Software-defined Wide Area Networks Research Articles

Software-Defined Wide Area Networks (SD-WANs): A Survey

SD-WANs are an innovative software-defined network (SDN) technology used to reinvent networks, services, and applications in wide area network (WANs). The development of SD-WANs ranges from network optimization in the past to service provision platforms at present and distributed computing systems in the future. The existing surveys on SD-WANs are fragmented, covering specific problems only, and are not comprehensive with detailed research directions. This paper seeks to provide a systematic survey on SD-WANs by introducing major research directions and stating specific problems. Therefore, four major research directions related to traffic engineering, network optimization and systems, service orchestration, and the security issues of SD-WANs are sequentially introduced, along with detailed statements relating to specific problems and the classification of state-of-the-art research. Finally, the trends and challenges regarding SD-WANs are summarized and our future work is described.

Software-Defined Virtual Private Network for SD-WAN

Software-Defined Wide Area Networks (SD-WANs) are an emerging Software-Defined Network (SDN) technology to reinvent Wide Area Networks (WANs) for ubiquitous network interconnections in cloud computing, edge computing, and the Internet of Everything. The state-of-the-art overlay-based SD-WANs are simply conjunctions of Virtual Private Network (VPN) and SDN architecture to leverage the controllability and programmability of SDN, which are only applicable for specific platforms and do not comply with the extensibility of SDN. This paper motivates us to refactor traditional VPNs with SDN architecture by proposing an overlay-based SD-WAN solution named Software-Defined Virtual Private Network (SD-VPN). An SDN-based auto-constructed VPN model and its evaluating metrics are put forward to automatically construct overlay WANs by node placement and service orchestration of SD-VPN. Therefore, a joint placement algorithm of VPN nodes and algorithms for overlay WAN service loading and offloading are proposed for SD-VPN controllers. Finally, a three-layer SD-VPN system is implemented and deployed in actual network environments. Simulation experiments and system tests are conducted to prove the high-efficiency controllability, real-time programmability, and auto-constructed deployability of the proposed SD-VPN. Performance trade-off between SD-VPN control channels and data channels is evaluated, and SD-VPN controllers are proven to be extensible for other VPN protocols and advanced services.

Seraph: Towards secure and efficient multi-controller authentication with [formula omitted]-threshold signature in multi-domain SDWAN

The multi-controller scheme is widely adopted in Software-Defined Wide Area Networks (SDWANs), where a WAN is segmented into multiple domains, each controlled by one controller. These controllers communicate with each other in-band, necessitating authentication before exchanging control messages. However, relying solely on identification of a single node for authentication exposes the network to spoofing attacks, jeopardizing its security. To address this issue, we present Seraph, an innovative (t,n)-threshold signature-based authentication scheme that verifies not only the node itself but also its “endorsement” nodes to establish its identity. We have investigated the best practice for defining the “endorsement” relationships concerning security and overheads, formulating the problem as an integer programming problem. We have demonstrated the polynomial-time hardness (NP-hardness) of the problem and proposed an efficient Seraph algorithm. Through our rigorous simulation analysis, we show that Seraph can provide comparative performance with Optimal and reduce time usage by over 90%.

KNOWLEDGE AND SKILLS FOR SOFTWARE-DEFINED NETWORKS MAINTENANCE ENGINEER

In this article we analyze the Russian developments in the field of software-defined networks and software-defined wide area networks, professional standards and job vacancies in order to determine knowledge and skills required of specialists. We conclude that there is a lack of practical manuals for training network engineers, and suggest possible topics for laboratory exercises for educational textbooks. This article can be useful for teachers of educational institutions of vocational secondary education, higher education, supplementary education in the development of work programs of disciplines, lecture material and laboratory workshops in the field of software-defined networks, as well as for students of the educational institutions and for junior network engineers.

Low-Cost, Open-Source, Experimental Setup Communication Platform for Emergencies, Based on SD-WAN Technology

The rapid advancement of communication technologies underscores the urgent need for robust and adaptable emergency communication systems (ECSs), particularly crucial during crises and natural disasters. Although network-based ECSs have been extensively studied, integrating open-source technologies, such as software-defined wide area networks (SD-WAN) with private long-term evolution (LTE) base stations, is a relatively unexplored domain. This study endeavors to fill this gap by introducing an experimental ECS platform that utilizes a hybrid network, incorporating a VoIP network to enhance open-source and on-premises communications in targeted areas. Our hypothesis posits that a hybrid network architecture, combining SD-WAN and private LTE, can substantially improve the reliability and efficiency of ECSs. Our findings, supported by the open-source OMNeT++ simulator, illuminate the enhanced communication reliability of the network. Moreover, the proposed platform, characterized by autonomous wireless 4G/LTE base stations and an Asterisk VoIP server, demonstrates improved quality of service (QoS) and quality of experience (QoE), with minimal data loss. This research not only has immediate practical applications but also bears significant implications for the development of cost-effective, open-source communication networks, optimized for emergencies, critical infrastructure, and remote areas.

A Stochastic Computational Graph with Ensemble Learning Model for solving Controller Placement Problem in Software-Defined Wide Area Networks

The Preponderance of literature has established that most of the metaheuristic algorithms were associated with identified challenges in solving the Controller Placement Problem in SD-WAN. This study proposed a Stochastic Computational Graph Model with an Ensemble Learning (SCGMEL) approach to address the scalability, intelligence, and high computational complexity challenges experienced by the existing metaheuristic algorithms. The proposed SCGMEL used stochastic gradient descent with momentum and learning rate decay, a computational graph model, and the eXtreme Gradient Boosted Trees (XGBoost) algorithm as the optimization and machine learning approaches. The proposed solution was tested using datasets from Internet Zoo topology with six objective functions: load balancing, maximum controller failure, average controller-to-controller latency, average switch-to-controller latency, and maximum controller-to-controller latency. The XGBoost outperformed other regression models, in predicting the number of controllers, with mean absolute error of 1.855751 versus 1.883536, 3.729863, and 3.829268 for the random forest, logistic regression, and K-nearest neighbor, respectively. Furthermore, the execution time, average and total CPU usages of the algorithms demonstrated the computational efficiency of the proposed SCGMEL over ANSGA-III, NSGA-II, and MOPSO with percentage decreases of 99.983%, 99.985%, and 99.446%, respectively. Consequently, the proposed SCGMEL was recommended for controller placement in SD-WAN, subject to the usage conditions.

Adaptive overlay selection at the SD-WAN edges: A reinforcement learning approach with networked agents

Software-Defined Wide Area Networks (SD-WANs) have emerged as a promising solution to address the connectivity demands of modern distributed enterprises. However, the effective application of the Software Defined Networking (SDN) paradigm in such broad and dynamic environments remains a significant challenge. In this paper, we present two novel contributions. First, we design a decentralized control plane for SD-WANs that leverages edge-based network monitoring and overlays’ configuration. Then we present a Reinforcement Learning-based orchestration plane that leverages local information for the enforcement of SD-WAN policies. Since traditional approaches suffer either a lack of scalability due to the problem’s complexity or suboptimal performance due to isolated decision-making, the proposed approach leverages a cooperative Multi-Agent Reinforcement Learning framework. Our novel cooperative approach is based on per-site agents that exchange a small amount of information to enhance performance while preserving scalability. To validate the efficacy of our proposed approach, we conducted an extensive experimental evaluation considering diverse SD-WAN scenarios. Results show that our framework is able to satisfy global network policies for a multi-site SD-WAN with different QoS requirements and cost constraints.

Dynamic relay node selection and routing for cloud-native Software Defined WANs

Cloud Native Software Defined Wide Area Networks (CN-WANs) are proposed to optimize the network performance based on the application requirement. In this paper, we propose a Relay Node Selection and Routing (RNSR) approach to minimize the number of relay nodes in CN-WANs under the end-to-end (E2E) transmission latency constraint. By doing so, we can not only ensure the Service Level Agreement (SLA) to applications, but also reduce the network operation expenses. To improve the system scalability, several algorithms are proposed for networks with different sizes. According to experiments on a prototype built on EC2 and extensive simulations in a custom in-house simulator, we demonstrate that RNSR has a superior performance on reducing the number of required relay nodes, outperforming the state-of-the-art benchmarks by up to 92.48% specifically. In addition, the algorithms designed for large scale networks will not suffer too much performance degradation but significantly improve the system scalability.

Particle swarm optimisation-based scalable controller placement with balancing constraints in software-defined wide area networks

Particle swarm optimisation-based scalable controller placement with balancing constraints in software-defined wide area networks

Large Language Model in SD-WAN Intelligent Operations and Maintenance

The integration of LLM (Large Language Model) into the intelligent operations and maintenance of SD-WAN (Software-Defined Wide Area Networks) is comprehensively explored. As the scale of the network continues to expand and its complexity increases, traditional operation and maintenance methods can no longer meet efficient and accurate requirements. Therefore, LLM technology was introduced, and the intelligent operation and maintenance of the data center network were realized by leveraging its powerful natural language processing capabilities. The importance and shortcomings of SD-WAN and the application scenarios of LLM in network operation and maintenance are first introduced, followed by an elaboration on how LLM can be used for network configuration, network optimization, network maintenance, and network security risk management. Through specific analysis, the significant effect of LLM in enhancing the efficiency and quality of operation and maintenance has been demonstrated. Finally, the advantages and challenges of employing LLM for intelligent network operation and maintenance are summarized, and future research directions are anticipated.

Exploring the Impact of Critical Programmability on Controller Placement for Software-Defined Wide Area Networks

Control latency is a critical concern for deploying Software-Defined Networking (SDN) into Wide Area Networks (WANs). A Software-Defined WAN (SD-WAN) can be divided into multiple domains controlled by multiple controllers with a logically centralized view. The control latency is related to the placement of controllers and mappings between switches and controllers. Existing solutions usually consider the propagation delay between switches and controllers as the evaluation metric and fail to consider many important factors of dynamic network states. In this paper, we propose () to optimize the control latency in SD-WAN. Inspired by the selection of critical flows, which have a critical impact on network performance, considers the programmability of critical flows at switches and uses this metric to decide the placement of controllers and mappings between switches and controllers. Simulation results show that can reduce the control latency by up to 62.3%, 27.5%, 58.3%, and 61.7% under, and topologies respectively, compared with baseline algorithms.

Mitigating the impact of controller failures on QoS robustness for software-defined wide area networks

Emerging cloud services and applications pose different Quality of Service (QoS) requirements for the network, where Software-Defined Wide Area Networks (SD-WANs) play a crucial role in QoS provisioning by introducing network programmability into network flows to enable dynamic flow routing and ensure low data transmission latency for these applications. However, controller failures may happen in SD-WANs, and all programmable flows that the failed controller previously controlled will become offline and lose the network programmability, resulting in the degradation of QoS. Existing control recovery solutions propose to remap offline switches/flows to available active controllers but cannot promise good recovery performance due to the following two problems: (1) the recovery performance suffers from either coarse-grained remapping granularity or introducing extra processing delays, and (2) QoS robustness cannot be guaranteed in the design of recovery solution. To this end, we propose Predator, a QoS-aware network programmability recovery scheme that utilizes the P4 Runtime enabled by existing P4 switches to achieve fine-grained per-flow remapping without introducing extra delays. Specifically, our proposed Predator categorizes flows based on their QoS requirements and smartly recovers offline flows based on their priorities to guarantee the QoS robustness for high-priority flows. Simulation results under real-world topology demonstrate that our proposed Predator can improve the recovered network programmability of high-priority flows by up to 505.5%, and substantially reduce the communication overhead of high-priority flows, compared with baselines.

Toward Flexible and Predictable Path Programmability Recovery Under Multiple Controller Failures in Software-Defined WANs

Software-Defined Networking (SDN) promises good network performance in Wide Area Networks (WANs) with the logically centralized control using physically distributed controllers. In Software-Defined WANs (SD-WANs), maintaining path programmability, which enables flexible path change on flows, is crucial for maintaining network performance under traffic variation. However, when controllers fail, existing solutions are essentially coarse-grained switch-controller mapping solutions and only recover the path programmability of a limited number of offline flows, which traverse offline switches controlled by failed controllers. In this paper, we propose () to provide predictable path programmability recovery under multiple controller failures in SD-WANs. The key idea of is to approximately realize flow-controller mappings using hybrid SDN/legacy routing supported by high-end commercial SDN switches. Using the hybrid routing, we can recover programmability by selecting a routing mode for each offline flow at each offline switch in a fine-grained way to fit the given control resource from active controllers and release a few control resource of active controllers by reasonably configuring some normal flows under legacy routing mode. Thus, can promise ample control resource to improve the recovery efficiency and further effectively map offline switches to active controllers. Simulation results show that outperforms existing switch-level solutions by maintaining balanced programmability and increasing the total programmability of recovered offline flows up to 660% under topology and 590% under topology.

Emergency Communication System Based on Wireless LPWAN and SD-WAN Technologies: A Hybrid Approach

Emergency Communication Systems (ECS) are network-based systems that may enable people to exchange information during crises and physical disasters when basic communication options have collapsed. They may be used to restore communication in off-grid areas or even when normal telecommunication networks have failed. These systems may use technologies such as Low-Power Wide-Area(LPWAN) and Software-Defined Wide Area Networks (SD-WAN), which can be specialized as software applications and Internet of Things (IoT) platforms. In this article, we present a comprehensive discussion of the existing ECS use cases and current research directions regarding the use of unconventional and hybrid methods for establishing communication between a specific site and the outside world. The ECS system proposed and simulated in this article consists of an autonomous wireless 4G/LTE base station and a LoRa network utilizing a hybrid IoT communication platform combining LPWAN and SD-WAN technologies. The LoRa-based wireless network was simulated using Network Simulator 3 (NS3), referring basically to firm and sufficient data transfer between an appropriate gateway and LP-WAN sensor nodes to provide trustworthy communications. The proposed scheme provided efficient data transfer posing low data losses by optimizing the installation of the gateway within the premises, while the SD-WAN scheme that was simulated using the MATLAB simulator and LTE Toolbox in conjunction with an ADALM PLUTO SDR device proved to be an outstanding alternative communication solution as well. Its performance was measured after recombining all received data blocks, leading to a beneficial proposal to researchers and practitioners regarding the benefits of using an on-premises IoT communication platform.

Software-defined Wide-area Networks in the Coevolution of Network and Computational Bandwidth

Software-Defined Wide-Area Networks (SD-WAN) are a technology that utilizes programmatic configuration to maximize network throughput. The main problem to achieve efficient use of network bandwidth with SD-WAN is the network delay (latency) in the communication. A network could be further slowed down by not enough memory or CPU resources. Here we conduct experiments, investigating the capability of an SD-WAN to maximize the network throughput at increasing levels of latency. We find that to a limited extent the computational optimization at the software side could offset the network limitations. At higher network latency the SD-WAN adds little value. Further increase of the capacity can only be achieved by hardware upgrades of the network bandwidth. Such solutions may be considered drivers of a coevolutional relationship between computational and network bandwidths, whereby the network use becomes more efficient.

INFORMATION SECURITY POLICIES AND STRATEGIES AND PRACTICES ADOPTED IN IT: THE IMPORTANCE OF CONSULTANCY IN SMALL AND MEDIUM-SIZED COMPANIES

Objective: Companies in the cybersecurity consulting market are expanding their services in periodic training to business stakeholders and enforcement of security policies. The objective of this work is to demonstrate the importance of consulting in information security policies aimed at small and medium-sized companies. Methods: It is characterized as a narrative literature review with a qualitative approach, which does not use explicit and systematic criteria for the search and critical analysis of the selected literature. Results: Tools needed for cybersecurity include endpoint detection and response (EDR), antivirus software, next-generation firewalls, Domain Name System (DNS) protection, email gateway security, intrusion detection and prevention, logging and log monitoring, endpoint protection, authentication and virtual private network (VPN) services, cloud-based security, web application firewalls (WAFs), software-defined wide area networks (SD-WAN), enterprise password management , privileged access management (GAP), vulnerability and threat management, and threat detection. Conclusions: In summary, SMBs seem to implement some of the basic cybersecurity measures only as part of their overall IT implementation. However, it appears that unless cybersecurity controls are included as part of an IT solution, many SMBs do not realize the resulting potential risks to their business.

Extended array model of star capacity-aware delay-based next controller placement problem for multiple controller failures in software-defined wide area networks

Extended array model of star capacity-aware delay-based next controller placement problem for multiple controller failures in software-defined wide area networks

Voyager: Revisiting Available Bandwidth Estimation With a New Class of Methods—Decreasing- Chirp-Train Methods

The available bandwidth (ABW) of a network path is a crucial metric for various applications, such as traffic engineering, congestion control, multimedia streaming, and path selection in software-defined wide-area networks (SDWAN). In recent years, a new class of measurement methods have been proposed to estimate the available bandwidth, decreasing-chirp-train methods. However, the performance and limitations of this new class of methods are neither well studied nor fairly compared beyond simulation studies. In this work, we implement Voyager, a modular framework that allows us to conduct a fair and thorough comparison of how a variety of modern bandwidth estimation methods perform under different network paths and traffic conditions. We shed light on the characteristics and limitations of the internal algorithms of various methods, and propose two new methods. We investigate the impact of various bottleneck types and traffic types, and we explore the performance of these methods on high speed links where interrupt coalescence can cause measurement noise. We finally test Voyager on long-distance Internet links and with live traffic and report our findings.

Maintaining Control Resiliency and Flow Programmability in Software-Defined WANs During Controller Failures

Providing resilient network control is a critical concern for deploying Software-Defined Networking (SDN) into Wide-Area Networks (WANs). For performance reasons, a Software-Defined WAN is divided into multiple domains controlled by multiple controllers with a logically centralized view. Under controller failures, we need to remap the control of offline switches from failed controllers to other active controllers. Existing solutions have three limitations: (1) the least flow programmability (e.g., the ability to change paths of flows) cannot be maintained; (2) active controllers could be overloaded, interrupting their normal operations; (3) network performance could be degraded because of the increasing controller-switch communication overhead. In this paper, we propose RetroFlow+ to recover the flow programmability and achieve low communication overhead during controller failures. By intelligently configuring a set of selected offline switches working under the legacy routing mode and several active controllers releasing a few control resources, RetroFlow+ enables active controllers to use the minimum control resource to sustain the flow programmability. RetroFlow+ also smartly transfers the control of offline switches with the SDN routing mode to active controllers to minimize the communication overhead from these offline switches to the active controllers. Simulation results show that RetroFlow+ realizes low communication overhead, recovers all offline flows under one and two controller failures, and improves the flow recovery percentage up to 70% under three controller failures, compared with the state-of-the-art solution.

Star capacity-aware latency-based next controller placement problem with considering single controller failure in software-defined wide-area networks

Star capacity-aware latency-based next controller placement problem with considering single controller failure in software-defined wide-area networks