Configuring The Priority Of The Current Device; Configuring The Maximum Hops Of An Mst Region - H3C S5120-EI Series Operation Manual

[Sysname] stp mode stp

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-enabled device can have different priorities
in different MSTIs.
Configuration procedure
Follow these steps to configure the priority of the current device in a specified MSTI:
To do...
Enter system view
Configure the priority of the current
device in a specified MSTI
After specifying the current 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.
Configuration example
# Set the device priority in MSTI 1 to 4096.
<Sysname> system-view
[Sysname] stp instance 1 priority 4096

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.
All the devices other than the root bridge in the MST region use the maximum hop value set for the root
bridge.
Configuration procedure
Follow these steps to configure the maximum number of hops of the MST region:
Use the command...
system-view
stp [ instance instance-id ] priority
priority
1-19
Remarks
—
Optional
32768 by default