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device that received it. This prevents devices beyond the reach of the maximum hop from participate in
spanning tree calculation, so the size of the MST region is limited.
Make this configuration on the root bridge only. All other devices in the MST region use the maximum
hop value set for the root bridge.
To configure the maximum number of hops of an MST region:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the maximum hops
of the MST region.
stp max-hops
hops
20 by default.
Configuring the network diameter of a switched
network
Any two terminal devices in a switched network are connected through a specific path composed of a
series of devices. The network diameter is the number of devices on the path composed of the most
devices. The network diameter is a parameter that indicates the network size. A bigger network diameter
indicates a larger network size. Based on the network diameter you configured, the system automatically
sets an optimal hello time, forward delay, and max age for the device.
To configure the network diameter of a switched network:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the network
diameter of the switched
network.
•
In STP/RSTP/MSTP mode:
stp bridge-diameter
diameter
•
In PVST mode:
stp vlan
vlan-list
bridge-diameter
diameter
Use one of the
commands.
The default setting is 7.
NOTE:
•
In STP/RSTP/MSTP mode, each MST region is considered as a device and the configured network
diameter takes effect only on the CIST (or the common root bridge), but not on the MSTIs.
•
In PVST mode, the network diameter configuration takes effect on the root bridge only.
Configuring spanning tree timers
The following timers are used for spanning tree calculation:
•
Forward delay
It is the delay time for port state transition. To prevent temporary loops on a network, the spanning
tree sets an intermediate port state, the learning state, before it transits from the discarding state to
the forwarding state, and requires that the port transits its state after a forward delay timer to make
sure that the state transition of the local port keeps synchronized with the peer.
•
Hello time
