 to automate the operational tasks and management of 5G networks [45]. Providing a zero-touch orchestration, operations, and management (ZOOM) enables an E2E management solution across telecom operators [138]. This section highlights the NFV architecture provided by ETSI ISG and recent research works to overcome NFV challenges such as NFV orchestration and management. 1.4.2.1 NFV Architecture The ETSI NFV ISG developed the requirements for NFV within telecom networks such as the requirements for hypervisor-based virtualization and security manage- ment [138, 139]. Furthermore, the ETSI NFV specification in [137] defines the NFV architectural framework, as presented in Fig. 1.9. The ETSI NFV architectural M. Alfaqawi et al. OSS/BSS VNF orchestrator VNF manager Virtual Virtual computing Virtual storage networking Virtualized Virtualization layer infrastracture manager (VIM) Computing Networking hardware Storage hardware hardware NFV-MANO Fig. 1.9 Network functions virtualization architectural framework framework has been integrated in 3GPP TS 28.500 [140] and considered as a reference for interoperability among all the telecom stakeholders. The NFV architecture in Fig. 1.9 is composed of four layers and can be summarized as follows [137, 141]: 1. VNF layer: It corresponds to the application plane and consists of two main parts as follows: (a) Virtual network functions (VNF): It is the virtualization of the NFs as the case for the network elements of 5GC, including mobility management entity (MME), serving gateway (SGW), and packet data network gateway (PGW). (b) Element management (EM) system: It is responsible for the management functionality, including fault, configuration, performance, and security, for one or several VNFs. 2. NFV infrastructure (NFVI) layer: It corresponds to the data plane and contains the hardware and software resources as follows: (a) Hardware resources: It provides processing, storage, and connectivity resources to the several VNFs through the virtualization layer or a hypervisor. (b) Virtu