Which of the following frame relay flow control mechanisms is used to signal routers that they should reduce the flow rate of frames?

FECN (Forward Explicit Congestion Notification) is a Frame Relay mechanism set by the network to signal congestion. When a frame experiences congestion, the network marks it with FECN, and the destination device can then use BECN (Backward Explicit Congestion Notification) to signal the source to reduce its transmission rate. DE (Discard Eligibility) is used to mark low-priority frames that can be dropped during congestion, while CIR (Committed Information Rate) is the guaranteed bandwidth. BECN signals the source directly about congestion.