中文摘要：

针对现有的数据流流量测量概率多重计数方法空间复杂度高和空间利用率低的问题,提出了一种基于两层位域的数据流流量测量方法.该方法分为两个步骤：数据捕获阶段.将到达数据包采用两个独立的哈希函数分别映射至两层位域;数据恢复阶段.对位域恢复得到的两个虚拟矩阵按位取交集,消除哈希碰撞引起的误差.实验结果表明,和概率多重计数方法相比,两层位域方法在存储空间降低75%的前提下,仍具有高的数据流估算精度.

英文摘要：

It is extremely difficult to measure traffic information with a growing network link speed.In recent years,increasing focus has been put on probabilistic algorithms which are fast enough to examine all packets and can provide estimates of the sizes of all flows.However,the previously proposed flow estimating algorithm of PMC has the drawbacks of poor space efficiency and large estimation error.To address the problem,a double bit field（D-BF）algorithm is proposed.The method is divided into two steps：the newly arrived packet is mapped to two bit fields using different hash functions in the data capturing stage;two virtual matrixes recovered from the bit fields have been intersected to eliminate errors caused by the hash collision in the data recovering stage.Experimental results show that the proposed D-BF is more accurate than PMC in flow estimate,while a reduction of 75%in memory space can be achieved.