ferent user types (the same performance as in TDM-based access and transport networks), reliability (in a similar manner as found in SDH transport networks, e.g. 50 ms link recovery after a failure), the possibility to guarantee the SLA, and provision of TDM emulation services [25]. There are two main types of interfaces in Carrier Ethernet: User-network interface (UNI). This is the interface between the customer network and the network operator, which separates the responsibilities between the end-user and the operator as network provider. NNI (network-network interface). This is the interface between two Carrier Ethernet networks. The bitrates on the physical interfaces are the same as those defined for the LAN Ethernet standards, which include 10, 100 Mbit/s, 1, 10, and further up to 100 Gbit/s in the 2020s. Further, each of the Ethernet services can be provided as port-based or as a VLAN service. The MEF defines Ethernet-based services in metropolitan areas by using Ethernet virtual connections (EVC). There are three main types of EVCs, also referred to as ser- vice types [26]: Ethernet line (E-Line). P2P EVC. Ethernet LAN (E-LAN). Multipoint-to-multipoint EVC. Ethernet tree (E-Tree). Routed multipoint EVC. There is also an operator virtual connection (OVC) when an EVC spans multiple Carrier Ethernet networks, SO end-to-end appears as a composition of segments (from different Carrier Ethernet networks) concatenated with the aim of forming an EVC. Such segments are in fact OVCs, the association of UNIs and ENNIs (external network to network interfaces) within a single Carrier Ethernet network. The QoS for EVC-based services is implemented by using several IEEE standards, which include IEEE 802.1Q for VLAN [27], IEEE 802. lad for provider bridges [28], and IEEE 802.1ah for provider backbone bridges (PBBs) [29]. Virtual LAN (VLAN). The E-Line service uses the IEEE 802.1Q standard for VLANs. They are created to provide virtualization of the Ethernet infrastructure, SO the differ- ent traffic can be separated into