What is the lowest path cost for an STP root port?

The lowest path cost for an STP (Spanning Tree Protocol) root port is the root cost, which reflects the total cost of the path from the switch to the root bridge within the network. In STP, the root port is the port on a switch that has the lowest path cost to the root bridge, meaning it is the most efficient route for data to travel to reach the root bridge.

Path costs in STP are determined primarily by the speed of the links in the network; faster links have lower costs. The root cost is calculated based on the cumulative costs of each segment of the network from the switch in question to the root bridge. Therefore, when determining the root port, switches consider the path cost, and this ensures that data takes the most efficient route through the network.

Other elements, such as neighbor port ID, bridge ID, and port speed, play roles in the STP process but do not directly represent the lowest path cost to the root bridge. The neighbor port ID may reference specific ports on adjacent switches, the bridge ID identifies the switches in the network hierarchy, and port speed contributes to the calculation of individual interface costs. However, none of these are used to define or determine the lowest path cost directly, which is