CCIE Practical Studies: Security (CCIE Self-Study)

Network-to-Network Interface

One item of concern for a service provider is the possibility that a Frame Relay network can cross between two networks that might not be Cisco equipment. Because each vendor supports Frame Relay standards, these vendors are also given the option of providing customizations to differentiate their product from another vendor's product.

To facilitate intervendor communication, the Network-to-Network Interface (NNI) port was defined as a bidirectional protocol to allow configuration, administration, and control information to be communicated between two networks. NNI consists of two independent unidirectional signaling protocols, one from each network, to provide bidirectional communications.

NNI supports status exchanges ...