throughput for media processing. The virtualized media handling VNFs, media SBCs and media servers use acceleration techniques of Intel's DPDK APIs, SR-IOV, or CPU pinning and nonuniform memory access (NUMA) (see Chapter 4) as supported by the cloud, in order to meet the required media processing performance requirements. Virtualized infrastructures typically use oversubscription mechanisms to optimize processor utilization. This could negatively impact performance of network functions since some virtualiza- tion functions running on the same physical host may be deprived of resources. The cloud needs Building the Network of the Future to support VM flavors where oversubscription is disabled to guarantee consistent allocation resources to VMs for network functions with stringent performance needs. Lastly, site selection and placement of VNFs at cloud sites supporting IMS services is based on ensuring that the end-to-end latency objectives for services meet the required minimum postdial delay for calls under sunny-day scenarios. 14.4.1.6 Hybrid Architecture (VNFs and PNFs) While the target end-state vision is to have all services use only VNFs, in reality, there will be a period of time where there will be virtual as well as PNFs. Once VNFs of a service are instanti- ated, connectivity is provisioned to existing PNFs of the service during orchestration. The VNFs are provisioned with parameters (e.g., fully qualified domain names of existing PNFs) to enable VNFs to discover and interface with the existing PNFs. End-to-end cross-domain operations will continue to be provided by OSS/BSS systems for hybrid environments. The IMS VNFs will coexist and will require interworking with the already deployed PNFs. Continued use of a single-subscriber home domain for both virtualized and existing implementations requires interworking between the virtualized and physical components. 14.4.2 EVOLVED PACKET CORE The currently deployed EPC platform is based on a number of purpose-built components. The EPC platform, as shown in Figu