 for rapid and dynamic orches- tration and management of a virtual service. It leverages cloud elasticity and automation to enable automated recovery and auto-scaling. Automated recovery rapidly brings the service back to a com- plete redundant mode in near real-time and improves the overall service reliability. The ability to auto-scale virtual services using a common pool of cloud resources enables adapting to changes in traffic in near real-time. Figure 14.3 shows the virtual service framework and the functions that it comprises. The sec- tions below describe the virtual service framework in more detail and highlight specific use cases for virtual services. 14.2.1.1 Software-Defined Service Framework The SDSF is a virtual network-function-centric architecture. It uses a layered approach where the layers are defined in terms of a cloud service model. It is based on design principles of decomposition of network functions and standardization of technology used for real-time services. Cloud-based paradigms are used to achieve both these characteristics. Each layer of the SDSF is exposed to first- and third-party developers for service design and creation and enables new business opportunities. Building the Network of the Future For many years, services were monolithic in that hardware was tightly coupled with software, there was no formal distinction between control and data systems, and the design of the network was highly dependent upon the service being delivered. The fundamental units of these networks were network elements strung together like beads on a string. The monolithic services are now composed from components from four decomposed layers of the SDSF, chained appropriately to provide services to the end user. Decomposition of network functions into granular VNFs enables time to market for services and drives efficient use of cloud and network resources. It enables instantiating and customizing only essential functions as needed for the service, thereby making service delivery more nimble. It provides f