Congestion management detects congestion in a network and resolves it, e.g., by dropping or marking packets. A challenge is to drop or mark the right packets if fair capacity sharing is desired, especially if a few heavy users monopolize the bandwidth, e.g., by opening many flows or using non-responsive transport protocols. To this end, we propose activity-based congestion management (ABC). Users are assigned reference rates and their traffic is equipped with activity information. The activity indicates by which factor the transmission rate of a user exceeds his reference rate. ABC leverages active queue management (AQM) in routers or switches and uses the packets' activity information to adapt the drop or mark probabilities of the AQM. ABC is scalable as switches do not require user states, multiple queues, or signalling. We investigated ABC by means of simulation under conditions where a heavy user wants to monopolize a bottleneck's bandwidth. ABC provides an ecosystem where users with non-responsive constant-bitrate (CBR) traffic can maximize their throughput on a congested bottleneck link by adapting their sending rate to their fair share induced by their reference rate. Users with responsive TCP traffic obtain approximately fair capacity shares. Moreover, ABC protectes TCP traffic when competing with traffic from CBR users. We investigate the impact of system parameters and give recommendations for configuration.
