 the edge and provide specific ser- vice features to customers. These are typically appliances. For example, firewalls that provide a security service or WAN acceleration devices that provide caching and prepositioning of common data elements. Control plane elements like RRs, DNS are also great candidates since they can be centralized and do not require a very high data plane requirement. Edge routing functions, such as PE routers are also likely to be virtualized. NFV BEST PRACTICES The Network Cloud will provide a base set of capabilities that can be used by VFs running on a ser- vice provider's network. The network cloud will provide and support the host, host OS, OpenStack, KVM hypervisor, and vSwitch/vRouter. It will provide an environment that allows each VM to run on its own partition, isolated from other VMs, on one physical server. The AT&T Open Network Automation Platform (ONAP) framework, described in Chapter 7, provides the service orchestra- tion and VF instantiation and configuration capabilities and it provides configuration management at instantiation as well as when in service. It collects fault, performance, application KPIs, and probe data from VFs and makes decisions to perform auto-recovery or auto-scaling of VFs based on collected data and vendor-provided engineering rules. It will trigger dynamic instantiation of new VFs for auto-recovery or auto-scaling as needed in conjunction with the service orchestrator. The network is primarily IPv6 based but is able to interact with IPv4-based components. The network cloud supports a variety of VFs with varying performance needs. Response time characteristics of supported VFs, can be categorized as follows: Real time is measured in milliseconds/microseconds and is the responsiveness required to support, for example, the low timing threshold for session initiation protocol (SIP) queries and responses Network Functions Virtualization Near-real time is a response measured in seconds Nonreal time is a response measured in minutes, hours, or days To ensur