Hercules: Heterogeneous Requirements Congestion Control Protocol
Neta Rozen-Schiff, Itzcak Pechtalt, Amit Navon, Leon Bruckman
TL;DR
The paper tackles the problem of highly heterogeneous QoS requirements under congestion by introducing Heterogeneous Requirements Fairness (HRF) and an online-learning congestion control protocol called Hercules. HRF defines fairness as the lexicographical max-min of normalized per-connection rates $\overline{x_i} = (x_i-a_i)/(b_i-a_i)$, guiding a rate-control strategy that combines an arctan-based penalty $H(\overline{x_i})$ with per-flow metrics (loss and RTT). Hercules implements this strategy as a QUIC module with a rate-control loop (slow-start, probing, moving) that converges to HRF, and it is evaluated against CUBIC, BBR, Reno, and Vivace, showing up to $3.5\times$ QoS gains and robust convergence. The results suggest a scalable path to fine-grained, heterogeneous congestion control in modern networks, with potential extensions to infer requirements from traffic content.
Abstract
Future network services present a significant challenge for network providers due to high number and high variety of co-existing requirements. Despite many advancements in network architectures and management schemes, congested network links continue to constrain the Quality of Service (QoS) for critical applications like tele-surgery and autonomous driving. A prominent, complimentary approach consists of congestion control (CC) protocols which regulate bandwidth at the endpoints before network congestion occurs. However, existing CC protocols, including recent ones, are primarily designed to handle small numbers of requirement classes, highlighting the need for a more granular and flexible congestion control solution. In this paper we introduce Hercules, a novel CC protocol designed to handle heterogeneous requirements. Hercules is based on an online learning approach and has the capability to support any combination of requirements within an unbounded and continuous requirements space. We have implemented Hercules as a QUIC module and demonstrate, through extensive analysis and real-world experiments, that Hercules can achieve up to 3.5-fold improvement in QoS compared to state-of-the-art CC protocols.
