3Com Switch 7750 Configuration Guide Guide

Leaf Node Configuration 243
Normally, the path cost of a port operating in full-duplex mode is slightly less than
that of the port operating in half-duplex mode.
When calculating the path cost of an aggregated link, the 802.1D-1998 standard
does not take the number of the ports on the aggregated link into account,
whereas the 802.1T standard does. The following formula is used to calculate the
path cost of an aggregated link:
Table 173 Specify the standard for calculating path costs
Operation Command Description
Enter system view system-view -
Specify the standard to be
used to calculate the default
path costs of the links
connected to the ports of the
switch
stp pathcost-standard {
dot1d-1998 | dot1t | legacy }
Optional
By default, the legacy
standard is used to calculate
the default path costs.
Table 174 Transmission speeds and the corresponding path costs
Transmission
speed
Operation mode
(half-/full-duplex)
802.1D-1998 IEEE 802.1t
Proprietary
standard
0 - 65,535 200,000,000 200,000
10 Mbps
Half-duplex/Full-du
plex
Aggregated link 2
ports
Aggregated link 3
ports
Aggregated link 4
ports
100
95
95
95
200,000
1,000,000
666,666
500,000
2,000
1,800
1,600
1,400
100 Mbps
Half-duplex/Full-du
plex
Aggregated link 2
ports
Aggregated link 3
ports
Aggregated link 4
ports
19
15
15
15
200,000
100,000
66,666
50,000
200
180
160
140
1,000 Mbps
Full-duplex
Aggregated link 2
ports
Aggregated link 3
ports
Aggregated link 4
ports
4
3
3
3
200,000
10,000
6,666
5,000
20
18
16
14
10 Gbps
Full-duplex
Aggregated link 2
ports
Aggregated link 3
ports
Aggregated link 4
ports
2
1
1
1
200,000
1,000
666
500
2
1
1
1