f lower level network layer errors on higher layers. That is, as a fault cascades upwards, its effect multiplies, potentially by thousands of times.1 18 A strategic layer can sit between the lower layers and the customer layer where data collected from the network and service quality converge. This is the integrated service layer that unifies performance management across SONET, Ethernet, IP and other optical network services. In optical networks, photonic switches and other all-optical network elements suf- fer from a lack of built-in performance-monitoring capabilities. This motivates a performance management layer between the optical and customer layers to correlate optical domain metrics with QoS metrics (such as BER or packet loss) with end-user quality (such as voice quality or availability). Measurements taken in the optical domain use statistical sampling on optical channels to measure the three compo- nents of wavelength character (signal power, noise and drift). This correlation must be made with proper equipment monitoring in the core and at the network edge. Simultaneous measurements of signal power, optical signal-to-noise ratio, BER, slips This was emphasized in a presentation given by a member of Astracon at Telemanagement World, Nice, in 2002. 6 Service Provisioning and Activation and framing errors are brought back into the integrated performance management layer for correlation, analysis and reporting at the customer layer. Network data are organized in various layers for better correlation at the applica- tion level and greater visibility of end-to-end QoS. Conforming to a standard proce- dure at each stage of network evolution helps ensure service quality. The service quality management (SQM) process has: 1. a service-provisioning request interface which returns an acceptance message saying that the service qualifies or is permitted 2. an SLA reporting interface. The service-provisioning request supports on-demand service provisioning requests and uses a common reference model such as a cable 