Kozlovski, Eugene; (2003) Quality-of-Service provisioning in IP/WDM networks with dynamic lightpath allocation. Doctoral thesis (Ph.D.), University College London (United Kingdom).

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Abstract

This thesis is focused on the investigation of Quality-of-Service (QoS) provisioning in fast-switched IP/WDM optical network architectures, supporting mission-critical service-differentiated Internet applications. First, drawbacks associated with QoS provisioning in currently proposed fast- switched optical networks, including those based on re-configurable optical core, optical burst switching (OBS) and optical packet switching (OPS), are discussed. To overcome these drawbacks, a novel approach, namely, the wavelength-routed optical burst-switched architecture (WR-OBS) is proposed and comprehensively investigated throughout this work. Contrarily to existing OBS approaches, WR-OBS bypasses optoelectronic buffering/processing of bursts in the optical domain, using connection- oriented, two-way lightpath reservation mechanism. A general framework for explicit QoS provisioning in WR-OBS is discussed and the design of the key WR-OBS network components, the control node and the edge-router, is presented. The QoS framework is based on a set of new burst scheduling algorithms that effectively maintain the required burst blocking probability for a given number of supported wavelengths, whilst bounding burst end-to-end delays. Novel network parameters, key to ensuring the QoS performance in WR-OBS, are introduced. In particular, the burst maximum scheduling delay, which governs the maximum time allowed for a burst to request a lightpath before being blocked, is shown to be critical in bounding the burst blocking probability. Furthermore, the WR- OBS restoration model, based on a novel failure-compensating burst scheduling technique, is presented. It is then successfully applied to the case of single link failures, for the first time analysing the implications of resource failures in OBS in terms of wavelength restoration over-provisioning. The trade-offs are quantified between the burst end-to-end delays and WR-OBS wavelength requirements, maintaining the bounded blocking probability. This analysis, carried out as a function of network physical connectivity, traffic loads and service differentiation, identifies the conditions, allowing the proposed architecture to operate with higher bandwidth utilisation with respect to that in statically-routed WDM networks. For both failure-free and link-failure cases, the WR-OBS wavelength savings are shown to be especially significant in sparsely connected network physical topologies. Finally, the design of a novel inter-domain network management system for automatic, QoS-capable IP service provisioning over the re-configurable WDM networks is investigated. The concept of the integrated IP/WDM network management is devised as a shorter-term solution to automating the network provisioning with respect to those, supporting finer switching granularities, including WR-OBS. A key component of this solution, the WDM routing manager, carrying out near real-time lightpath setup on-demand, is implemented using novel component-oriented and object-oriented software programming techniques. A detailed experimental scenario is then developed and the system successfully tested on a representative network set-up. The results of this thesis can be used for the analysis and design of future Internet-over-optical network architectures, supporting QoS-guaranteed multi-service performance, whilst maximising the utilisation of network resources.

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