Multi-Stage Fiber Delay Line Buffer in Photonic Packet Switch for Asynchronously Arriving Variable-Length Packets

Abstract

We study photonic packet switches to support asynchronously arriving variable-length packets. A scheduler for contention resolution is operated in electrical domain even when data street of the buffer is provided in optical domain. In this scheme, the scheduler may be a bottleneck. To compensate the gap of high-speed optical transmission and slow-speed electronic processing, we propose a multi-stage fiber delay line (FDL) buffer architecture that forms a tree structure in which each node has a block of FDLs and a scheduler. This is especially useful for output-buffer switches in which scheduling complexity is proportional to the number of ports of the packet switch. Through a newly-developed approximate analytical method, we show the optimum unit length of the fiber delay lines to decrease packet loss probability. We also show the sufficient number of FDLs in the two-stage buffer.

Autonomous optical buffer system for synchronous packets with priority control

“…Optical buffering is a key function in these systems to avoid packet collision. Although optical slow light can be a potential candidate to adjust short delay timing, optical fiber delay lines (FDLs) are regarded to be most useful elements for packet buffering [1].…”

All-Optical Autonomous First-in–First-out Buffer Managed with Carrier Sensing of Output Packets

“…One is a feedforward architecture, consisting of parallel FDLs that have different lengths corresponding to desired delay times. A combination of input and output buffered switch [6] and multistage FDL buffer [7] were reported as feedforward architectures. The other is an architecture consisting of feedback-looped FDLs.…”

Optical Switching Node with Different Shared Devices for Contention Avoidance and Its Performance

“…However, because only TWCs that avoids contention in the frequency domain are used for the contention avoidance, contention avoidance is impossible in the situation that the output port has been occupied. While, it is possible to avoid contention in the time domain by using FDL, and the optical switching node that is composed of matrix optical switch, 2x2 switch and fixed length multiplexd buffer by FDL was proposed [4]. However, contention avoidance is only in the time domain in this model [4].…”

“…While, it is possible to avoid contention in the time domain by using FDL, and the optical switching node that is composed of matrix optical switch, 2x2 switch and fixed length multiplexd buffer by FDL was proposed [4]. However, contention avoidance is only in the time domain in this model [4]. It is thought that further contention avoidance can be done if both TWCs and FDLs are used more effectively.…”