Dynamic Ring-Based Multicast with Wavelength Reuse for Optical Network on Chips

摘要

Multicast communication, which widely exists in multicore systems, can occupy a large quantity of network resources and lead to severe traffic congestions. Optical Network on Chip (ONoC) is considered as a promising interconnection technology for future multicore processors, due to its remarkable advantages of high bandwidth capacity and transmission speed. However, traditional multicast schemes cannot well utilize the limited number of wavelength channels in ONoC. In this paper, we propose a novel multicast scheme, DWRMR, based on Dynamically-established and Wavelength-Reusable Multicast Rings. In DWRMR, the multicast ring, which connects the source core with all destinations via a cyclic routing path, is dynamically constructed for each multicast group. Then multicast packets are transmitted in the manner of single-send-multi-receive using only single wavelength. The same wavelength can also be reused in link-disjoint multicast rings. Most importantly, in our scheme the established multicast ring can be shared among cores in the same multicast group for interactive multicast traffic via optical-token arbitration, which avoids setting up exclusive multicast routing paths for each core. We formulate the multicast ring routing and wavelength allocation problem as an integer linear programming problem, and propose a heuristic algorithm that is able to accommodate more multicast rings under the wavelength limitation. Simulation results indicate that DWRMR can reduce more than 50% of packet delay with slight hardware cost, or require only half number of wavelengths to achieve the same performance, compared with existing schemes.