Conclusions and Future Work

Abstract

This thesis presents a QoS-based methodology for the solution to the problem of wavelength routing tailored to specific clients of the upcoming optical transport networks, in regular network operation as well as in the operation of service restoration. With regard to wavelength routing with service guarantees, the connection accommodation based on optical QoS is considered, through which the appropriate allocation of wavelengths on concatenated network elements is performed, the necessary transmission quality is achieved, and the required management and surveillance functions are provided. Two basic approaches for QoS-based wavelength routing are proposed, differing in the way of handling the quality attributes. The first approach treats the wavelength routings and service accommodation separately, while in the second approach, a graph-theoretical methodology is proposed where the quality attributes of importance for service guarantees are directly routed. Both approaches have been implemented by numerical analyses and simulations, with a number of strategies to show their practical usability. The method of separate routing and evaluation of quality attributes requires less computational effort and faster running times, but is less suitable for transparent networks due to the correlation of the analog end-to-end attributes along wavelength paths. The directly routed quality attributes, where twofold wavelength routing metrics, i.e. QoS metrics (service requirements) and resource metrics (quality constraints), are considered, is shown to deliver the solution to wavelength routing problem for multi-service WDM networks with multiple quality constraints. However, like most of the QoS-routing algorithms for data networks currently proposed, also this one is characterised by a prohibitively high algorithm time complexity.