H3C Technologies H3C S7500E Series Switches - Manual (Page 180)

13-28
Link speed Duplex state 802.1d-1998 802.1t Private standard
10 Gbps
Single Port
Aggregate Link 2 Ports
Aggregate Link 3 Ports
Aggregate Link 4 Ports
2
2
2
2
2,000
1,000
666
500
2
1
1
1
When calculating path cost for an aggregate interface, 802.1d-1998 does not take into account the
number of member ports in its aggregation group as 802.1t does. The calculation formula of 802.1t is:
Path Cost = 200,000,000/link speed (in 100 kbps), where link speed is the sum of the link speed values
of the non-blocked ports in the aggregation group.
Configuring path costs of ports
Follow these steps to configure the path cost of ports:
To do... Use the command... Remarks
Enter system view system-view —
Enter 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
stp [ instance instance-id ]
cost cost
Required
By default, MSTP
automatically calculates the
path cost of each port.
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.
Configuration example
# Specify that the device use 802.1d-1998 when calculating the default path costs of its ports.