Browsing by Author "Ali, Ahsan"

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Performance modeling and analysis of TCP and UDP flows over software defined networks
(2019-03-15)
Lai, Yuan-Cheng
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Ali, Ahsan
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Hossain, Md Shohrab
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Lin, Ying-Dar
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資訊工程學系
Software Defined Networking (SDN) decouples the control plane from the data plane, thereby facilitating network virtualization, dynamic programmability and flexibility in network management. Previous studies on SDN modeling focus only on packet-level arrivals. However, if flow-level arrivals are not also considered, the model cannot properly reflect the true probability of packets being sent to the controller. Accordingly, the present study proposes two analytical models for predicting the performance of TCP and UDP flows over SDN, respectively, given the assumption of both flow-level arrivals and packet-level arrivals. In constructing the models, the switch and controller are considered jointly and four-dimensional states are used to evaluate the steady-state probabilities of the states. Analytical formulae are derived for the average packet delay and packet loss probability of the TCP and UDP flows. Simulation results very well match with the analytical ones, thereby validating our analytical models. The results show that TCP significantly outperforms UDP over SDN architectures. In particular, TCP reduces the packet delay by 12 similar to 50% and the packet loss probability by 25 similar to 100%.
Performance Modeling and Analysis of TCP Connections over Software Defined Networks
(2017-01-01)
Lai, Yuan-Cheng
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Ali, Ahsan
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Hassan, Md. Mahadi
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Hossain, Md. Shohrab
;
Lin, Ying-Dar
Software Defined Networking (SDN) decouples the control plane from the data plane, thereby enhancing flexibility in network management. Earlier works on SDN modeling only focused on packet-level arrivals without considering flow-level arrivals. However, a model without considering flow-level arrivals cannot correctly reflect the probability of sending packets to the controller. In this paper, we propose an analytical model of SDN considering flow-level (TCP connection) arrivals and packet-level arrivals simultaneously. We use an analytical method termed as 4D state model, which uses four-dimensional states. We have derived the state transition rates of the model and also the packet delay and packet loss probability. We have conducted numerical analysis and extensive simulations. Our results show good matches, which verify the suitability and correctness of our analysis. Error ratios of the analytical results for 4D state model and M/M/1 model against simulation results are also given. Results show that for data packet delays, 4D state can achieve error ratios of 1.16 similar to 3.30%, which is much better than 8.57 similar to 35.7% attained by M/M/1 model, which only considers packet-level arrivals.