What Does The Root Port Mean?

What Does the Root Port Mean?

The root port is the single selected port that has the lowest path cost to the root bridge. On the bridge switch, the root port is the lowest spanning-tree path cost from the switch to the root bridge.

• The root port has the shortest path to the root bridge or is the direct connection to the single root bridge.
• On the root bridge, if there is more than one connection connecting to the root bridge, the cost of the port is calculated by estimating the bandwidth of each link.
• Once the root switch is selected, in the network every other switch must select a single port on it to reach the root bridge. A root port is defined as a single selected less path cost to the root switch or bridge is called as the root port. The root switch never has a root port. If the root bridge is at the root so there is no need for the root port to extend the root.
• The root port is the only selected port other than the root bridge.
• The root port has the least path cost from the non-bridge port to the bridged port.
• On the non-root switch, only one root port is present.
• If the switch has more than one port to extend to the root switch, it is needed to select a single specific port for the transmission. With the help of spanning tree protocol algorithms, this selection of port is done. The selection is based on the path from the switch to the root switch having the least path cost.
• Suppose that the 4th switch wants to transfer the packets to the root switch which is switch 1. If there is more than one path to reach the destination choose one with the least path cost. In this case, witch 4 has two paths to switch 1 either from switch 2 or through switch 3.
• It contains two ports one start from switch 4 to switch 3 and the other start from switch 4 to switch 2. Switch 4 needs to select the optimal path that has a minimum-cost path to the destination. The port where this path is connected is the root port of that switch 4.