Siemens SCALANCE X-300 Configuration Manual page 198

Configuration using Web Based Management and Command Line Interface
4.5 The Switch menu
Spanning tree configuration with an IE switch
The parameters for the spanning tree protocol are displayed and set in the "Spanning Tree
Configuration" dialog:
Figure 4-84
The left-hand side of the page shows the configuration of the IE switch. The right-hand side
shows the configuration of the root bridge that can be derived from the spanning tree frames
received by an IE switch. The data shown here is therefore read-only. If an IE switch is the
root bridge, the information on the left and right matches. The meaning of the parameters is
as follows:
Bridge Priority / Root Priority
Which switch becomes the root bridge is decided by the bridge priority. The bridge with the
highest priority (in other words, with the lowest value for this parameter) becomes the root
bridge. If several switches in a network have the same priority, the switch whose MAC
address has the lowest numeric value will become the root bridge. Both parameters, bridge
priority and MAC address together form the Bridge Identifier. Since the root bridge manages
all path changes, it should be located as centrally as possible due to the delay of the frames.
The value for the bridge priority is a whole multiple of 4096 with a range of values from 0
through 65,535.
Bridge Address / Root Address
The MAC address of the IE switch or root bridge.
Root Port
The port over which the device communicates with the root bridge.
Topology Changes / Last Topology Change
The entry for the IE switch shows the number of reconfiguration actions due to the spanning
tree mechanism since the last startup. For the root bridge, the duration is displayed in
minutes (m appended after the number) since the last reconfiguration.
Bridge Hello Time / Root Hello Time
Each bridge sends configuration frames (BPDUs) regularly. The interval between two such
frames is the Hello time.
198
Spanning Tree Configuration
Configuration Manual, 10/2014, C79000-G8976-C187-22
SCALANCE X-300 / X-400