ware, enabling common software to support multiple SOC suppliers, multiple access protocols, and multiple access technologies. Software development kit. Building the Network of the Future 11.4.9 SDN ACCESS CONTROLLERS Integrating the access network with the rest of the network cloud architecture requires access soft- ware components managed by local SDN access controllers. This integrates with a wide range of software components such as the ONAP subsystems (see Chapter 7) that also integrate with other components such as OSSs. Three types of controllers are utilized in the network cloud architecture, as discussed in Chapter 7: Infrastructure controllers create and maintain underlying software environment by instan- tiating and managing virtual machines or containers used to support the access network. The distributed nature of the access network may require extended configurations of infra- structure controllers. Application controllers are utilized to support and manage required applications, includ- ing those that support access. Network controllers are utilized to support and manage network elements that form the software defined network infrastructure (SDNI). There are two major functions performed by the network controllers that support access: the control plane management function, and the data plane flow control function. These functions are separated in the ONAP access architecture. Because the access network is distributed, the data plane functions for some access network components must be distributed, which can require the introduction of new components. AT&T's work with OCP and leading industry hardware suppli- ers for a new type of vOLT hardware has already been described. The distributed nature of access technology may potentially also require new approaches for distributing data plane functions. For example, distributed network control functions are needed to provide QoS and traffic prioritization to meet performance measures for shared media access and concentration points in the access net- work,