Evaluating Multipath TCP Resilience against Link Failures

Standard TCP is the de facto reliable transfer protocol for the Internet. It is designed to establish a reliable connection using only a single network interface. However, standard TCP with single interfacing performs poorly due to intermittent node connectivity. This requires the re-establishment of connections as the IP addresses change. Multi-path TCP (MPTCP) has emerged to utilize multiple network interfaces in order to deliver higher throughput. Resilience to link failures can be better supported in MPTCP as the segments’ communication are maintained via alternative interfaces. In this paper, the resilience of MPTCP to link failures against several challenges is evaluated. Several link failure scenarios are applied to examine all aspects of MPTCP including congestion algorithms, path management, and subflow scheduling. In each scenario, the behavior of MPTCP is studied by observing and analyzing the throughput and delay. The evaluation of the results indicates MPTCP resilience to a low number of failed links. However, as the number of failed links increases, MPTCP can only recover full throughput if the link failure occurs on the server side. In addition, in the presence of link failures, the lowestRTT MPTCP scheduler yields the shortest delivery time while providing the minimum application jitter.