H3C S7500E-X Configuration Manual page 95

You can specify a standard for the device to use in automatic calculation for the default path cost.
The device supports the following standards:
•
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.
When you specify a standard for the device to use when it calculates the default path cost, follow
these guidelines:
•
When it calculates the path cost for an aggregate interface, IEEE 802.1t takes into account the
number of Selected ports in its aggregation group. However, IEEE 802.1d-1998 does not take
into account the number of Selected ports. The calculation formula of IEEE 802.1t is: Path cost
= 200,000,000/link speed (in 100 kbps). The link speed is the sum of the link speed values of
the Selected ports in the aggregation group.
•
IEEE 802.1d-1998 or the private standard always assigns the smallest possible value to a
single port or aggregate interface with a speed exceeding 10 Gbps. The forwarding path
selected based on this criterion might not be the best one. To solve this problem, perform one of
the following tasks:
Use dot1t as the standard for default path cost calculation.
Manually set the path cost for the port (see
To specify a standard for the device to use when it calculates the default path cost:
Step
Enter system view.
1.
Specify a standard for the
2.
device to use when it
calculates the default path
costs of its ports.
Table 8 Mappings between the link speed and the path cost
Link speed Port type
0 N/A
Single port
Aggregate interface
containing two Selected
ports
Aggregate interface
10 Mbps
containing three Selected
ports
Aggregate interface
containing four Selected
ports
Single port
Aggregate interface
containing two Selected
100 Mbps
ports
Aggregate interface
containing three Selected
"Configuring path costs of
Command
system-view
stp pathcost-standard
{ dot1d-1998 | dot1t | legacy }
Path cost
IEEE
802.1d-1998
65535
100
19
82
ports").
Remarks
N/A
By default, the calculation
standard is legacy.
Private
IEEE 802.1t
standard
200000000 200000
2000000 2000
1000000 1800
666666 1600
500000 1400
200000 200
100000 180
66666 160