A signaling network node is configured for identifying a received signaling message as belonging to one of a plurality of prescribed originating node groups, based on prescribed message class selection criteria. Each originating node group has at least one originating node and is assigned at least one congestion threshold relative to a message rate (e.g., messages per unit time or number of bytes per unit time). The signaling network node determines the message rate for each corresponding originating node group; if the message rate for an originating node group exceeds the corresponding at least one congestion threshold, the signaling network node outputs a congestion signaling message to the originating node having sent the signaling message, for reduction of the corresponding message rate.