What is a Root Port

Once the Root Bridge (Switch) is elected, every other Switch in the network must select a single port on it to reach the Root Bridge (Switch). The single selected port on a Switch with least Path Cost to the Root Bridge is called the Root Port. Root Bridge (Switch) will never have a Root Port. Root Bridge (Switch) is at the Root and therefore there is no need of a Root Port to reach the root.

The above layout of Switches shows that Switch 4 has two ports to reach the Root Bridge. If there are multiple ports present in a Switch to reach the Root Bridge (Switch). Spanning Tree Protocol Algorithm must select the best port from them to reach the Root Bridge. Here the port with least path cost (4+4=8) is marked as Root Port.