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We introduce an inline measurement method that can overcome difficulties in measurement task in high-speed network environment, such as short packet transmission intervals and Interrupt Coalescence function deployed in the high-speed Network Interface Cards. The method adjusts the number of packets involved in a packet burst of an active TCP connection, and utilises the inter-intervals of the bursts of the corresponding ACK packets for bandwidth measurement. Experiment results show that the proposed inline measurement method can measure the bandwidth in the network paths at least 1-Gbps or higher.

Abstract-In high-speed networks, such as 1-Gbps or higher networks, bandwidth measurement algorithms that utilize packet transmission/arrival intervals, such as packet trains and packet pairs, have a number of problems. First, network measurement for large bandwidth requires short packet transmission intervals, which causes a heavy load on the CPU. Second, network interface cards for high-speed networks usually employ Interrupt Coalescence (IC), which rearranges the arrival intervals of packets and causes bursty transmission of packets. In the present study, we introduce ICIM (Interrupt Coalescence -aware inline measurement ), a new bandwidth measurement approach that overcomes these two problems. ICIM utilizes the data packets of an active TCP connection for the measurement. In order to determine the available bandwidth, rather than adjusting the packet transmission intervals, the TCP sender instead adjusts the number of packets involved in a burst and checks whether the inter-intervals of the bursts of corresponding ACK packets are increased or not. Simulation results show that ICIM can measure the bandwidth as high as some Gbps while requiring a number of data packets that is only 1/100 of that of the existing stream-based algorithm.

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