). In the past, CPE followed the same approach as network equipment, that is, implemented as appliances. However, CPE is undergoing the same transformation using NFV. This allows a single device to provide multiple functions when needed, under software control. When redesigning CPE using NFV, the approach taken was to allow functions to operate either on the premise inside the new virtualized CPE or in the network, on the Network Cloud. For the on- premises network functions within the CPE, innovation was required to create a suitable execution environment. Unlike the Network Cloud where multiple servers are available to scale up or down VNF, the CPE environment is limited to typically a single CPU chipset. To allow for software porta- bility and to leverage the open source ecosystem, again Kernel-based Virtual Machine (KVM) was selected as the hypervisor to allow multiple VNF to share the CPU in individual virtual machines. (There are less security concerns here since CPE is dedicated to a single customer.) One of the most challenging aspects for CPE is management. Since CPE is located on-premises at the point between the end of a customer's wide area network (WAN) service and the local network, it is important to provide an operational network connection capability. This is done by Transforming a Modern Telecom Network-From All-IP to Network Cloud sharing the WAN service segregating the traffic with special virtual LAN (VLAN) or IP addresses. However, before the service is initiated or during service after a failure, the WAN connection may not be available. The solution was to leverage mobile access to the Network Cloud and provide a "call home" capability. This second connection allows for remote "test and turn-up" procedures and in the case of WAN failure, diagnosis and fault location determination. This is discussed in more detail in Chapter 10. 2.5.7 NETWORK ACCESS Access is used to describe the portion of the network that goes from homes and businesses to net- work infrastructure buildings called central o