Browsing by Author "Wang, Lei"

Nowadays many hosts have more than one network interface. For example, mobile smartphones are generally equipped with cellular network and WiFi network interfaces. If users can utilize all available network interfaces simultaneously, it allows a potential improvement in terms of network redundancy and performance. To use multiple network interfaces simultaneously, many multi- path communication networking protocols are proposed. At the transport layer, Multipath TCP (MPTCP) is a protocol for multipath communication, which in fact is an extension to regular TCP. MPTCP allows to spread the traffic onto several TCP subflows which take different network paths. Its advantage is the ability to balance the load, improve the connection resilience in case of path failure and maximize connection throughput. Congestion control and packet scheduling are two important components for MPTCP design. Congestion control is in charge of controlling induced network load, while packet scheduling is responsible for the distribution of data over multiple paths and improper scheduling decisions might introduce higher delay. Therefore, congestion control algorithms and packet schedulers are two components which greatly impact the performance of MPTCP. Four MPTCP congestion control algorithms, that is, Cubic congestion control algorithm, linked increases algorithm (LIA), opportunistic linked increase algorithm (OLIA) and wVegas algorithm, and two schedulers, that is, round robin (RR) scheduler and lowest RTT first (LowestRTT) scheduler, are deeply studied in the thesis. Furthermore, we design experiments to evaluate and compare the different MPTCP congestion control algorithms and packet schedulers. The experimental evaluation results show that Cubic congestion control algorithm could achieve highest aggregate throughput of all, but is less fair to competing flows than the others. OLIA can achieve similar aggregate throughput to LIA, but is more fair and responsive than LIA. OLIA is also more stable and responsive than LIA, while wVegas is unstable in terms of responsiveness to network changes. When compared with OLIA and LIA, wVegas behaves similar to OLIA but better than LIA in terms of fairness to competing TCP flows. As for two MPTCP schedulers, the results show that RR scheduler has a lower delay jitter than LowestRTT scheduler in rate limited traffic mode. Besides, LIA and OLIA have a lower delay jitter with LowestRTT scheduler than wVegas has.