层次型多中心的SDN控制器部署

软件定义网络(SDN)通过转发与控制分离,借助控制面的集中化实现网络的灵活性和开放性.控制器部署是SDN部署运行的基础和前提.针对层次型多中心SDN的控制器部署问题,该文采用多层k路划分方法实现大规模SDN网络的区域划分,将传统的SDN多控制器直接部署转化为区域划分和域内控制器部署,同时通过减少图划分的域间割边数以降低SDN跨域流数量以提高流表构建效率.通过实验验证,较其他传统方法,该文提出的层次型多中心控制器部署方法可有效减少网络通信代价,降低流表构建代价.     

SO-CPP: Sailfish optimization-based controller placement in IoT-enabled software-defined wireless sensor networks

One of the expanding network topologies that is frequently utilized to improve network development by successfully separating the control plane and data plane is software-defined networking (SDN). In order to function inside complex sensor networks, the SDWSN system frequently relies on centralized controller logic that pulls global network information. In wireless sensor networks (WSNs), using several SDN controllers is known as a promising strategy due to reliability and performance considerations. However, using numerous controllers increases the synchronization overhead between the controllers. Consequently, it is a difficult research challenge to discover the best placement of SDN controllers to enhance the performance of a WSN, subject to the maximum number of controllers calculated based on the synchronization overhead. This research introduces a novel technique to overcome the controller placement problem (CPP) by optimizing multi-constraints within the sensor networks. For selecting the optimal controllers and placing them in an optimal location, a novel sailfish optimization (SO) strategy is introduced that can enhance the search space and maintain optimal global values throughout the iteration. Then, node clustering is performed using the fuzzy-C-means (FCM) clustering technique, which can reduce energy consumption and path delay within the network. The overall latency obtained by the proposed method is about 0.51 and 0.56 ms, and a total run time of 4 ms for both single sink and multi-sink, respectively. The proposed method is implemented in the MATLAB platform, and different performance metrics are analyzed and compared with existing techniques.     

Balanced multiple controllers placement with latency and capacity bound in software-defined network

Software-defined network (SDN) used a network architecture which separates the control plane and data plane. The control logic of SDN was implemented by the controller. Because controller's capacity was limited, in large scale SDN networks, single controller can not satisfy the requirement of all switches. Multiple controllers were needed to han-dle all data flows. By the reason that the latency between controller and switch would significantly affect the forwarding of new data flow, the rational placement of controllers would effectively improve the performance of entire network. By partition the network into multiple sub domains, on the base of spectral clustering, a method that added a balanced de-ployment object function into k-means was given and a balanced multiple controllers placement algorithm in SDN net-works which has the latency and capacity limitations was proposed. In this approach, a penalty function was introduced in the algorithm to avoid isolation nodes appearing. The simulations show that this algorithm can balance partition the net-work, keep the latency between controller and switch small and keep loads balancing between controllers.     

一种考虑软件定义网络控制节点故障的控制器部署和交换机迁移方法

在软件定义网络(SDN)中,若控制节点发生不可恢复的故障,则相关交换机需向其他控制节点迁移,这将导致网络性能下降。针对这一问题,该文提出一种考虑SDN控制节点故障的控制器部署和交换机迁移方法。与现有算法仅优化交换机迁移方法不同,该方法同时考虑控制器部署位置的影响。首先利用标号传播算法构造备选子集并划分双层子集,然后在每个子集中选取合适位置部署控制器,最后为子集内节点分配相应的master和slave控制器。实验结果表明,与现有算法相比,所提方法可有效解决交换机迁移后控制器超载的问题;通过调整参数,权衡控制器故障前后网络性能,可明显改善交换机迁移后的控制链路平均时延。     

HR-DO: High reliable–delay optimized controller placement in software-defined networking

Currently, networking technologies are pivoting towards software-defined networking (SDN) due to its easy management and centralized control system. The SDN network metrics, such as latency, scalability, robustness, and reliability largely depends on controller placement in the network domain. In view of betterment and best progression of network quality, the above mentioned network metrics need to be laid more emphases by considering controller placement. To achieve better network quality, an HR-DO (high reliable–delay optimized controller placement) is proposed. Fuzzy C-means, a meta-heuristic optimization algorithm, is used to optimize the number of controllers required in the network due to its effectiveness in cluster selection. It also eases the network latency. In addition, a minimal cut set-based Boolean logic approach and natural connectivity metric are used to improve the reliability and robustness of SDN with minimum worst-case latency. To check the performance, the proposed HR-DO is implemented on a topology-zoo network data set (OS3E and Chinanet). For comparison purposes, OCPA and K-means algorithms are taken into the account of latency, reliability, and robustness as parameters. The performance of the HR-DO approach outperforms over K-means and OCPA with respect to latency, reliability, and robustness.     

基于时延的LEO卫星网络SDN控制器动态放置方法

针对控制器进行信息同步维护全局网络视图时网络时延大的问题,基于对网络时延的分析提出了一种能够满足动态组网覆盖需求的SDN控制器放置方法。首先,根据卫星与终端的相对速度设计基于冗余覆盖的卫星子网划分机制;然后,对卫星网络分布式控制网络时延的进行研究,建立基于时延的控制器放置模型;最后,将控制器放置问题转化为基于软容量限制的设备放置问题,设计近似算法对模型进行求解。实验结果表明,所提方法能够在满足网络覆盖需求的同时优化网络时延。     

软件定义网络中可靠性优化控制器的位置研究(英)

By decoupling control plane and data plane,Software-Defined Networking(SDN) approach simplifies network management and speeds up network innovations.These benefits have led not only to prototypes,but also real SDN deployments.For wide-area SDN deployments,multiple controllers are often required,and the placement of these controllers becomes a particularly important task in the SDN context.This paper studies the problem of placing controllers in SDNs,so as to maximize the reliability of SDN control networks.We present a novel metric,called expected percentage of control path loss,to characterize the reliability of SDN control networks.We formulate the reliability-aware control placement problem,prove its NP-hardness,and examine several placement algorithms that can solve this problem.Through extensive simulations using real topologies,we show how the number of controllers and their placement influence the reliability of SDN control networks.Besides,we also found that,through strategic controller placement,the reliability of SDN control networks can be significantly improved without introducing unacceptable switch-to-controller latencies.     

面向软件定义广域网的路径可编程性保障研究综述

软件定义网络(SDN)被誉为下一代网络的关键技术。近年来,SDN已经成为学术界与工业界的热点。广域网是SDN应用到工业界的一个重要的场景。基于SDN的广域网被称为软件定义广域网(SD-WAN)。在SD-WAN中,SDN控制器通过控制流转发路径上的SDN交换机来实现流的路径可编程性。然而,控制器失效是SD-WAN中一种常见的现象。当控制器失效时,流转发路径上的交换机会失去控制,流的路径可编程性将无法得到保障,从而无法实现对网络流量的灵活调度,导致网络性能下降。该文对SD-WAN控制器失效场景下保证路径可编程性的研究工作进行了综述。该文首先阐述了当控制器失效时,SD-WAN中路径可编程性保障研究的背景及意义。随后,在查阅分析了国内外相关文献的基础上,介绍了当前在控制器失效时SD-WAN对交换机的主流控制方案。最后,对现有研究成果可能的进一步提高之处进行了总结,并对此研究的未来发展与研究前景进行了展望。     

自治系统内IP子网和SDN子网的互联机制

SDN网络与传统IP网络的互联机制是当前学术界的研究热点,但现有解决方案并不能适用于所有应用场景。为此提出了一个基于OSPF协议的IMISA架构,在一个包含 SDN 子网（基于OpenFlow）和IP子网的自治系统范围内,通过给SDN控制器添加一个OSPF路由模块,利用OSPF协议交换各自的网络信息,最终实现了2种网络的互联。     

面向SDN网络虚拟化平台的控制器放置算法

随着网络技术发展,以网络虚拟化为手段解决TCP/IP网络体系结构僵化问题已成为未来网络领域发展的主流方向之一.SDN(software defined networking,软件定义网络)作为一种新兴的网络体系结构,为网络虚拟化提供了有效的解决方案.首先总结了当前具有代表性的SDN网络虚拟化平台,并对比了SDN与传统网络环境中部署虚拟网的区别,然后针对SDN网络虚拟化平台中的虚拟网络映射问题,提出一种时延敏感的虚拟化控制器放置算法,最后通过实验验证了该算法在提高网络资源的利用效率的同时,保证了控制器与底层交换机的通信时延在可接受范围之内.     

基于时延的软件定义网络快速响应控制器部署

目前大多数针对软件定义网络(SDN)中控制器的部署方案均重点考虑传输时延(PD)对性能的影响,忽略了发送时延(TD)对于部署效果的影响。该文提出基于时延的网络快速响应控制器部署方案。首先,在合理考虑传输和发送两类时延的基础上,完善了已有的平均时延/最大时延最小化模型,并对两种模型是否存在最优解进行了理论证明;其次,利用模糊集理论得出了一种时延优化模型;第三,结合是否考虑发送时延提出了两种部署算法：传输算法和输送算法。为了测试方案的性能,选取实际网络拓扑及数据进行验证。结果表明输送算法在网络的响应速度及稳定性方面优于传输算法,时延优化模型在总时延方面较平均时延/最大时延最小化模型效果更优。     

Stateful firewall‐enabled software‐defined network with distributed controllers: A network performance study

SummarySoftware‐defined network (SDN) is constructed by decoupling the control and data plane from the forwarding devices. The control plane operations are managed by centralized or distributed controllers, and the data plane operation is managed by respective forwarding devices. SDN provides an easy and efficient management solutions for software‐programmed consolidated middlebox in virtual machines. Additionally, SDN with centralized controller faces complications like scalability, network bottle neck, and single point failure. In this study, a stateful inspection firewall acts as a middlebox in distributed SDN‐controlled network. The controller is programmed with a failure detection and recovery mechanism to provide reliability and redundancy and enhance the overall performance of the network. The objective of stateful firewall on SDN architecture is to secure the network by monitoring the current connections and maintain its state information until the connection is active. In this paper, the performance of firewall‐enabled SDN with centralized and distributed controllers are measured, compared, and analyzed. The experiments are done using POX controller, and the results are verified by Mininet network emulation tool. The results show that the stateful firewall‐enabled SDN with distributed controller network improves the security, reliability, availability, and overall performance of the network. In the proposed SDN, average network throughput is improved by 43%, average network delay is reduced by 4%, average channel utilization is increased by 40%, average network overhead is reduced by 26%, and average network response time is reduced by 23%.     

Deep Learning Based Analog Beamforming Design for Millimetre Wave Massive MIMO System

Software-defined networking (SDN) is a new approach that overcomes the obstacles which are faced by conventional networking architecture. The core idea of SDN is to separate the control plane from the data plane. This idea improves the network in many ways, such as efficient utilization of resources, better management of the network, reduced cost, innovation with new evolution, and many others. To manage all these changes, there is a great need for an efficient controller to improve the utilization of resources for the better performance of the network. The controller is also responsible for the analysis and monitoring of real-time data traffic. There is a great need for a high-performance controller in networking industries, data centres, academia, and research due to the tremendous growth of distributed processing-based real time applications. Therefore, it is crucial to investigate the performance of an open-source controller to provide efficient traffic routing, leading to improved utilization of resources for the enhanced performance metrics of the network. The paper presents an implementation of SDN architecture using an open-source RYU SDN controller for the network traffic analysis. The proposed work evaluates the performance of SDN architecture based custom network topology for a node to node performance parameters such as bandwidth, throughput and roundtrip time, etc. The simulation results exhibit an improved performance of the proposed work in comparison to the existing default network topology for SDN.

     

软件定义网络中基于时延和负载的多控制器部署策略研究

多控制器体系结构的出现,解决了经典软件定义网络(SDN)架构控制层以单一集中控制器为主,在大规模网络环境中的可扩展性问题。在多控制器体系结构中,由于生成转发规则并将其填充到交换机的任务被委托给了控制器,网络的性能在很大程度上取决于控制器的放置。该文以降低总时延和均衡控制器间负载为目标,提出了一种基于子网划分的多控制器部署算法(MCPA)。该算法改造谱聚类算法以保证网络连通性并加入离群点处理算法和负载均衡处理算法。仿真结果表明,该算法能够有效地对网络进行划分,在保证网络总时延较低的情况下使各个控制器的负载保持均衡。     

Toward manageable middleboxes in software‐defined networking

Software‐defined networking (SDN) acts as a centralized management unit, especially in a network with devices that operate under the transport layer of the OSI model. However, when a network with layer 7 middleboxes (MBs) is considered, current SDNs exhibit limitations. As such, to achieve a real‐centralized management unit, a new architecture is required that decouples the data and control planes of all network devices. In this report, we propose such a complementary architecture to the current SDN in which SDN‐enabled MBs are included along with contemporary SDN‐enabled switches. The management unit of this architecture improves network performance and reduces routing cost by considering the status of the MBs during flow forwarding. This unit consists of the following two parts: an SDN controller (SDNC) and a middlebox controller (MBC). The latter selects the best MBs for each flow and the former determines the best path according to its routing algorithm and provides information via the MBC. The results show that the proposed architecture improved performance because the utilization of all network devices including MBs is manageable.     

基于SDN的多控制器部署策略的研究

随着SDN在大型网络以及广域网中的需求,如何合理、高效地部署SDN控制器,从而以较低的部署成本,获得较好的网络性能,是当前研究的热点.针对控制器数量、部署位置问题以及交换机与控制器之间的映射关系的问题,首先给出一种分布式的控制器部署方式并设定了网络相关参数,以流建立请求代价为优化目标,提出了一种基于贪心算法的控制器部署策略方案.最后通过仿真实验将所提出方案与ACL方案进行对比,证明了所提方案在性能方面有一定的提升.     

SDN中基于Q-learning的动态交换机迁移算法

由于网络流量动态变化,控制器负载均衡成为大规模部署软件定义网络研究的重点.提出基于Q-learning的动态交换机迁移算法,首先对软件定义网络中的控制器部署问题建模,再应用Q-learning反馈机制学习实时网络流量,最后根据Q表格将交换机从高负载控制器动态迁移到低负载控制器上,实现控制器的负载均衡.仿真结果表明,所提算法能够获得较低的控制器负载标准方差.     

Exploiting the control power of SDN during the transition from IP to SDN networks

The emerging software‐defined networking (SDN) paradigm introduces new opportunities to improve network performance due to the flexibility and programmability provided by a logically centralized element named controller. However, a rapid adoption of the full SDN architecture is difficult in the short term due to economic and technical reasons. This paper faces the SDN nodes replacement problem during the transition from traditional IP networks to fully deployed SDN networks. Six different replacement methods are proposed to select the most appropriate set of traditional IP nodes to be upgraded to SDN‐enabled switches at a particular transition stage. To show the effectiveness of the proposed methods, they have been applied on an optimization problem currently studied by the research community: the power consumption problem. An integer linear programming formulation is presented to solve it and a genetic algorithm is evaluated through simulations on realistic network topologies. Results highlight that energy‐efficiency in hybrid IP/SDN networks can be significantly improved by only replacing a reduced number of IP nodes.     

Dynamic handover algorithm with interference cancellation in 5G networks for emergency communication

The integration of 5G networks with cognitive radio (CR) technology enables the software‐defined networking (SDN) infrastructure to support emergency applications. In future, CR can be integrated with 5G and many wireless networks like Wi‐Fi, WSN, and MANET for efficient spectrum utilization with higher data rate and lower latency. This CR technology allows unlicensed users to access the licensed spectrum, whenever it is free. In this paper, an efficient SDN architecture with cognitive ability for emergency network is proposed in which the SDN controller prolong communication between disaster victims and first responders and so the first responders can arrive at the spot directly and rescue the victims. The SDN controller has cognitive ability so that the victims can utilize the vacant licensed band to communicate with the first responders, thereby improving the spectrum utilization of the network. Another two main challenges during emergency are the occurrence of interference and link failure. The proposed dynamic handover algorithm with interference cancellation (DHAIC) cancels the interference between the nodes inside the network and performs dynamic handoff, whenever link failure occurs between the cluster head (CH) and the controller. An optimum throughput and minimal delay is achieved to ensure the network performance.     

Dynamic control plane management for software‐defined networks

Software‐defined network (SDN) is an emerging network paradigm that allows flexible network management by providing programmability from a separated control plane. Because of the centralized management scheme that SDN adopts, intensive control plane overhead incurs as the scale of SDN increases. The control plane overhead is mainly caused by a massive amount of control messages generated during data plane monitoring and reactive flow instantiation. By far, very few works have addressed the overhead issue on reaction flow instantiation; therefore, we mainly focus on alleviating such overhead in this work. To achieve this goal, we propose a new control plane management (CPMan) method. CPMan aims to realize the following two objectives: first, reduce the number of control messages exchanged through the control channel and second, evenly distribute the control workload across multiple controllers to mitigate the potential performance bottleneck. To realize the former, we propose a lightweight feedback loop‐based control scheme, whereas for the latter, we propose a dynamic switch‐to‐controller (DSC) placement scheme. To show the feasibility of our proposal, we implemented a prototype of the two proposed schemes on top of a carrier‐grade SDN controller and validated its performance in an emulated network. We achieved approximately 57.13% overhead reduction with feedback loop‐based control scheme, while achieved approximately 98.68% balance ratio with DSC placement scheme. Copyright © 2016 John Wiley & Sons, Ltd.