If you change the standard that the device uses in calculating the default path cost, the port path
cost value set through the stp cost command will be invalid.
When the path cost of a port is changed, MSTP will re-calculate the role of the port and initiate a
state transition. If you use 0 as instance-id, you are setting the path cost of the CIST.
# Specify that the device use 802.1d-1998 when calculating the default path costs of its ports.
[Sysname] stp pathcost-standard dot1d-1998
# Set the path cost of GigabitEthernet 1/0/3 on MSTI 2 to 200.
[Sysname] interface gigabitethernet 1/0/3
[Sysname-GigabitEthernet1/0/3] stp instance 2 cost 200
Configuring 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 an MSTP-enabled device, a port can have different priorities in different MSTIs, and the same port
can play different roles in different MSTIs, so that data of different VLANs can be propagated along
different physical paths, thus implementing per-VLAN load balancing. You can set port priority values
based on the actual networking requirements.
Make this configuration on the leaf nodes only.
Follow these steps to configure the priority of a port or a group of ports:
Enter system view
or port group
Configure the port priority
Enter Ethernet interface
view, or Layer 2
Enter port group view
Use the command...
stp [ instance
instance-id ] port priority
Use either command.
128 for all ports by default.