A First Analysis of Multipath TCP on Smartphones

Multipath TCP is a recent TCP extension that enables multihomed hosts like smartphones to send and receive data over multiple interfaces. Despite the growing interest in this new TCP extension, little is known about its behavior with real applications in wireless networks. This paper analyzes a trace from a SOCKS proxy serving smartphones using Multipath TCP. This first detailed study of real Multipath TCP smartphone traffic reveals several interesting points about its behavior in the wild. It confirms the heterogeneity of wireless and cellular networks which influences the scheduling of Multipath TCP. The analysis shows that most of the additional subflows are never used to send data. The amount of reinjections is also quantified and shows that they are not a major issue for the deployment of Multipath TCP. With our methodology to detect handovers, around a quarter of the connections using several subflows experience data handovers.