SRPT-ECF: challenging Round-Robin for stream-aware multipath scheduling

Multipath TCP has long been the standard multipath transport protocol. However, the recent introduction of Multipath QUIC has changed the landscape by allowing multiple streams to coexist, bringing opportunities for further optimization but also a new set of challenges. New stream-aware scheduling algorithms are necessary to account for this new variable. We show that, perhaps counter-intuitively, serving streams using a Round-Robin strategy yields poor performance when looking at stream completion time. We then describe SRPTECF, our novel stream-aware multipath scheduling algorithm. We show that our algorithm is optimal in a simple network model and that it exhibits good properties on HTTP/2 traces. We then sketch how it could be implemented within Multipath QUIC to schedule web resources with HTTP/2, paving the way for low-latency multipath HTTP/3 implementations.