Contention resolution and QoS provisioning using sparse fiber delay lines in WDM networks

In this paper, we combine fiber delay lines (FDL) and optical wavelength conversion (OWC) as the solution for the burst contention problem in optical burst switching (OBS). We present a placement algorithm, k-WDS, for the sparse placement of FDLs at a set of selected nodes in the network. The algorithm can handle both uniform and non-uniform traffic patterns. Our extensive performance tests show that k-WDS provides more efficient placement of optical fiber delay lines than the well-known approach of placing the resources at nodes with the highest experienced burst loss. Performance results are also given to compare the benefit of using FDLs alone, OWCs alone, as well as a mixture of both FDLs and OWCs. A new algorithm, A-WDS, for the placement of an arbitrary numbers of FDLs and OWCs is presented and evaluated under different uniform and non-uniform traffic loads using network simulation of the NSFNET topology and randomly generated graphs. The paper is concluded by presenting the design of a cost-effective optical switch equipped with variable-delay FDL bank. Based on the switch design, a scheme to provide differentiated services for multiple classes of traffic is presented and evaluated.