3com 5500-SI Manual Do Utilizador

Leaf Node Configuration 181

Refer to “Configuring MSTP Operation Mode”.

Refer to “Configuring the Timeout Time Factor”.

Refer to “Configuring the Maximum Transmission Speed of a Port”.

Refer to “Setting a Port as an Edge Port”.

The path cost of a port is related with the speed of the connected link. A port of an 
MSTP-enabled switch can have different path costs for different spanning tree 
instances. By configuring proper path costs, you can enable flows of different VLANs 
to travel along different physical links to implement VLAN-based load balancing.

Path cost can be configured manually or be determined by the switch.

Currently, the following standards are available for calculating path costs of ports on a 
switch:

■

dot1d-1998: Adopts the IEEE 802.1D-1998 standard to calculate the default path 
costs of ports.

■

dot1t: Adopts the IEEE 802.1t standard to calculate the default path costs of 
ports.

■

legacy: Adopts the standard defined by 3Com-3Com Technology Co., Ltd to 
calculate the default path costs of ports.

Table 160   Specify the standard for calculating path costs

Enter system view

system-view

-

Specify the standard for 
calculating the default path 
costs of links connecting to 
the switch

stp pathcost-standard { 
dot1d-1998 | dot1t | legacy 
}

Optional
By default, the IEEE 802.1t 
standard is used to calculate the 
default path costs of ports.

Table 161   Transmission speeds and the corresponding path costs

0

—

65,535

200,000,000

200,000

10 Mbps

Half-Duplex

Full-Duplex

Aggregated Link 2 Ports

Aggregated Link 3 Ports

Aggregated Link 4 Ports

100

99

95

95

95

2,000,000

1,999,999

1,000,000

666,666

500,000

2,000

2,000

1,800

1,600

1,400