Master Thesis - 2009

High speed and large capacity backbone network is required for future high quality multimedia services. All optical WDM networks have been expected as one of promising solutions. In optical WDM networks corresponding to various network services, wavelength paths have various lengths of holding time according to services. In addition, the usage of optical devices such as wavelength converters is considered to avoid the contention of wavelengths. Long term connections occupy the network resources, such as wavelengths and converters, for a long time. As a result, other connections cannot use these resources. It is desirable not to assign many resources, especially many converters, for long term connections. Although many efficient methods for routing and wavelength assignment have been proposed, more effective use of resources is expected with considering holding time. of optical path.

In this thesis, a path set-up method considering the holding time of connections is proposed. The proposed method classifies connections into two classes and sets up optical path based on these classes. For long term connections, each path is reserved with the wavelength as same as possible to balance utilization of converters among all nodes. For short term ones, the route and wavelengths are selected based on history of successful transmissions that did not interrupt long term ones. Most of these information for path set-up method is managed in autonomous and distributed database. As a result, utilization efficiency of network resources and call blocking probability are improved.

Finally, the effectiveness of the proposed method is evaluated through simulation experiments. In particular, the proposed method can reduce call blocking probability less than 90% of conventional approach, especially, in the case that most of requests are classified into short term connections.