## 2 Enabling Technologies in Next-Generation Network Communications: SDN and NFV  
SDN technology has emerged as a new network paradigm, characterized by separating the data plane from the control plane, aiming to simplify the management and configuration of traditional networks [18]. This shift in control, previously tightly integrated into individual network devices, allows the underlying infrastructure to be abstracted for applications and network services, treating the network as a logical or virtual entity. Figure 1 illustrates the basic architecture of SDN from a logical perspective. As depicted, the SDN architecture is divided into three layers: application, control, and infrastructure. * Applications Layer: These software programs execute specific tasks within an SDN environment, supplanting and expanding functions traditionally embedded in hardware devices of a conventional network. Examples of SDN applications include load balancing, security, or traffic engineering. * Control Layer: Serving as the core intelligence of an SDN network, the SDN controller receives instructions and requirements from the application layer. It translates and relays these instructions to network devices in the infrastructure layer. Centralized network management through automated SDN applications facilitates the deployment and modification of network services, making it quicker and more straightforward. * Infrastructure Layer: This layer is composed of the devices, which are network components that implement open standards (e.g., OpenFlow), enabling them to control forwarding and data processing capabilities within the network. The control plane and data plane are distinct layers resulting from the separation of control and forwarding functions, providing applications with more network state information compared with protocols used in traditional networks. This enhanced information dissemination is facilitated by the presence of the network controller proposed by SDN. This technology provides agility, enabling dynamic flow management and optimizing resources for the changing needs of applications run by users in the cluster, which may have varying requirements in terms of features and QoS [19]. Communication and interaction between SDN components occur through APIs (Application Programming Interfaces). The API between defined SDN applications and the SDN controller is commonly referred to as the northbound API. Conversely, the API defined between the SDN controller and SDN network devices is known as the southbound API. Figure 1: SDN functional architecture. The SDN technology provides a series of important benefits that are outlined below:  
* Improved automation and management. * Deliver new network services quickly and easily. * Implement a wide range of network policies. * Reduced costs. * Increased agility. * Improved security. On the other hand, NFV offers significant advantages in provisioning services in next-generation networks. This paradigm's primary goal is to decouple network functions from the physical devices on which they run. Moreover, NFV has the potential to facilitate and enhance the deployment of new services with greater agility [20], allowing for meeting the low latency and high-reliability requirements needed by applications [21]. Typically, deploying new sophisticated network services like firewalling, load balancing, IPS (Intrusion Prevention System), IDS, routing, or WAN optimization demands the acquisition of specialized and costly hardware-based appliances by enterprises. This process also involves the installation of new equipment, which requires physical space, increases energy costs, demands specialized knowledge, and occasionally presents integration challenges. NFV seeks to revolutionize the architecture of network operators by leveraging standard virtualization technology. This transformation aims to consolidate various types of network equipment onto standard high-volume servers, switches, and storage solutions prevalent in data centers, network nodes, and end-user premises.