The Private Network to Network Interface is a routing protocol for ATM
networks. It enables the creation of private virtual circuits (PVC)
over wide areas across any number of PNNI enabled ATM switches defining
only the endpoints (edge devices) without defining the connections on the
intermediate switches (inside the ATM cloud). This protocol dynamically
assigns and creates the circuit, allowing for routing around malfunctioning
areas and better load distribution according to the requested bandwidth and
Quality of Service (QoS).
Currently on version 1.0, PNNI is a standard protocol defined by the ATM
Forum.
Source: OmniSwitch/OmniRouter User Manual, chapter 14 (Configuring and
Monitoring PNNI).