This read-write enable/disable switch turns on or off the interface's reaction to Backward Explicit Congestion Notification (BECN) signals coming back from the Frame Relay network. An admin toggles it to decide whether the local device throttles its own sending rate when the network reports that traffic in the reverse direction is congested. For example, an admin troubleshooting steady throughput drops during peak hours might enable(1) BECN flow control so bursty senders back off automatically instead of continuing to flood a congested path.