TCP在光突发交换试验网络中性能的实验研究

在光突发交换试验网络中对TCP的性能进行了实验研究.首先研究了丢包对网络性能的影响,表明突发包丢失将导致TCP吞吐量的快速下降,并且丢包率越高,可用的TCP传输带宽越窄.然后分别详细研究了OBS试验网络中的延时损伤和报文段关联增益,以及对TCP传输性能的影响.最后综合考虑这些因素.实验结果表明,在本OBS试验网络中存在一个不随丢包率变化的最优化突发包组装时间250us使得可用TCP带宽最大化.为了最大限度地提高TCP的传输性能,组包时间应该选择等于或稍大于这个最优值.

Experimental Study of TCP Performance on an Optical Burst Switching Network Testbed

Transmission Control Protocol (TCP) performance over optical burst switching (OBS) is experimentally investigated on OBS testbed. The effect of burst losses on TCP performance over the OBS testbed is studied. The result shows that burst losses will lead to a network wide drop in TCP throughput and higher burst loss probabilities will result in lower available TCP bandwidth. Then the effects of delay penalty and correlation benefit are investigated in detail. Taking into consideration these effects, experimental results show that there exists an optimal assembly period to maximize the TCP bandwidth, and the optimal value is about 250 μs in the testbed, which is independent of the burst loss probabilities. To make the OBS testbed work steadily and improve the performance of TCP over the testbed to the greatest extent, the chosen burst assembly period should be equal to or slightly greater than the optimal value.