As some of you reading this dive into metro ethernet you should know some terminology
• User-Network Interface (UNI): The UNI is a physical Ethernet port on the service provider side of the network along with a predefined set of parameters to provide data, control and management traffic exchange with the end-customer CPE device. The customer CPE device can be a Layer 2 Ethernet switch, Layer 3 routing node or some of LTE nodes.
• Network-to-Network Interface (NNI): NNI is represented by the physical Ethernet port on the service provider access node that is used to interconnect two Ethernet MANs of two different service providers. We are also using E-NNI as a reference point for the interconnection of Layer 2 MAN service with Layer 3 service nodes—the provider edge router (PE), a broadband network gateway (BNG), vertical handover (VHO), etc—in the provider network.
• Ethernet Virtual Connection (EVC) is the architecture construct that supports the association of UNI reference points for the purpose of delivering an Ethernet flow between subscriber sites across the MAN.