A software-defined network (SDN) is a new paradigm that separates control and forwarding. With the growth of SDN deployment scale, the centralized control plane becomes a bottleneck restricting the expansion of SDN networks. To avoid the problem of limited processing power in the wide area network (WAN), we focus on the multi-controller deployment in hierarchical architecture for software-defined WAN (SDWAN). The hierarchical architecture divides the control plane into multiple levels. The root controller has a global view. The domain controller is only responsible for the control in local networks. In this paper, we use the improved Louvain algorithm to discover the hierarchical community structure. Considering the load balancing and request delay in each partition and reliability of the control plane, we formulate the modeling and propose a hierarchical multi-controller deployment algorithm for the scalability of the SDWAN. The simulation results show that compared with the traditional algorithms, the proposed algorithm not only reduces the average request delay to a certain extent and effectively improves the performance of load balancing in each partition, but also efficiently enhances the reliability of the control plane in the SDWAN and achieves the good effect on the execution efficiency.INDEX TERMS Software-defined WAN, controller deployment, hierarchical architecture, Louvain algorithm.
Network virtualization (NV) is widely considered as one of the key technologies for future networks, which allows multiple virtual networks (VNs) to run on the same substrate network simultaneously. Software defined networking (SDN) can be used as a platform to realize NV. Therefore, the NV-based SDN has attracted intensive attention from both academic and industry in recent years. In this article, we focus on virtual network embedding (VNE) problem, which is one of the most important technologies of NV. Specifically, resource situation of underlying network (RSUN) is not considered in previous VNE algorithms, which seriously affects the efficiency of VNE. To solve this problem, we develop two heuristic algorithms to select the appropriate VNE according to RSUN. Our proposed algorithms adopt a novel node-ranking method, which fully considers the node topology and resource attributes, to sort physical nodes. In addition, two sorting approaches for virtual nodes and the global matching embedding (GME) approach are proposed. Our numerical analyses validate our proposed schemes and algorithms in terms of the average revenue to cost ratio, the average revenue, and the average VN request acceptance ratio. INDEX TERMS Network virtualization, virtual network embedding, SDN, global resource matching, node-ranking approach.
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