Performance comparison of congestion control strategies for multi-path TCP in the NORNET testbed

Multi-path transport has become a hot topic in Internet protocol research with the evolution of emerging technologies, particularly with the market penetration of access terminals having multiple network interfaces (e.g. smartphones with LTE/UMTS and Wi-Fi interfaces). Multi-Path TCP (MPTCP) is an extension of TCP that allows a connection to create several subflows for utilizing multiple network paths. Using multiple end-to-end TCP connections as subflows, MPTCP distributes data to different subflows over multiple ISPs, so as to enhance network robustness and improve throughput. This paper first presents MPTCP's architecture and multi-path congestion control algorithm concepts. Then, it examines three test scenarios in the NORNET testbed, particularly highlighting the performance difference between using uncoupled and coupled congestion controls in multi-homed, real-world Internet setups. The results show that MPTCP with coupled CCs gets more benefits than TCP and demonstrates the lower aggressiveness in comparison to MPTCP with uncoupled CCs.