H3C Technologies H3C S10500 Series Switches - Manual (Page 97)

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To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface
view
interface interface-type
interface-number
Enter
interface
view or port
group view
Enter port group view
port-group manual
port-group-name
Required
Use either command.
Configure the path cost of the ports (in
STP/RSTP mode)
stp cost cost
Configure the path cost of the ports (in
PVST mode)
stp vlan vlan-list cost cost
Configure the path cost of the ports (in
MSTP mode)
stp [ instance instance-id ] cost cost
Required
Use any command.
By default, the system
automatically calculates the
path cost of each port.
NOTE:
When the path cost of a port changes, the system re-calculates the role of the port and initiates a state
transition.
Configuration example
# In MSTP mode, specify the device to calculate the default path costs of its ports by using IEEE
802.1d-1998, and set the path cost of GigabitEthernet 1/0/3 to 200 on MSTI 2.
<Sysname> system-view
[Sysname] stp pathcost-standard dot1d-1998
[Sysname] interface gigabitethernet 1/0/3
[Sysname-GigabitEthernet1/0/3] stp instance 2 cost 200
# In PVST mode, specify the device to calculate the default path costs of its ports by using IEEE
802.1d-1998, and set the path cost of GigabitEthernet 1/0/3 to 2000 on VLANs 20 through 30.
<Sysname> system-view
[Sysname] stp mode pvst
[Sysname] stp pathcost-standard dot1d-1998
[Sysname] interface gigabitethernet 1/0/3
[Sysname-GigabitEthernet1/0/3] stp vlan 20 to 30 cost 2000
Configuring the port priority
The priority of a port is an important factor in determining whether the port can be elected as the root
port of a device. If all other conditions are the same, the port with the highest priority will be elected as
the root port.
On a spanning tree device, a port can have different priorities and play different roles in different
spanning trees, so that data of different VLANs can be propagated along different physical paths,
implementing per-VLAN load balancing. You can set port priority values based on the actual networking
requirements.
Follow these steps to configure the priority of a port or a group of ports: