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With the advantage of practical way to experiment with new network protocols in realistic settings, NOX and OpenFlow switch networks are becoming extremely popular. However, because of basic characteristics of NOX and OpenFlow switch based on the separation between control and data plane, every OpenFlow switch faces a long transmission and retransmission delay when it fails to transmit its data. Until now, the virtualized programmable networks only consider how to achieve the throughput for the direct link between OpenFlow switches. Since wireless channel experiences different conditions and NOX and OpenFlow switch networks supports the maximum flow size threshold, the aggregated flow size of a neighbor OpenFlow switch may be delivered faster than through the direct link if the neighbor link has higher RSS (Received Signal Strength). In this paper, we propose a flow-based hybrid mechanism to improve performance in NOX and wireless OpenFlow switch networks. The main idea of this scheme is that when the transmission of a OpenFlow switch fails, one of neighbor OpenFlow switches with better channel condition transmits the lost frame as well as the own data using flow aggregation scheme. To do so, every OpenFlow switch should manage overhear table to buffer the transmitted packets that is not yet acknowledged. We also present algorithms to retransmit lost packets, to maintain the overhear table and to compensate for the retransmission of packets of other OpenFlow switches. Simulation results show that the proposed flow-based hybrid mechanism can significantly improve the system throughput and the throughput gain.
Vehicular Technology Conference (VTC Fall), 2011 IEEE
Date of Conference: 5-8 Sept. 2011