The Root Port is the port on the Bridge (Switch) with the least Path Cost from the switch to the Root Bridge. A Designated Port is the port on a Local Area Network (LAN) segment with the least cost to the root bridge.
• There can be ONLY one Root Port on a Bridge (Switch). There may be multiple Designated Ports on a Bridge (Switch).
All the ports on a Root Bridge (Switch) are Designated Ports and there is no Root Port on a Root Bridge (Switch).
• A Root Port can NEVER be a Designated Port.
• If one end of a Local Area Network (LAN) segment is a Dedicated Port, other end is called as Non Designated Port (marked as NDP), if it is NOT a Root Port. Non Designated Port will be always in Blocking State, to avoid Layer 2 Switching loops.