Accurate-ECN: An ECN Enhancement with Inband Network Telemetry

On one hand, the congestion notification mechanism Explicit Congestion Notification (ECN) can only provide coarse-grained congestion signal, which is not sufficient to indicate accurate network and congestion status. On the other hand, the emerging learning-based intelligent congestion control and route selection mechanisms require fine-grained network states information to take accurate actions. This calls for the development of enhanced ECN mechanism to provide precise congestion information and network states. In this work, we design Accurate-ECN, an enhancement of ECN with Inband Network Telemetry (INT) to collect and report detailed network congestion states by attaching network state metadata to the data packets and send back to the sender through TCP ACK by the packet receiver. We designed the Accurate-ECN frame format and the data packet parsing process, and implement the mechanism through the P4 language. Finally, through evaluation, Accurate-ECN is demonstrated to provide various precise network states under different congestion levels.