Fun with the Spanning Tree Protocol

Main task of STP protocol is automated management of network topology with redundant channels. In general, almost all type of networks are unable to accept loops(rings) in their structure. Really, if network equipment is connected with superfluous lines, then without additional measures frames would be delivered to recipient as a several one - this would result in a fault.

But business require redundancy, thus there is an STP - it takes care that all physical loops are logically disabled unless one of lines gives a fault - in this case STP enables line that is currently in reserve. STP should guarantee that at each point of time only one of several duplicate links is enabled & should automatically switch between them on demand (fault or physical topology change).