CCNA Data Center DCICT 640-916 Official Cert Guide

Spanning Tree Protocol

To support high availability within a Layer 2 domain, switches are normally interconnected using redundant links. STP is a Layer 2 control plane protocol that runs on switches to ensure that you do not create topology loops when you have these redundant paths in the network. To create loop-free topology, STP builds a treelike structure by blocking certain ports in the network. A root bridge is elected, and STP ensures that only one network path to the root bridge exists. All network ports connecting to the root bridge via an alternative network path are blocked. Switches exchange information using bridge protocol data units (BPDU), and this information is used to elect a root bridge and perform subsequent network configuration ...