ases the all-Ethernet network (on layer 2) with all-IP network (on layer 3) is becoming the reality on the two endpoints of the communication sessions, end-users on one end (either humans or machines) and data centers (where typically servers and data bases are located) on the other. Of course, communication can also be peer-to-peer (e.g. between users connected via Ethernet on both ends of the communication end-to-end session). Ethernet is used for all fixed access networks in the last meters (at home or office or at public places). The mobile access networks are based on completely different technolo- gies than Ethernet or WiFi on the lowest two layers of the protocol stack (i.e. physical and data-link layers, below the network layer where IP is positioned). Due to the widespread use of Ethernet access networks in LAN or MAN environments, Ethernet-based NGN is becoming increasingly important as a network architecture. In practice, main network nodes such as routers and gateways (which are routers with additional functionalities) have primarily Ethernet physical ports for interconnection with other network elements (other routers, multiplexers, etc.). The main idea for Ethernet in NGN is to use the Ethernet frame format throughout the NGN networks end-to-end, without frame conversion. However, for the purpose of QoS provisioning Ethernet frames (in the header) must contain information about the QoS, that is to have implemented IEEE 802.1Q standard. Ethernet-based NGN is intended for use of Ethernet technology over any physical media, including fixed and wireless (e.g. WiFi) environments (in the transport stratum of the NGN) in access, core, and transport networks [15], as shown in Figure 3.8. One should note that there are requirements to provide end-to-end Ethernet, such as user equipment needing to support the same Ethernet format for various existing tech- nologies, including capabilities for operation and maintenance, load sharing, protection and restoration; VPNs; virtual LANs; auto-configuration capability