基于掩码匹配的报文双抽样方法

基于掩码匹配的报文抽样算法是一种实用性较强的分布式流量抽样算法,但是该算法在测量报文到达时间间隔的分布这一重要网络流量特征时性能较差。首先根据误差理论分析了产生这一问题的原因,为了降低测量的系统误差,在原算法中引入了双抽样的改进方案。考虑到改进后的算法会给测量系统带来额外的负担,提出了增加了抽样掩码位数的解决办法,并且论证了其可行性。最后基于实际的网络流量数据进行了实验验证,结果表明：改进后的算法测得的报文到达时间间隔的分布符合真实的分布情况,并且对其它网络性能指标的测量精度影响较小。

A Packet Double Sampling Method Based on Mask Matching

The packet sampling algorithm based on mask matching is a practical distributed traffic sampling algorithm. But the algorithm is ineffective in measuring an important network traffic characteristic, which is the distribution of packet arrival time interval. First of all, the reason leading to the problem is analyzed according to the error theory. Then, an improved program of double sampling is introduced in the initial algorithm in order to reduce the system error of measurement. As the improved algorithm will bring extra burden to the measurement system, a solution which is to increase the sampling mask bits is put forward and its feasibility is demonstrated. Finally, the improved algorithm is tested with the actual network traffic data. The experiment results show that the measurement of the distribution of packet arrival time interval is in line with the real situation. And it has little effect on the measurement accuracy of other network performances.