Contributions to topology discovery, self-healing and VNF placement in software-defined and virtualized networks

The evolution of information and communication technologies (e.g. cloud computing, the Internet of Things (IoT) and 5G, among others) has enabled a large market of applications and network services for a massive number of users connected to the Internet. Achieving high programmability while decreasing complexity and costs has become an essential aim of networking research due to the ever-increasing pressure generated by these applications and services. However, meeting these goals is an almost impossible task using traditional IP networks. Software-Defined Networking (SDN) is an emerging network architecture that could address the needs of service providers and network operators. This new technology consists in decoupling the control plane from the data plane, enabling the centralization of control functions on a concentrated or distributed platform. It also creates an abstraction between the network infrastructure and network applications, which allows for designing more flexible and programmable networks. Recent trends of increased user demands, the explosion of Internet traffic and diverse service requirements have further driven the interest in the potential capabilities of SDN to enable the introduction of new protocols and traffic management models. This doctoral research is focused on improving high-level policies and control strategies, which are becoming increasingly important given the limitations of current solutions for large-scale SDN environments. Specifically, the three largest challenges addressed in the development of this thesis are related to the processes of topology discovery, fault recovery and Virtual Network Function (VNF) placement in software-defined and virtualized networks. These challenges led to the design of a set of effective techniques, ranging from network protocols to optimal and heuristic algorithms, intended to solve existing problems and contribute to the deployment and adoption of such programmable networks.For the first challenge, this work presents a novel protocol that, unlike existing approaches, enables a distributed layer 2 discovery without the need for previous IP configurations or controller knowledge of the network. By using this mechanism, the SDN controller can discover the network view without incurring scalability issues, while taking advantage of the shortest control paths toward each switch. Moreover, this novel approach achieves noticeable improvement with respect to state-of-the-art techniques. To address the resilience concern of SDN, we propose a self-healing mechanism that recovers the control plane connectivity in SDN-managed environments without overburdening the controller performance. The main idea underlying this proposal is to enable real-time recovery of control paths in the face of failures without the intervention of a controller. Obtained results show that the proposed approach recovers the control topology efficiently in terms of time and message load over a wide range of generated networks. The third contribution made in this thesis combines topology knowledge with bin packing techniques in order to efficiently place the required VNF. An online heuristic algorithm with low-complexity was developed as a suitable solution for dynamic infrastructures. Extensive simulations, using network topologies representative of different scales, validate the good performance of the proposed approaches regarding the number of required instances and the delay among deployed functions. Additionally, the proposed heuristic algorithm improves the execution times by a fifth order of magnitude compared to the optimal formulation of this problem.Postprint (published version

Review of Path Selection Algorithms with Link Quality and Critical Switch Aware for Heterogeneous Traffic in SDN

Software Defined Networking (SDN) introduced network management flexibility that eludes traditional network architecture. Nevertheless, the pervasive demand for various cloud computing services with different levels of Quality of Service requirements in our contemporary world made network service provisioning challenging. One of these challenges is path selection (PS) for routing heterogeneous traffic with end-to-end quality of service support specific to each traffic class. The challenge had gotten the research community\u27s attention to the extent that many PSAs were proposed. However, a gap still exists that calls for further study. This paper reviews the existing PSA and the Baseline Shortest Path Algorithms (BSPA) upon which many relevant PSA(s) are built to help identify these gaps. The paper categorizes the PSAs into four, based on their path selection criteria, (1) PSAs that use static or dynamic link quality to guide PSD, (2) PSAs that consider the criticality of switch in terms of an update operation, FlowTable limitation or port capacity to guide PSD, (3) PSAs that consider flow variabilities to guide PSD and (4) The PSAs that use ML optimization in their PSD. We then reviewed and compared the techniques\u27 design in each category against the identified SDN PSA design objectives, solution approach, BSPA, and validation approaches. Finally, the paper recommends directions for further research

Scalable ReliableControllerPlacementinSoftwareDefinedNetworking

Software Defined Networking (SDN) is a new networking paradigm that facilitates a centralized system of computer networks by decoupling the control and data plane from each other, where a controller maintains the management of a global view of the network. SDN architectures can provide programmatic interfaces in communication networks that significantly simplify network management. Hence, the controllability and manageability of a network can be improved. On the one hand, the placement of controllers can significantly impact network performance in terms of controller responsiveness. On the other hand, SDN offers the ability to have controllers distributed over the network to solve the single point of failure problem at the control plane, increasing scalability and flexibility. However, there are some inevitable problems for such networks, especially for controller-related problems. For instance, scalability, reliability, and controller availability are some of the hottest aspects of SDN. More precisely, failure of the controllers themselves may lead to the impact of these aspects and the collapse of the network performance. Despite the issues mentioned above, the controller placement challenges must be appropriately addressed to take advantage of the SDN. The connections between the controller (control plane) and the switches (data plane) in SDN are established by either an in-band or an out-of-band control mechanism. New challenges still arise regardin the connection availability and provide more protection for the connection between the data and control planes. A disconnection between the two planes could result in performance degradation. Although the SDN offers the advantage of an environment of multiple distributed controllers, yet the intercommunication factor between these controllers is still a key challenge. This thesis investigates the issues mentioned above and organizes them into four stages. First, dealing with the controller placement problem as the most crucial concern in SDN, via exploiting the independent dominating set approach to ensure a distribution of controllers with lowest response times. We propose a new node degree-based algorithm named High Degree with Independent Dominating Set (HDIDS) for the controller placement problem in the SDN networks. HDIDS is composed of two phases to deal with controller placement: (1) determining candidate controller instances by selecting those nodes with the highest degree; and (2) partitioning the network into multiple domains, one controller per domain. To further improve network performance, reliability, and survivability, one solution is to deploy backup controllers to satisfy the quality of service requirements. In this regard, as a second step, we enhance the controller placement approach by designing a reliable and survivable controller placement strategy. This strategy relies on the efficient deployment of backup controllers by constructing virtual backup domains set(s) to ensure the durability and resilience of network control management. The approach design is called a Survivable Backup Controller Placement approach. Furthermore, to achieve reliable control traffic between data and control planes in an in-band control network, as a third stage, we design and implement an In-band Control Protection Module that finds a set of ideal paths for the control channel under the failure conditions. The proposed protection mechanism protects as much control traffic as possible. Finally, we present a practical approach for the controller placement problem in software defined networks aiming to minimize the inter-controller communication delay time and the delay time between controller and switches. The principal concept employed in this approach is the Connected Dominating Set. Further, we present an algorithm using the Minimum Connected Dominating Set, which minimizes the delay time between the distributed SDN controllers

Review of SDN-based load-balancing methods, issues, challenges, and roadmap

The development of the Internet and smart end systems, such as smartphones and portable laptops, along with the emergence of cloud computing, social networks, and the Internet of Things, has brought about new network requirements. To meet these requirements, a new architecture called software-defined network (SDN) has been introduced. However, traffic distribution in SDN has raised challenges, especially in terms of uneven load distribution impacting network performance. To address this issue, several SDN load balancing (LB) techniques have been developed to improve efficiency. This article provides an overview of SDN and its effect on load balancing, highlighting key elements and discussing various load-balancing schemes based on existing solutions and research challenges. Additionally, the article outlines performance metrics used to evaluate these algorithms and suggests possible future research directions

A Comprehensive Survey of In-Band Control in SDN: Challenges and Opportunities

Software-Defined Networking (SDN) is a thriving networking architecture that has gained popularity in recent years, particularly as an enabling technology to foster paradigms like edge computing. SDN separates the control and data planes, which are later on synchronised via a control protocol such as OpenFlow. In-band control is a type of SDN control plane deployment in which the control and data planes share the same physical network. It poses several challenges, such as security vulnerabilities, network congestion, or data loss. Nevertheless, despite these challenges, in-band control also presents significant opportunities, including improved network flexibility and programmability, reduced costs, and increased reliability. Benefiting from the previous advantages, diverse in-band control designs exist in the literature, with the objective of improving the operation of SDN networks. This paper surveys the different approaches that have been proposed so far towards the advance in in-band SDN control, based on four main categories: automatic routing, fast failure recovery, network bootstrapping, and distributed control. Across these categories, detailed summary tables and comparisons are presented, followed by a discussion on current trends a challenges in the field. Our conclusion is that the use of in-band control in SDN networks is expected to drive innovation and growth in the networking industry, but efforts for holistic and full-fledged proposals are still needed

Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey

Wireless sensor networks (WSNs) consist of autonomous and resource-limited devices. The devices cooperate to monitor one or more physical phenomena within an area of interest. WSNs operate as stochastic systems because of randomness in the monitored environments. For long service time and low maintenance cost, WSNs require adaptive and robust methods to address data exchange, topology formulation, resource and power optimization, sensing coverage and object detection, and security challenges. In these problems, sensor nodes are to make optimized decisions from a set of accessible strategies to achieve design goals. This survey reviews numerous applications of the Markov decision process (MDP) framework, a powerful decision-making tool to develop adaptive algorithms and protocols for WSNs. Furthermore, various solution methods are discussed and compared to serve as a guide for using MDPs in WSNs

Assessment of connectivity-based resilience to attacks against multiple nodes in SDNs

In Software Defined Networks (SDNs), the control plane of a network is decoupled from its data plane. For scalability and robustness, the logically centralized control plane is implemented by physically placing different controllers throughout the network. The determination of the number and placement of controllers is known as the Controller Placement Problem (CPP). In the regular (i.e., failure-free) state, the control plane must guarantee a given maximum delay between every switch and its primary controller and a given maximum delay between every pair of controllers. In general, these delay bounds allow multiple solutions and, so, other goals can be used to determine the best CPP solution. In this paper, we assess the connectivity-based resilience to malicious attacks against multiple network nodes of the CPP solutions obtained with three different aims: the regular state delay optimization without any concern about attacks, the regular state delay optimization taking into consideration the worst-case attacks and the resilience optimization to attacks against multiple nodes. We assess the CPP solutions considering attacks of targeted nature (when the attacker has complete knowledge of the data plane) and attacks of non-targeted nature (i.e., random and epidemic attacks). We present computational results providing an analysis of the CPP solutions to the different types of attacks. The main conclusion is that the connectivity-based resilience between the different CPP solutions strongly depends on the network topology, the regular state delay bounds and the type of attacks. Finally, we provide insights on how SDN operators can consider the conducted assessment when deciding the controller placements in their networks.publishe

Towards the Practical Implementation of Throughput-Optimal Traffic Engineering in Software Defined Networks

Broadband Wireless Networking topics: 5G, wireless underground sensor networks, software defined networkingThe new emerging networking paradigm of Software Defined Networks, a solution that separates the network control plane from the data forwarding plane, has been the main focus of recently research works. Nevertheless, Traffic Engineering is an important problem to optimize the network performance, especially for a centralized controlled network such as the SDN, by dynamically analyzing, predicting, and regulating the behavior of data transmitted over that network. Therefore, a first version of a new TE management tool called TECS-SENNA - Traffic Engineering Control System for SDN/OpenFlow Networks - is being developed. The connection of TEs with the tool provides a dynamically and globally optimized network resource allocation in such a way that the overall performance can be improved, including throughput, latency, stability, and load balancing, while satisfying the per-flow QoS requirements.El nuevo paradigma de redes emergente llamado Software Defined Networks, una solución que separa el plano de control del plano de envío de datos, ha sido el único foco principal de las recientes investigaciones. Sin embargo, la ingeniería de tráfico es un problema importante para optimizar el rendimiento de la red, especialmente para redes centralizadas y controladas como las redes SDN, analizando, prediciendo y regulando dinámicamente el comportamiento de los datos transmitidos a través de la red. Por eso, en este proyecto se ha construido una primera versión de una nueva herramienta de gestión de ingeniería de trafico llamada TECS-SENNA – Traffic Engineering Control System for SDN/OpenFlow Networkds. La conexión de ingeniería de tráfico con la herramienta proporciona una optimización de la asignación de recursos de red de manera global y dinámica, para que el rendimiento pueda ser mejorado, incluyendo la candencia, la latencia, la estabilidad y el equilibrio de carga, y satisfaciendo los requisitos por flujo de la cualidad de servicio.El nou paradigma de xarxes emergent anomenat Software Defined Networks, una solució que separa el pla de control del pla d’enviament de dades, ha estat l’únic focus principal de les recerques recentment. Però l’enginyeria de trànsit és un problema important per tal d’optimitzar el rendiment de la xarxa, especialment per xarxes centralitzades i controlades com les xarxes SDN, analitzant, fent prediccions i regulant dinàmicament el comportament de les dades transmeses a través de la xarxa. Per això, en aquest projecte s’ha construït una primera versió d’una nova eina de gestió d’enginyeria de trànsit anomenada TECS-SENNA – Traffic Engineering Control System for SDN/OpenFlow Networks. La connexió de l’enginyeria de trànsit amb l’eina proporciona una optimització de l’assignació de recursos de xarxa de manera global i dinàmica per tal que el rendiment pugui ser millorat, incloent la cadència, la latència, l’estabilitat i l’equilibri de càrrega i satisfent els requisits per flux de qualitat de servei