Root Port - The port on the bridge with the lowest “root path cost”; the port closest to the root bridge.
Bridge Operating States:
Forwarding - Active state where the bridge is forwarding packets and an active member of the network as a designated bridge.
Learning - Intermediate state before “forwarding” where the bridge is learning the Address Filtering information.
Listening - Intermediate state between “blocking” and “learning” where the bridge is just monitoring the network.
Blocking - Inactive state where the bridge is only participating in STAP enough to know when it should move into the “forwarding” state.
Disabled - Inactive state where the bridge is not participating in the network.
Spanning Tree Overview
The Spanning Tree Algorithm Protocol (STAP) is a method by which bridges in a connected network configure themselves so as to prevent loops in the network. The ports on the bridges that are determined to be redundant are placed into Blocking state, only to be used in case the primary bridge fails. Consequently, this protocol provides a way of automatically backing up network connections.
By controlling which ports on which bridgesare active or inactive, the STAP transforms the network into a tree architecture, eliminating logical loops in the network. The dotted lines in Figure
B - 2 ONline Ethernet Bridge Module Installation and Operation Guide
