User Network Interface

User Network Interface or more commonly known as UNI is a term used in the ATM technology and frame relay networks. As the name states it is an interface protocol, well this interface protocol is present in the ATM technology between the ATM end user and a private ATM switch, both of which are an essential part of the ATM technology and without which this technology cannot work. The end user is usually the client a person who is using this technology and the switch refers to the place in the ATM network from where the data is shared and transmitted throughout the network with the help of different services, belonging to different classes.

It is not at all necessary that this connection or interface is present only between the end user and the private ATM switch. It can be present between two devices that are connected at the ATM edges in a network, along with this application; this interface can also be applied between a private ATM switch and an ATM switch that is owned by the public carrier.

It should be noted that there is another interface technology too, named NNI, which stands for network to network interface, however, the role of NNI is quite different than the UNI or user network interface, so these two technologies shouldn’t be mixed up, which is quite a common error on the behalf of the network administrators.

In the networking world some of the major specifications are also defined for the UNI. These specifications are named Metro Ethernet Forum or MEF, which is responsible for defining a bi-directional Ethernet reference point for the Ethernet delivery services. The second specification that has been released for UNI is Optical Networking Forum which defines the UNI software interface for the user systems.