in large networks. Comprehensive simulation results show that with our route computation logic design, providing lookahead routing in the multicast router only costs less than 20% area overhead and this percentage keeps decreasing with larger network sizes. Compared with the basic lookahead routing design, our design can save area by over 50%. With header compression and lookahead multicast routing, the network performance is improved by 22% in a (16 x 16) network on average.