At a network-connected device, congestion at an egress queue can be detected. A potential source of congestion can be identified based on characteristics of a packet that caused the egress queue to become congested. The source of congestion can be a congestion group of transmitters. A group congestion message can be sent to the group of transmitters. The message can identify the packet that caused the egress queue to become congested. Transmitters can respond to the message by reducing their peak transmission rate.