Reducing Buffer Space in Multipath Schemes

One major drawback of multipath transferring schemes, which is inspired by the usage of different paths with diverse delays, is the emergence of reordering among packets of a flow. This reordering brings some substantial problems (like larger delay and buffer space) to the transport applications. In this paper, we present a novel UDP-based multipath scheme for in-order delivery to the receiver by scheduling of packets among multiple paths. This method imposes the minimum possible delay and a small buffer space on the receiver’s application. We theoretically prove the optimality of the proposed method. Finally, through simulation experiments, we show that the performance of our multipath method is comparable with the best-case one-path transmission with aggregated bandwidth

Routing Bandwidth Guaranteed Paths with Restoration in Label Switched Networks

Label switched networks have become increasingly attractive to both network providers and customers. By creating aggregate, bandwidth-reserved flows, these networks offer routing flexibility, predictable bandwidth usage, and quality-of-service (QoS) provisioning. This flexibility in routing enables fault-persistent QoS reservations, where connectivity and allotted bandwidth remains available, even if some links or network nodes fail. The automatic switch-over from a now-defunct path to a new, working path is known as restoration. Restoring bandwidth-guaranteed paths requires allocation of resources on backup paths that will be used in the event of faults. In this paper, we investigate distributed algorithms for routing with backup restoration. Specifically, we propose a new concept of Backup Load Distribution Matrix that captures partial network state, greatly reducing the amount of routing information maintained and transmitted while achieving efficient bandwidth usage. We present and simulate two new distributed routing algorithms, which provide significant improvements in rejection rates and provide substantial savings in bandwidth used and call setup time compared to existing algorithms

Differentiated quality-of-recovery and quality-of-protection in survivable WDM mesh networks

In the modern telecommunication business, there is a need to provide different Quality-of-Recovery (QoR) and Quality-of-Protection (QoP) classes in order to accommodate as many customers as possible, and to optimize the protection capacity cost. Prevalent protection methods to provide specific QoS related to protection are based on pre-defined shape protection structures (topologies), e.g., p -cycles and p -trees. Although some of these protection patterns are known to provide a good trade-off among the different protection parameters, their shapes can limit their deployment in some specific network conditions, e.g., a constrained link spare capacity budget and traffic distribution. In this thesis, we propose to re-think the design process of protection schemes in survivable WDM networks by adopting a hew design approach where the shapes of the protection structures are decided based on the targeted QoR and QoP guarantees, and not the reverse. We focus on the degree of pre-configuration of the protection topologies, and use fully and partially pre-cross connected p -structures, and dynamically cross connected p -structures. In QoR differentiation, we develop different approaches for pre-configuring the protection capacity in order to strike different balances between the protection cost and the availability requirements in the network; while in the QoP differentiation, we focus on the shaping of the protection structures to provide different grades of protection including single and dual-link failure protection. The new research directions proposed and developed in this thesis are intended to help network operators to effectively support different Quality-of-Recovery and Quality-of-Protection classes. All new ideas have been translated into mathematical models for which we propose practical and efficient design methods in order to optimize the inherent cost to the different designs of protection schemes. Furthermore, we establish a quantitative relation between the degree of pre-configuration of the protection structures and their costs in terms of protection capacity. Our most significant contributions are the design and development of Pre-Configured Protection Structure (p-structure) and Pre-Configured Protection Extended-Tree (p -etree) based schemes. Thanks to the column generation modeling and solution approaches, we propose a new design approach of protection schemes where we deploy just enough protection to provide different quality of recovery and protection classe