H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 69)

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CAUTION:
•
After configuring a device as the root bridge or a secondary root bridge, you cannot change the priority
of the device.
• During root bridge selection, if all devices in a spanning tree have the same priority, the one with the
lowest MAC address will be selected as the root bridge of the spanning tree.
Configuring the maximum hops of an MST region
By setting the maximum hops of an MST region, you can restrict the region size. The maximum hops
configured on the regional root bridge will be used as the maximum hops of the MST region.
The regional root bridge always sends a configuration BPDU with a hop count set to the maximum value.
When a device receives this configuration BPDU, it decrements the hop count by 1 and uses the new hop
count in the BPDUs it propagates. When the hop count of a BPDU reaches 0, it is discarded by the device
that received it. This prevents devices beyond the reach of the maximum hop from taking part in spanning
tree calculation, which limits the size of the MST region.
Make this configuration on the root bridge only. All other devices in the MST region use the maximum
hop value set for the root bridge.
Follow these steps to configure the maximum number of hops of an MST region:
To do... Use the command... Remarks
Enter system view system-view —
Configure the maximum hops of
the MST region
stp max-hops hops
Required
20 by default.
Configuring the network diameter of a switched network
Any two terminal devices in a switched network are interconnected 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
devices. The network diameter is a parameter that indicates the network size. A bigger network diameter
indicates a larger network size.
Follow these steps to configure the network diameter of a switched network:
To do... Use the command... Remarks
Enter system view system-view —
Configure the network diameter of the
switched network
stp bridge-diameter diameter
Required
7 by default.
NOTE:
•
Based on the network diameter you configured, the system automatically sets an optimal hello time,
forward delay, and max age for the device.
• In MSTP mode, each MST region is considered as a device and the configured network diameter is
effective only for the CIST (or the common root bridge), but not for MSTIs.