Spanning Tree Protocol (STP) is a networking protocol that is used to prevent loops from forming in a network. Loops in a network can occur when there are multiple paths between two devices, which can lead to broadcast storms, MAC table instability, and other issues. STP works by identifying all of the potential paths between devices and then disabling all but one of the paths to prevent loops from forming.
STP uses a process called the Spanning Tree Algorithm (STA) to determine the best path to use. The STA works by electing a root bridge, which is the switch that is at the top of the spanning tree. Once the root bridge is elected, the STA then assigns a cost to each of the links in the network, with the lowest cost path being the one that is used to forward traffic. The STA then sends out BPDU (Bridge Protocol Data Unit) messages to each of the other switches in the network to let them know which path to use.
The STP protocol is a dynamic protocol, which means that it constantly monitors the network for changes, such as a link failure or the addition of new devices. If a change is detected, the STA will recalculate the spanning tree and determine if a new path needs to be enabled or if an existing path needs to be disabled. This helps to ensure that the network continues to function properly and that loops do not form, even in the event of a failure or other issue.
Once understood, you’ve got another tool in your box to make your network more redundant and reliable 🙂