Advanced Information Technology of Slot-Switching Network Schemes for on All-Optical Variable-Length Packet

Abstract

Problem Statement: The purpose of this paper was to investigate all optical packet switching, because it was the key to the success of the future Internet. It can meet the stringent bandwidth requirement of future Internet applications, such as real-time video streaming. Due to the lack of optical Random Access Memory (RAM), however, the all-optical schemes studied in the literature were either not flexible enough to accommodate Internet packets, which were variable-length in nature, or fail to schedule packets at switches to achieve low loss rate. Approach: The aim of this paper was thus to tackle the flexibility and utilization issues in all-optical packet switches, even at the absence of optical RAM. We approached this paper by first studied a new slotted model for all-optical variable-length packet switching, which was called Variable-length-Packet Fixed-Length Slot (VPFS) switching. Results: We proved by mathematical analysis the theoretical maximum utilizations that can be achieved by the model in two variant schemes. Then we proposed a new scheduling algorithm for shared-fiber-delay-line switches in order to achieve low loss rate when the utilization approaches the maximum. We justified our design by simulation. In our finding, through mathematical analysis and computer simulation, our proposed switching model and scheduling algorithm can be coupled well to achieve good performance for all-optical packet switches. We also found that the selection of the slot size in the network was very critical as it determined the transmission overhead and hence the utilization of the all-optical network. Our research limitation depended on slot size. Although a small slot size was critical for high utilization with our model, it was not always preferable. It was because a small slot size increased the switching and scheduling complexity at the switch. Thus the selection of an optimum slot size for the network was a compromise between utilization and complexity. Conclusion/Recommendations: A fast scheduling algorithm has been studied in order to reduce the scheduling complexity so as to increase the utilization without much penalty. In regard to the practical implications, the VPFS was a promising model to fully utilize the huge capacity of all-optical networks and to accommodate variable-length packets for future Internet traffic. With VPFS, the selection of the slot size was critical, and it was a compromise between the network utilization and scheduling complexity.