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Performance computation and implementation of distributed controllers for reliable software-defined networks

JOURNAL OF SUPERCOMPUTING 2021年第11期77卷 12790-12800页

作者： Alqahtani, Abdulrahman Saad Bisha Univ Coll Comp & Informat Technol Dept Comp Sci Bisha Saudi Arabia

Software-defined networks (SDNs) are designed to cover the dynamic operations of network factors and the complex role of controlling components to achieve scalability and security. In SDNs, the operating process is computed through a centralized controller, and failure of the controller leads to the entire network's breakdown. Since the centralized controller's reliability is due to a single point of failure, the implementation of distributed controllers for reliable SDN networks (IDCR) has been applied to resolve this difficulty. The focus of this approach is to enhance the reliability of the SDNs with distributed controllers. In this approach, the broad network is divided into smaller subnetworks, and each network is operated through a controller to decrease the number of breakdowns. Here, reliability was computed through the route and connection reliability. Then, the controller with the highest reliability is regarded as the coordinator controller. The simulation results have proven that the IDCR approach reduces both the network delay and the failure probability. Furthermore, the approach decreases the controller overhead.

关键词： Software-defined networks distributed controllers Coordinator Reliability improvement Connection reliability Neighborhood degree

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Improving the Reliability of Software-Defined Networks with distributed controllers Through Leader Election Algorithm and Colored Petri-Net

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WIRELESS PERSONAL COMMUNICATIONS 2019年第1期109卷 645-656页

作者： Moazzeni, Shadi Khayyambashi, Mohammad Reza Movahhedinia, Naser Univ Isfahan Fac Comp Engn Dept Comp Architecture Esfahan Iran

Software-Defined Networks (SDNs) are developed to compensate the complicated function of the controlling parts of the given network elements and making the scalability easier. In SDNs, the controlling operations are implemented by a logically centralized controller, where the occurrence of failure resulting in separation of the control and data plane is inevitable. Since the reliability of centralized controllers is low due to their being of the single point of failure, the focus of this study is to improve the reliability of the SDNs with distributed controllers. In this article, the wide networks are partitioned into smaller subnetworks, where each one is being controlled by a controller in order to reduce the failure effect(s). In each subnetwork, its reliability is calculated by considering the number and degree of nodes and the loss rate of the links and then is transmitted among the controllers through the Leader Election and Dijkstra Algorithms. Afterward, the controller with the highest reliability rate is considered as the coordinator through the newly proposed Coordinator Finder Algorithm. In practice, when a controller fails, the coordinator would choose the appropriate controller for its subnetwork in a transitory manner, where the fault tolerance and accuracy would be improved and the latency would reduce. A newly designed Colored Petri-Net is applied to verify this proposed method.

关键词： Software-Defined Networks distributed controllers Reliability Colored Petri-Net Coordinator

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Study on optimal state estimation strategy with dual distributed controllers based on Kalman filtering

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High Technology Letters 2019年第1期25卷 105-110页

作者： Chen Yawen Wang Zhuwei Fang Chao Xu Guangshu Zhang Yanhua School of Information and Communications Engineering Beijing University of Technology

Considering dual distributed controllers, a design of optimal state estimation strategy is studied for the wireless sensor and actuator network(WSAN). In particular, the optimal linear quadratic(LQ) control strategy with estimated plant state is formulated as a non-cooperative game with network-induced delays. Then, using the Kalman filter approach, an optimal estimation of the plant state is obtained based on the information fusion of the distributed controllers. Finally, an optimal state estimation strategy is derived as a linear function of the current estimated plant state and the last control strategy of multiple controllers. The effectiveness of the proposed closed-loop control strategy is verified by the simulation experiments.

关键词： optimal state estimation strategy wireless sensor and actuator network(WSAN) distributed controllers Kalman filter network-induced delays

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Traffic pattern-based load-balancing algorithm in software-defined network using distributed controllers

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2019年第17期32卷

作者： Gasmelseed, Hatim Ramar, Ramalakshmi Kalasalingam Acad Res & Educ Dept Comp Sci & Engn Krishnankoil India

Programmability and decoupling of the data plane and control plane in software-defined networking (SDN) make the enterprise's network to focus on this new paradigm and to deploy their applications on it. Furthermore, supporting of distributed controllers in SDN opens the opportunities to address the limitations of centralized controller's architecture, which in turn improves the overall performance of the network. This study proposes a new load-balancing algorithm to handle the load based on the traffic pattern specifically transmission control protocol (TCP) and user datagram protocol (UDP) traffic. Additionally, this study uses a distributed SDN controller's architecture to host the load balancer application. This study also employs a failover mechanism on the distributed architecture to achieve high-availability environment and to ensure the redundancy and reliability of the network. The obtained results prove the effectiveness of the proposed algorithm in terms of availability, which is increased by 11%, response time is reduced by 98%, transaction rate is also increased by 258%, throughput is increased by 206%, concurrency is reduced by 63%, and packet loss is reduced by 86% while comparing with random, round-robin, and weighted round-robin algorithms in addition to ease the integration and deployment in distributed controllers.

关键词： distributed controllers failover high availability load balancing SDN traffic pattern

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The role of the inter-controller consensus in the placement of distributed SDN controllers

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COMPUTER COMMUNICATIONS 2017年 113卷 1-13页

作者： Zhang, Tianzhu Giaccone, Paolo Bianco, Andrea De Domenico, Samuele Politecn Torino Dept Elect & Telecommun Turin Italy

We consider a distributed Software Defined Networking (SDN) architecture adopting a cluster of controllers to improve network scalability and reliability. Different from previous works that focused solely on the control traffic exchanged between controllers and switches, we additionally consider the control traffic exchanged among the controllers (e.g., the control traffic to keep the shared data structures synchronized). We advocate a careful placement of the controllers, which should take into account both the two kinds of control traffic. We evaluate, for some real ISP network topologies, the delay tradeoffs for the controller placement problem and we propose a novel evolutionary algorithm to find the corresponding Pareto frontier. Furthermore, we develop a simple model to estimate the reaction time perceived by the switches, which is accurately validated in an operational Software Defined WAN (SDWAN). We also formalize the optimization problem to minimize the reaction time and devise a novel approximation algorithm, whose performance is assessed against the optimal solver in real ISP network topologies. Our work provides novel quantitative tools to optimize the planning arid the design of the network supporting the control plane of SDN networks, especially when the network is very large and in-band control plane is adopted. We also show that for operationally distributed controllers (e.g., OpenDaylight and ONOS), the location of the controller that acts as leader in the consensus algorithm has a strong impact on the reactivity perceived by the switches. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Software defined networking distributed controllers Controller placement problem Consistency data models

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Verifying distributed controllers with Local Invariants 2

Verifying Distributed Controllers with Local Invariants

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IEEE International Conference on Software Quality, Reliability and Security (QRS)

作者： Wang, Yiqun An, Shengwei Ma, Xiaoxing Cao, Chun Xu, Chang Nanjing Univ State Key Lab Novel Software Technol Inst Comp Software Deptartment Comp Sci & Technol Nanjing 210023 Jiangsu Peoples R China

ISBN: (纸本)9781509041275

controllers restrict systems to behave only in good manners. Different from controlling monolithic systems where controllers can be automatically synthesized from specifications, controlling distributed systems often has to use distributed controllers that are manually programmed. To ensure their correctness, manually programmed controllers themselves need to be formally verified. This task can be challenging due to the complexity caused by the autonomy and asynchrony of distributed controllers. The limited scalability of existing model checkers also exacerbates the problem. In this paper we explore the modeling and verification of distributed controllers using Alloy. Besides resorting to the Small Scopes Hypothesis of the Alloy methodology, we also leverage local invariant based modular verification techniques for better scalability. A local invariant characterizes a logical relationship between a local sub-system and its neighbors and abstracts away the concrete interactions. These concrete interactions would otherwise explode the system state space during verification. The approach is first illustrated with the well-understood Two-Phase Commit protocol, and then is applied to the verification of several dynamic software update protocols, which gives an initial evidence of its effectiveness.

关键词： distributed controllers Alloy Modular Verification Dynamic Software Update

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distributed controllers for Multi-Agent Coordination Via Gradient-Flow Approach

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2015年第6期60卷 1471-1485页

作者： Sakurama, Kazunori Azuma, Shun-ichi Sugie, Toshiharu Tottori Univ Grad Sch Engn Tottori 6808552 Japan Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan

This paper provides a unified solution for a general distributed control problem of multi-agent systems based on the gradient-flow approach. First, a generalized coordination is presented as a control objective which represents a wide range of coordination tasks (e.g., consensus, formation and pattern decision) in a unified manner. Second, a necessary and sufficient condition for the gradient-based controllers to be distributed is derived. It turns out that the notion of clique (i.e., complete subgraph) plays a crucial role to obtain any distributed controllers. Furthermore, all such controllers are explicitly characterized with free design parameters. Third, it is shown how to choose an optimal controller in a systematic way among all distributed ones, where an optimality measure is introduced for the generalized coordination. Finally, the effectiveness of the proposed method is demonstrated through simulations, where a distributed pattern decision is discussed as an example of the generalized coordination.

关键词： distributed controllers generalized coordination gradient-flow method multi-agent systems

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Model-based development of distributed embedded controllers - rapid prototyping using IOPT-Tools and FPGAs -

Model-based development of distributed embedded controllers ...

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International Conference on FPGA Reconfiguration for General-Purpose Computing (FPGA4GPC)

作者： Gomes, Luis Univ Nova Lisboa Fac Ciencias & Tecnol UNINOVA CTS Campus Caparica P-1200 Lisbon Portugal

ISBN: (纸本)9781509013593

Adoption of a model-based development attitude can benefit the design of distributed embedded controllers, allowing adequate support for designer's needs integrating reusability of already available components, as well as design automation tools. Selection of Petri nets as reference modeling formalism provides support for a comprehensive specification and documentation of the system, complementing graphical expressiveness with formal verification capabilities. A Petri nets based development flow targeted for the design of distributed embedded controllers and cyber-physical systems is presented. Input-Output Place-Transition Petri nets (IOPT nets) are used as the underlying formalism, allowing explicit representation of dependencies on input and output signals and events (as common whenever generation of code for controllers is foreseen). distributed execution is addressed adding the concept of time domains and communication channels to IOPT nets. The IOPT-Tools tool chain framework supports the whole development process from specification to implementation, including tools for model edition, simulation, properties verification, and automatic code generation targeting for deployment into specific implementation platforms (where VHDL coding is used for hardware-based implementation and C coding is selected for software-oriented implementation).

关键词： Petri nets IOPT IOPT-Tools distributed controllers model based development

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Online Replacement of distributed controllers in Software Defined Networks 21

Online Replacement of Distributed Controllers in Software De...

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21st IEEE International Conference on Parallel and distributed Systems ICPADS

作者： Zhang, Jingjing Song, Ping Liu, Yi Qian, Depei Beihang Univ Sino German Joint Software Inst Beijing Peoples R China

ISBN: (纸本)9780769557854

To deploy Software Defined Networks (SDN) in large-scale datacenters, distributed controllers need to be used to achieve scalability and reliability. In such kind of continuously running systems, maintenance often involves online replacement of specified nodes in distributed controllers to upgrade their hardware/software, while the service interruption of controllers and processing errors are not allowed. In addition, load-balancing needs to be re-considered since the hardware of controllers may become heterogeneous due to the replacement. To address this problem, this paper proposes ORDIC, an Online Replacement method of distributed SDN Controller in a disruption-free manner. ORDIC enables the safe disruption-free replacement of a specified controller while ensuring network switches utilize resources of the new controller efficiently. In this paper, we build the prototype system on Floodlight to demonstrate our design and test the performance. The experimental results show that: during the replacement process, ORDIC can efficiently allocate appropriate loads to the new controller, so as to improve the overall performance of the distributed controller platform.

关键词： Software Defined Networking(SDN) distributed controllers Online Replacement Load Balancing

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distributed control for automated vehicle groups using control barrier and control Lyapunov functions

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ASIAN JOURNAL OF CONTROL 2025年第0期

作者： Hayashi, Yuzuki Cao, Wenjing Mukai, Masakazu Kogakuin Univ Dept Elect & Elect Engn 1-24-2Nishi shinjukuShinju ku Tokyo 1638677 Japan Sophia Univ Dept Engn & Appl Sci Chiyoda Ku Tokyo Japan

With the increasing demands for courier services, economic losses and environmental problems resulting from driver shortages, traffic accidents, and congestion continue to plague the logistics industry. Consequently, many studies of platooning exist to solve the above problems. This paper presents a procedure for the composition of automated vehicle groups required for platooning in real-world vehicle control. In particular, adaptive cruise control is considered, and each automated vehicle is equipped with velocity, intervehicular distance, relative velocity, and slope monitoring sensors. distributed control is performed using the controllers installed on each vehicle. The adopted control method uses quadratic programming with a control barrier function and a control Lyapunov function formulated as constraints. On solving the optimization problem, we discover that the driving forces can be optimized, and a group of vehicles maintaining a constant convergence intervehicular distance can be configured using mathematical equations and simulations.

关键词： automated vehicle composition of vehicle groups control barrier function control Lyapunov function distributed controllers

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