QoS Performance in IP over WDM Networks

We address the issue of how to provide basic Quality of Service (QoS) in optical burst-switched WDM networks with limited fiber delay lines (FDLs). Unlike existing buffer-based QoS schemes, the novel offsettime-based QoS scheme we study in this paper does not mandate any buffer for traffic isolation, but nevertheless can take advantage of FDLs to improve QoS. This makes the proposed QoS scheme suitable for the next generation Optical Internet. The offset times required for class isolation when making wavelength and FDL reservations are quantified, and the upper and lower bounds on the burst loss probability are analyzed. Simulations are also conducted to evaluate the QoS performance in terms of burst loss probability and queuing delay. We show that with limited FDLs, the offset-time-based QoS scheme can be very efficient in supporting basic QoS. Index Terms IP over WDM networks, fiber delay lines, Quality of Service, priority, class isolation, QoS performance.