Multipath TCP Scheduling for Thin Streams: Active Probing and One-Way Delay-Awareness

Multipath TCP (MPTCP) is a recent TCP evolution that uses multiple TCP subflows and thereby different network paths for a single MPTCP connection. The MPTCP scheduler has a significant impact on the overall performance of MPTCP, as it maps outgoing packets on TCP subflows. In this paper, we identify limitations of today's MPTCP schedulers for thin streams. We present a novel MPTCP scheduler which overcomes today's limitations for thin streams by using i) active probing of unused subflows and ii) timely one-way delay information. A systematic evaluation within our MPTCP Linux Kernel implementation shows that our novel scheduler outperforms established MPTCP schedulers with regard to application-layer round-trip time without sacrificing efficiency and throughput.