Devices, networks, systems, methods, and processes for congestion signaling in a communication network are provided herein. The congestion signaling may be performed from a lower protocol layer circuit of a network device of the communication network to a higher protocol layer circuit of the network device. The lower protocol layer circuit may maintain a Low Latency, Low Loss, and Scalable throughput (L4S) data queue. The L4S data queue may buffer one or more L4S data packets of at least one L4S data flow for transmission. The lower protocol layer circuit may further detect a congestion in the L4S data queue and transmit, to the higher protocol layer circuit, a congestion signal configured to indicate the detected congestion. The transmission of the congestion signal may enable the higher protocol layer circuit to mark one or more subsequent L4S data packets of the L4S data flow to indicate the congestion.