stance 1 Instance 2 Instance 1 Instance 1 Instance 2 Instance N Instance 1 Instance 2 Instance N Instance 1 Instance 2 Instance 1 Instance 1 Instance 2 Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Guest os Hypervisor os Hypervisor os Hypervisor os Physical Server Physical Server Physical Server FIGURE 14.21 Resiliency scheme. 14.4.2.4.2 Monitoring Every VM in the various VNFs that comprise the virtual EPC generates fault, service, and perfor- mance events that are collected by the ONAP platform that has analytics, management, and control functions that automate the monitoring, recovery, and scaling of VMs (see Chapter 6). 14.4.2.4.3 Resiliency Each VNF in a virtual EPC instance consists of several types of VMs (traffic servers, control nodes, database engines, traffic directors, load balancers, etc.) (Figure 14.21). In such an environment, resiliency is achieved via the following methods: 1. Anti-affinity rules applied to VMs that should not share a host 2. Distribution of VMs across availability zones 3. Maintaining availability zone affinity across failures and scaling functions 4. Geo-diverse distribution of virtual EPC instances 14.4.2.5 Integration with ONAP The following capabilities of ONAP are used in lifecycle management of the various EPC VNFs and their components: 1. Instantiation of VM groups using OpenStack heat templates. 2. Design of VM groups in a manner that allows similarly scalable VMs to scale-out and scale-in. 3. Automatic configuration of the various VMs in each VNF instance using multiple con- figuration tools (such as NETCONF/YANG, Ansible, etc.); this configuration function is invoked during different portions of the VM life cycle (instantiation, recovery, rebuild, scaling, etc.) 4. Monitoring of both the infrastructure and the VM components; analytics engines are driven by rules that allow real-time correlation of different types of fault, performance, and service events. 5. Recovery of failed VMs, networks, and othe