Fault tolerance in the data plane of software-defined networks

Failures in networks result in service disruptions which may cause deteriorated Quality of Service for the end users. Since SDN is becoming the mainstream paradigm for networks, especially for data centers, correct implementation of the fault tolerance for SDN-based networks is crucial. Current SDN data plane fault tolerance approaches can be classified as reactive and proactive which may or may not rely on the involvement of the central controller, respectively. However, none of them qualify as complete solutions, providing only partial remedies. In this work, we propose a dynamic protection approach that considers not only the existing faults within the network but also the quality of alternative paths. We also investigate how application based parameters are affected by possible failures. To this end, we explore the change in Quality of Experience (QoE) caused by link failures under different cases using Dynamic Adaptive Streaming over HTTP (DASH) for video streaming. Since tremendous amount of traffic is generated in modern networks, the congestion issue is faced more frequently. Even though the video streaming paradigm, DASH, is proposed as a solution for the changing condition of the networks, it is not sufficient considering the heavily loaded links that show the symptoms of the link failures. Therefore, the flexible implementation of the data plane fault tolerance scheme that can be applied to other problems like congestion in networks is crucial. Thus, we apply the data plane fault tolerance approach in SDN to improve the QoE of DASH clients in the case of congestion as well as the failure.