Operation Manual – MSTP
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 MSTP Configuration
1-24
1.3.4 Configuring the Priority of the Current Device
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-compliant device can have different priorities in different MST instances.
I. Configuration procedure
Follow these steps to configure the priority of the current device:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Configure the priority of
the current device
stp
[
instance
instance-id
]
priority priority
Optional
32768 by default
Caution:
z
Upon specifying the current 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.
II. Configuration example
# Set the device priority in MST instance 1 to 4096.
<Sysname> system-view
[Sysname] stp instance 1 priority 4096
1.3.5 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 setting configured on the regional root bridge will be used as the
maximum number of 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 as the remaining 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 are unable to take
part in spanning tree calculation, and thereby the size of the MST region is confined.
