HP VPN Firewall Appliances Network Management Configuration Guide

93
Table 15 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 200000000 200000
10 Mbps
Single port
100
2000000 2000
Aggregate interface
containing 2 Selected ports
1000000 1800
Aggregate interface
containing 3 Selected ports
666666 1600
Aggregate interface
containing 4 Selected ports
500000 1400
100 Mbps
Single port
19
200000 200
Aggregate interface
containing 2 Selected ports
100000 180
Aggregate interface
containing 3 Selected ports
66666 160
Aggregate interface
containing 4 Selected ports
50000 140
1000 Mbps
Single port
4
20000 20
Aggregate interface
containing 2 Selected ports
10000 18
Aggregate interface
containing 3 Selected ports
6666 16
Aggregate interface
containing 4 Selected ports
5000 14
10 Gbps
Single port
2
2000 2
Aggregate interface
containing 2 Selected ports
1000 1
Aggregate interface
containing 3 Selected ports
666 1
Aggregate interface
containing 4 Selected ports
500 1
When it calculates path cost for an aggregate 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.
When the link speed of a single port exceeds 10 Gbps and the standard for default path cost calculation
is dot1d-1998 or legacy, the path cost of a single port or an aggregate interface takes the smallest value.
This affects the reasonableness of forwarding path selection. To solve this problem, use dot1t as the
standard for default path cost calculation, or manually set the path cost for a port (see "Configuring path
co
sts of ports
").