Specifications

Functions
RS2-4R
Release 1.0 03/04
4.4 Spanning Tree Algorithm
105
Fig. 34: Flow chart for determining root path
Using the network diagram (see Fig. 35), it is possible to follow the logic in
the flow chart (see Fig. 34) for determining the root path. The bridge with the
numerically smallest bridge identification (in this case, bridge 1) is selected
as the root bridge. In this example the partial paths all have the same path
costs. The path between bridge 2 and bridge 3 is removed because a con
-
nection from bridge 3 to the root bridge via bridge 2 would result in twice the
path costs.
Equal
path costs?
Determine root path
no
yes
Equal
priority in
bridge identification?
Equal
port priority?
yes
yes
Path with lowest
path costs = root path
Path with highest
port priority
= root path
Path with highest
priority in bridge
identification = root path
no
no
Path with lowest
port number
= root path
Root path determined