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.