H3C S5120-EI Series Operation Manual page 130

Table 1-7 Link speed vs. path cost
Link speed
0 —
Single Port
Aggregate Link 2 Ports
10 Mbps
Aggregate Link 3 Ports
Aggregate Link 4 Ports
Single Port
Aggregate Link 2 Ports
100 Mbps
Aggregate Link 3 Ports
Aggregate Link 4 Ports
Single Port
Aggregate Link 2 Ports
1000 Mbps
Aggregate Link 3 Ports
Aggregate Link 4 Ports
Single Port
Aggregate Link 2 Ports
10 Gbps
Aggregate Link 3 Ports
Aggregate Link 4 Ports
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...
Enter system view
Enter Ethernet
interface view
Enter
or Layer-2
interface view
aggregate
or port group
interface view
view
Enter port
group view
Configure the path cost of the
port(s)
Duplex state
65535
100
100
100
100
19
19
19
19
4
4
4
4
2
2
2
2
Use the command...
system-view
interface interface-type
interface-number
port-group manual
port-group-name
stp [ instance
instance-id ] cost cost
1-29
802.1d-1998 802.1t
200,000,000
2,000,000
1,000,000
666,666
500,000
200,000
100,000
66,666
50,000
20,000
10,000
6,666
5,000
2,000
1,000
666
500
—
Required
Use either command.
Configurations made in interface
view will take effect on the current
port only; configurations made in
port group view will take effect on all
ports in the port group.
Required
By default, MSTP automatically
calculates the path cost of each port.
Private standard
200,000
2,000
1,800
1,600
1,400
200
180
160
140
20
18
16
14
2
1
1
1
Remarks