Comparison of Multipath TCP and CMT-SCTP based on intercontinental measurements

The market penetration of access devices with multiple network interfaces has increased dramatically over the last few years. As a consequence, there is a strong interest to use all of the available interfaces concurrently to improve data throughput. Corresponding extensions of established Transport protocols are receiving considerable attention within research and standardization. Currently two approaches are in the focus of the IETF: The Multipath TCP (MPTCP) extension for TCP and the Concurrent Multipath Transfer extension for SCTP (CMT-SCTP). This paper evaluates and compares implementations of these two loadsharing protocols by using both lab measurements and intercontinental testbed realized via the Internet between Europe and China. The experiments show that some performance critical aspects have not been taken into account in previous studies. Furthermore, they show that the simple scenario with two disjoint paths, which is typically used for evaluation, does not sufficiently cover the real Internet environment. Based on these insights, we highlight that the different path management strategies of the two protocols have a significant impact on their performance in real Internet scenarios.