A network system (10). The system comprises a first network node (N.sub.6), and the node comprises an input (30.sub.IN) for receiving packets. During operation, the first network node operates as a downstream node when receiving packets at the input from an upstream node (N.sub.5). The node also comprises a buffer (30), coupled to the input and for storing received packets, and circuitry (32) for detecting when a number of packets stored in the buffer exceeds a buffer storage threshold. The node also comprises circuitry (32), responsive to a detection by the circuitry for detecting that the number of packets stored in the buffer exceeds the buffer storage threshold, for issuing a message to the upstream node. The message selectively commands the upstream node to reduce a rate of transmission of packets from the upstream node to the downstream node to a non-zero rate.