Editorial: Special issue on SDN‐based wireless network virtualization
Yulei Wu, Zheng Yan, Zhiwei Zhao, Ahmed Al‐Dubai · Concurrency and Computation Practice and Experience · 2019
With the rapid development of hardware and software technologies, an increasing number of mobile devices, eg, smartphones and tablets get connected to the Internet, which results in a large proportion of traffic attributed to mobile devices.1 The mobile users have therefore increasingly high demands to access the Internet with guaranteed Quality-of-Experience.2, 3 Software-Defined Networking (SDN)4, 5 is an emerging network architecture where network control is decoupled from data forwarding and provides a powerful tool for fine-grained network management. The SDN-based network virtualization techniques have been widely used by Internet Service Providers to facilitate the service delivery with such performance guarantees, where network routers and switches are dynamically coordinated under the SDN APIs in wired networks.6 With the rapid advancement of wireless network technologies, many last mile connections go for wireless. However, the SDN-based wireless network virtualization is not straightforward. Many research challenges still need to be resolved before practical large-scale deployment. The accepted eight papers in this special issue are devoted to addressing the state-of-the-art technologies related to SDN, wireless network, network virtualization, security issues, and performance improvements. These papers can be organized under the following key themes: trust model and management, SDN security, and network performance optimization. The contributions of these papers are outlined below. There are two accepted papers aiming at establishing frameworks for trust models, management, and methodologies. The paper “A Trust Management Framework for Software-Defined Network Applications” proposed a trust management framework for SDN applications.7 It evaluates the applications' trust values according to their impact on the network performance. With the prototype system based on a floodlight controller, the framework is shown to be accurate and effective. Different from the above work, the paper “Graph Encryption for All-path Queries”8 aimed at providing the ability to store sensitive graph data to untrusted servers. A searchable symmetric encryption scheme is proposed to support all-path queries. The proposed scheme is proved to be able to adaptively semantically secure in the semihost settings. The scheme can be widely applied in the network virtualisation as graph data structures are commonly used to represent the topology of substrate and virtual networks. Security is one of the most important topics in SDNs. There is one accepted paper in this issue focusing on this topic. The paper “A Comprehensive Survey of Security Threats and Their Mitigation Techniques for Next-Generation SDN Controllers”9 provided a comprehensive survey of the security threats and corresponding mitigation techniques for SDN controllers. In this survey, a detailed classification for various security attacks on the control plane has been provided. Besides, the latest corresponding mitigation techniques are also presented and summarized. Based on the survey, future directions on a number of security issues such as policy violation and malware injection are discussed. DDoS attack is one of the most popular and threatening attacks for SDNs. Two accepted works are focused on this specific topic and have made contributions from different aspects. In the paper “An Intelligent Trust Model for Hybrid DDoS Detection in Software Defined Networks”,10 a trust evaluation and management model for hybrid DDoS detection in SDNs is proposed, where the extreme learning machine is applied. The proposed model can monitor the trust values of the OpenFlow switches in real time and thus can respond to different types of DDoS attacks. The model provides a more efficient alternative for DDoS detection in SDNs. The paper “Machine Learning Algorithms to Detect DDoS Attacks in SDN”11 managed to exploit different kinds of machine learning algorithms to avoid three kinds of DDoS attacks (controller attack, flow table attack, and bandwidth attack). Compared to the above work on trust model, this paper deals with the problem in a different way and considers more kinds of attacks. SDN and NFV have attracted increasing research attentions in recent years. The various network resources, traffic patterns, user demands, and protocol policies have significant impact on the network performance, which makes the performance optimization a challenging problem. The paper “The Optimization of Virtual Resource Allocation in Cloud Computing Based on RBPSO”12 considered the task requirements from different users to manage virtual machines. A novel algorithm with resampled binary particle swarm optimization is proposed. Compared with the existing works, the efficiency of the proposed algorithm is improved, the population diversity is maintained, and redundant calculations are reduced. The paper “Traffic Modeling and Performance Evaluation of SDN-Based NB-IoT Access Network”13 specifically considered the impact of network traffic in the SDN-based Narrowband Internet of Things (NB-IoT) network. SDN-enabled NB-IoT is discussed in this paper. Besides, the network performance is evaluated and modeled using various network parameters in the NB-IoT networks. The analysis and simulation results can be used in the SDN controller to dynamically allocate resources and make network management decisions to satisfy different performance requirements of NB-IoT applications. The paper “LBBESA: An Efficient Software-Defined Networking Load-Balancing Scheme Based on Elevator Scheduling Algorithm”14 dealt with the problem of load balancing in SDNs, based on the elevator scheduling algorithm. According to the real-time measurement of the server loads, the regional elevator allocation is applied to coordinate the connection of the clients' requests. The throughput and scalability are improved. The articles presented in this special issue have provided insights in fields related to SDN, wireless networks, network virtualization, and network security, including the trust models and methodologies, SDN DDoS attacks, and performance optimization for various SDN-enabled networks. We wish the readers can benefit from the insights of these papers and contribute to these rapidly growing areas. We would like to express our deep thanks to the Editor-in-Chief, Professor Geoffrey Fox, for providing us with the opportunity to host this special issue in Concurrency and Computation: Practice and Experience. We also thank all the authors who submitted their papers. Last but not least, we thank the thoughtful work of the many reviewers who have provided invaluable evaluations and recommendations.