Network - to - network interface between public data networks providing the frame relay data transmission service 提供帧中继数据传输业务的公用数据网之间的网络?网络接口
百科解释
In telecommunications, a network-to-network Interface (NNI) is an interface which specifies signaling and management functions between two networks. NNI circuit can be used for interconnection of either signalling (e.