... many as for a full mesh Chapter 3: Frame Relay CCNA Exploration 4.0 47Configuring Frame Relay Subinterfaces 6Introducing Frame Relay ãCost Effectiveness of Frame Relay Customers only pay ... Relay cloud.–Some networks use Frame Relay itself, but others use digital circuit switching or ATM cell relay systems. 44 Frame Relay Flow Controlã Frame Relay reduces network overhead by ... that control the Frame Relay congestion-notification mechanisms. The FECN, BECN, and DE bits are the last three bits in the Address field. 8The Frame Relay WANã Frame Relay has lower overhead...