Management of buffer space for the concurrent multipath transfer over dissimilar paths

Abstract

An efficient multipath transport is an emerging issue because it provides greater aggregated throughput than the usage of one active path. An extension of the stream control transmission protocol that serves the multipath transport is the concurrent multipath transfer (CMT-SCTP). Using the CMT-SCTP over dissimilar paths is a challenge. Two paths are dissimilar if they possess different characteristics such as bandwidth or delay. Moreover, CMT-SCTP maintains a common buffer at the sender and receiver. No matter how the paths differ in quality, the fast paths are unable in improving aggregated throughput because of the out-of-sequence data at the receiver. This out-of-sequence data may also cause buffer blocking. The current state-of-the-art technique suggests that, the buffer should be split through various paths, in accordance with the number of paths. The technique assigns an equal amount of buffer space to the slow and fast paths. This also limits the performance of fast paths because of the small parts of the buffer. We propose a buffer splitting technique (CMT-RTTA) that maintains the outstanding data over the paths based on RTT (round trip time). A destination with a shorter RTT will be allowed to occupy more buffer space than those with a longer RTT. Additionally, we adopted a priority where the sender transmits data to the destinations with shorter RTTs first, followed by the destinations with longer RTTs. To evaluate the performance of CMT-RTTA we have established a real Internet lab setup. The experiments show that CMT-RTTA improved the throughput of CMT-SCTP on average by 14% when the maximum bandwidth dissimilarity is applied.