阐述了网络层拓扑发现与数据链路层拓扑发现之间的区别,分析了数据链路层拓扑发现的研究现状和存在的不足。为改进这一不足,在总结子网内部的直接连接定理和间接连接定理的基础上,提出了一种新的数据链路层拓扑发现算法,并结合该算法,利用树的后序遍历算法作为拓扑图形的显示方法,开发了具有数据链路层拓扑发现功能的网络拓扑系统。 The differences between topology discovery at the network layer and topology discovery at the data link layer are described, and the research status and existing problems of topology discovery at the data link layer are analyzed. In order to improve this problem, this paper proposes a new data link layer topology discovery algorithm based on summarizing the direct connection theorem and indirect connection theorem in the subnet. Combining with this algorithm, we use the tree postorder traversal algorithm as Topology graphics display method, the development of a data link layer topology discovery network topology system.