Dynamic Failover for SDN-based Virtual Networks

Software-Defined Networking (SDN) is one of the emerging network technologies that aims to operate and manage networks in more flexible and efficient manner. Among various features from SDN, Network Virtualization (NV) is one of the most promising network technologies that provides the ability to provision multiple virtual networks on top of underlying physical networks in a way to improve network utilization and provide flexibility. Since virtual networks are dependent on underlying physical network, failures in the physical network in turn can affect virtual networks. To provide a transparent failover solution for virtual networks, a Network Hypervisor (NH)-based approach gains more and more popularity, as this approach does not expose too much details of the physical network to tenant controllers. NH-based approach can be further categorized into two folds - restoration and protection. Restoration has a drawback that failover time increases proportionally with the number of switches along the path, while protection has a weakness that it cannot deal with dynamic changes of network states. To address the drawbacks of these approaches, we propose a dynamic failover method by properly combining the two approaches that aims to preserve the dynamicity while reducing the failover time. To show the feasibility, we have designed and implemented the proposed failover method by enhancing existing open source network hypervisor, OpenVirteX (OVX), and evaluated its performance in an emulated network environment. Our outcomes show the improvement of performance on delay compared to the exiting method.