关键词: NT,链路利用率，链路性能推断，EM算法

Abstract: The link utilization is an important parameter to describe the running state of the network. At present the research on the link parameter inference technology of network tomography is based on the single source measurements.And the multiple source network tomography has many advantages. I}hc link utilization estimation technology based on multiple source tomography was researched. The joining measurement method was proposed and multiple source link utilization is identifiable if the network is measured by the new method. Furthermore, the necessary and sufficient condilion of the measurement sub-network selection to make the link identifiable was proposed. At last, the maximum likelihood estimation of link utilization computed by the EM algorithm was derived and the effectiveness of that was validated by the model simulation and network simulation results.

Key words: Network tomography, Link utilization, Link parameter inference, EM algorithm