 this area as more operational experience is gained. 16.7 NFV DATA AND MEASUREMENTS As background before we discuss NFV measurements, let us review the network service measure- ment life cycle in the traditional legacy networks as defined by the telecommunications manage- ment network (TMN) model defined by ITU-T for managing open systems in a communications network. TMN is part of the ITU-T Recommendation Series M.3000. Service network management was grouped into five functional areas, designated FCAPS-fault, configuration, accounting, performance, and security: Fault management-detect and notify faults encountered by the network element Configuration management-expose configuration, inventory, and software attributes Accounting management-collect usage information of all network element resources Performance management-monitor and report performance measurements at service and network level Security management-secure and authorize access to network devices, resources, and services Building the Network of the Future Each functional area is then integrated in a layered architecture, and measurements are exposed at the network element and element management system layer (EML): Network element layer (NEL) defines interfaces for the network elements, instantiating functions for device instrumentation. EML provides management functions for network elements on an individual or group basis. It also supports an abstraction of the functions provided by the NEL. Examples include collecting statistical data for accounting purposes, and logging event notifications and performance statistics. 16.7.1 NFV DATA MODEL The NFV data model has flattened and abstracted the original legacy network service data model. Further, it has made the NFV data model independent from EMS as there is a uniform management system (ONAP) now responsible for the NFV management. The NFV model maintains parity with the legacy network service data model and also enhances it where needed. It relies on telemetry data from the native cloud infrastructure 