The rapid development in both Internet application and emerging optical technology is bringing about fundamental changes in networking philosophies. To support the burst traffic on the Internet efficiently, optical burst switching is a way to streamline both protocol and hardware in building the next generation optical Internet. In this paper, we first give an overview of the optical burst switching schemes and burst reservation concepts. After comparisons, we find that the one called Just-Enough-Time (JET) performs the best and allows service differentiation. In the JET mechanism, a parameter, QoS offset time, acts as a very important character. Then we mainly discuss how to choose an appropriate QoS offset time with a dynamic programming model, which is constructed to find out the balance between the loss probability and the utilization of the buffering. Finally, we propose a bran-new strategy, which changes the QoS offset time according to the load of different service. In this way, we can further improve the utilization of the channel, meanwhile, with the loss probability guaranteed.
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