Explanation/Reference:
http://www.cisco.com/en/US/docs/switches/metro/me3400/software/release/12.2_25_ex/configuration/ guide/swcdp.html Cisco ME 3400 Series Ethernet Access Switches allow the following port types to be provisioned:
*User network interface (UNI)-The demarcation point between the service provider and the customer network. UNIs connect to hosts, such as IP phones and other devices. By default, a UNI port is in disabled admin state; it blocks any Layer 2 control protocol such as CDP and STP.
*Enhanced network interface (ENI)-Provides the same functionality as the UNI port. However, ENIs can be configured to pass Layer 2 control protocols, including:
-CDP
-LLDP
-STP
-EtherChannel Link Aggregation Control Protocol
-Port Aggregation Protocol
*Network-to-network interface (NNI)-The demarcation point between service provider networks. NNI ports are used to connect to other Ethernet switches or routers and are in the enabled admin state by default.
NNI ports do not have any filtering restrictions.
Each port type has specific default characteristics that determine its functionality. For example,10/100M ports are generally configured as UNIs with two SFPs configured as NNIs (Cisco ME 3400-24TS). Each port can be configured as another type and subsequently, the port inherits the default behavior of the additional type.
The Cisco ME 3400 Series switches allow the provisioning of UNI-ENI VLANs. UNI-ENI VLANs are associated to a UNI-ENI port connected to CE devices on the customer network and used to isolate traffic arriving at the VLAN from different customers. UNI-ENI VLANs can have two states: isolated and community. In the default isolated state, the VLAN does not forward traffic between any UNI-ENI ports.
Traffic can pass between NNIs and between NNI and UNI-ENI ports. In community state, the VLAN passes traffic between UNI-ENI ports without any restrictions.
In Cisco ANA NetworkVision, UNI-ENI VLANs are identified in the VLAN Type property under the Bridges logical inventory. Port types are displayed under the physical inventory port properties