It aims to minimize the number of occurrences of user perceived congestion. Frame relaying networks should not allow users to monopolize network resource usage at the expense of other users.
Congestion control includes both congestion avoidance and congestion recovery mechanisms.
The user data received will be as the data sent except the address and FCS field which can be modified by the network. The network does not guarantee message delivery therefor frames may be dropped. Frame relay networks using in-band congestion signaling report congestion by using bits in the frame address field. The network is able to inform end stations about congestion by using two fields in the frame address field. The FECN bit will be set in frames flowing in the direction in which the network is experiencing congestion.