Software Defined Networking(SDN)is programmable by separation of forwarding control through the centralization of the controller.The controller plays the role of the‘brain’that dictates the intelligent part of SDN t...Software Defined Networking(SDN)is programmable by separation of forwarding control through the centralization of the controller.The controller plays the role of the‘brain’that dictates the intelligent part of SDN technology.Various versions of SDN controllers exist as a response to the diverse demands and functions expected of them.There are several SDN controllers available in the open market besides a large number of commercial controllers;some are developed tomeet carrier-grade service levels and one of the recent trends in open-source SDN controllers is the Open Network Operating System(ONOS).This paper presents a comparative study between open source SDN controllers,which are known as Network Controller Platform(NOX),Python-based Network Controller(POX),component-based SDN framework(Ryu),Java-based OpenFlow controller(Floodlight),OpenDayLight(ODL)and ONOS.The discussion is further extended into ONOS architecture,as well as,the evolution of ONOS controllers.This article will review use cases based on ONOS controllers in several application deployments.Moreover,the opportunities and challenges of open source SDN controllers will be discussed,exploring carriergrade ONOS for future real-world deployments,ONOS unique features and identifying the suitable choice of SDN controller for service providers.In addition,we attempt to provide answers to several critical questions relating to the implications of the open-source nature of SDN controllers regarding vendor lock-in,interoperability,and standards compliance,Similarly,real-world use cases of organizations using open-source SDN are highlighted and how the open-source community contributes to the development of SDN controllers.Furthermore,challenges faced by open-source projects,and considerations when choosing an open-source SDN controller are underscored.Then the role of Artificial Intelligence(AI)and Machine Learning(ML)in the evolution of open-source SDN controllers in light of recent research is indicated.In addition,the challenges and limitations associated with deploying open-source SDN controllers in production networks,how can they be mitigated,and finally how opensource SDN controllers handle network security and ensure that network configurations and policies are robust and resilient are presented.Potential opportunities and challenges for future Open SDN deployment are outlined to conclude the article.展开更多
Software-defined networking(SDN),a new networking paradigm decoupling the software control logic from the data forwarding hardware,promises to enable simpler management,more flexible resource usage and faster deployme...Software-defined networking(SDN),a new networking paradigm decoupling the software control logic from the data forwarding hardware,promises to enable simpler management,more flexible resource usage and faster deployment of network services.It opens network functionality,application programmability,and control-to-data communication interfaces that used to be closed in conventional network devices,offering endless opportunities but also challenges for both existing players and newcomers in the market.Through a comprehensive and comparative exploratory of SDN state-of-theart techniques,standardization activities and realistic applications,this article unveils historic and technical insights into the innovations that SDN offers toward an emerging open network eco-system.We closely examine the critical challenges and opportunities when the networking industry is reshaped by SDN.We further shed light on future development directions of SDN in broad application scenarios,ranging from cloud datacenters,network operating systems,and advanced wireless networking.展开更多
以柔性直流为基础的配电网柔性互联与交直流混合配电网结构将给传统的配电系统运行方式带来巨大变革和挑战。首先简要介绍了一个含大规模新能源接入、集中式储能和负荷,以及融合交、直流微电网的典型多端直流配电网系统,并阐述了基本的...以柔性直流为基础的配电网柔性互联与交直流混合配电网结构将给传统的配电系统运行方式带来巨大变革和挑战。首先简要介绍了一个含大规模新能源接入、集中式储能和负荷,以及融合交、直流微电网的典型多端直流配电网系统,并阐述了基本的分层运行控制框架;然后针对底层稳定控制,分析了直流配电网电压基本控制策略;接着从直流配电网电压波动抑制、直流配电网稳定与阻尼控制,以及直流配电网多运行模式切换控制3个方面综述了提升直流配电网稳定性的关键控制技术。针对直流配电网优化运行关键技术,首先介绍了基于日前调度和实时优化控制的分层优化框架,然后从基于智能软开关(soft open point,SOP)的柔性互联配电网和复杂交直流配电网2类主要场景讨论了直流配电网长时间尺度下的优化调度问题。最后展望了直流配电网运行控制关键技术发展趋势。研究指出:就地控制需要更加柔性化以适应未来交直流配电网灵活功率控制的需求;优化运行控制将深度融合先进信息通讯、量测技术以及大数据、人工智能等技术。论文研究可为直流配电网的运行控制提供参考。展开更多
双碳和新型配电系统构建目标下优化多种灵活型资源位置与容量是实现该目标的重要技术路线。为此,兼顾规划运行的经济性和安全性,提出一种考虑越限风险的主动配电网中可再生分布式电源(distributed genevation,DG)、智能软开关(soft open...双碳和新型配电系统构建目标下优化多种灵活型资源位置与容量是实现该目标的重要技术路线。为此,兼顾规划运行的经济性和安全性,提出一种考虑越限风险的主动配电网中可再生分布式电源(distributed genevation,DG)、智能软开关(soft open point, SOP)、储能(energy storage, ESS)的两阶段协调规划方法。阶段1以综合成本与越限风险最小为目标优化DG、SOP与ESS的位置和容量。阶段2属于联合SOP、网络重构、有载调压变压器、电容器组、需求响应和储能多种调节手段的多目标运行优化。同时,以基于灰靶决策技术的LDBAS算法和二阶锥优化的混合方法为规划优化的求解工具。在IEEE 33节点配电系统上仿真,测试结果证明了所提两阶段协调规划模型能够有效地提高系统运行效率、增强灵活性、降低运行安全风险及经济成本。展开更多
基金supported by UniversitiKebangsaan Malaysia,under Dana Impak Perdana 2.0.(Ref:DIP–2022–020).
文摘Software Defined Networking(SDN)is programmable by separation of forwarding control through the centralization of the controller.The controller plays the role of the‘brain’that dictates the intelligent part of SDN technology.Various versions of SDN controllers exist as a response to the diverse demands and functions expected of them.There are several SDN controllers available in the open market besides a large number of commercial controllers;some are developed tomeet carrier-grade service levels and one of the recent trends in open-source SDN controllers is the Open Network Operating System(ONOS).This paper presents a comparative study between open source SDN controllers,which are known as Network Controller Platform(NOX),Python-based Network Controller(POX),component-based SDN framework(Ryu),Java-based OpenFlow controller(Floodlight),OpenDayLight(ODL)and ONOS.The discussion is further extended into ONOS architecture,as well as,the evolution of ONOS controllers.This article will review use cases based on ONOS controllers in several application deployments.Moreover,the opportunities and challenges of open source SDN controllers will be discussed,exploring carriergrade ONOS for future real-world deployments,ONOS unique features and identifying the suitable choice of SDN controller for service providers.In addition,we attempt to provide answers to several critical questions relating to the implications of the open-source nature of SDN controllers regarding vendor lock-in,interoperability,and standards compliance,Similarly,real-world use cases of organizations using open-source SDN are highlighted and how the open-source community contributes to the development of SDN controllers.Furthermore,challenges faced by open-source projects,and considerations when choosing an open-source SDN controller are underscored.Then the role of Artificial Intelligence(AI)and Machine Learning(ML)in the evolution of open-source SDN controllers in light of recent research is indicated.In addition,the challenges and limitations associated with deploying open-source SDN controllers in production networks,how can they be mitigated,and finally how opensource SDN controllers handle network security and ensure that network configurations and policies are robust and resilient are presented.Potential opportunities and challenges for future Open SDN deployment are outlined to conclude the article.
基金supported in part by agrant from the National Natural Science Foundation of China(NSFC)(Grant Nos.61370232 and 61520106005)
文摘Software-defined networking(SDN),a new networking paradigm decoupling the software control logic from the data forwarding hardware,promises to enable simpler management,more flexible resource usage and faster deployment of network services.It opens network functionality,application programmability,and control-to-data communication interfaces that used to be closed in conventional network devices,offering endless opportunities but also challenges for both existing players and newcomers in the market.Through a comprehensive and comparative exploratory of SDN state-of-theart techniques,standardization activities and realistic applications,this article unveils historic and technical insights into the innovations that SDN offers toward an emerging open network eco-system.We closely examine the critical challenges and opportunities when the networking industry is reshaped by SDN.We further shed light on future development directions of SDN in broad application scenarios,ranging from cloud datacenters,network operating systems,and advanced wireless networking.
文摘以柔性直流为基础的配电网柔性互联与交直流混合配电网结构将给传统的配电系统运行方式带来巨大变革和挑战。首先简要介绍了一个含大规模新能源接入、集中式储能和负荷,以及融合交、直流微电网的典型多端直流配电网系统,并阐述了基本的分层运行控制框架;然后针对底层稳定控制,分析了直流配电网电压基本控制策略;接着从直流配电网电压波动抑制、直流配电网稳定与阻尼控制,以及直流配电网多运行模式切换控制3个方面综述了提升直流配电网稳定性的关键控制技术。针对直流配电网优化运行关键技术,首先介绍了基于日前调度和实时优化控制的分层优化框架,然后从基于智能软开关(soft open point,SOP)的柔性互联配电网和复杂交直流配电网2类主要场景讨论了直流配电网长时间尺度下的优化调度问题。最后展望了直流配电网运行控制关键技术发展趋势。研究指出:就地控制需要更加柔性化以适应未来交直流配电网灵活功率控制的需求;优化运行控制将深度融合先进信息通讯、量测技术以及大数据、人工智能等技术。论文研究可为直流配电网的运行控制提供参考。
文摘双碳和新型配电系统构建目标下优化多种灵活型资源位置与容量是实现该目标的重要技术路线。为此,兼顾规划运行的经济性和安全性,提出一种考虑越限风险的主动配电网中可再生分布式电源(distributed genevation,DG)、智能软开关(soft open point, SOP)、储能(energy storage, ESS)的两阶段协调规划方法。阶段1以综合成本与越限风险最小为目标优化DG、SOP与ESS的位置和容量。阶段2属于联合SOP、网络重构、有载调压变压器、电容器组、需求响应和储能多种调节手段的多目标运行优化。同时,以基于灰靶决策技术的LDBAS算法和二阶锥优化的混合方法为规划优化的求解工具。在IEEE 33节点配电系统上仿真,测试结果证明了所提两阶段协调规划模型能够有效地提高系统运行效率、增强灵活性、降低运行安全风险及经济成本。
