The current trend of converging various network types, coupled with the rising traffic volumes and the increasing use of real-time and multimedia applications, has necessitated the transportation of diverse types of traffic, particularly those sensitive to latency. Traditional TCP/IP networks fall short in providing the required Quality of Service (QoS) for these applications, prompting the development of supplementary mechanisms to meet the necessary service levels. Additionally, the advent of new multimedia and cloud services, the expansion of the Internet of Things (IoT), and the integration of optical and wireless communications within the 5G optical network framework demand modifications to network infrastructure. These changes are essential to accommodate scalable traffic growth while simultaneously maintaining high levels of dynamic connectivity, complete flexibility, and enhanced energy efficiency. Within this context, QoS is crucial across all layers of the OSI model, ensuring effective and reliable data transmission within network systems.