Although navigating a spanning-tree topology is a rather tedious process, it is usually the only way to verify that the STP is operating as it was intended. Many times, you will have a diagram of the switches in the network showing the physical or logical interconnections. The spanning-tree topology, however, usually goes undocumented until there is a problem.
You might have to troubleshoot a network that is foreign to you, or one that is not completely documented. In this case, you need to get an idea of the current active STP topology—especially the root bridge location.
Find the root bridge.