A differentiated optical services model for WDM networks

This article addresses the issues of scalable end-to-end QoS in Metropolita n DWDM networks serving as transit networks for IP access networks. DWDM of fering a few wavelengths has been deployed in the past in backbone networks to upgrade point-to-point transmission where sharing is based on coarse gr anularity. This type of DWDM backbone network, offering a few lightpaths, p rovides no support for QoS services traversing the network. As DWDM network s with larger numbers of wavelengths penetrate the datacentric metro enviro nment, specific IP service requirements such as priority restoration, scala bility, dynamic provisioning of capacity and routes, and support for coarse -grain QoS capabilities will have to be addressed in the optical domain in order to achieve end-to-end QoS over a DWDM network. We propose a QoS servi ce model in the optical domain called differentiated optical services (DoS) based on a set of optical parameters that captures the quality and reliabi lity of the optical lightpath.