Retransmission policies for concurrent multipath transfer using SCTP multihoming

Concurrent multipath transfer (CMT) uses the stream control transmission protocol's (SCTP's) multihoming feature to distribute data across multiple end-to-end paths in a multihomed SCTP association. We propose five retransmission policies for CMT. We demonstrate the occurrence of spurious retransmissions in CMT with all of the five policies, and propose an amendment to the timeout retransmission mechanism to avoid spurious retransmissions. We also modify the Cwnd Update for CMT (CUC) algorithm to allow better cwnd growth in CMT with the different retransmission policies. We then evaluate the retransmission policies using ns-2 simulations, and discuss the distributions of traffic that result. We operate under the strong assumptions that the receiver's advertised window does not constrain the sender, and that the bottleneck queues on the end-to-end paths used in CMT are independent.