Abstract: The no-symmetrical existing in networks routers means that “source-destination” and “destination-source” router
links are not always equal during topology discovery.It makes route-lost problem.Adding measure nodes can cause large flow. This paper proposes a method that it uses bidirectional way to discover the link which is hidden.Experiment show this algorithm
can find more links than other algorithms in same conditions，can cause less-load in network and can be fit for
large-scale networks.