B Spanning Tree
Discussion
This appendix briefly discusses the Spanning Tree Algorithm and Protocol (STAP) and how it is used with the Bridge Module. For greater detail about the internal workings of STAP, consult source books designed for this type of information, such as the IEEE Draft Standard 802.1(d).
Spanning Tree Terminology
The following terms are used in this appendix:
Root Bridge - The Root Bridge is at the top of the tree structure and is determined by having the lowest bridge priority/bridge address. Set the bridge priority through the management commands. Since this value is of higher precedence than the bridge address, it should be set carefully to make sure the correct bridge has assumed root status.
Designated Bridge - The bridge responsible for forwarding packets for that LAN. It is determined by having the lowest “root path cost” for that LAN.
Bridge Address - The Ethernet Address for that Bridge Module.
Root Path Cost - The distance between a bridge and the root bridge is called the root path cost. The summation of all the port costs of the root ports of the designated bridges between the bridge and root.
