network to network interface (ATM) (NNI)

The Network to Network Interface (NNI) is a specification for the interface between different networks and service providers, for example between public networks and user networks.

ATM interfaces

For frame relay, these specifications were developed by the Frame RelayForum; for ATM, they were developed by the ATM Forum. The ATM Forum has developed two different interfaces: One interface is called NNI or public NNI and forms the interfaces between ATM nodes, the second interface refers to the interface between public ATM nodes and private networks. This interface is called private NNI or Private Network to Network Interface( PNNI).