User's Manual

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configure the Max Age to a relatively small value, then the calculation of the spanning tree will be relatively
frequent, and the system may regard the network block as link failure. If you configurethe Max Age to a
relatively big value, then the link status will go unnoticed in time.
The Max Age of bridge is 20 seconds by default.
35.2.6 Value of the path cost of a port
The path cost is related with the link rate of the port. If the link rate is required to be high, the path cost should
be set to a small value; when the path cost is set to its default value, RSTP can automatically check the link
rate of the current Ethernet port and calculate the corresponding path cost.
Run the following commands in interface configuration mode.
Command Purpose
spanning-tree rstp cost
value Sets the path cost of a port.
no spanning-tree rstp cost
Resumes the path cost of a port to the default
value.
It is especially noted that the settings of the path cost will lead to the recalculation of the spanning tree, so
users are recommended to take the default value and wait RSTP to calculate the path cost of the current
Ethernet port automatically.
By default, the path costs of all Ethernet ports of a bridge are all set to 2000,000 at the 10Mbps port rate, or
set to 200,000 at the 100Mbps port rate.
35.2.7 Setting the Port Priority
Port priority settings can be used to designate a specific Ethernet port to be contained in the spanning tree. In
general, the smaller the value is, the higher the port priority is, and the Ethernet port has more possibility to be
contained in the spanning tree. If all Ethernet ports of a bridge adopt the same priority value, the index number
of an Ethernet port decides whether the Ethernet port has a high priority or not.
Run the following commands in interface configuration mode.
Command Purpose
spanning-tree rstp port-priority
value Sets the port priority.
no spanning-tree rstp port-priority
Resumes the port priority to the default value.
It should be noted that the change of the priority of an Ethernet port can lead to the recalculation of the spanning
tree.
The priority of all Ethernet ports of a bridge is 128 by default.
35.2.8 Setting the Edge Port
The edge port means this port connects terminal devices of a network. A mandatory edge port will enter the
forwarding state after link-up. In port configuration mode, run the following command to set the edge port of
RSTP:
Command Purpose
spanning-tree rstp edge
Sets the edge port.