QoS provisioning in WDM ring networks with tunable transceivers

In this paper, we propose two algorithms and a node architecture to access the shared medium and to support priority based quality-of-service (QoS) in WDM ring networks. The algorithms give priority to a node having high priority request in reserving a destination node and/or a data-channel. The first algorithm selects a data-channel based on earliest availability of the data-channel, and the second with minimum scheduling latency. Both the schemes employ reservation mechanism, however, they differ from the traditional reservation mechanism in that no explicit release of the reserved resources take place. The proposed schemes are contention-free, easy to implement and require no buffers at nodes. The proposed node architecture is configured around tunable transceiver(s) and thus makes the scheme scalable. We study performance of both the schemes, by simulation, for bursty traffic modeled using an M/Pareto distribution, and compare the performance with another token based algorithm. We found that our schemes perform better in terms of wavelength utilization. However, delays are higher due to the single tunable transceiver used in our scheme as opposed to an array of transmitters and receivers in the previous work.