Frame relay is a protocol for routing frames through the network based on the IP address field (data link connection identifier) in the frame and for managing the route or virtual connection.
Frame-relay networks in the U.S. support data transfer rates at T1 (1.544 mbps) and T3 (45 mbps) speeds. You can think of frame relay as a way of utilizing existing T1 and T3 lines owned by a service provider. Most telephone companies now provide Frame Relay service for customers who want connections at 56 kbps to T1 speeds. (In Europe, Frame Relay speeds vary from 64 kbps to 2 mbps. In the U.S., Frame Relay is quite popular because it is relatively inexpensive. However, it is being replaced in some areas by faster technologies, such as asynchronous transfer mode (ATM).