网络拓扑的自动发现在现代网络管理中非常重要，本文在已有研究成果的基础上，着重于以太网多层网络拓扑自动发现，提出一种基于SN禅协议的新的自动拓扑发现算法。该算法包括逻辑拓扑发现和物理拓扑发现两个部分:在逻辑拓扑方面，只需要网管人员知道管理主机IP即可自动搜索一个网络管理域的拓扑结构 在物理拓扑发现方面，本算法和已有算法相比，降低了交换机的转发地址表(AFTAddresoForwarding Table)的信息要求，同时能够发现各个子网中哑设备(DumbDeviceS)的存在及其与周边设备的连接关系。本以太网拓扑自动发现算法具有简洁、高效的特点，能自动发现通信网内路由器(Routers)、子网(Subnet)、交换机(Swltche:)以及终端主机(Hosts)之间逻辑连接结构和物理连接结构。-It is a very important task to discover the network topology automatically in modern network management. Based on achievements that have existed, this paper presents a new snmp-based algorithm of discovering network topology automatically. This algorithm includes logic topology discovering and physical topology discovering. Network administrator just input ip address of the management host, then it can get all the logic topology view of an network management domain, it is completely automatic　 as to the physical discovering, this algorithm decreases the requirements of AFT of switches, compared with other algorithms. Furthermore, it can detect dumb devices and the link relationship with other devices around them. This automatic discovering algorithm features its simpleness and effectiveness, it can get logic and physical link relationship of all active nodes, including routers, subnets, switches and terminal hosts.