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Automatic discovery of physical topology plays a crucial role in enhancing the manageability of modern large Ethernet mesh networks. Despite the importance of the problem, earlier research and commercial network management tools have typically concentrated on either discovering active topology, or proprietary solutions targeting specific product families. Recent works - have demonstrated that physical topology can be determined using standard SNMP MIB, but these algorithms depend on Filtering Database and rely on the so-called spanning tree protocol (IEEE 802.1d) in order to break cycles, thereby avoiding the possibility of infinitely circulating packets and deadlocks. A previous work  requires that Filtering Database entries are completed; however it is a very critical assumption in a realistic Ethernet mesh network. In this paper, we have proposed a new topology discovery algorithm which works without the complete knowledge of Filtering Database. Our algorithm can discover complete physical topology including inactive interfaces eliminated by the spanning tree protocol in LEMNs. The effectiveness of the algorithm is demonstrated by an implementation.