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

A Novel Placement Algorithm for the Controllers Of the Virtual Networks (COVN) in SD-WAN with Multiple VNs

The escalation of communication demands and the emergence of new telecommunication concepts such as 5G cellular system and smart cities requires the consolidation of a flexible and manageable backbone network. These requirements motivated the researcher to come up with a new placement algorithm for the Controller of Virtual Network (COVN). This is because SDN and network virtualisation techniques (NFV and NV), are integrated to produce multiple virtual networks running on a single SD-WAN infrastructure, which serves the new backbone. One of the significant challenges of SD-WAN is determining the number and the locations of its controllers to optimise the network latency and reliability. This problem is fairly investigated and solved by several controller placement algorithms where the focus is only on physical controllers. The advent of the sliced SD-WAN produces a new challenge, which necessitates the SDWAN controllers (physical controller/hosted server) to run multiple instances of controllers (virtual controllers). Every virtual network is managed by its virtual controllers. This calls for an algorithm to determine the number and the positions of physical and virtual controllers of the multiple virtual SD-WANs. According to the literature review and to the best of the author knowledge, this problem is neither examined nor yet solved. To address this issue, the researcher designed a novel COVN placement algorithm to compute the controller placement of the physical controllers, then calculate the controller placement of every virtual SD-WAN independently, taking into consideration the controller placement of other virtual SD-WANs. COVN placement does not partition the SD-WAN when placing the physical controllers, unlike all previous placement algorithms. Instead, it identifies the nodes of the optimal reliability and latency to all switches of the network. Then, it partitions every VN separately to create its independent controller placement. COVN placement optimises the reliability and the latency according to the desired weights. It also maintains the load balancing and the optimal resources utilisation. Moreover, it supports the recovering of the controller failure. This novel algorithm is intensively evaluated using the produced COVN simulator and the developed Mininet emulator. The results indicate that COVN placement achieves the required optimisations mentioned above. Also, the implementations disclose that COVN placement can compute the controller placement for a large network ( 754 switches) in very small computation time (49.53 s). In addition, COVN placement is compared to POCO algorithm. The outcome reveals that COVN placement provides better reliability in about 30.76% and a bit higher latency in about 1.38%. Further, it surpasses POCO by constructing the balanced clusters according to the switch loads and offering the more efficient placement to recover controller-failure