fication of alarms, resource utilization, performance, and availability. The VNF transaction logging can be in the form of traditional session detail records or other standard- ized form. The event reporting is generally expected to be in streaming event form using a stan- dardized protocol. The alerts can also be in the form of operator programmable threshold crossing alerts. 16.9.1 VNF RESOURCE CONSUMPTION AND OPERATIONAL METRICS Service providers define and use key capacity indicators (KCIs) to assess the loads and dimension- ing profiles of VNFs and to monitor system health as well as unit costs. The metrics are optimized through rigorous capacity planning and management optimization practices that are typically auto- mated using closed-loop mechanisms in the NFV environment. Examples of KCIs used to optimize both resource consumption and performance, include CPU utilization Memory utilization Storage I/O load Network bandwidth utilization Building the Network of the Future Achieving predictable performance and optimal unit cost is intrinsically complex. The dynamic nature of a cloud environment cannot provide a real-time hard guarantee for performance and resource consumption. There is typically a tradeoff between predictability of resource availability and optimal resource allocation. In a traditional single-tenant architecture and design, trending and profiling can be used for allocating the resources. The problem becomes much harder in multiten- ant environments when additional dimensions are inserted into predicting both aggregate and indi- vidual tenant behavior. The operator's responsibility is to allocate adequate resources and engineer appropriate capacity for all tenants, while also ensuring that the resources are optimized. Overbooking resources is a critical operational management practice. The overbooking practice relies on the assumed behavior of subscribers and the probability that they will not all operate at their peak SLA at the same time, or at all times. Predictive traffic profiling is an 