Quentin De Coninck

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.

Observing real smartphone applications over multipath TCP

A large fraction of smartphones have both cellular and WiFi interfaces. Despite this, smartphones rarely use them simultaneously because most of their data traffic is controlled by TCP, which can only use one interface at a time. Multipath TCP is a recently standardized TCP extension that solves this problem. Smartphone vendors have started to deploy Multipath TCP, but its performance with real smartphone applications has not been studied in detail yet. To fill this gap, we port Multipath TCP on Android smartphones, and propose a framework to analyze the interactions between real network-heavy applications and this new protocol. We use eight popular Android applications and analyze their usage of the WiFi and cellular networks (especially 4G/LTE).

Multipath QUIC: Design and Evaluation

Quick UDP Internet Connection (QUIC) is a recent protocol initiated by Google that combines the functions of HTTP/2, TLS, and TCP directly over UDP, with the goal to reduce the latency of client-server communication. It can replace the traditional HTTP/TLS/TCP stack and the IETF has chartered a working group to standardize it. QUIC encrypts all data and most protocol headers to prevent interferences from middleboxes. Motivated by the success of Multipath TCP (MPTCP), we design Multipath QUIC (MPQUIC), a QUIC extension that enables a QUIC connection to use different paths such as WiFi and LTE on smartphones, or IPv4 and IPv6 on dual-stack hosts. We implement MPQUIC as an extension of the quic-go implementation. We evaluate the benefits of QUIC and MPQUIC by comparing them with TCP and MPTCP in a variety of settings. MPQUIC maintains MPTCPs benefits (aggregation benefit, network handover). Without packet losses, while performance of single-path TCP and single-path QUIC are similar, MPQUIC can outperform MPTCP. In lossy scenarios, (MP)QUIC is more suited than (MP)TCP.

Poster: Evaluating Android Applications with Multipath TCP

Smartphones are the most popular mobile multihomed devices. End-user expects that thanks to their WiFi and cellular interfaces, they are able to seamlessly use all available networks. Unfortunately, reality tells us that seamless coexistence between cellular and WiFi is not as simple as what the user expect. Several cellular/WiFi coexistence technologies have been proposed during the last years. Some of them have been deployed. Recently, Multipath TCP received a lot of attention when it was selected by Apple to support its voice recognition (Siri) application. As of this writing, Siri is the only deployed smartphone application that uses Multipath TCP. and there is no public information about the benefits of using Multipath TCP with it. Multipath TCP is a TCP extension that allows to send data from one end-to-end connection over different paths. On a smartphone, Multipath TCP allows the applications to simultaneously send and receive data over both WiFi and cellular interfaces. It achieves this objective by establishing one TCP connection, called subflow, over each interface. Once the subflows have been established, data can be sent over any of the subflows. Researchers have analyzed the performance of Multipath TCP in such hybrid networks. However, these analyses have been performed with bulk transfers between laptops and servers. As of this writing, no detailed analysis of the performance of real smartphone applications with Multipath TCP has been published. We fill this gap in this paper by proposing a framework that automates user actions on Android smartphone applications to perform network measurements. We use it to analyze how eight popular smartphone applications interact with Multipath TCP.

Observing real Multipath TCP traffic

We analyse a Multipath TCP dataset collected from multipath-tcp.org consecutively in 5 months.Multipath TCP correctly passes through a wide range of Internet paths.Current implementations of Multipath TCP try to utilise additional paths as quickly as possible.Multipath TCP could be further improved in terms of traffic overhead and path management. 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 extension, little is known about its behavior in real networks. We analyze a five-month trace collected on multipath-tcp.org using Multipath TCP. This first detailed study of real Multipath TCP traffic reveals several interesting points about its behavior in the wild. With packets from thousands of hosts using IPv4 and/or IPv6, we confirm that Multipath TCP correctly passes through a wide range of Internet paths. We observe long Multipath TCP connections that benefit from handovers and also connections composed of subflows having very different round-trip-times. We also analyze some inefficiencies in the current Multipath TCP implementations and quantify the importance of reinjections, i.e. the transmission of the same data over two or more subflows.