Spanning tree is a link layer network protocol invented by Radia Perlman, that ensures a loop-free topology for any bridged LAN. Thus, the basic function of STP is to prevent bridge loops and ensuing broadcast radiation. As the name suggests, it creates a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches), and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes. The STP is a simple protocol, but what is the better way to remember it? Singing!

The spanning-tree protocol is used to cut loops that redundant links create in bridge networks. These packets are not attested by the system, so an attacker could spoof the BPDU and compromise the network stability! See below to understand BPDU attack: In this example the Ciscozine1 switch is elected Root Bridge due to the lower MAC-address (suppose that all the switches have the same priority).

The Spanning Tree Protocol is an OSI layer-2 protocol that ensures a loop-free topology for any bridged LAN. Spanning tree allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links. Bridge loops must be avoided because they result in flooding the network. The Spanning Tree Protocol (STP), is defined in the IEEE Standard 802.1D. As the name suggests, it creates a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches), and [...]