Concurrent Multipath Transfer during path failure

We investigate how path failure influences Concurrent Multipath Transfer (CMT) using SCTP multihoming. We show that CMT suffers from significant “receive buffer blocking” which degrades performance during both permanent and short-term failure. To improve performance, we introduce a new “Potentially-Failed” (PF) destination state, and revise CMT’s failure detection and (re)transmission policies to include the PF state. Using simulation, we demonstrate that the modification called CMT-PF outperforms CMT during failure – even with aggressive failure detection thresholds and varying receive buffer constraints. In non-failure scenarios, CMT-PF performs on par or better but never worse than CMT. Finally, we confirm these simulation results using FreeBSD implementations of CMT and CMT-PF. Based on our findings, we recommend CMT-PF be used in existing and future CMT implementations and RFCs.