3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring Leaf Nodes 121
instances. Setting an appropriate path cost allows VLAN traffic flows to be
forwarded along different physical links, thus to enable per-VLAN load balancing.
The device can automatically calculate the path cost; alternatively, you can also
configure the path cost for ports.
Specifying a standard that the device uses when calculating the path cost
You can specify a standard for the device to use in automatic calculation for the
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.
Follow these steps to specify a standard for the device to use when calculating the
default path cost:
To do... Use the command... Remarks
Enter system view system-view -
Specify a standard for the
device to use when
calculating the default path
cost of the link connected
with the device
stp pathcost-standard {
dot1d-1998 | dot1t | legacy }
Optional
The device uses the private
standard by default.
Tab le 14 Link speed vs. path cost
Link speed Duplex state 802.1D-1998 802.1t
Private
standard
0 - 65535 200,000,000 200,000
10 Mbps Single Port
Aggregated Link
2 Ports
Aggregated Link
3 Ports
Aggregated Link
4 Ports
100
100
100
100
2,000,000
1,000,000
666,666
500,000
2,000
1,800
1,600
1,400
100 Mbps Single Port
Aggregated Link
2 Ports
Aggregated Link
3 Ports
Aggregated Link
4 Ports
19
19
19
19
200,000
100,000
66,666
50,000
200
180
160
140