Browsing by Author "Wang, I-Chih"

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Deploying QoS-assured Service Function Chains with Stochastic Prediction Models on VNF Latency
(2017-01-01)
Lei, Tsung-Han
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Hsu, Yao-Tsung
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Wang, I-Chih
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Wen, Charles H. -P.
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電機工程學系
Current Network Function Virtualization (NFV) with Virtualized Network Functions (VNFs) running as virtual machines on commodity servers enables flexibility to Service Function Chaining (SFC). Specific applications may require Quality of Service (QoS) on end-to-end latency. However, the processing delay and the queuing delay of VNFs varies with virtual resource configurations (vCPU and vMemory), as well as physical usage (traffic amount, CPU utilization). Moreover, packet delays are randomly distributed, instead of a fixed value. To accurately model the latency distribution of one VNF, a prediction method using random-forest regression is proposed. Evaluation results show that our method can predict the latency distribution of the two sample VNFs with only 10% errors. On the basis of the model, a QoS-assured SFC deployment algorithm is also presented to guarantee end-to-end latency and bandwidth consumption of users. Experiments show that our algorithm enables high degree of scalability with polynomial runtime, and meanwhile maximizes user acceptance rates with 6% difference from the optimal solution from the mixed integer programming.
Dynamic Switch Migration in Distributed Software-Defined Networks to Achieve Controller Load Balance
(2019-03-01)
Xu, Yang
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Cello, Marco
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Wang, I-Chih
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Walid, Anwar
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Wilfong, Gordon
Multiple distributed controllers have been used in software-defined networks (SDNs) to improve scalability and reliability, where each controller manages one static partition of the network. In this paper, we show that dynamic mapping between switches and controllers can improve efficiency in managing traffic load variations. In particular, we propose balanced controller (BalCon) and BalConPlus, two SDN switch migration schemes to achieve load balance among SDN controllers with small migration cost. BalCon is suitable for the scenarios where the network does not require a serial processing of switch requests. For other scenarios, BalConPlus is more suitable, as it is immune to the switch migration blackout and does not cause any service disruption. Simulations demonstrate that BalCon and BalConPlus significantly reduce the load imbalance among SDN controllers by migrating only a small number of switches with low computation overhead. We also build a prototype testbed based on the open-source SDN framework RYU to verify the practicality and effectiveness of BalCon and BalConPlus. Experiment confirms the results of the simulations. It also shows that BalConPlus is immune to switch migration blackout, an adverse effect in the baseline BalCon.
FASIC: A Fast-recovery, Adaptively Spanning In-band Control Plane in Software-Defined Network
(2017-01-01)
Su, Yu-Lun
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Wang, I-Chih
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Hsu, Yao-Tsung
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Wen, Charles H. -P.
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電機工程學系
To operate a reliable SDN network, the control plane should be robust in order to guarantee the correctness of traffic forwarding. For in-band control, the traffic flows along with the data plane without a dedicated control network. Thus, the failure of data plane may isolate the switches from control plane and lead to erroneous forwarding behavior. In this paper, we design a control plane, FASIC, which can bootstrap the control network autonomously and adaptively span the control plane with the control-link switching mechanism. By implementing our design with Open vSwitch (OVS), OpenDayLight OVSDB Integration (ODL-OVSDB) and Floodlight software, we demonstrate that FASIC is an in-band control solution which is feasible under support of the available SDN and OpenFlow resources. Compared with standard OVS, the experimental result shows that FASIC reduces 87.83% of control plane downtime under hard link failure and incurs zero downtime under congestion. The preemptive control-link switching can prevent the control-link failure when it suffers from heavy traffic load.
Improving Quality of Experience of Service-Chain Deployment for Multiple Users
(2018-01-01)
Wang, I-Chih
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Wen, Charles H-P
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Chao, H. Jonathan
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電機工程學系
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Department of Electrical and Computer Engineering
The fifth generation (5G) mobile communication network aims at providing high-rate, low-latency services. When a user subscribes a chain of service functions (a.k.a. service chain) from the telecom providers, a Service Level Agreement (SLA) is specified according to his requirement. Deploying service chains optimally has always been a big issue. Several previous works have presented various strategies of service-chain deployment for optimizing either latency or computational resources; however, over-optimization of latency or computational resource is not necessarily equivalent to improvement on quality of experience. Therefore, in this paper, we formally formulate this problem of optimizing quality of experience with the queuing theory and mixed-integer linear programming. In addition, we propose an efficient algorithm named "QoE-driven Service-Chain Deployment with Latency Prediction" for deploying a service chain for a user in practice. According to the experiments, our algorithm reduces >99% rejections and >99% waiting time, notably elevating the quality of experience for users.