H3C Technologies H3C S12500-X Series Switches - Manual (Page 90)

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Configuring the device priority
Device priority is a factor in calculating the spanning tree. The priority of a device determines whether the
device can be elected as the root bridge of a spanning tree. A lower value indicates a higher priority.
You can set the priority of a device to a low value to specify the device as the root bridge of the spanning
tree. A spanning tree device can have different priorities in different MSTIs.
During root bridge selection, if all devices in a spanning tree have the same priority, the one with the
lowest MAC address is selected as the root bridge of the spanning tree. You cannot change the priority
of a device after it is configured as the root bridge or as a secondary root bridge.
To configure the priority of a device in a specified MSTI:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the priority of
the current device.
• In STP/RSTP mode:
stp priority priority
• In MSTP mode:
stp [ instance instance-list ] priority
priority
The default setting is 32768.
Configuring the maximum hops of an MST region
Restrict the region size by setting the maximum hops of an MST region. The hop limit configured on the
regional root bridge is used as the hop limit for the MST region.
Configuration BPDUs sent by the regional root bridge always have a hop count set to the maximum value.
When a device receives this configuration BPDU, it decrements the hop count by one, and uses the new
hop count in the BPDUs that it propagates. When the hop count of a BPDU reaches zero, it is discarded
by the device that received it. Devices beyond the reach of the maximum hop can no longer participate
in spanning tree calculations, so the size of the MST region is limited.
Make this configuration only on the root bridge. All other devices in the MST region use the maximum
hop value set for the root bridge.
To configure the maximum number of hops of an MST region:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the maximum hops
of the MST region.
stp max-hops hops The default setting is 20.
Configuring the network diameter of a switched
network
Any two terminal devices in a switched network are connected through a specific path composed of a
series of devices. The network diameter is the number of devices on the path composed of the most