Failure Recovery In SDN: A Segment Routing Based Link Protection Approach

The present computer network has been evolved into a complex structure with a growing challenge to manage and scale modern day’s requirements. A new approach to tackle these difficulties is SDN, which empowers network with programmability and is designed to perform fine grained traffic forwarding decisions. However, similar to the need of traditional networks, fault tolerance is necessary to achieve high availability. In this thesis, we propose a link protection method based on the Segment Routing (SR) for rapid failure recovery in OpenFlow based SDN. Our proposed scheme performs local recovery at the switch level without the controller intervention, thus significantly reducing the total recovery time. Additionally, it reduces initial load on the controller while proactively computing the backup paths by minimizing the algorithm complexity. Moreover, memory efficiency is achieved by using a per-link protection with aggregated flow rules instead of traditional per-flow based protection mechanism. In Segment Routing, we may encounter the limitation on the size of the label stack, known as Segment List Depth (SLD). Therefore, we also propose an efficient label encoding algorithm to mitigate the SLD impact.

Failure Recovery In SDN: A Segment Routing Based Link Protection Approach

The present computer network has been evolved into a complex structure with a growing challenge to manage and scale modern day’s requirements. A new approach to tackle these difficulties is SDN, which empowers network with programmability and is designed to perform fine grained traffic forwarding decisions. However, similar to the need of traditional networks, fault tolerance is necessary to achieve high availability. In this thesis, we propose a link protection method based on the Segment Routing (SR) for rapid failure recovery in OpenFlow based SDN. Our proposed scheme performs local recovery at the switch level without the controller intervention, thus significantly reducing the total recovery time. Additionally, it reduces initial load on the controller while proactively computing the backup paths by minimizing the algorithm complexity. Moreover, memory efficiency is achieved by using a per-link protection with aggregated flow rules instead of traditional per-flow based protection mechanism. In Segment Routing, we may encounter the limitation on the size of the label stack, known as Segment List Depth (SLD). Therefore, we also propose an efficient label encoding algorithm to mitigate the SLD impact.

Augmentation of DC-Link Protection System of PMSG Based Wind Turbine Using Fuzzy Logic Controlled Buck Controller System

Recently, permanent magnet synchronous generator (PMSG) is one of the most familiar type of generator for wind power plant (WPP). Generally, PMSG is connected to gird using back to back converter. During fault period, power imbalance situation is happened between machine side and gird converter. As a result, the DC-link voltage can be rise significantly which can damage the whole converter system. In this paper, a novel DC-Link protection system of buck converter based on fuzzy logic is designed in order to augment the transient stability of the PMSG system. The new buck converter along with its control system is designed to manage the supplied voltage of the braking resistor during fault period. For investigating the performance of the proposed system, fault analysis is performed on different case scenarios PSCAD/EMTDC software.

A Proactive Link Based Fast Recovery Strategy for Survival Elastic Optical Networks

In this paper, we proposed a link based fast connection recovery strategy. A backup path either reserved in advance or searched dynamically after the failure occurred in the network. Both these recovery strategy required large backup capacity. We analyse three network parameters such as recovery time (RT), bandwidth blocking probability (BBP), and network capacity utilization ratio (NCU) for randomly generated source to destination request for three topologies that is COST239, ARPANET and NSFNET and compare the results for shared link protection (SLP), dedicated link protection (DLP), and our proposed link protection (PLP) scheme. Our proposed scheme shows the minimum RT compared to other two strategies.