Feedback-Based Path Failure Detection and Buffer Blocking Protection for MPTCP

A multipath TCP (MPTCP) is a promising protocol that has been standardized by the Internet Engineering Task Force to support multipath operations in the transport layer. However, although the MPTCP can provide multiple transmission paths and aggregate the bandwidth of multiple paths, it does not consistently achieve more throughput (goodput) nor a greater connection resilience. Currently, the MPTCP is vulnerable to path failure or underperforming subflows, which cause transmission interruption or throughput (goodput) degradation. Unfortunately, there is no exact rule for declaring a path failure or preventing the usage of underperforming subflows in the MPTCP. In this paper, we propose a novel path failure detection method referred to as feedback-based path failure (FPF) detection. In addition, we propose a new decision method called buffer blocking protection (BBP) to address the underperforming subflows for the MPTCP. Measurement results indicate that the FPF detection reduces transmission interruption time by the fast path failure decision, which can prevent duplicate transmission interruption events and unnecessary retransmissions. Furthermore, the FPF detection is sufficiently robust in terms of packet loss and the delay difference between paths. The results additionally show that the BBP method prevents goodput degradation due to underperforming subflows. Consequently, the MPTCP with the BBP method can at least achieve the throughput performance of a single Transmission Control Protocol (TCP), which uses the best path regardless of the delay difference between paths.