User-space Multipath TCP performance analysis

Abstract

Abstract The Transmission Control Protocol (TCP) is widely used for network communication due to its reliability, but it struggles with utilizing multiple network interfaces in modern devices like smartphones. To address this, the Internet Engineering Task Force (IETF) proposed the Multipath TCP (MPTCP) protocol, which can leverage multiple interfaces. The main implementation of MPTCP is integrated into the Linux kernel, but newer technologies like the Data Plane Development Kit (DPDK) enable user space packet processing without relying on the kernel. However, existing user space packet processing methods lack support for MPTCP, which requires services provided by TCP. Some open-source projects aim to bridge this gap by modifying user space TCP/IP stacks to support MPTCP, potentially leading to performance improvements similar to TCP. In this research a user-space MPTCP stack will be implemented for performance analysis purposes. This MPTCP implementation was built upon an existing userspace TCP stack, mTCP. To evaluate its functionality, we set up an Nginx server running on a multipath TCP in-kernel implementation. Subsequently, we deployed a user-space client containing our modified MPTCP implementation and initiated communication between the client and server instances. The evaluation involved the utilization of profiling tools to assess the performance of the developed MPTCP implementation. The obtained results were analyzed and discussed, highlighting findings and implications. Specifically, it was found that the developed implementation had a performance deterioration of 85% w.r.t. the kernel-space MPTCP implementation and a deterioration of 34.25% w.r.t. the user-space mTCP (TCP/IP) stack used as the base TCP/IP stack upon which the user-space MPTCP stack was built. Finally, the study addresses inherent limitations and suggests directions for future research.