Performance Evaluation of Asynchronous Optical Packet Switches with FDL Buffers

• Main Authors: Jyun-Ming Chen, 陳均銘
• Other Authors: Woei Lin
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/27803804930904859109

碩士 === 國立中興大學 === 資訊科學與工程學系所 === 99 === Resolving packet contention is a main issue in the design of network and switch architecture. Packet contention in network switches occurs when multiple packets are destined to the same output port at the same time. Buffering is a conventional solution for contention avoidance. In the optical domain, buffering typically uses fiber delay lines (FDLs) to delay an optical signal for a discrete, fixed amount of time. Many asynchronous optical packet switches (OPSs) rely on the use of feed-forward buffers. However, they often require a great number of FDLs for buffering contending packets, and they become economically infeasible for implementation. The feedback buffer is a promising approach to reducing FDL buffer size, because it can efficiently circulate packets through an FDL buffer to achieve a prescribed amount of delay time. The main objective of this thesis is to study the performance of asynchronous OPSs with feedback FDL buffers. We evaluate the performance of feedback FDL buffers, and compare it with that of feed-forward buffers with respect to buffer size and buffer utilization. Two packet forwarding schemes are proposed for scheduling packets and managing FDL buffers, respectively. We examined two major system parameters of the feedback architecture: they are FDL buffer size and recirculation limit. Through simulation, we analyze their joint effects on system performance. Our simulation results show that raising recirculation limit can effectively enhance the system performance. The results indicate that through the proposed buffer management scheme, we can determine an optimal buffer size and achieve the lowest packet blocking under various working conditions.