Frame relay: protocols and private network applications

The authors discuss possible protocols for both data transfer and connection control in frame relay and describe the application of frame relay in private ISDN-based networks. First, the functions and frame structure associated with the frame sublayer and the operation of the frame-relaying process are reviewed. Then, the Q.931 procedures are examined for control of frame-relay connections at user-network interfaces, as well as the transport of the associated Q.931 messages across these interfaces, for several scenarios. Finally, the use of frame relay as a transport mechanism is described for all forms of packet-oriented traffic in private networks, focusing in particular on the synergy between the use of Q.931 procedures with appropriate extensions for inner-node signaling and the use of frame-relay to transport Q.931 messages within the network. Possibilities are briefly suggested for the evolution of private networks with frame relay into integrated packet networks