H3C Technologies H3C S3100 Series Switches - Manual (Page 251)

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Follow these steps to configure the path cost for a port in Ethernet port view:
To do... Use the command... Remarks
Enter system view system-view —
Enter Ethernet port view
interface interface-type
interface-number
—
Configure the path cost for the
port stp [ instance instance-id ]
cost cost
Required
An MSTP-enabled switch can
calculate path costs for all its
ports automatically.
Changing the path cost of a port may change the role of the port and put it in state transition. Executing
the stp cost command with the instance-id argument being 0 sets the path cost on the CIST for the port.
Configuration example (A)
# Configure the path cost of Ethernet 1/0/1 in MSTI 1 to be 2,000.
1) Perform this configuration in system view
<Sysname> system-view
[Sysname] stp interface Ethernet 1/0/1 instance 1 cost 2000
2) Perform this configuration in Ethernet port view
<Sysname> system-view
[Sysname] interface Ethernet 1/0/1
[Sysname-Ethernet1/0/1] stp instance 1 cost 2000
Configuration example (B)
# Configure the path cost of Ethernet 1/0/1 in MSTI 1 to be calculated by the MSTP-enabled switch
according to the IEEE 802.1D-1998 standard.
1) Perform this configuration in system view
<Sysname> system-view
[Sysname] undo stp interface Ethernet 1/0/1 instance 1 cost
[Sysname] stp pathcost-standard dot1d-1998
2) Perform this configuration in Ethernet port view
<Sysname> system-view
[Sysname] interface Ethernet 1/0/1
[Sysname-Ethernet1/0/1] undo stp instance 1 cost
[Sysname-Ethernet1/0/1] quit
[Sysname] stp pathcost-standard dot1d-1998
Configuring Port Priority
Port priority is an important criterion on determining the root port. In the same condition, the port with the
smallest port priority value becomes the root port.
A port on an MSTP-enabled switch can have different port priorities and play different roles in different
MSTIs. This enables packets of different VLANs to be forwarded along different physical paths, so that
VLAN-based load balancing can be implemented.
You can configure port priority in one of the following two ways.