Design of optical and electronic combined buffer architecture for optical packet switches

Optical packet switch systems with fiber-delay-line (FDL) buffers provide high-throughput, energy-efficient, and transparent forwarding. However, the FDL buffer experiences scalability issues, and thus, cannot accommodate a large amount of network traffic. In this paper, we first investigate network performance of the FDL buffer. Due to the discrete-time nature of the FDL buffer, throughput is not improved drastically in spite of adding extra FDLs. Then, we propose optical and electronic combined buffer architecture. The combined buffer is composed of the FDL buffer and a supplementary electronic buffer having power management functions according to its occupancy. The combined buffer uses only the FDL buffer and keeps its energy efficiency when traffic volume is low. In doing so, this architecture reduces power consumption to 70% of the buffer composed only of electronic devices under non-peak traffic. As the traffic volume increases, the combined buffer turns on its electronic devices and accommodates the increased traffic. Simulation results reveal that the proposed buffer architecture obtains 70% larger throughput than that of the existing FDL buffer.