H3C Technologies H3C S5120 Series Switches - Manual (Page 184)

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To do... Use the command... Remarks
Enter system view system-view —
Configure the work mode of
MSTP
stp mode { stp | rstp | mstp }
Required
MSTP mode by default
Configuring the Priority of a Device
Device priorities participate in spanning tree calculation. The priority of a device determines whether it
can be elected as the root bridge of a spanning tree. A lower value indicates a higher priority. By setting
the priority of a device to a low value, you can specify the device as the root bridge of the spanning tree.
An MSTP-enabled device can have different priorities in different MSTIs.
Make this configuration on the root bridge only.
Follow these steps to configure the priority of a device in a specified MSTI:
To do... Use the command... Remarks
Enter system view system-view —
Configure the priority of the
current device in a specified
MSTI
stp [ instance instance-id ]
priority priority
Required
32768 by default
z
After configuring a device as the root bridge or a secondary root bridge, you cannot change the
priority of the device.
z
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 switch 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. Thus, devices beyond the reach of the maximum hop can no longer take part in
spanning tree calculation, and thereby the size of the MST region is confined.
Make this configuration on the root bridge only. All the devices other than the root bridge 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 —