Methods and systems for managing packet flow in a local network in a manner that allows network devices at the edge of the network to use minimal buffer memory while maximizing use of bandwidth allocated on an interconnect between the local network and an external network. Packet flows facing external network problems are scaled back, reducing redundant traffic on the interconnect and allowing for use of small buffers in edge devices. A flow source marks a subset of packets within a flow for preferential treatment within the local network. The flow source then adjusts the flow rate only responsive to failures in transmission of the marked packets. In some implementations, an edge device removes the markings prior to packet egress. The local network honors the preferential treatment markings such that a loss of a marked packet is more likely to occur on an external network than on the local network.