3Com 8800 Configuration Manual page 560

3Com Switch 8800 Configuration Guide
The actual rate counts.
2) Calculating the path cost
Full-duplex and non-aggregation port at a rate less than 1 GE
Path cost = [200,000,000 / (rate × 10)] – 1
Other ports
Path cost = 200,000,000 / (rate × 10)
II. DOT1D-1998 calculation standard
1) Calculating the rate
Aggregation port
If the port is up, the actual rate counts. If the port is down, the rate is determined by that
of the port which goes up first in the aggregation group. If all the ports in the
aggregation group are down, the rate of the aggregation port is 0.
Non-aggregation port
The actual rate counts.
2) Calculating the path cost
Table 38-17 details the correspondence between the rate range and the path cost
values of the ports.
Table 38-17 Correspondence between the rate range and the path cost values
[0, 10]
(10, 100]
(100,1000]
(1000,10000]
> 10000
III. The Switch 8800 legacy calculation standard
1) Calculating the rate
Aggregation port
Rate range
Chapter 38 MSTP Region-configuration
Path cost value
99 (for full-duplex port)
95 (for aggregation port)
100 (default)
18 (for full-duplex port)
15 (for aggregation port)
19 (default)
3 (for aggregation port)
4 (default)
2 (for aggregation port)
1 (default)
1
38-25