ReMP TCP: Low Latency Multipath TCP

More and more Internet-enabled devices, such as server instances or smartphones, have multiple network interfaces. Multipath TCP (MPTCP) has proven to increase bandwidth for these devices, while remaining compatible with the existing network infrastructure and applications. For interactive applications and services, however, low latency and low jitter often is more important than bandwidth. In this paper, we rethink the MPTCP approach, focusing on end-to-end latency and jitter. We propose ReMP TCP, an MPTCP extension that sends data redundantly over multiple paths in the network. Exchanging bandwidth for latency, this approach guarantees the lowest possible latency in existing best-effort networks. The integration into the MPTCP protocol provides benefits such as transparent end-to-end connection establishment, multipath-enabled congestion control, and the prevention of head of line blocking. We discuss end-to-end latency in multipath environments considering both queuing delays and packet drops. Further, we evaluate the performance of our ReMP TCP Linux Kernel implementation for data center and mobile scenarios in Mininet and real world experiments. We show for a real world mobile scenario in a stressed environment that ReMP TCP can halve the average round-trip time and reduce its standard deviation by a factor of 19.