| Optical Burst Switching (OBS) network belongs to those three optical switching networks which have been studied extensively in current days. The most important feature of OBS is that the control data packet and information data packet are transmitted along separate channels. This transmission mechanism not only reduces the delay which caused by the path-building, but also avoids the necessary for the optical buffer (or the optical RAM) which current optical techniques can not perfectly solve. Hence, the OBS becomes one of the key issues in optical networks.The assembly algorithms in the OBS edge node are chosen as the research objective, and the research method is mainly through software simulation. Firstly, the hierarchy of OBS network as well as the structure and function of core node and edge node (the edge node is emphasized) are summed up. Further more, the assembly mechanisms in current research papers are concluded. And then, some kinds of traffic distribution functions (including the self-similar distribution) and queuing methods or models are simulated and discussed.In the course of studying the assembly algorithms, the basic assembly algorithms are emphasized. And three typical assembly algorithms are simulated in the novel simulation models. They are Fixed Assembly Size (FAS) algorithm, Fixed Assembly Period (FAP) algorithm and Hybrid Threshold Assembly algorithm which is also named as Max Burst-Size Max Assembly Period algorithm (MSMAP). The simulation results are compared and discussed in this thesis. Besides the work above, two types of optimized mechanisms, such as priority mechanism and sub-queue mechanism, are introduced, whose purpose is to make further study on how to apply the quality of service (QOS) mechanism in the assembly algorithms. And the simulation results show that these two mechanisms can effectively reduce the queuing length as well as the queuing delay. It means that the performance of assembly algorithms improves. |
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