Stp Pathcost-Standard - H3C S5120-SI Series Command Reference Manual

stp pathcost-standard

Syntax
stp pathcost-standard { dot1d-1998 | dot1t | legacy }
undo stp pathcost-standard
View
System view
Default Level
2: System level
Parameters
dot1d-1998: The device calculates the default path cost for ports based on IEEE 802.1d-1998.
dot1t: The device calculates the default path cost for ports based on IEEE 802.1t.
legacy: The device calculates the default path cost for ports based on a private standard.
Description
Use the stp pathcost-standard command to specify a standard for the device to use when calculating
the default path costs for ports of the device.
Use the undo stp pathcost-standard command to restore the system default.
By default, the device calculates the default path cost for ports based on a private standard.
Note that:
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.
Table 1-11 shows the path costs calculated using different standards at different link speed. When
calculating path cost for an aggregate port, 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.
Table 1-11 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
Path cost in
802.1d-1998
Duplex state
65535
100
100
100
100
19
19
19
19
Path cost in
IEEE 802.1t
standard standard
200,000,000
2,000,000
1,000,000
666,666
500,000
200,000
100,000
66,666
50,000
1-28
Path cost in
private standard
200,000
2,000
1,800
1,600
1,400
200
180
160
140