Example Of Manipulating The Root Path - Hirschmann RS20 User Manual

Spanning Tree
5.4 Example of manipulating the
root path
You can use the network plan
fig. 31) for determining the root path. The Administrator has performed the
following:
– Left the default value of 32,768 (8000H) for every bridge apart from bridge
1, and
– assigned to bridge 1 the value 16,384 (4000H), thus making it the root
bridge.
In the example, all the sub-paths have the same path costs. The protocol
blocks the path between bridge 2 and bridge 3 as a connection from bridge 3
via bridge 2 to the root bridge would mean higher path costs.
The path from bridge 6 to the root bridge is interesting:
 The path via bridge 5 and bridge 3 creates the same root path costs as
the path via bridge 4 and bridge 2.

STP selects the path using the bridge that has the lowest MAC address
in the bridge identification (bridge 4 in the illustration).
 There are also 2 paths between bridge 6 and bridge 4. The port identifier
is decisive here.
Note: Because the Administrator does not change the default values for the
priorities of the bridges in the bridge identifier, apart from the value for the
root bridge, the MAC address in the bridge identifier alone determines which
bridge becomes the new root bridge if the current root bridge goes down.
UM Redundancy Configuration L2E
Release 7.1 12/2011
5.4 Example of manipulating the root
(see fig. 32) to follow the flow chart
path
(see
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