What is Spanning Tree Protocol (STP)?
Spanning Tree Protocol (STP) is an OSI layer-2 protocol which ensures a loop free topology for any bridged LAN. It is define in the IEEE 802.1d spanning tree where STP is created within a mesh network of connected layer-2 bridge. It disables the links which are not part of that tree and leaves a single active path between any two network nodes. To explain how STP works, we can look at the simple network in the diagram. The network exist two pathways to any specific switch. This redundancy in network will sometime cause loop dilemma. This is when STP comes into play. It can block any specific port so that only one pathway is available to any given switch. Also, when a main link fails, it can easily redirect traffic to the other route to achieve fail-over solution for the network.
