A differentiated optical services model for WDM networks

This article addresses the issues of scalable end-to-end QoS in Metropolitan DWDM networks serving as transit networks for IP access networks. DWDM offering a few wavelengths has been deployed in the past in backbone networks to upgrade point-to-point transmission where sharing is based on coarse granularity. This type of DWDM backbone network, offering a few lightpaths, provides no support for QoS services traversing the network. As DWDM networks with larger numbers of wavelengths penetrate the datacentric metro environment, specific IP service requirements such as priority restoration, scalability, 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 service model in the optical domain called differentiated optical services (DoS) based on a set of optical parameters that captures the quality and reliability of the optical lightpath.