The physical topology discovery for switched Ethernet based on connections reasoning technique

Accurate and up-to-date knowledge of topology serves as the base of a number of network management functions, such as performance monitoring and evaluation, fault detection and location, resource allocation and etc. Firstly the main achievements in topology discovery for LAN are introduced and the defects of those methods are pointed out in this paper. Then the basic theories for connections reasoning technique (CRT) based on the predication logic are proposed. This technique translates the topology discovery into a math problem of logic reasoning, so that topology of LAN can be studied by mathematic tools. A new algorithm for topology discovery based on this mechanism is proposed in this paper. Compared with current discovery algorithms, this method excels in: 1) making use of AFT more effectively in topology discovery, so the whole topology can be build up by just a part of AFTs; and 2) naturally resolving the problem of topology discovery for multiple subnet switched domain.