Configuring The Maximum Hops Of An Mst Region - 3Com MSR 50 Series Configuration Manual

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Configuring the
Maximum Hops of an
MST Region
n
To do...
Configure the priority of the
current device
CAUTION:
Upon 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 MST instance 1 to 4096.
<Sysname> system-view
[Sysname] stp instance 1 priority 4096
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.
After a configuration BPDU leaves the root bridge of the spanning tree in the MST
region, its hop count is decremented by 1 whenever it passes a device. When its
hop count reaches 0, it will be discarded by the device that has received it. As a
result, devices beyond the maximum hops are unable to take part in spanning tree
computing, and thereby the size of the MST region is restricted.
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.
Configuration procedure
Follow these steps to configure the maximum hops of the MST region
To do...
Enter system view
Configure the maximum hops
of the MST region
A larger maximum hops setting means a larger size of the MST region. Only the
maximum hops configured on the regional root bridge can restrict the size of the
MST region.
Configuration example
# Set the maximum hops of the MST region to 30.
<Sysname> system-view
[Sysname] stp max-hops 30
Configuring the Root Bridge
Use the command...
stp [ instance instance-id ]
priority priority
Use the command...
system-view
stp max-hops hops
463
Remarks
Optional
32768 by default
Remarks
-
Optional
20 by default