pecific Virtual Network Functions Service Policy Manager Shared Network Services Abstraction & API Application Controller Exposure Network Platform as a Service Resource Infrastructure as a Service Abstraction & API Virtual Service Control Loop Exposure Software Defined Service Framework Framework Virtual Service Framework FIGURE 14.3 Virtual service framework. 7. Policy-driven auto self-healing and scaling 8. Enable a virtual cloud-based test model to speed certification and reduce capital cost 9. Enable scaling of services at a lower cost The virtual service framework defines the software-defined service framework (SDSF). It piv- ots from the concept of one universal platform for all real-time services to one where services are instantiated on demand on a common commodity-based infrastructure. It leverages the basic principles of NFV that decouples hardware from software and transforms dedicated network func- tions into software-based VNFs that can run on a common cloud infrastructure while maintaining service requirements for performance, availability, reliability, and security in a multitenant cloud environment. It facilitates mechanisms to customize and instantiate only the essential network func- tions that are required for a specific service by decomposing current network functions into granu- lar smaller VNFs. Session state is decoupled from the VNFs. This minimizes registration storms and enables a better user experience where a user's session is maintained if the VNFs at a site fail. Services are deployed in virtual zones with smaller failure domains, impacting fewer customers under failure scenarios. N+K georesiliency is used for efficient use of resources. The virtual service framework defines an ecosystem for service definition and creation. The set of decomposed VNFs forms the basis of a VNF catalog that can be used by service designers for rapid and on-demand creation of a service. Beyond service definition and creation, the virtual service framework defines a virtual service control loop framework