R3721-F3210-F3171-HP High-End Firewalls Network Management Configuration Guide-6PW101

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Specifying a standard for the device to use when calculating the default path cost
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.
To specify a standard for the device to use when calculating the default path cost:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Specify a standard for the
device to use when
calculating the default path
costs of its ports.
stp pathcost-standard
{ dot1d-1998 | dot1t | legacy }
Optional.
legacy by default.
CAUTION:
If you change the standard that the device uses in calculating the default path costs, you restore the path
costs to the default.
NOTE:
W
hen calculatin
g
path cost for an a
gg
re
g
ate interface, IEEE 802.1t takes into account the number of
Selected ports in its aggregation group, but IEEE 802.1d-1998 does not. The calculation formula of IEEE
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 Selected ports in the aggregation group.
Table 21 shows the mappings between the link speed and the path cost.
Table 21 Mappings between the link speed and the path cost
Link speed Port type
Path cost
IEEE
802.1d-1998
IEEE 802.1t Private standard
0 N/A 65535 200,000,000 200,000
10 Mbps
Single Port
100
2,000,000 2,000
Aggregate interface
containing 2 Selected ports
1,000,000 1,800
Aggregate interface
containing 3 Selected ports
666,666 1,600
Aggregate interface
containing 4 Selected ports
500,000 1,400
100 Mbps
Single Port
19
200,000 200
Aggregate interface
containing 2 Selected ports
100,000 180
Aggregate interface
containing 3 Selected ports
66,666 160