The Spanning-Tree Protocol constructs a topology that has one path for every node on the network.
This "tree" originates from the root bridge.
A "root bridge" exchanges topology information with designated bridges in a spanning-tree implementation in order
to notify all other bridges in the network when topology changes are required.
This prevents loops and provides a measure of defense against link failure.
Designated switches are the closest one to the root, for each LAN segment.
The designated switch handles all communication from that LAN segment towards the root bridge.
One of its ports is its root port, each non-root switch has one. The root port is the interface that gives the best path to the root switch.
I hope this answers your questions, if you want more information about this subject, search on cisco.com with the keywords "Spanning Tree Protocol" or ask it here :)
Regards,
M Freijser
