Technology-related disasters:a survey towards disaster-resilient software defined networks

Resilience against disaster scenarios is essential to network operators, not only because of the potential economic impact of a disaster but also because communication networks form the basis of crisis management. COST RECODIS aims at studying measures, rules, techniques and prediction mechanisms for different disaster scenarios. This paper gives an overview of different solutions in the context of technology-related disasters. After a general overview, the paper focuses on resilient Software Defined Networks

The Role of Inter-Controller Traffic for Placement of Distributed SDN Controllers

We consider a distributed Software Defined Networking (SDN) architecture adopting a cluster of multiple controllers to improve network performance and reliability. Besides the Openflow control traffic exchanged between controllers and switches, we focus on the control traffic exchanged among the controllers in the cluster, needed to run coordination and consensus algorithms to keep the controllers synchronized. We estimate the effect of the inter-controller communications on the reaction time perceived by the switches depending on the data-ownership model adopted in the cluster. The model is accurately validated in an operational Software Defined WAN (SDWAN). We advocate a careful placement of the controllers, that should take into account both the above kinds of control traffic. We evaluate, for some real ISP network topologies, the delay tradeoffs for the controllers placement problem and we propose a novel evolutionary algorithm to find the corresponding Pareto frontier. Our work provides novel quantitative tools to optimize the planning and 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 operational distributed controllers (e.g. OpenDaylight and ONOS), the location of the controller which acts as a leader in the consensus algorithm has a strong impact on the reactivity perceived by switches.Comment: 14 page

Multi-controller Based Software-Defined Networking: A Survey

Software-Defined Networking (SDN) is a novel network paradigm that enables flexible management for networks. As the network size increases, the single centralized controller cannot meet the increasing demand for flow processing. Thus, the promising solution for SDN with large-scale networks is the multi-controller. In this paper, we present a compressive survey for multi-controller research in SDN. First, we introduce the overview of multi-controller, including the origin of multi-controller and its challenges. Then, we classify multi-controller research into four aspects (scalability, consistency, reliability, load balancing) depending on the process of implementing the multi-controller. Finally, we propose some relevant research issues to deal with in the future and conclude the multi-controller research

Software Defined Networks based Smart Grid Communication: A Comprehensive Survey

The current power grid is no longer a feasible solution due to ever-increasing user demand of electricity, old infrastructure, and reliability issues and thus require transformation to a better grid a.k.a., smart grid (SG). The key features that distinguish SG from the conventional electrical power grid are its capability to perform two-way communication, demand side management, and real time pricing. Despite all these advantages that SG will bring, there are certain issues which are specific to SG communication system. For instance, network management of current SG systems is complex, time consuming, and done manually. Moreover, SG communication (SGC) system is built on different vendor specific devices and protocols. Therefore, the current SG systems are not protocol independent, thus leading to interoperability issue. Software defined network (SDN) has been proposed to monitor and manage the communication networks globally. This article serves as a comprehensive survey on SDN-based SGC. In this article, we first discuss taxonomy of advantages of SDNbased SGC.We then discuss SDN-based SGC architectures, along with case studies. Our article provides an in-depth discussion on routing schemes for SDN-based SGC. We also provide detailed survey of security and privacy schemes applied to SDN-based SGC. We furthermore present challenges, open issues, and future research directions related to SDN-based SGC.Comment: Accepte

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

Flexible architecture for the future internet scalability of SDN control plane

Software-Defined Networking (SDN) separates the control plane from the data plane. The initial SDN approach involves a single centralized controller, which may not scale properly as a network grows in size. Distributed controllers have emerged to address the disadvantages of a single centralized controller. The control architecture needs to be distributed with traffic control between switches and controllers and among the controllers in order to allow SDNs for several thousand switches. One of the most significant research challenges for distributed controller architectures is to effectively manage controllers, which includes allocating enough controllers to appropriate network locations. To address these daunting issues, we make the following major contributions: This thesis expands the method of solving the Control Placement Problem (CPP) based on the K-means and K-center algorithms to include a Hierarchical Controller Placement Problem (HCPP), located at a high level of Super Controller (SC), a middle level of Master Controllers (MCs), and the lowest level of domain controllers (DCs). The optimization metric addresses latency between the controller and the switches assigned to it.. The proposed architecture and methodology are implemented using the topology of Western European NRENs from the Internet Topology Zoo. The entire network topology is divided into clusters, and the optimal number of controllers (DCs) and their placement are determined for each cluster. MC placement optimization determines the optimal number of MCs and their optimal placement. As a second contribution, an accumulated latency is defined to solve CPP, which takes into account both the latency between the controller and its associated switches and the latency between controllers. Under the constraint of latency, an optimization problem is formulated as per mixed-integer linear programming (MILP). The goal of the research is to reduce accumulated latency while also reducing the number of network controllers and optimizing their placement to achieve an optimal balance. The performance of the developed method is evaluated on Internet2 OS3E real network topology. To achieve the third objective, a metric was developed that includes reliability. The communication latency between controllers should also be considered because a low controller-switch delay does not always imply a short controller-controller delay for a particular controller placement. As the third contribution, we propose a novel metric for CPP to improve the reliability of controllers that takes into account both communication latency and communication reliability between switches and controllers, as well as between controllers. When a single link fails, reliability is taken into account. This aspect concluded by identifying the optimal controller placement to achieve low latencies in control plane traffic. The goal of this project is to reduce the average latency. As the fourth contribution, this study evaluates the Joint Latency and Reliability-aware Controller Placement (LRCP) optimization model. As the evaluation metric, control plane latency (CPL) is defined as the sum of the average switch-to-controller latency and average inter-controller latency. The latency of the control plane, utilizing the actual latencies of the real network topology, is calculated for every optimum placement in the network. In the case of a failure of the single link, the actual CPL for LRCP placements is calculated and evaluated to determine how good LRCP placements are. CPL metrics are used to compare latency and reliability metrics with other models. This study provides proof that the developed methodologies for large-scale networks are highly powerful in terms of searching for all feasible controller placements while assessing the outcomes. In addition, compared to previous work including latency among controllers and reliability for an event of single-link failure.La xarxa definida per programari (SDN) separa el pla de control del pla de dades. L’enfocament SDN inicial implica un únic controlador centralitzat, que pot no escalar correctament a mesura que la xarxa creixi de mida. Els controladors distribuïts han sorgit per abordar els inconvenients d’un únic controlador centralitzat. . Un dels reptes de recerca més importants per a les arquitectures de controladors distribuïts és gestionar de manera eficaç els controladors, que inclou l’assignació de controladors suficients a les ubicacions de xarxa adequades. Per abordar aquests problemes, fem les següents contribucions. Aquesta tesi amplia el mètode de resolució del Problema de Col·locació de Control (CPP) basat en els algorismes de K-means i K-center per incloure un Problema de Col·locació de Controladors Jeràrquics (HCPP), situat a un nivell alt de Super Controller (SC), un nivell de controladors mestres (MC) i el nivell més baix de controladors de domini (DC). La mètrica d’optimització és la latència entre el controlador i els commutadors assignats a aquest. L’arquitectura i la metodologia proposades s’implementen utilitzant la topologia de NREN d’Europa occidental de l’Internet Topology Zoo. La topologia de la xarxa es divideix en clústers i es determina el nombre òptim de controladors de domini (DC) i la seva ubicació per a cada clúster. L’optimització de la ubicació de MC determina el nombre òptim de MC i la seva col·locació òptima. Com a segona contribució, es defineix una latència acumulada per resoldre el CPP, que té en compte tant la latència entre el controlador i els seus commutadors associats com la latència entre controladors. Sota la restricció de la latència, es formula un problema d’optimització segons la programació lineal de nombres enters mixts (MILP). L’objectiu de la investigació és reduir la latència acumulada alhora que es redueix el nombre de controladors de xarxa i optimitza la seva col·locació per aconseguir un equilibri òptim. El rendiment del mètode desenvolupat s’avalua en la topologia de xarxa real d’Internet2 OS3E. Per aconseguir el tercer objectiu, es va desenvolupar una mètrica que inclou la fiabilitat. També s’ha de tenir en compte la latència de comunicació entre controladors perquè un retard baix entre el commutador i el controlador no sempre implica un retard curt del controladorcontrolador per a una ubicació concreta dels controladors. Com a tercera contribució, proposem una nova mètrica per al CPP per millorar la fiabilitat dels controladors que tingui en compte tant la latència de la comunicació com la fiabilitat de la comunicació entre commutadors i controladors, així com entre controladors. La fiabilitat es té en compte quan falla un únic enllaç identificant la col·locació òptima dels controladors per aconseguir baixes latències en el trànsit del pla de control. L’objectiu d’aquest projecte és reduir la latència mitjana. Com a quarta contribució, aquest estudi avalua el model d’optimització Joint Latency and Reliability-aware Controller Placement (LRCP). Com a mètrica d’avaluació, la latència del pla de control (CPL) es defineix com la suma de la latència mitjana de commutador a controlador i la latència mitjana entre controladors. La latència del pla de control, utilitzant les latències reals de la topologia de xarxa real, es calcula per a cada col·locació òptima a la xarxa. En el cas d’una fallida en un únicenllaç, es calcula i s’avalua el CPL real de les ubicacions LRCP per determinar com de bones són les ubicacions LRCP. Les mètriques CPL s’utilitzen per comparar les mètriques de latència i fiabilitat amb altres models. Aquest estudi proporciona la prova que les metodologies desenvolupades per a xarxes a gran escala són molt potents pel que fa a la recerca de totes les ubicacions de controladors factibles mentre s’avaluen els resultats. A més, en comparació amb el treball anterior, inclou la latència entre els controladors i la fiabilitat per a un esdeveniment de fallada d’un enllaç únic.Las redes definidas por software (SDN) separan el plano de control del plano de datos. El enfoque inicial de SDN implica un único controlador centralizado, que puede no escalar adecuadamente a medida que una red crece en tamaño. Los controladores distribuidos han surgido para abordar las desventajas de un único controlador centralizado. Uno de los retos de investigación más importantes para las arquitecturas de controladores distribuidos es la gestión eficaz de los controladores, que incluye la asignación de suficientes controladores en las ubicaciones adecuadas. Para hacer frente a estos problemas, realizamos las siguientes contribuciones principales: Esta tesis amplía el método de resolución del Problema de Colocación de Controles (CPP) basado en los algoritmos K-means y K-center para incluir un Problema de Colocación de Controladores Jerárquicos (HCPP), situado en un nivel alto de Super-controladores (SC), un nivel medio de Controladores Maestros (MC), y el nivel más bajo de controladores de dominio (DC). La métrica de optimización es la latencia entre el controlador y los conmutadores asignados al mismo. . La arquitectura y la metodología propuestas se implementan utilizando la topología de las NREN de Europa Occidental del TopologyZoo. La topología completa de la red se divide en clústeres, y se determina el número óptimo de controladores de dominio (CD) y su colocación para cada clúster. La optimización de la colocación de los MC determina el número óptimo de MC y su colocación óptima. Como segunda contribución, se define una latencia acumulada para resolver el CPP, que tiene en cuenta tanto la latencia entre el controlador y sus conmutadores asociados como la latencia entre los controladores. Bajo la restricción de la latencia, se formula un problema de optimización según la programación lineal de enteros mixtos (MILP). El objetivo es reducir la latencia acumulada al tiempo que se reduce el número de controladores de la red y se optimiza su ubicación para lograr un equilibrio óptimo. El rendimiento del método desarrollado se evalúa en la topología de Internet2 OS3E. Para lograr el tercer objetivo, se desarrolló una métrica que incluye la fiabilidad. La latencia de la comunicación entre controladores también debe tenerse en cuenta, ya que un bajo retardo entre controladores y conmutadores no siempre implica un corto retardo entre controladores para una determinada ubicación de los mismos. Como tercera contribución proponemos una nueva métrica para el CPP para mejorar la fiabilidad de los controladores que tiene en cuenta tanto la latencia de la comunicación como la fiabilidad de la comunicación entre los conmutadores y los controladores, así como entre los controladores. Se tiene en cuenta la fiabilidad cuando falla un solo enlace. Este aspecto concluye con la identificación de la ubicación óptima de los controladores para lograr bajas latencias en el tráfico del plano de control. El objetivo es reducir la latencia media. Como cuarta contribución, este estudio evalúa el modelo de optimización Joint Latency and Reliability-aware Controller Placement (LRCP). Como métrica de evaluación, la latencia del plano de control (CPL) se define como la suma de la latencia media entre conmutadores y controladores y la latencia media entre controladores. La latencia del plano de control, utilizando las latencias reales de la topología de la red, se calcula para cada ubicación óptima en la red. En el caso de un fallo de un enlace, se calcula y evalúa la CPL real para las colocaciones de LRCP con el fin de determinar lo buenas que son las colocaciones de LRCP. Las métricas CPL se utilizan para comparar las métricas de latencia y fiabilidad con otros modelos. Este estudio demuestra que las metodologías desarrolladas para redes a gran escala son muy potentes en cuanto a la búsqueda de todas las ubicaciones factibles de los controladores mientras se evalúan los resultados. Además, en comparación con los trabajos anteriores, que incluyen la latencia entre controladores y la fiabilidad para un caso de fallo de un solo enlacePostprint (published version

Managing Industrial Communication Delays with Software-Defined Networking

Recent technological advances have fostered the development of complex industrial cyber-physical systems which demand real-time communication with delay guarantees. The consequences of delay requirement violation in such systems may become increasingly severe. In this paper, we propose a contract-based fault-resilient methodology which aims at managing the communication delays of real-time flows in industries. With this objective, we present a light-weight mechanism to estimate end-to-end delay in the network in which the clocks of the switches are not synchronized. The mechanism aims at providing high level of accuracy with lower communication overhead. We then propose a contract-based framework using software-defined networking where the components are associated with delay contracts and a resilience manager. The proposed resilience management framework contains: (1) contracts which state guarantees about components behaviors, (2) observers which are responsible to detect contract failure (fault), (3) monitors to detect events such as run-time changes in the delay requirements and link failure, (4) control logic to take suitable decisions based on the type of the fault, (5) resilience manager to decide response strategies containing the best course of action as per the control logic decision. Finally, we present a delay-aware path finding algorithm which is used to route/reroute the real-time flows to provide resiliency in the case of faults and, to adapt to the changes in the network state. Performance of the proposed framework is evaluated with the Ryu SDN controller and Mininet network emulator

Resilience support in software-defined networking:a survey

Software-defined networking (SDN) is an architecture for computer networking that provides a clear separation between network control functions and forwarding operations. The abstractions supported by this architecture are intended to simplify the implementation of several tasks that are critical to network operation, such as routing and network management. Computer networks have an increasingly important societal role, requiring them to be resilient to a range of challenges. Previously, research into network resilience has focused on the mitigation of several types of challenges, such as natural disasters and attacks. Capitalizing on its benefits, including increased programmability and a clearer separation of concerns, significant attention has recently focused on the development of resilience mechanisms that use software-defined networking approaches. In this article, we present a survey that provides a structured overview of the resilience support that currently exists in this important area. We categorize the most recent research on this topic with respect to a number of resilience disciplines. Additionally, we discuss the lessons learned from this investigation, highlight the main challenges faced by SDNs moving forward, and outline the research trends in terms of solutions to mitigate these challenges