H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – MSTP
H3C S7500E Series Ethernet Switches Chapter 1 MSTP Configuration
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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 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.
When a device becomes the root bridge of the CIST or MSTI of an MST region , the
maximum hop in the configuration BPDUs generated by this device defines the network
diameter of the spanning tree to define how far the spanning tree can reach in this MST
region. All the devices other than the root bridge in the MST region use the maximum
hop value set for the root bridge.
I. Configuration procedure
Follow these steps to configure the maximum hops of the MST region: