物理拓扑结构发现的目标是确定网络中的各种设备以及这些设备物理端口之间的链路连接关系，这对于网络性能监测与评估、故障发现与定位、资源分配与管理等一系列维护工作具有重要意义。本文所提供的基于谓词逻辑推理和基于生成树协议的优化拓扑发现算法，在AFT数据不完全的情况下，能够有效计算出网络节点信息，从而克服了现有链路层网络拓扑发现方法的不足，提高了获得网络物理拓扑的可能性。

The objective of the physical topology discovery is to determine the connection relationship between various equipments in the network and the link between physical ports, which is very important for maintenance work, and with which the performance of the network can be monitored and evaluated efficiently and the fault discovery and positioning is also made easy. This paper proposes an optimization algorithm based on the predicate logic reasoning and the spanning tree protocol. It can effectively compute node information under the circumstances that the topology discovery AFT(Address Forwarding Table) data are incomplete. Thus the algorithm can overcome the shortcomings of the existing link layer network topology discovery, to obtain a possible physical topology network. This paper provides a new way to discovery link layer topology, with the link deducation technology, "to repair and revise" the uncomplete root AFT data. The shortcomings of the predicate logic and STP(Spanning Tree Protocol) algorithm are remedied, and the advantages are taken.