Key Technologies In Optical Burst Switching Networks

Optical Burst Switching (OBS), combining high-speed optical transmission/switching technology and flexible electronic processing, has attracted considerable research attention from both academic and industrial fields. Although OBS is a promising solution for future IP/DWDM all-optical network, a lot of key issues such as TCP transmission and end to end delay are still under studied. Moreover, most of current researches focus on theoretical topics such as network protocols and algorithms in OBS, while few experimental activities are reported.In this dissertation, some key issues such as burst assembly, resource scheduling and end-to-end QoS are investigated, and some feasible solutions are proposed. Then a testbed based on Label switching method for OBS network is demonstrated, and some key technologies in this testbed are discussed, finally some latest experimental results are presented. Following are details.1) The performance of TCP traffic over OBS network is discussed. The transmission performance of TCP traffic is investigated at the situation when Data burst and ACK burst are dropped individually. Simulation models have been constructed and experiments on OBS testbed have been carried out to evaluate the discussed issues. It turns out that Data burst losing result in worse network performance than ACK burst losing. Based on this result, high class of QoS can be assigned to Data burst when network contention happens to maintain TCP transmission at a comparable high level at bad network situation.2) A group-based scheduling (GS) algorithm with features of simplicity, high bandwidth efficiency and QoS capability is proposed. GS-scheduling algorithm schedule multi-bursts after a delay window time, by doing so it can better utilize the burst voids and achieve high bandwidth efficiency. Moreover, a contention resolution is proposed to handle the problem about contentions happening between bursts with the same class of QoS. Simulation results show that GS-scheduling demonstrate a better performance than LAUC scheduling algorithm.3) A novel DS-JET algorithm based on control packet duplication is proposed. DS-JET algorithm achieve powerful capability by coupling with current JET scheduling algorithms while features on low time consuming during the processing on network intermediate node, which result in lower network end to end latency than JET algorithms. Furthermore, the influence of path length priority effect can be reduced in DS-JET mechanism. Simulation results show that DS-JET demonstrates better performance in burst blocking probability, network throughput and end to end QoS provision.4) A testbed based on label switching for OBS network is demonstrated for the first time in China, and its network architecture and especially core router architecture are discussed, with emphasis on resource scheduler, optical cross-connect and system control/management module which provide a research platform for assembly algorithm, scheduling algorithm and routing/signaling protocols respectively. Finally, some corresponding experimental results are presented, in which various modules such as optical switch, burst assembler, resource scheduler and burst receiver are verified and network latency in the testbed is evaluated. Moreover, a multi-QoS traffic transmission experiment over the testbed is discussed which will be helpful for future research on up-layer application in optical network.