documents that network engineers then had to translate into the specific vendor configuration language of the associated network element. Any introduction of new network capabilities took extra time waiting for documentation, testing configuration, and implementing the configuration in OSS. The new pro- cess involves defining capabilities using the Yet Another Next Generation (YANG) modeling lan- guage. YANG templates, which are vendor neutral, create a portable and more easily maintained definitive representation of desired network functionality. Another benefit is that simulation can be used to verify correctness before using the templates with actual network functionality. In AT&T's approach to SDN, all SDN controllable elements are treated similarly, whether they are implemented as classic PNF or the more modern virtualized network functions (VNF). The Network Cloud SDN controller has a number of subsystems and is designed to operate in conjunc- tion with the Open Network Automation Platform (ONAP). It combines a service logic interpreter (SLI) with a real-time controller based on Open Daylight (ODL) components. The SLI executes scripts that define actions taken on lifecycle events such as service requests and closed-loop con- trol events. SLI scripts that are frequently used or complex can be encapsulated as a java class that runs in the ODL framework then reused as a single script operation. Another function is network resource autonomous control, which is used to associate (assign) network resources with service instances. At the bottom of the controller are adapters that can interact with a wide variety of network element control interfaces. These can range from older element management system (EMS) style "provisioning" to real-time network transactions using Border Gateway Protocol (BGP). No control framework would be complete without a policy function. Policy rules can be defined based on events collected from NFVI and services running on it. Events can trigger changes in algorithms at enforcement point