Research On Router Buffer Sizing

With rapid development of Internet traffic and transmission technology, current router buffer size may have a major challenge to its performance. But so far, the study on the router buffer sizing has no unified conclusion.Firstly, the thesis reviews the researches of buffer sizing problem, mainly focuses on five typical buffer sizing methods based on the model of TCP protocol, and then concludes from comparison that buffer sizing methods based on different assumptions and objectives should be adapted to different networks. Meanwhile we study several primary factors which influence buffer requirement, and mainly analyze how TCP protocols and queue management mechanisms interact with buffer size. In conclusion we point out when high speed TCP protocols and AQM are used in high bandwidth-delay network, buffer size is supposed to be reduced greatly.Combined with throughput optimization theory, this thesis presents a novel adaptive router buffer sizing algorithm based on link state (BSLS). BSLS imports a judging factor by virtue of differential idea, and adopts the MIMD mechanism to change the value of available buffer threshold dynamically. The results under diversified load levels showed that, BSLS algorithm could maintain high throughput, by achieving proper trade-off between queue delay and congested loss rate.Due to the fact that channel bandwidth is time-varying and the random nature of CSMA/CA, the thesis presents a novel adaptive router buffer sizing algorithm (ABS). This algorithm combines with idle rate of MAC queue to distinguish the level of channel contention, and then use AIAD mechanism to adjust available buffer threshold. By which this algorithm can maintain high throughput whilst achieving low inter-service time.Finally, the dissertation summarizes the current existing open issues, and provides some further interesting directions.