d, localized, and resolved. The ONAP operations team is responsible for deploying ONAP instances, updating ONAP software, and detecting, troubleshooting, and resolving ONAP issues. ONAP-like functionality and automation also applies to operating ONAP, enabling many of the ONAP opera- tions functions to also be fully automated. 15.4 MIGRATING TO THE NETWORK CLOUD Rolling out NFV and ONAP technologies is a journey that must be executed with minimal customer impact-even in the face of the rapid change at both the control plane and data plane. Given the tremendous scale and diversity of networks like AT&T's, the reality is that not all traffic can be suddenly switched to being carried on the new SDN/NFV infrastructure. A typical customer con- nection will likely traverse both virtual and physical network elements for the foreseeable future, and thus virtual network functions will need to operate in harmony with physical network elements; similarly, ONAP will need to seamlessly operate with legacy OSSs and business support systems (BSSs). Building the Network of the Future 15.4.1 ROLLING OUT NETWORK CLOUD TECHNOLOGIES Unlike in the past where automation has essentially been an afterthought, automation is at the very heart of the Network Cloud vision. SDN and NFV together offer a "clean slate" opportunity, rather than continuing to build on legacy systems that have evolved along a complex journey over time. However, achieving this vision at scale while also ensuring that we continue to deliver carrier grade network performance and superior customer experience is akin to changing out the engine of the car while driving down the highway at 100 miles an hour. And the operations team is at the heart of performing this engine change. AT&T is aggressively deploying VNFs and ONAP across different networks and services. Such an aggressive rollout equates to tremendous change. Given the tight service requirements of carrier- grade services, this change must be executed with acceptable risk and minimal customer impact. So, how d