Performance Evaluation of Multipath Transport Protocol in Asymmetric Heterogeneous Network Environment

Performance of multipath transport protocols is known to be sensitive to path asymmetry. The potential difference between each path in terms of bandwidth, delay and packet-loss significantly decreases the overall performance when a single data flow is carried over multiple asymmetric paths. In this paper, we evaluate and analyse Concurrent Multipath Transfer extension of Stream Control Transport Protocol (CMT-SCTP) under various scenarios of network asymmetry. We identify various causes of performance bottle-neck under different asymmetric scenarios, review the impact of delayed SACK under path asymmetry and show that the total achievable good-put of a reliable inorder data flow over multiple heterogeneous paths is ruled by the characteristics of the perceived worst path by the transport protocol. Finally to support our study, we derive a simple analytical proof to support our simulated experimental results of NS-2.