ents in several core locations in the network is driven by vendor design constraints as well as a desire for traffic management and balancing within the ser- vice provider's network. SBCs are typically deployed at distributed access node sites. Access layer components are placed close to the traffic source to minimize RTP latency issues. 14.4.1.2 SDN/NFV Implementation The design and implementation of the virtualized IMS service platforms is in a manner that aligns with the SDN/NFV-based virtual service framework. The framework introduces a layered service adaptation and abstraction approach with lower layers such as IaaS provided by a common cloud infrastructure and the specific VNFs needed for the service being the responsibility of the network design team. Common NPaaS services and capabilities are provided and used by the virtualized network functions. The existing physical IMS service platforms will coexist for services and will need to interwork with the new virtualized service platforms for a time period until all PNFs are migrated to VNFs. Figure 14.14 shows the service design approach for a virtualized IMS services platform. The virtualized IMS services platform design is based on the virtual service framework and aligns with Service Platforms Decoupled Hardware and software Tightly coupled hardware and software Virtual Service ControlLoop Frameworkto orchestrate Virtual Monolithic platform engineered for all IMS services Services and interface with SDN Controller Redundant data stored in multiple NEs Data stored in a consolidated reliable DB Reduces complexity: Specialized interface for DB access (Diameter) Decompose modules into functional components Specialized functional modules Eliminate specialized interfaces Virtual Service SDN Controller IMS Service Platform Control Loop Framework (L1 to L3) (L4 to L7) Software Defined Service Framework Routing Identity Mgmt. Media Function Control Session Service Specific Registrar Control Common Off The Shelf Hardware Hosted on Common Cloud FIGURE 14.14 Virtual