R3303-HP 6600/HSR6600 Routers Layer 2 - LAN Switching Configuration Guide

65
Table 11 shows a comparison between link speeds and path costs for each of these standards.
Table 11 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
Configuration guidelines
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.
Configuration procedure
To specify a standard for the device to use when it calculates the default path cost: